I am trying to find the microbial count, Specifically a) total aerobic microbes b) total yeast and mould C) E.Coli and d)Salmonella sp.
Could anyone suggest a medium for enumeration of above microbes?
You can use Soybean casein digest agar for total aerobic microbial count. For total yeast and mould you can use Sabouraud dextrose agar.
To test E.coli in sample, first add pretreated -incubated sample to sterile macconkey broth and after further incubation subculture on Macconkey agar.
For salmonella, add pretreated-incubated sample to RVSE broth and after incubation subculture on XLD agar plate.
Standard test procedure described in USP chapter 61 and 62. Refer this.
You can use Soybean casein digest agar for total aerobic microbial count. For total yeast and mould you can use Sabouraud dextrose agar.
To test E.coli in sample, first add pretreated -incubated sample to sterile macconkey broth and after further incubation subculture on Macconkey agar.
For salmonella, add pretreated-incubated sample to RVSE broth and after incubation subculture on XLD agar plate.
Standard test procedure described in USP chapter 61 and 62. Refer this.
There is no way to measure absolute microbial count using cultivation dependent practices. But, you can get a rough idea about those species which are cultivable. From here you can speculate but it would not be absolute count for all bacteria. For such a purpose, you have to go for NGS analysis...
Hello Puhazh, it looks like you are interested in working with cultivable microbes. If that is the case then you should adopt the expression "Total aerobic bacterial count" and not total aerobic MICROBIAL count, since you have already separated yeast and mold counts. For economic reasons, you could use Plate Count Agar (PCA) for total aerobic bacteria, Potato Dextrose Agar (PDA) for molds, Yeast extract-Malt extract Agar (YMA) for yeasts, Shigella-Salmonella (SSA) agar for Salmonella and Eosine Methylene Blue (EMB) agar for Escherichia coli. Otherwise, Ayushi's suggestions work well.
You should specify the type of sample you want to analyze. Not all the media are good for all kind of samples.
It depends upon the type of sample you are working on, for example, if it is water, the medium suggested is Tryptone glucose soy agar/ Tryptone soy agar, Reasoner's 2A medium, for isolating viable aerobic bacteria. However, membrane filtration, followed by culturing of membrane is also done.
If, however, your sample is processed/ semi-processed ingredient (as you work in leather research), the process should be more elaborate, first involving a step of homogenization or culture in liquid medium such as nutrient broth/ tryptic soy broth, followed by a concentration, such as centrifugation, finally to be cultured on solid medium. All steps need to be standardized.
Finally, for specific organisms, selective media have to be used as mentioned in previous answers.
Thank you for all for valuable suggestions. Especially Dr. Maurice Ekpenyong and Dr. Ayushi Hirpara
what type of sample do you want to analyse? different medias are appropriate for different samples.
- The spread plate relies on bacteria growing a colony on a nutrient medium so that the colony becomes visible to the naked eye and the number of colonies on a plate can be counted.
- Selective media can be used to restrict the growth of non-target bacteria.
- The pour plate method is used when the analysis is looking for bacterial species that grow poorly in air, for example water samples.
Hello Dr. Selvan, You can use Plate Count agar for total aerobic bacterial count, Chloramphenicol Yeast Glucose Agar for enumeration of yeast and mould. For E.Coli Mac Conkey agar or EMB agar. For Salmonella sp Xylose Lysine Deoxycholate agar is recommended.
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