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Journal of Biological Sciences

Year: 2005 | Volume: 5 | Issue: 2 | Page No.: 193-200
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Authors

Md. Mozammel Hoq

Khandaker Al Zaid Siddiquee

Hiroko Kawasaki

Tatsuji Seki

Keywords

Eight bacillus bacteria newly isolated from the effluents of tannery and poultry farms using a feather enrichment technique were identified on the basis of 16S ribosomal RNA gene sequence analysis, physiological and carbohydrates assimilation tests. Of them, 3 isolates were revealed as the strains of Bacillus licheniformis, two as B. cereus group and one each of B. subtilis, B. borstelensis and B. sphericus. Most of them demonstrated significant levels of keratinolytic protease on keratinous substrates (feather meal or hair keratin) in basal medium as a sole source of carbon, nitrogen and sulphur at 37°C and pH 8.0 in shake culture. Supplementation of yeast extract and molasses with feather in the basal medium increased the enzyme activity by most of the bacillus cultures. Commercial feather meal supported higher activity than that of commercial keratin powder. Of the bacillus species, B. subtilis MZK-7 and three strains of B. licheniformis displayed higher levels of keratinolytic activity under comparable conditions. The enzyme activity was found to be a function of cultivation times by different bacillus cultures. B. borstelensis MZK-6 had reached to its maximum activity after 32 h while the others did the same after 48 to 60 h on feather meal. The hydrolysis of synthetic peptides tested suggests that, among others, the enzymes from B. licheniformis strains and B. subtilis MZK-7 possess high levels of chymotripsin like (active towards Suc-Ala-Ala-Ala-pNA) and proteinase-K, elastase and subtilisin like (active towards Suc-Ala-Ala-Pro-Phe-pNA) protease activities. The protease inhibition studies with the enzymes from B. licheniformis strains and B. subtilis MZK-7 demonstrated the enzyme as serine protease while that of from B. borstenlensis MZK-6 and two strains B. cereus group demonstrated the neutral protease. The present results will be a useful basis for future studies on biotechnological production and application of keratinolytic enzymes.
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