Food Microbiology - Science topic

Also check https://www.researchgate.net/publication/337021052_Fermentation_of_plant-based_milk_alternatives_for_improved_flavour_and_nutritional_value

Hi there, to my opinion, although the result si "only" questionable ( as opposed to unsatisfactory), you should run a 5 M investigation, although you might ot get a definite root cause. Also was the expected value low? have you ever calculated you uncertainties of measurement? Once every thing on your side is OK, only then could you place the cause onto transportation and storage.

Best

Kindly read this sir.

Also check https://www.researchgate.net/figure/Sugar-fermentation-using-Phenol-Red-broth-test_tbl1_326991009/amp

Dear

The composition of Phenol Red Carbohydrate Broth has been introduced in the following link:

.... 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

I recommend answer

best wishes

This method is recommended by the International Commission for Bee Botany:

Ten grams of honey is dissolved in 20 ml of warm water (40 C).

The solution is centrifuged for 10 min at 2500 r/min, the supernatant solution is decanted, and the sediments are collected into a conical tube and treated with an acetolysis mixture (acetic anhydride : conc. sulphuric acid = 9:1 V/V) for approximately 30 min at room temperature.

After treatment with the acetolysis mixture, the sediments are rinsed with distilled water, centrifuge for 5 min at 2500 r/min, and preserve for study.

Also check https://pubmed.ncbi.nlm.nih.gov/6808789/

I agree with you why not.

Kindly check http://www.ftik.usm.ac.id/aoac-official-methods-of-analysis.pdf

The progress of science in the field of oenological yeasts led to the use of GMOs in the field of viticulture being considered by the IOV (International Organization of Vine and Wine) in 2015. This revision was framed within the International Agreement of the Cartagena Protocol on Biodiversity Security. In this Agreement, three branches were defined where recombinant DNA technology could be applied:

1. Plants

2. Yeast

3. Obtaining enzymes from genetically modified organisms It is worth mentioning that in 2003, both Canada and the United States of America accepted the use of these microorganisms, qualified them within the GRAS (Generally Recognized as Safe) category and today they can be acquired commercially.

@Dear Prof. Sami,

There is one correction* in the sense that I had posted my response earlier but not on this thread. But I distinctly remember a similar question came up for discussion on RG platform some time back.

Regards,

The simple answer is that they are equivalent- one MPN is equal to one CFU. Both units measure the estimated number of bacteria in a water sample. Both are recognized by a variety of scientific and regulatory bodies worldwide including the US Environmental Protection Agency (EPA) and the International Standardization Organization (ISO). The difference is in how the measurement is obtained. The use of either MPN or CFU is based on the method used for the detection of bacteria and both are valid measurements for bacteria limits.

For CFUs, bacteria grow on a solid medium, like agar.  Afterward, colonies of bacteria are counted.  For an MPN measurement, samples grown in a liquid medium, like multiple tube fermentation and Colilert.  Positive wells/tubes are then counted and an MPN conversion table is used to generate a numeric result.  

In short, laboratories and agencies worldwide use both MPN and CFU interchangeably. 

Both measurements are well-established means to estimate the number of bacteria in a sample, and both carry a 95% confidence interval.  

Also, you can compare the performance of each biochemical compound related to any factor analyzed by DCA or NMDS using the mentioned software in comparison with that of outcome from control samples (plant cultured alone without bacteria).

Best,

Saeed

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,

I obtained useful information from your reply on this RG question,

Regards for all

Tumour micro environment demonstrates immunosuppressive status due to various soluble factors such as IL-10, TGF-β, vascular endothelial growth factor (VEGF) , prostaglandin E2 ( PGE2), HMGB1, indoleamine-2,3-dioxygenase (IDO), as well as soluble forms of phosphatidylserine, Fas receptors, and MHC class I-related chain.

Prevailing inflammatory status will facilitate the abundance of 'inflammophilic' periodonto pathogens in OSCC tumour micro environment. P. gingivalis and F. nucleatum are classical examples as such.

by PCR

Ok, let me try...

On Columbia blood agar (with defibrinated blood incorporated after sterilization of the base medium) Listeria monocytogenes will grow and will give also a clear β-haemolysis reaction.

On TSA growth of the bacterium is obvious, though not so abundant (i.e. small colourless colonies and slow growth on the agar plate). For this to occur, 0.6% yeast extract should be added, thus making TSAYE, which corresponds to the preffered general purpose medium for L. monocytogenes. In general, yeast extract seems to be an important ingredient in the media used for Lm, since its use is suggested also by ISO 11290 in blood agar.

On XLD Lm will not grow, I can tell you that. I came up with that mistake once...

For the other culture media you mention, I can't tell.

Regards!

Dear Dr Manjur,

Your requests are already granted by the researchers above. We shall discuss and see more easy alternative ways.

Best regards.

Thank you Antonio for your suggestion.

following

Heat is generated by moving the water molecules in the microwave. The water in the cell is likewise expressed. Since the water inside the bacterial cell will be heated, the bacteria will die with the effect of this heat.

Dear Taghreed Hafez,

You may be able to produce water soluble chitosan by yourself!

Vahid

Based on the OIE-Listed Crustacean diseases 2017 report

1. Necrotizing Hepatopancreatitis (NHP) caused by NHP bacterium (NHPB)

2. ACUTE HEPATOPANCREATIC NECROSIS DISEASE (AHPND) caused by Vibrio parahaemolyticus

I wish you good presentation

The traditional way would be centrifugation. Other methods would be for filter membranes but would require specific equipment. Sedimentation does not always occur, it depends on the strain. Evaporation and drying may be an option but temperature control is required.

The recovery of salmonellae from egg products was studied, by use of three different enrichment procedures: (i) selenite broth, (ii) selenite broth containing 10% sterile feces, and (iii) the lactose pre-enrichment procedure. Brilliant Green Agar was used throughout as the recovery medium. Although the lactose pre-enrichment methodology promoted Salmonella recovery from samples containing small numbers of dormant organisms, the efficiency of this enrichment method is adversely affected by unfavorable coliform-Salmonella ratios. Under such conditions, early subculture of lactose broth into selenite broth is indicated. Selenite broth containing 10% sterile feces was more efficient than the lactose pre-enrichment methodology in promoting the growth of “dormant” salmonellae. Albumen adversely affected recovery of salmonellae from selenite broth, whereas whole egg and egg yolk enhanced Salmonella recovery from this medium. The selenite-feces medium presents a solution to the major problems encountered in the detection of salmonellae in egg products and offers an approach to a single medium in which food-borne salmonellae will manifest themselves with a minimum of laboratory manipulation.

Hi:

In order to pellet cells, people usually use around 5000 g (centrifugal acceleration 5000 times the gravity on earth) for 10 minutes.

Regards

there must be mixed culture microbes . isolate and allow for some time succession may take place for you to know if its fungi or bacteria or algae or possibly protein micelles

Please have a look at these PDF attachments.

Nice

by LAMP vageli.

Thank you for your help. This article really helped me.

yes on two conditions that i will be allowed to start PhD in the same field at same place. find attached my cv

 Regards

ogori A.F

Dear Meilina,

PCA and PDA are used to make two different counts. You use PDA to detect yeast and mould and you use PCA to detect bacteria in general. As pH of both medium are different they tend to show different counts even if they come from the same sample.

One possible explanation is that all yeasts that could not grow at the "high" pH (around 7) of PCA are able to grow only on PDA (pH 3.5). Which would be very likely as fresh fruit tend to have a high count of yeasts and strawberries have a low pH.

It should be easy to verify this just by taking a look of at the microscope of some of your colonies just to make sure you have two different populations on each medium.

Good luck! 

Hi Karen:

That is a big issue. I think that the beads are not universal for all microbial cells and would only work specifically for some targets such as Salmonella,etc. I am afraid that you would have to consider classical methods such as filtration and centrifugation. I am enclosing a couple of references as starting point.

Best regards

Jorge

you can used preciptation with amonium sulphate or with aceton and centrifuge then check assay of enzyme after dialysis (just when used NH4SO4)

I think you mean uniform temperature inside an incubator. Well, we all know that air is a bad conductor of heat and therefore, to get even distribution of heating or cooling in any closed chamber, you must have a blower (may be for an incubator it may be a gentle blower type as compared to an oven). To keep the temperature constant your thermostat should be of a good quality.

You most welcome

Houda

Thank you! But if I want rough estimation of bacteria, ATP test is suitable?

What, precisely, is your aim? Do you just want to see the protein in the gel (e.g., for quantification), or do you want to purify the active enzyme (e.g., for kinetic measurements or industrial use)?

In the former case, I'd start with 7 M urea, 2 M thiourea, 10 mM DTT and 1%SDS. 

In the latter case detergents with fat-like structure (lyso-lipids, fatty acids, FOS-choline, LysoFos, neopentenyl glycols) may be able to to solubilise functional protein. In any case, I'd start with a careful literature search. A day in the library can save you months in the lab!

If you are trying to knock-out bacterial genes using lambda-red system, I suggest you use electroporation rather than heat shock for linear DNA. Because electroporation gives higher transformation efficiency and you need a lot of linear DNA going into bacteria to have a chance for DNA recombination! 

I could suggest you have a look on this paper for detail

When it comes to viability studies, it is common to use a cocktail of different strains, so that the study is more robust. Ideally, you could select strains that are usually found in the food you are testing (preferably those which are more difficult to kill) or even strains involved in previous food poisoning outbreaks. But if you're dealing with a project in its early stage, you can also use an ATCC strain, just to conduct the preliminary tests. Good luck!!

Dear sir

The Arabic gum will affect on the physicochemical, sensory and flow behavior characteristics of yoghurt and the recommended rat of addition from 0.2 and not more that 0.5% according to the total solid contents of yoghurt milk

shenana

Thanks so much.

phytase It is an enzyme and passes several steps of purification ..Definitely  Aspergillus niger is GRAS 

Hello dear Claudia Gentil!

Most probably it is a Helminth eggs.

Please try to write the name of this worm and you will find a lot of info in the internet.

I also have attached a document related with the microbial risks associated with cabbage.

Hope that this info will be helpful.

Have a nice day and successful research.

Sincerely,

Vitalijs

You can cook the meat so that all the bacteria are dead and ensure its sterile. Then go for doping with your Ecoli and use chemicals as you suggest as preservative.

Dear Maliha,

Low molecular weight chitosan is very potent anti-fungal substance. The following references will help you to know the details:

Hi Hoshi, thank you! The second article is close to what I'm looking for

Yes..you will need to sample aseptically (in sterile containers) and transport your samples in an iced cooler box and analyze within at least 24 hours. the faster you do the analysis the better the results and the more they will be truly representative of the original sample.

Electroporation

When you perform the total plate count you will be able to observe the growth of fungus as well as bacteria.

Once there is growth on the plate you can perform different staining techniques and after microscopic examination you can perform confirmatory spore staining 

You can go for 16s RNA gene sequencing or perform API test to determine the species of bacteria based on the biochemical reactions.

Go to a local veterinarian or vet school and ask for a sample.  Most are happy to collaborate.  You may need an IACUC protocol though.

One of the easiest approach is Ginkgo (http://qb.cshl.edu/ginkgo) . It was published for low coverage / single cell data. Check it out if you like.

Excellent answers all round. And in addition, we may consider hurdles those forms of Unit Operations with a focus on preservation, i.e. shelf-life and food safety promotion. From food technology, we see the order of unit operations adopted for any food production processes, depends on a range of factors - but mainly the type of product desired. So, I agree with Jagan above, the combination of hurdles adopted will depend on the food product. Another interesting concept is to consider parallel versus sequential/ consecutive hurdles. Examples of parallel hurdles? Storing acidified food @ low temperature produces parallel hurdles of low pH and low temperature. Products with modified atmosphere packaging are frequently stored at low temperature.

The MPN values you found you just multiply by are you collect material

If the area is 2 cm2, You just multiply by 2

chances are based on what microbe it is and how its pathogenesis takes place with respect to the host. most microbes do hold a symbiotic relationship with its host plant.

You won't get such direct reports. You must first do the basic characterisations like MW etcAnd then from any data bases for proteins you may get some data.

Hi Jag pal,

You have taken 100 ul (0.1ml) sample from your stock which you prepared by suspending 10g in 90 ml water. You have got 50 CFU/100ul  which is equivalent to 500CFU/ml. I am not using any dilution factor here as you have not diluted your sample. Now you can convert your 500 CFU/ml to grams :

As you know your 90 ml water is in 10 grams

hence 1ml will be in 10/90 = 0.111g

hence your

500CFU/ml = 500 CFU/0.111g  = 4545.45 CFUs/g

Hope it helps

Thank you Rafik Karaman. 

Hi 

Please can look in attach file 

You should look up standard analysis  documents/ standard such as British Pharmacopoeia    https://www.pharmacopoeia.com/  , some older version is downloadable  

I'm not sure what's your point. You may want to look into different flavour extraction methods. Doing the study of volatile aromatic compounds would be interesting in this case. You have to be very careful in selecting different extraction methods like SPME, Purge and Trap, SDE. It is always better to combine different extraction methods to find the best result. I would suggest you to use two dimentional GC, in coupling with TOF (GC × GC/TOF-MS). This is very sensitive and recently used technique. 

 Kefir grain contains mixture of different LAB and yeast species. It is not impossible bu so difficult. I agre with Prof.Dr. Bozanic. You can create kefir culture.

The decrease in pH may be due to production of organic acids. I just think the increase in pH observed after the decrease may be due to some of these acids (eg lactic acid) are metabolized (act as substrate) to support microbial growth. Because this reduces the concentration of the acid hence an increase in pH. To  ascertain this you need to measure titratable acidity (TA) too and see how that changes along the course of microbial growth.

Dear Diptiman Choudhury basend on my knowledge about gut colonization by Lactobacillus I think that the result of your research could be reached:

1 - using (or isolating) a Lactobacillus strain endowed with high adhesion properties to human gut ;

2 - growing it under condition promoting adhesion

3 - carrying out in vitro experiment to verify if it can adhere after different killing treatment (please note that many molecules involved in adhesion are sensitive to physico-chemical treatments)

4 - verify in in vivo experiments (eg. mouse) the best result from step 3 so, in addition, to understand how long it can colonise (or persist in) the gut

The immunostimolation by dead lactobacillus cells should have been already published (sorry I do not remember the paper!) so you can take advantages from that results.

However, in order to reach you goal I have some problem to understand your previous questions.

Wishing you successfull experiments

Best regards

FBaruzzi

Dear Geoffrey Onserio Nyamagwa, First of all you have to optimize the growth of Bacillus amyloliquefaciens. For this you have to take Nutrient broth and from many literatures it is found that the pH is 7.0 and temp. is 30-40 degree celcius for Bacillus amyloliquefaciens. What ever it may be strains varies therefore you have to optimize the growth by changing pH and temp. and use shaker incubator of above 150 rpm. Hope it will help You. All The Best.

-AKM

Hello

You can add some additives  for food , It is prebiotis 

exp. 1-add Arabic gum in ice cream  is increase the probiotic bacteria and I now work on add Arabic gum in yogurt .

2-Fermented onion is increase the probiotic , onion is prebiotic  

vickie - e-mail me.. The question is how you know it's a false positive in the Bax; could be a false negative in the "standard method" too. 

You need some more N source for good bacterial growth.  Peptone or yeast extract would be good or if you want to keep it defined, ammonium chloride or nitrate.  You do need to be sure there is enough oxygen for growth. 

Cellulose won't be affected by acid.  You can collect the pellet and wash with HCl.  if you want to wash with base you need to add sodium borohydride to protect the cellulose from the base.  Base will likely alter the crystalline structure.

Please, make sure the inoculation size  of bacteria and isolation  source must be from  Human sources 

Yes the serotype of C. muytjensii strain 51329 is Cmuy O:2.  See

Jarvis, K.G., Yan, Q.Q., Grim, C.J., Power, K.A., Franco, A.A., Hu, L., Gopinath, G., Sathyamoorthy, V., Kotewicz, M.L., Kothary, M.H., Lee, C., Sadowski, J., Fanning,S., Tall, B.D., 2013. Identification and characterization of five new molecular serogroups of Cronobacter spp. Foodborne Path.Dis. 10, 343-352.

 

Dear Bridget,

This might help you a little.

Excellent Stephane, Thank you so much. you have answered my question perfectly. 

For your information, I am developing a specific method for marine yeast isolation that is why there are yeast and mold together.

The number of yeast cells and mold is not known to me but both in the seawater sample.

I used the YPD broth as enrich media as  explained before for 2 days then used the culture to inoculate a fresh media for 2 days then inoculate a fresh media for another 2 days 

this method is published briefly here https://www.researchgate.net/publication/261719490_Marine_Yeast_Isolation_and_Industrial_Application

but now I am writing a research article with full details on the isolation method, characterization  and identification of marine yeast. 

so many thinks a gain and if you have supporting reference for what you explained will be very much appreciated 

Abdelrahman