Eight different low cost starchy agroresidues
namely Barley (B), Wheat bran (WB), Sattu (S), Rice
powder (RP), Corn flour (CF), Rice husk (RH), Yellow
peas split (YPS) and arrowroot (A) were used for solid
culturing of
Bacillus subtilis
DJ5 for production of novel
hyperthermostable β amylase. Various process parameters
like initial moisture content, inoculum load, medium pH
and incubation temperature affecting enzyme production
were optimized to ensure maximum enzyme yield. Only
10 % inoculums load and medium pH of 6.9 was found
sufficient to achieve maximum enzyme production in all
substrates in a decreasing order, B>WB>S>RP>
CF>RH>YPS>A. Optimum β amylase production
was highly dependent on initial moisture content of substrate
as observed from varying requirement of moisture
for different substrates. Only 50 % moisture was sufficient
for maximum enzyme production of 84.29 U/gdm in CF.
For B, RH, YPS, and A 60 % initial moisture resulted in
higher production of 120.34, 35.19, 26.59, and 21.58 U/
gdm, respectively, at 37 °C. However, for S and RP higher
(70 %) moisture content allowed 113.4 and 85.56 U/gdm
enzyme production, respectively. Under optimized conditions,
maximum β amylase production was observed after
25 h for A, YPS, RH, RP; 41 h for B, WB, CF, and 45 h
for S.
