Science topic

Lactic Acid Bacteria - Science topic

The lactic acid bacteria (LAB) comprise a clade of Gram-positive, low-GC, acid-tolerant, generally non-sporulating, non-respiring rod or cocci that are associated by their common metabolic and physiological characteristics
Questions related to Lactic Acid Bacteria
  • asked a question related to Lactic Acid Bacteria
Question
2 answers
is it correct to use PNP instead of ONP in drawing the standard curve to estimate the activity of B-galactosidase isolated from lactic acid bacteria
Relevant answer
Answer
10/2/22
Dear Marym,
What substrate are you using to measure B-Gal activity? Is it pNP-Beta-D-Galactoside (pNP-Gal) or oNP-Gal? Beta-Gal releases hydroxylated-nitrophenol from both of these substrates. You then measure the absorbance of the OH-nitrophenol to calculate the # moles of the beta-galactoside hydrolyzed by the enzyme to determine its activity. If you are using pNP-Gal as your substrate, you should use p-nitrophenol to prepare your calibration curve instead of o-nitrophenol. The reverse is true if you use oNP-Gal as the substrate. This is because oNP and pNP have different extinction coefficients, i.e., different absorbances for solutions of the same concentration of these substances. You can check this out for yourself by making solutions of oNP and pNP at the same concentration and reading their Abs (e.g., 405 nm) on a spectrophotometer. If you use oNP to prepare the calibration curve but used pNP-Gal as the substrate, this will give you erroneous results.
I hope this information helps you.
Bill Colonna, Iowa State University, Ames, Iowa, USA, wcolonna@iastate.edu
  • asked a question related to Lactic Acid Bacteria
Question
4 answers
I want to save money and time by testing my cultures directly from MRS broth, without inoculating an agar medium to pick up a colony.
Will I have the same result by adding hydrogen peroxide directly to my broth culture or trying the slide method inoculating the loop with broth culture instead of picking up a colony from agar medium?
Relevant answer
Answer
Hello, use the pure MRS broth and add hydrogen peroxide and see the reaction. If your culture in broth reaction more intensive it mens catalase activity. The iron ions in media also can react with hydrogen peroxide.
  • asked a question related to Lactic Acid Bacteria
Question
1 answer
Hey, i'm working on LAB to make it in capsules.. how can i encapsulate the bacteria ? what are the protocols ?
Relevant answer
  • asked a question related to Lactic Acid Bacteria
Question
8 answers
Hello, researchers
I used sodium benzoate as a preservative while working on improving the shelf life of beverages. It inhibited yeast from growing while promoting the growth of lactic acid bacteria. What could be the reasons?
Relevant answer
Answer
Actually, as the salt of any other acids, sodium benzoate may inhibit the growth of lactic acid bacteria depending on its concentration. Here, it just eliminates yeasts regarded as their competitors, it can achieve more nutrients to be grown.
  • asked a question related to Lactic Acid Bacteria
Question
3 answers
i came across the various kits avalable for AKP activity in mammalian system. But i want to check AKP activity in group of LAB. WIll the same kit works for the same or i need to purchase other one? Also can we check the activity manually? Is there any protocol avalable?
Relevant answer
Answer
Thank you Rani and Kashif. I have gone through the protocol but i am getting my AKP activity in pellet instead of supernantent. Even i tried Triton X-100 and again sonicate cell suspension. But to my surprise no activity was in supernatent. One possibility is, as it is a membrane bound enzyme (i am guessing tightly bound) and it is not getting detached upon sonication. however research papers shows they had done it without using any detergent and only sonication serves the purpose. Can you suggest what should i need to do. thanks in advance
  • asked a question related to Lactic Acid Bacteria
Question
6 answers
This is my first time doing experiments with bacteria. I use probiotic to alleviate disease state. I use live bacteria for oral gavage.
I am comaring probiotic and probiotic with biofilm. For probiotic i can culture them in large scale and freeze dry untill use.
For the bacteria with biofilm I have no idea if freeze dry will be okay or it will destroy the biofilm.
If anyone has experience or can recommend any paper that will be helpful.
I will use lactic acid bacteria if that is important.
Relevant answer
Answer
  • asked a question related to Lactic Acid Bacteria
Question
5 answers
I tried making MRS broth but it is hard as a brick. Is there any practical tip to make it or it is what it is?
Relevant answer
MRS Broth is a medium for the cultivation and enumeration of Lactobacillus spp. This product has the same formulation as LAB093 MRS Agar with the omission of agar. You can see the Composition in Technical Data. Or you can Buy the ready MRS medium from the Chemical company.
  • asked a question related to Lactic Acid Bacteria
Question
2 answers
I am isolating lactic acid bacteria from fermented soy whey. Why is it that in most of the papers lactic acid bacteria are isolated on MRS agar at 37 degrees Cwhen that is not the fermentation temperature of the original sample. For example in my area, soy whey ferments at an average temperature of 25 degrees Celsius depending on the weather.
Relevant answer
Answer
If you want to isolate the dominant microbiota of fermentation use fermentation temperature. If you want to see the total biodiversity of culturable microorganisms use 22, 30, 37, 42 'C for growing.
Good luck!
  • asked a question related to Lactic Acid Bacteria
Question
4 answers
I'm currently conducting a study on Lactic Acid Bacteria. I'd like to know if any other groups of bacteria other than LAB can grow on MRS agar.
Relevant answer
Answer
MRS Agar and Broth were designed to encourage the growth of the `lactic acid bacteria' which includes species of the following genera: Lactobacillus, Streptococcus, Pediococcus and Leuconostoc. All these species can produce lactic acid in considerable amounts.
  • asked a question related to Lactic Acid Bacteria
Question
7 answers
I want the procedure how to isolate probiotic potential lactic acid bacteria from Fruits
Relevant answer
Answer
Also check please the following useful RG link:
  • asked a question related to Lactic Acid Bacteria
Question
4 answers
I am planning to make cholesterol assimilation test for my pure lactic acid bacteria cultures. However, i have a water-insoluble cholesterol. So, how can i dissolve this in mrs agar and also not give to any harmness to incubate my cultures
Relevant answer
Answer
Reply to Mohamedelfatieh Ismael : Is it reasonable to do so? After all, ethanol may affects the bioactivity of bacteria Mohamed-Elfatieh Ismael
  • asked a question related to Lactic Acid Bacteria
Question
5 answers
At present, I try to keep the bacteria powder at 37 °C for a month to observe the stability of the Lactic acid bacteria powder through the production process.
Is there a way to quickly know the stability of freeze-dried Lactic acid bacteria powder used in products?
Relevant answer
  • asked a question related to Lactic Acid Bacteria
Question
5 answers
Probiotics and Therapeutic effects of lactic acid bacteria isolated from freshly harvested fish and water samples against wound-borne pathogens. I need an expert advise now . Thanks
Relevant answer
Answer
U want to isolate the same bacterial strains from the fish and water?
  • asked a question related to Lactic Acid Bacteria
Question
3 answers
I have grown a mixed culture of E.coli and lab (different strains) together in a microplate. I would now like to see if lab is alive and would like to enumerate on an agar plate which could only allow lab to grow inhibiting other bacteria from growing? Is it possible? Do we have any specific media for that. I tried growing E.coli on MRS and the E.coli grew pretty well, so I am sure MRS won't work, is there any other culture media which can only allow lactic acid bacteria to grow suppressing E.coli.
Relevant answer
Hi, why don't you try this method!
You can use the same media you used on microplates.
  • asked a question related to Lactic Acid Bacteria
Question
4 answers
I use dual culture technique. On a PDA plate, i put 3 of 10ul lactic acid bacteria (LAB) broth in the corner of my petri dish. Each of the LAB is located 3cm away from my fungus (which is at the centre of the plate). The picture is attached here.
Relevant answer
Answer
Radial growth of fungi is determined by measuring zone of inhibition. For instance, you measure areas where fungi could not cover lactic acid bacteria thus the height and breadth and find the average. You can equally treat the lactic acid bacteria suspension with blank antibiotic disc. After streaking the fungi on PDA with a sterile cotton swab. Place the treated antibiotic disc on your inoculated PDA and allow for incubation.
You still have to replicate it.
Thank you.
  • asked a question related to Lactic Acid Bacteria
Question
5 answers
I am studying on antibacterial activity of lactic acid bacteria. I activated my bacteria cultures and test pathogens for two times during two days.
During my research on methodology, some researchers used supernatant part of bacteria. I wonder that, can I use either my bacteria or pathogens without any special preparing (so i used my cultures with their own broth solutions).
For this purpose, i spread my pathogens to blood agar as 100 uL, then drying, then i add my active bacteria in the wells.
Relevant answer
Answer
A variety of laboratory methods can be used to evaluate or screen the in vitro antimicrobial activity of an extract or a pure compound. The most known and basic methods are the disk-diffusion and broth or agar dilution methods. Other methods are used especially for antifungal testing, such as poisoned food technique. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5762448/
  • asked a question related to Lactic Acid Bacteria
Question
12 answers
Im working on a project which is antimicrobial activity-producing lactic acid bacteria as biocontrol agents in plants. I want to use F. oxysporum as tested fungi for in vitro and in vivo test. However, Im not really sure how to prepare the spore suspension for this fungi.
Relevant answer
Answer
Firstly, you must grow the fungus Fusarium oxysporum on PDA and incubate it in incubation for ten days on 25 C, then add 10 ml distilled water to the plate and shake it well by using glass rod to remove the spores from the mycelium, collect the distilled water with spores in tube and consider it as crude suspension.
  • asked a question related to Lactic Acid Bacteria
Question
3 answers
I need to transport lactic acid bacteria using anaerobic transport media like carl Blair and Thioglycolate broth , so rather than this media or other else what is the best appropriate transport media for lactic acid bacteria may be to escape of temperature fluctuation.
Relevant answer
Answer
Viability Medium Göteborg Anaerobically III is the best transporter medium for anaerobic bacteria. We prepared this medium based on articles of Jørgen Slots for the transport of anaerobic bacteria isolated from periodontal and endodontic sites. Viability is Ok after 24 hours at room temperature, maybe more time.
DOI: 10.1128/jcm.15.4.606-609.1982
  • asked a question related to Lactic Acid Bacteria
Question
2 answers
Hello. I want to ask if anyone knows methods for survivability in simulated GIT fluids and also aggregation (auto- and co-aggregation) using well plates (24 or 96 wells) for lactic acid bacteria? We want to use an absorbance microplate reader to hold the experiments.
Relevant answer
Answer
I have used the protocol in this paper in the past to determine auto and co-aggregation. It worked well. but was for a small study (not published).
  • asked a question related to Lactic Acid Bacteria
Question
3 answers
What is the best culture medium and growth condition (pH and temperature) for production of industrial bacteriocin by lactic acid bacteria including Enterococcus faecium, Lactobacillus salivarius, Lactobacillus plantarum, and Pediococcus acidilactici?
Relevant answer
Answer
Hello Dear as Alaa, MRS and BHI are the best media for bacteriocin production, specially when supplemented with( Glucose and other sugars). So, the optimum Temperature, Period and pH; 32-37℃, 16-24 hr, and 5.5-6.5
  • asked a question related to Lactic Acid Bacteria
Question
13 answers
Hello, I am looking to do probiotic tests for my lactic acid bacteria and I need to use bile salts powder that I have at my disposal in lab. there are two different colors one white and one green, is there a difference? What do you recommend ? at the same time if you have a particular protocol for this test. thanks in advance
Relevant answer
Answer
Hi Dr Mohamed-Cherif Bentahar . White bile is a colorless fluid devoid of pigments, bile salts, and cholesterol found in an occluded biliary system. Decolorization of the bile in an obstructed biliary system occurs because the biliary epithelium continues to secrete mucus in stagnant bile. But a green bile is a fluid made by the liver and stored in our gallbladder. Bile salts help with the digestion of fats in our bodies. They also help us to absorb fat-soluble vitamins like A, D, E, and K. See the links :
  • asked a question related to Lactic Acid Bacteria
Question
4 answers
I have done antibiotic susceptibility assay for my lactic acid bacteria strains using 96 well microtitter plate. I need to know any software to interpret results.
Relevant answer
Answer
Thank you ...
  • asked a question related to Lactic Acid Bacteria
Question
6 answers
Hi all,
Is it possible to separate live and dead Lactic acid bacteria by centrifugation?
If so, what kind of gradient solution and condition would you recommend?
Any suggestion would be appreciated in advance.
Thank you.
Relevant answer
Answer
No.. but you can re culture it
  • asked a question related to Lactic Acid Bacteria
Question
4 answers
I am interested in labeling Lactobacillus plantarum with either a red (preferably) or a green fluorescent protein. Can anyone recommend a paper that describes a molecular tool for doing this?
Thank you for your help.
Relevant answer
Answer
Hi Mark,
The authors of this paper may be able to provide you with one of their constructs, if not how to make them and the vectors to start with are well described.
Frank
  • asked a question related to Lactic Acid Bacteria
Question
7 answers
Hi. Does anyone have experience freeze drying LAB using non-glass vials/ ampoules? Thank you in advance. :)
Relevant answer
Answer
Hi, I have a similar problem. It is going to be difficult for me to take out the centrifuged materials using a refrigerated centrifuge unless dried.
And I'm concern if centrifuge can have negative effect on my plastic vail or not.
Anyone with experience, please.
  • asked a question related to Lactic Acid Bacteria
Question
6 answers
I am looking for researchers working on anticancer properties of probiotic lactic acid bacteria isolated from fermented food products.
Relevant answer
Answer
Kindly check the following RG link:
In which most of the probiotic lactic acid bacteria (LAB) that are usually involved in natural ferments and widely used in the food manufacturing industry can produce exopolysaccharides (EPS), surface carbohydrate polymers with diverse biological functions, it had been shown that LAB EPS are potentially complementary and alternative medicines against cancer. EPS show anti-proliferative effects on a variety of tumor cells from the intestine, liver, breast, etc.
  • asked a question related to Lactic Acid Bacteria
Question
7 answers
I need to get the lactic acid bacteria count 106 cfu/ml. Please suggest me a method to get the exact count. I have commercial LAB inoculants.
Relevant answer
Answer
You must establish a connection between CFU/ml and absorbance (optical density OD). Take bacterial culture samples at regular intervals during the growth process. Make serial dilutions after measuring the optical density of the samples. Plate diluted samples in triplicate on agar plates (typically 10ˆ5 to 10 ˆ 7 dilutions) and count colonies after incubation. Calculate the CFU/ml value. Make a graph that shows the relationship between CFU/ml and OD. The OD of your sample can then be calculated.
  • asked a question related to Lactic Acid Bacteria
Question
3 answers
I'm during study on my master's thesis. My study is about optimalization of culturing of probiotic lactic acid bacteria. I used Design Expert software. Program draw 13 experiments with 2 factors for optimization (factors: pH, temperature) . I'm using Central Composite Design. I have problem because i have 4 measuring points my culture ( in 12hour, 18h, 36h, 48h) which i can't include in factors. Is it possible to combine all data from my all measuring points with 13 experiments each to know which conditions and time is the best for my bacterial strain?
  • asked a question related to Lactic Acid Bacteria
Question
8 answers
Im currently working on growing LAB strains isolated from Kefir drink...
those LAB stocks grew faily good on MRS Agar plate. (incubated for 24hr at 37'C)
so, i took loopful of colonies and inoculated in MRS broth(pH adjusted to 6.5, 37'C for 48hrs) but only showed very minimal growth.
and when subcultured it 10% to MRS broth, it showed no growth at all...
i have tried incubating them aerobically (shaking) and anaerobically in chamber but still, no growth was observed.
Can anyone give me a idea regarding growing Lactic Acid Bacteria in MRS broth?
Relevant answer
Answer
Make cell suspension 2% of LAB and add it to flask of 100 ml broth MRS shake well and incubate at the optimum temperature about 32 C° for 48 h, the growth well appear as pellets.
  • asked a question related to Lactic Acid Bacteria
Question
8 answers
During my study, I am trying to find acid and bile salts tolerances of potentially probiotic lactic acid bacteria. To find their survival ratio, I used pour plate method by using MRS/M17 agar. Hovewer, I can not find a meaningful result. So I may try absorbance measurement to find a result. So, do you mind that, is that an unacceptable method for reputable journals ? What should you reccomended to me?
Regards
Relevant answer
Answer
Dear david, as you said, I can apply absorbance measurement, are'nt you?
  • asked a question related to Lactic Acid Bacteria
Question
3 answers
I tried to isolate Bifidobacterium species using the BSM agar. However, molecular identification of the isolates by 16S rRNA gene sequencing resulted in 97+ to 99.6 % similarity to different Lactobacillus species. Can I take this result as it is? Is it reliable? Or could it possibly be that there was an error in the molecular identification technique somewhere? Please kindly guide me with your experiences if you have one. Thanks in advance.
Relevant answer
Answer
I totally agree with Dr. Alaa Kareem Niamah as molecular identifications are very accurate and cannot be wrong because they are designed as genetic maps of microorganisms. But there are rare cases in which it gives negative results and not different and this is for several reasons (the isolates may have been isolated from food materials and some of the components of the food affected the sensitivity of the kit, or sometimes the concentration of the bacterial broth may be less than the sensitivity of the kit, Sometimes, and in rare cases, mutations occur in the bacteria that make them resistant to heating also affect the sensitivity of the kit), but these cases are recorded for special types of bacteria, and they rarely occur.
  • asked a question related to Lactic Acid Bacteria
Question
3 answers
I tried to isolate lactic acid bacteria using MRS and M17 agar media, and I targeted yeasts on SDA plate treated with chloramphenicol. However to my greatest surprise, molecular identification of an isolate from SDA by 16S rRNA gene sequencing resulted in a 99.05 % similarity to Lactobacillus parabuchneri. Can I take this result as it is? Is it reliable? Or could it possibly be that there was an error in the molecular identification technique somewhere? By the way, I didn't even Gram-stain isolates from SDA plates as I already presumed that they must be yeasts, although they had similar colony morphology with LAB. Please kindly guide me with your experiences if you have one. Thanks in advance.
Relevant answer
Answer
Hello, the 99.05 % similarity is well enough but to be sure for more than 99.05% perform API test which is well developed for lactobacilli and will give you additional approval.
Good luck !
  • asked a question related to Lactic Acid Bacteria
Question
4 answers
Hello,
I am trying to isolate lactic acid bacteria from spoiled vegetables using MRS agar (with 1.5% CaCO3) by direct plating and incubating at 30 °C under aerobic conditions. Is there any difference for autoclaving MRS and calcium carbonate together, or autoclaving independently and after cooling down then mixing calcium carbonate and MRS together? What I did was autoclaved together and found that the lactic acid bacteria did not grow well. What is the reason?
Thank you in advance.
Relevant answer
Answer
Good question
  • asked a question related to Lactic Acid Bacteria
Question
13 answers
Our ultrafreezer has broken three years ago and we still don't know when (or if) it will get fixed. So ever since, I've been stocking my bacterial strains (mainly lactic-acid bacteria and foodborne pathogens) at -20 °C (freezer) in broth + 25% glycerol. However, I am deeply concerned about the damaging effect of glycerol at higher temperatures than -80. I had noticed that many stock tubes were not viable anymore after about a year of stocking...
Do you know a procedure for long-term stocking that I can use at -20 °C? With a lower concentration of glycerol perhaps, or even with DMSO...
Thank you
Edit: Bacterial strains are not cloned. We maintain them in De Man, Rogosa and Sharpe (MRS - lactic-acid bacteria) and Brain Heart Infusion (BHI - pathogenic strains) media.
Relevant answer
Answer
Good question
  • asked a question related to Lactic Acid Bacteria
Question
3 answers
Dear All,
I have problems with spoilage caused most likely by lactic acid bacteria in vegan sliced sausage. The product was stored at ~7°C in vacuum packaging and after three weeks it got yellow spots. Due to literature research I am pretty sure that it is Leuconostoc gelidum that causes these yellow spots.
I also had problems some months ago with slime after some weeks of storage and I think this was also caused by lactic acid bacteria. The problem in this case (pilot plant) is the recontamination of the product by the slicing process which is done manually.
Do you have any suggestion, which preservative agent works best against lactic acid bacteria or Leuconostoc gelidum in particular?
thanks,
Wolfgang
Relevant answer
Answer
.... of most bacteria, including food pathogens, spoilage bacteria, and the lactic acid bacteria used in vegetable fermentations, are readily destroyed by heating to 160°F (71°C), especially when the pH is low. Acid and low pH are also toxic to most bacteria. https://www.ars.usda.gov/ARSUserFiles/60701000/FoodSafetyPublications/p328.pdf
  • asked a question related to Lactic Acid Bacteria
Question
7 answers
I know that there are a lot of LAB present but I would like to know is there any LAB that able to produce cellulase naturally.
Relevant answer
Answer
I dont hear this but may be can produce this enzyme unnaturally
  • asked a question related to Lactic Acid Bacteria
Question
4 answers
Use of special medium (MRS) to isolate and diagnose lactic acid bacteria
However, it appears that this medium can grow many yeasts and molds on it
My question is that MRS is not a suitable medium for isolating lactic acid bacteria, rather other factors and conditions must be used for the success of the isolation process. What are the best of these conditions?
Relevant answer
Answer
Hello, it usual picture when you want to isolate lactic acid bacteria from samples with yeast and mould content. The MRS is reach medium with glucose which is ideal for yeast and mould grow. Normally of you have high titre of LAB in sample they will eliminate other microorganisms grow by lactic acid formation. But in your case better to use antifugal substances When seeding samples with high probability of row any yeast and mould use Nistatin (100-200U/mL) to avoid yeast and fungus growth and it worked well or cyclohexamide which also working well.
  • asked a question related to Lactic Acid Bacteria
Question
3 answers
What is the purpose of transferring 0.1ml aliquot taken from main aggregation mixture to another tube with 3.9 ml of the buffer and take OD. Can we take OD directly from aliquot taken from main mixture without transferring it to another tube?
Relevant answer
Answer
You can benefitted from the paper attached
  • asked a question related to Lactic Acid Bacteria
Question
4 answers
in my research, for a protocol to isolate lactic acid bacteria i found that some papers added 0,8% of CaCo3 to MRS medium and I didn't know why.
Relevant answer
  • asked a question related to Lactic Acid Bacteria
Question
6 answers
to evalue the benefict of cheese on health as antioxydant activity in cheese coagulated by Lactic acid bacteria with out presure
Relevant answer
Answer
agree with Dr Ana Rojas
  • asked a question related to Lactic Acid Bacteria
Question
14 answers
Hello,
I am trying to isolate lactic acid bacteria from fermented fish using MRS agar (with 0.3% CaCO3) by direct plating and incubating at 37 °C under anaerobic conditions. After 48 hours of incubation, milky white colonies came up (as shown in picture) but with no clear zones around the colonies. In literature, lactic acid bacteria produce a clear zone around it's colonies in MRS agar supplemented with CaCO3 due to production of acid. Should I consider picking the colonies without clear zone or have I done some mistake while preparing the agar medium?
Thank you in advance.
Relevant answer
Answer
Mohammad Afzal Hossain Thank you so much for your suggestions.
  • asked a question related to Lactic Acid Bacteria
Question
5 answers
when I blast the existed primers specially 16s rDNAs , I cant get good results.
Relevant answer
Answer
27F and 1492R are most widely used primers for 16srRNA conserved region identification.
  • asked a question related to Lactic Acid Bacteria
Question
14 answers
Hello,
I am actually working on probiotic lactic acid bacteria, can you help me, please to know the preferable percentage of viability of LAB after its passage through the GIT
for example, if my initial viability is 100 % what is the minimum needed after treatment with bile or acid?
Thank you
Relevant answer
Answer
LAB also has antioxidant effects and can stimulate endogenous antioxidants so it is good for boosting the immune system
  • asked a question related to Lactic Acid Bacteria
Question
1 answer
I am doing large-scale fermentations and have significant problems with bacterial contamination which I suspect are lactic acid bacteria. I would like to add an antibiotic that will not affect the yeast and can be easily inactivated afterwards by, for instance, autoclaving.
Relevant answer
Answer
cephalothin, cefuroxime, ceftriaxone or cefoxitin (10 mg/L)
  • asked a question related to Lactic Acid Bacteria
Question
11 answers
What is the best method for encapsulation of lactic acid bacteria in proteins in acidic conditions?
Relevant answer
Answer
Kindly visit given URL for detail.
  • asked a question related to Lactic Acid Bacteria
Question
3 answers
I have already done making the said bacteria's growth curve, and now my supervisor demands me to calculate the carbon-source (glucose) loss/usage by the lactic acid bacteria alongside the growth curve which is 36 hours with 4 hour interval.
what is the best method to calculate the glucose usage? do the calculation involves kit or can be done by tool such as spectrophotometer
Relevant answer
  • asked a question related to Lactic Acid Bacteria
Question
8 answers
Hello everybody. I would like to order a bioreactor for lactic acid bacteria production and would like to know the requirements of this system.
Relevant answer
Answer
Mohaddaseh Ramezani :
In my opinion and experience, there are no specific bioreactor requirements for the cultivation and production of lactic acid bacteria. It is important that the bioreactor is capable to control cultivation parameters needed for lactic acid bacteria, like pH, temperature, the concentration of dissolved oxygen, etc.
There exist many producers of laboratory fermenters e.g. Bioengineering, FerMac Bioreactors, Lambda, Eppendorf, V Tech, Solida Fermenters, and many more.
Best regards
Vit
  • asked a question related to Lactic Acid Bacteria
Question
5 answers
Is there any research article that reported the presence of lactic acid bacteria in baked foods like bread and injera that withstand the baking temperature?
Relevant answer
Answer
Presence of Lactic Acid Bactaria is well known in fermentation of cereals along with legumes. They will survive at the room temperature, as soon they go to high temp. to a range of 180 degree Celsius, they have to die. or their activity will go down. Similar things may happen in Ingera, an African food and other bakery products, their survival is doubt while preparing thse products.
  • asked a question related to Lactic Acid Bacteria
Question
6 answers
One review ( ) mentioned that "Many LAB are known to produce exopolysaccharides (EPS), and care should be taken with interpreting OD-values as these will be influenced by the produced EPS" and I noticed some papers showed they measure the OD at 595 nm instead of 600 nm. Could someone explain thoroughly why people choose 595 nm but not other wavelength?
Relevant answer
Answer
Hi Xiangang
It does not seem to be logically necessary to choose exactly 595nm. For optical densities you are measuring a transmission in a turbid solution not an extinction.
You avoid wavelenghts close to the UV spectra to filter out results from dissolved molecules and blank against your medium to eliminate VIS-Colours in the samples
If there is a possible maximum extinction of undissolved by-molecules that have maximum of exactly 595nm, they will be already visible at 590nm or 600nm.
You have to take in mind too, that a linear progression of the results for turbid solutions is only given up to arround ext. 0,7, above this value it is usefull to dilute.
Possible reasons might also be: Perhaps researchers had good experiences with this wavelenght.. or used instruments with exactly this (fixed) filter.
Anyway: the value for ODs can differ between single photometers it is not 100% consistent, if you want to exactly estimate the rate of living cells, you should perform a living cell count, f.e. via plating.
  • asked a question related to Lactic Acid Bacteria
Question
20 answers
I want to isolate LAB from fermented foods such as fermented sorghum that produces bacteriocins which can be applied on raw and cooked meat as a preserving strategy 
Relevant answer
Answer
Hi
MRS is the best medium for LAB isolation and cultivation .
  • asked a question related to Lactic Acid Bacteria
Question
3 answers
I am currently reviewing research into the production of vitamin B12 by lactic acid bacteria. One paper has reported their results by quantifying the level of dicyanocobalamin, but I have been unable to determine if this form of B12 is bioavailable. All other papers I have read have reported cyanocobalamin, methylcobalamin and/or adenosylcobalamin as the available forms.
Any help clarifying the difference between cyanocobalamin and dicyanocobalmin would be really appreciated!
Relevant answer
Answer
Hi,
Please see in attach file
  • asked a question related to Lactic Acid Bacteria
Question
6 answers
Hi I'm looking for a topic for my master's thesis that is related to lactic acid bacteria and related to nutrition. Please guide me.
Relevant answer
Answer
Study on functional and probiotic dairy or food products.
  • asked a question related to Lactic Acid Bacteria
Question
5 answers
What do you recommend cheaper culture media instead of MRS media for Lactobacillus bacteria ssp. plantarum?
Relevant answer
Answer
MRS medium is rich in minerals and growth factors and hence is used for such fastidious lactobacilli.However, it could be replaced successfuly by a media based on whey enriched with minerals in many studies,
  • asked a question related to Lactic Acid Bacteria
Question
4 answers
I am writing a proposal where one of my aims would be to use Bioinformatics tools to see if a specific strain of Lactic Acid Bacteria has homology to general iron utilization genes in microbes (perhaps using BLASTn or CLUSTALx,w).
I am new to bioinformatics and assuming I know nothing, what resources should I look at, how to start the process and how to even write it in my proposal are all just a big blur.
Any advice?
Relevant answer
  • asked a question related to Lactic Acid Bacteria
Question
3 answers
I want to understand what does Lactic Acid do on the cells themselves, not the product.
Relevant answer
Answer
3/5/20
Dear Ivan,
Lactic acid bacteria (LAB), like other bacteria, derive energy from the Embden-Myerhoff (glycolytic) pathway. The starting material is glucose (or similar sugar); the end product is pyruvic acid. In carrying out glycolysis, the cells consume NAD, converting it into NADH. Once all the NAD is converted to NADH, glycolysis stops. To keep the pathway operating so the cells can grow, the cells need to re-generate NAD from NADH (See attached.).They do this using the enzyme lactic acid dehydrogenase (LDH). This converts pyruvic acid into lactic acid, which is excreted by the cells. LDH requires NADH as a cofactor to reduce pyruvic to lactic. During the reaction, the cells regenerate NAD to allow glycolysis to continue. So, conversion of pyruvic to lactic is essential for continuation of the cells' metabolism and energy production.
I have grown LAB a number of times. The presence of lactic acid in the fermentation medium doesn't seem to hurt the cells. Lactic acid is produced commercially this way. See the attached growth profile which we prepared a few years ago.
I hope this information helps you.
Bill Colonna
Center for Crops Utilization Research, Iowa State University, Ames, IA , USA
  • asked a question related to Lactic Acid Bacteria
Question
3 answers
I am screening Lactic acid bacteria for their proteolytic activity. For this i have created wells over 10% supplemented MRS agar and filled culture in it. After 24-48 hrs a white colored opaque halo was observed near the wells. however, a clear zone was also observed just after the periphery of white colour opaque zone.
Relevant answer
Answer
Hi,
The white zones is growth of Lactic acid bacteria, You should after growth (24-48h), remove the bacteria cells by centrifuge and pass during milporfilter (0.22).
  • asked a question related to Lactic Acid Bacteria
Question
2 answers
Effect  on bay laurel (Laurus nobilis , prebiotics) on gut lactic acid bacteria of common carp (Cyprinus Carpio)..
Relevant answer
Answer
Please have a look at the following RG link.
  • asked a question related to Lactic Acid Bacteria
Question
1 answer
Hello Dear Scientist, I am doing research on bacteriocin, specially to isolate bacteriocin producing lactic acid bacteria. after centrifugation at 10,000rpm for 20min at 4oc, it was difficult stil to isolate bacteriocin producing. may NaHO has effect on bacteriocin. Instead of Catalase , i used sodium thiosulafate. so my question is do NaHO and Sodium thiosulfate damage the bacteriocin. Please would you informe me the most appropriate methods, chmeicals and reagents used to isolate bacteriocin and bacteriocin producing lactic acid bacteria from your research experiance and from your scientific knowedge.
Relevant answer
Answer
Hi,
NaOH is not damage for the bacteriocin but deceasing of inhibition activity
  • asked a question related to Lactic Acid Bacteria
Question
3 answers
Why HNO3 (Nitric acid) used for biosorption of heavy metal by lactic acid bacteria and what is the role of HNO3 and what is the good method of biosorption of heavy metals e.g. cadmium (Cd)
(II), lead (Pb) (II), arsenic (As) (III), and mercury (Hg) (II)
Relevant answer
Answer
@ Abdul, Nitric acid is used because nitric acid at low concentration 0.05N is very effective in desorbing the biosorbed metal ions. Many methods can effectively be used for biosorption for example, chemical methods such as chemical precipitation, electrochemical treatment, oxidation/reduction; physical methods such as ion exchange membrane technology, reverse osmosis and biological methods such as using microorganisms including bacteria, fungi or algae.
  • asked a question related to Lactic Acid Bacteria
Question
22 answers
I was trying to amplify 16S rRNA gene of my Lactic acid bacteria (LAB) isolates. However, some commonly used primers failed to amplify some of my LAB isolates. Can anybody suggest the best primer pair for this purpose?
Relevant answer
Answer
Do not you think the suggestion
27F (5’-AGAGTTTGATCCTGGCTCAG-3’)
1492R (5’-GGTTACCTTGTTACGACTT-3’)
is too longer? Have you got any a solid reason?
Thanks
  • asked a question related to Lactic Acid Bacteria
Question
3 answers
I have got to analyse a semi-liquid food product that's blowing out with some gas production, thereby shortening the shelf life. Lab analysis expectedly identified some heterofermenters. Just wondering what will be the best approach to stopping gas production and possibly eliminating the lactic acid bacteria without using preservatives, so the shelf-life can be extended.
Thanks
Relevant answer
Answer
You could try UV sterilization.
  • asked a question related to Lactic Acid Bacteria
Question
18 answers
I need this in my search.can anyone help me?
Relevant answer
Answer
Please take a look at this useful RG link.
  • asked a question related to Lactic Acid Bacteria
Question
4 answers
Hi :)
I want to know the exact lactic acid bacteria identification primer.
Which gene should I use?
Thank you!
Relevant answer
Answer
Hi,
It is sometimes easy and applicable to differentiate distinct species from each other using other primes rather than 16S rRNA. Yet, LAB have very close species and subspecies. Considering some subspecies belonging to lactococci or species belonging to enterococci (E. durans vs E. hirae or E. thailandicus), it is a matter of a few nucleotide which makes the difference. For instance the genome of above mentioned species have similarity of 99.6% or higher. Therefore, it is even sometimes not enough to amplify the part of 16S rRNA, like 900bp out of 1500bp. Considering eucaryotes in which specific factors such as ß-tubulin could be used for differentiation where ITS1-5.8S-ITS2 or D1/D2 subdomain of LARGE subunit is not enough, it is very hard to find such kind of primer/primers for LAB. To this end, 16S rRNA is the most accurate and reasonable method for LAB in which correct identification is crucial.
Best regards!
  • asked a question related to Lactic Acid Bacteria
Question
10 answers
I'm currently doing my undergraduate thesis on probiotic viability in yogurt and for its enumeration, i would need my culture media to be selective only to l. acidophilus strains. I would very much appreciate recommendations. thanks!
Relevant answer
Answer
Hi,
Replace glucose in the MRS media with sorbitol or salicin.
  • asked a question related to Lactic Acid Bacteria
Question
4 answers
Hi,
I am trying to transfer a plasmid which has a big size (15kb) to Lactic acid bacteria specially L. plantarum and LGG but not successful yet. Does anyone have any suggestion?
Relevant answer
Answer
Hello, as already mentioned electroporation widely used in transformation of big size plasmids.
See info attached may be useful for you.
Good luck!
  • asked a question related to Lactic Acid Bacteria
Question
2 answers
I would like to purchase a microplate reader to assay bacterial growth kinetics when exposed to different conditions (i.e.:salt concentration, different sugars, etc.). Ideally, I am looking for an instrument that combines temperature control (mesophilic bacteria), and continuous measurement of the O.D. (let’s say up to 48 hrs). Could anyone that has some experience in bacterial growth assays advice a not too expensive instrument?
  • asked a question related to Lactic Acid Bacteria
Question
5 answers
I need to confirm the probiotics colonies. Three consecutive decimal dilutions were inoculated in MRS agar and incubated at 30 ºC under anaerobiosis (5% CO2) for 4 days. After the period of incubation I did the count of the colonies but I dont know this colonies . Which colonies should I count as lactic acid bacteria? Please kindly share your experience with these colonies of possible lactic acid bacteria or yeast ?
Relevant answer
Answer
Hi,
They are lactic acid bacteria .
  • asked a question related to Lactic Acid Bacteria
Question
8 answers
I isolate LAB in MRS A + CaCO3 medium, but until now I cannot find the reason why a clear zone formed around the colony. I am wondering whether there are any researchers that can explain this question.
Relevant answer
Answer
I Agree with,
Ami Rameshbhai Patel
  • asked a question related to Lactic Acid Bacteria
Question
4 answers
I am doing research on the effect that rare earth metals produce as environmental pollutants on the lactic acid fermentation process and the quality and safety of foodstuffs made that requires it.
Relevant answer
Answer
Hello, I think you shuld start your research!
  • asked a question related to Lactic Acid Bacteria
Question
7 answers
Where can I obtain/purchase Lactococcus lactis IL 1403? Which cell culture collection has this strain?
Relevant answer
Answer
Hi Andrea, I could not find IL1403 in any culture collection that time. I searched the research groups having papers which IL1403 was used. Then I asked for them. One of them finally sent it to me. You can also search the groups close by you. Hope it works
  • asked a question related to Lactic Acid Bacteria
Question
8 answers
Hello everyone. I have tried to test lactic acide bacteria for their co ggergtion ability with E.coli but I'm having problems.I have to read the DO at t=0 and after 1h of incubation. But after I incubate The DO increses and as a result I get a negative value. What could be the reson behind it and Is their any protocole you can share with me that will help me get a positive DO.
Relevant answer
Answer
Negative absorbance also may happen due to the problem of the instrumen calibration. You should use uninoculated sterile media to blank the machine by setting it to 0 absorbance (by pressing autozero). It will standardize the turbidity of the media without any cells in it.
  • asked a question related to Lactic Acid Bacteria
Question
4 answers
what are the most effective lactic acid bacteria in the biocontrol of fungal and bacterial plant diseases?!
Relevant answer
Answer
Trichoderma harzianum is a fungus that is also used as a fungicide. It is used for foliar application, seed treatment and soil treatment for suppression of various disease causing fungal pathogens. Commercial biotechnological products such as 3Tac have been useful for treatment of Botrytis, Fusarium and Penicillium.
  • asked a question related to Lactic Acid Bacteria
Question
7 answers
hello
I am working on the probiotic characterization of some  new isolates of lactic acid bacteria, i want to know if I could use the optical density to find the survival rate of the LABs instead of  the method of the plate counting.
thank you for help
Relevant answer
Answer
You couldn't use the optical density to find the survival rate of the LABs instead of  the plate counting method because Optical density measures live and dead bacterial cells numbers.
  • asked a question related to Lactic Acid Bacteria
Question
8 answers
is Lactobacillus MRS agar used to isolate all Lactic acid bacteria? agan i need to supplement 0.3% of Calcium Carbonate to MRS agar, how can i supllemnt , before or after sterilization( autoclaving) the media?
Thank you
Relevant answer
Answer
MRS agar normally used to isolate lactobacilus or all type of LAB, you can add specific nutrients if you want to isolate specific LAB, calcium carbonate can be added before autoclaving the media, but I usually add bromocresol purple into media, which is the same thing.. regards
  • asked a question related to Lactic Acid Bacteria
Question
5 answers
I want to find different plasmid sequences from lactic acid bacteria with gene sequence of ORFs, particularly replication origins and accessory genes. Is there such a database where I can find one?
Are there also ways to predict the type of replication mechanism using motif prediction of replication origins?
May I also ask, what is the importance of plasmid segregational stability in a transformed host. What does it mean if the host loses its plasmid after 100 or 200 generations? Are there important implications of the type of replication mechanism it observes?
Please send me link or related literature. Thank you in advance!
Relevant answer
Answer
Hi Ed,
Good luck!
Reta
  • asked a question related to Lactic Acid Bacteria
Question
4 answers
I used boiling method to extract DNA from lactic acid bacteria. as follow procedure:
Fifty microliter of dH2O is added to the pellet. After vortexing, the sample is boiled at 98°C for 10 minutes by placing in thermocycler . The suspension is centrifuged at 13000 g for 7 minutes and the supernatant is kept frozen until used
but this method doesn't have repeatedly. could you help me to optimize this method?
Relevant answer
Answer
Hi Paria,
I have found it can be difficult to lyse Gram positive LAB by boiling in water. Instead you could try using an enzymatic lysis buffer treatment first.
A typical lysis buffer recipe is:
20mM Tris-Cl (pH 8), 2mM EDTA, 1.2% Triton X-100 and 10 mg/ml lysozyme (added immediately prior to use).
Make up concentrated stock solutions of the components and mix into the working buffer prior to use.
eg. for 100 ml of buffer combine:
1M Tris-Cl (2 ml) ,0.5M EDTA (0.4 ml), Triton X-100 (1.2 ml). Make sure the buffer is at pH 8.
As you are using small volumes at a time, you could take 5 ml of this buffer and add 50 mg of lysozyme (10 mg/ml).
If you incubate your cells in this buffer for 30 minutes at 37 degrees prior to the boiling step it should work. You can centrifuge the sample and freeze supernatant as you have done previously.
Good luck.
  • asked a question related to Lactic Acid Bacteria
Question
7 answers
I am using some Lactobacillus strains in my study and I want to measure the production of Lactic acid by these bacteria. I am aware of several kit (abcam, cyman, sigma) which can help me to measure the concentration of Lactic acid but I want to know, if there is any procedure to measure Lactic acid concentration without using commercial kit.
Relevant answer
Answer
Thank you Dr. Carole. Even I was looking for a reference on the same topic.
  • asked a question related to Lactic Acid Bacteria
Question
13 answers
If I cannot use the commercially available ones? Thanks!
Relevant answer
Answer
Also, you can use any antifungal agent with MRS media to prevent growth of candida
  • asked a question related to Lactic Acid Bacteria
Question
11 answers
I would like to know if is it possible that cell morphology of lactic acid bacteria can change during long term storage in freeze-drying ampoules stored for more than 20 years.
Relevant answer
Answer
I have been working with lactic acid bacteria (LAB) for the last ten years and your question is totally feasible and related to one of the biggest ignored field of microbiology (bacterial culture storage).
I would recommend to you to read "Stress Responses of Lactic
Acid Bacteria" by Effie Tsakalidou. It has a lot of good information that might be useful to you.
I have attached the book in case you do not have access to it.
Best,
-AB
  • asked a question related to Lactic Acid Bacteria
Question
2 answers
Unsuccessful experiment with ruthenium red
To distinguish between EPS-producing (S. thermophilus) and nonproducing (E. coli) cells, M17 agar medium containing 0.08% ruthenium red and ruthenium red milk plates (RRM) (consisted of 0.5% yeast extract, 10% skim milk powder, 1% sucrose, 1.5% agar and 0.08 g L- of ruthenium red) were used. After incubation at 37 ºC for 24 h and 48 h, every strain gave whitish (maybe pale pinkish) colonies. It was unclear.
Stock solution: 0.0877 g of ruthenium red [Ruthenium(III) chloride oxide, Alfa Aesar] in 8.77 ml distilled water was sterilized.
0.8 ml ruthenium red stock was added to 100 ml molten M17 and 100 ml molten RRM agar just prior to pouring it into petri plates. What could be wrong with that?
Relevant answer
Answer
I only had success myself using this method when I used Ruthenium Red from Sigma. I used one from Acros Organics originally and even though same formula, weight and CAS# received totally different results. Your agar should be pink to red. The plates should also be protected from light.
  • asked a question related to Lactic Acid Bacteria