Question

Food Microbiology Laboratory question,

**********Question********** (PLease help me to figure out the answers after reading/ using following text, thx a lot)

1. Deeply analyse and explain the result of this lab (results is provide in the following text)

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Laboratory: Microbiological analysis of food products (3M Petrifilm E.coli/Coliform (EC) count plate)

Used media:3M Petrifilm E.coli/Coliform (EC) count plate

3M EC count plates are designed to identify both E. coli and other coliforms. It contains crystal violet and bile salt which can inhibit gram-positive bacteria. E. coli will produce blue precipitate after reacting with the glucuronidase activity indicator. Coliform bacteria will ferment lactose contained in the EC count plate and produce acid, which will turn pH indicator into red color.

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Food products used: 2 Char sui samples (Store at 4°C and room temperature for 20 hours)

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Procedure:

3.1 The 3M™ Petrifilm™ E.coli/Coliform Count Plate provides a confirmed result of coliform and E. coli enumeration in 24 to 48 hours. It eliminates the confirmation steps and reduces the detection time and overall lab costs.

3.2 Open the cover of the Petrifilm, pipette 1 ml 10-1 dilution and 1 ml from 10-2 dilution from both food samples, on each of a 3M Petrifilm E.coli/Coliform Count Plates. (A total of 4 Petri-films for 2 food samples)

3.3 Incubate plates at 37oC for 24h. Confirmed E. coli coliforms are blue colonies with associated gas bubbles.

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Results:

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Answer 1

coliforms have optimum temperature around 37 degree celsius. At 4 degree celsius the growth of coliforms are reduced due to reduced cellular metabolism. when food are stored at 4 degree celsius, due to reduced metabolism of bacteria, spoilage is delayed. Food remains fresh for longer time. When food is kept at room temperature, elevated temperature causes higher metabolism, which causes increase in growth of microbes. This causes sopilage of food. This is why at 4 degree celsius there is less coliform present, where as at room temperature there is more no. of coliforms.