Growth Optimization of Thermophilic Bacteria Bacillus thermoamylovorans and Brevibacillus sp. in Producing Keratinolytic Enzyme

Abstract

Some thermophilic bacteria have been isolated from Tanjung Sakti hot spring. Two isolates which qualitatively showed keratinolytic activity, identified as Bacillus thermoamylovorans and Brevibacillus sp., were optimized the growth in producing keratinase enzyme. Keratinase is a group of proteolytic enzyme which able to hydrolyze insoluble protein (keratin). In this research, whole chicken feathers were used as keratin substrate. The growth curves and measurement of keratinase enzyme activities were determined to the isolates, with a span of measuring 4 hours during 48 hours incubation, and gained the growth and optimum enzyme activity at 28 h incubation. The isolates were then observed the growth and keratinase activity at several different temperatures and pH. The results showed that the optimum temperature and pH for both isolates were same, i.e. at temperature 70° C and pH 7. The effect of adding a source of carbon and nitrogen into the medium were also observed. The growths of both isolates were increased on the addition of 1% glucose and 0.4% casein.