Published on August 2019 | Solid-state fermentation, microbiology
Amylase production on different agrowastes by Bacillus subtilis KR1 sp. strain (accession number KX354353) under solid-state fermentation was carried out. Among the various agro-waste residues, wheat bran was the most effective substrate for amylase production (82.60±0.636 U/gds). 10% v/w was optimum inoculum size for amylase yield (86.014±0.464 U/gds). KR1 showed optimum amylase titer after 48 hours (82.02±0.351 U/gds). Among different mineral salt solutions, moistening agents (MAII, - KH2PO4 - 11 .0; NaH2PO4 - 6.1; KCI 3.0; MgSO4 7H20 - 0.1-pH 7.2 in g/L.) was the best inducer of amylase production (81.68±1.07 U/gds). Optimum pH and temperature for amylase production were pH 7.5 (83.87±0.716 U/gds) and 40°C (91.22±0.971 U/gds) respectively. Among different supplementary carbon and nitrogen sources, soluble starch (126.15±0.844 U/gds) and yeast extract (93.06±0.958 U/gds) were optimum inducers. Among different metal ions, calcium acted as the best inducer of amylase titer (103.43±0.64 U/gds). In addition, pretreated wheat straw was used for amylase production and it was found that combinatorial treatment of steam and irradiation (50 kGy) was found to be the most effective inducer of amylase (201%). In addition the strain under study was halotolerant, thermotolerant and alkalitolerant so it holds promise for various industrial applications.