Screening of Various Organic Substrates and the Development of a Suitable Low-Cost Fermentation Medium for the Production of a-Amylase by Bacillus subtilis

The production of extracellular amylase by Bacillus subtilis has been studied in solid-state fermentation (SSF). In a sequential order, various process parameters were optimized for maximum amylase production. The tested process parameters were different solid substrates such as banana husk (BH), water melon husk (WMH), lentil bran (LB), wheat bran (WB), melon husk (MH) and maize oil cake (MOC), different incubation time (24–144 h), particle size (500–2500 mm), initial moisture content of the substrate (40–70 %, by mass per volume), inoculum size (10–60 %, by mass per volume) and inoculum concentration (10–60%, by volume per mass). The maximum production of amylase (4857 U/mg) was achieved when 1 % starch (by mass, particle size of 1500 mm) was added to banana husk as the solid substrate, fermented for 72 h at 37 °C, at an inoculum level of 30 % (by volume per mass), and initial moisture content of 60 % (by volume per mass).