Cold-adapted microorganisms are widely distributed in nature and form a major part of the Earth’s microbial population. Artificial cold environments such as refrigeration systems represent a small part of their total habitats. The present study aimed to isolate psychrotrophic bacteria from refrigerated milk and evaluate their ability to produce hydrolytic enzymes. The psychrotrophic count ranged from 58–85 × 10² CFU/ml using the serial dilution and plate count method. Among the isolates obtained, was identified based on morphological and biochemical characteristics with reference to Bergey’s Manual of Determinative Bacteriology (9th edition). The identification was further confirmed by 16S rRNA gene sequencing. The isolate showed enzyme production at different temperatures and pH levels. Maximum protease activity (0.28 U/ml) was observed at 20°C and pH 7. The activity decreased at temperatures and pH values above or below this optimum. These results indicate that Ornithinimicrobium humiphilum SSoC1 can produce cold-active protease enzymes and may have potential industrial applications.
Syed Nisar Ahmed* (Mon,) studied this question.