Studies on Proteolytic Psychrotrophic Stenotrophomonas maltophilia from Milk and Fermented Milk Products

Psychrotrophic bacteria are able to multiply in a cold environment (7 degrees C) during refrigerated storage of milk and fermented milk products. They also produce heat resistant exoenzymes such as protease, lipase which degrade protein and fats in milk and milk products and contribute in spoilage of dairy products during refrigerated storage. Ten dairies from Nashik region of Maharashtra in India were assessed for studying the psychrotrophic bacteria present in milk and fermented milk products. During searching of such psychrotrophic bacteria from milk and fermented milk products, one of the isolate was identified as Stenotrophomonas maltophilia on the basis of morphological, biochemical, physiological features as well as 16SrRNA sequencing. The base sequence of the isolate was submitted to NCBI GenBank to assign the accession number. The isolate was also analyzed for protease production at refrigeration temperature. The protease enzyme was estimated by qualitative as well as by quantitative methods. Enzyme shows optimum activity at pH of 7 and at 35 degrees C within 10 minutes.