title: Isolation, screening and characterization of thermophilic Bacillus species isolated from dairy products.
abstract: Proteolytic thermophilic bacterial cultures (171 strains) were isolated from different milk and milk products. After screening these isolates for protease production in a liquid medium, fifty that exhibited enzyme activity in excess of 100 units/ml were selected and identified. Twenty-nine were Bacillus stearothermophilus (constituting 58% of the total), twelve were B. coagulans, five were B. circulans and four were B. licheniformis. Skim milk powder contributed the maximum number of B. stearothermophilus (64.7%) followed by raw milk (63.2%) and pasteurized milk (44.4%). When the culture supernatant liquids from the selected isolates were given heat treatment, five cultures retained 100% protease activity at 65 degrees C for 30 min. Protease of B. stearothermophilus RM-67 had the maximum heat resistance because it retained 87.5% of its activity at 70 degrees C for 30 min.
mesh_terms: D000818:Animals; D001407:Bacillus / Q000201:enzymology / Q000302:isolation & purification*; D001419:Bacteria / Q000378:metabolism; D002417:Cattle; D003611:Dairy Products; D005516:Food Microbiology; D001411:Geobacillus stearothermophilus / Q000201:enzymology / Q000302:isolation & purification / Q000378:metabolism; D006358:Hot Temperature; D007225:Infant Food; D008892:Milk / Q000382:microbiology*; D008894:Milk Proteins / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism
chemical_list: D008894:Milk Proteins; D010447:Peptide Hydrolases