Explain Theory or Principle of Gram Staining of Bacterial Cultures?

Foods are rich in various nutrients and can support the growth and survival of microorganisms. The microbial load on foods vary depending on the way they are produced, processed, transported and handled. These microorganisms can deteriorate the food and may be responsible for causing food borne diseases, which sometimes, may be serious and fatal. Therefore, it is essential to analyze the food samples for the microbial quality. Presence of coliforms by using multiple tube technique indicates the possibility of feacal contamination and presence of pathogens in a sample.

By SPC, presence of large number of microbes suggests poor sanitary and hygienic conditions, temperature abuse, inadequate processing or post processing contamination and there are increased chances of food spoilage. One type of medium and incubation conditions may not necessarily reveal the total number of microbes in a food sample and may not be suitable for all samples. The various procedures and techniques can be used for microbes determination in a food sample depending on the purpose. The Standard Plate Count (SPC) is one of the most widely used method for enumerating the microbes and to know the microbiological quality of the food samples. Both pour plate and spread plate techniques can be employed.