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
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
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?
Hey, i'm working on LAB to make it in capsules.. how can i encapsulate the bacteria ? what are the protocols ?
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?
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?
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.
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?
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.
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.
I want the procedure how to isolate probiotic potential lactic acid bacteria from Fruits
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
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?
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
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.
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.
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.
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.
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.
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.
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?
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
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.
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.
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.
Hi. Does anyone have experience freeze drying LAB using non-glass vials/ ampoules? Thank you in advance. :)
I am looking for researchers working on anticancer properties of probiotic lactic acid bacteria isolated from fermented food products.
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.
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?
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?
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?
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.
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.
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.
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...
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.
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?
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.
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?
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?
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.
to evalue the benefict of cheese on health as antioxydant activity in cheese coagulated by Lactic acid bacteria with out presure
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.
when I blast the existed primers specially 16s rDNAs , I cant get good results.
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?
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.
What is the best method for encapsulation of lactic acid bacteria in proteins in acidic conditions?
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
Hello everybody. I would like to order a bioreactor for lactic acid bacteria production and would like to know the requirements of this system.
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?
One review (
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
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!
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.
What do you recommend cheaper culture media instead of MRS media for Lactobacillus bacteria ssp. plantarum?
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.
I want to understand what does Lactic Acid do on the cells themselves, not the product.
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.
Effect on bay laurel (Laurus nobilis , prebiotics) on gut lactic acid bacteria of common carp (Cyprinus Carpio)..
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.
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)
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?
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.
I need this in my search.can anyone help me?
I want to know the exact lactic acid bacteria identification primer.
Which gene should I use?
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!
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?
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?
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 ?
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.
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.
Where can I obtain/purchase Lactococcus lactis IL 1403? Which cell culture collection has this strain?
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.
what are the most effective lactic acid bacteria in the biocontrol of fungal and bacterial plant diseases?!
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
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?
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!
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?
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.
If I cannot use the commercially available ones? Thanks!
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.
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?