Abstract
An α-amylase producing bacterial strain was isolated from sago factory effluent discharged soil and identified as Bacillus cereus. Production of extracellular α-amylase by B. cereus was studied in solid-state fermentation. Different substrates like wheat bran, maize bran, corn bran, millet bran, rice bran, greengram bran, blackgram bran, cassava peel powder, cotton seed oil cake, coconut oil cake, sesame oil cake and groundnut oil cake were screened to select the suitable substrate for the production of α-amylase. Among the agro-wastes, wheat bran was found to be the best substrate. Various physical and chemical parameters were optimized. Maximum α-amylase yield was achieved at pH 7 with inoculum level of 10% at 50°C and an incubation period of 72 h. The optimum ratio of substrate to moisture level was found to be 1:2 and substrate weight to flask volume was 1:50. Supplementation of starch at 1% (w/w) concentration and yeast extract at 1.5% (w/w) concentration resulted in maximum production of α-amylase. Calcium chloride at a concentration of 1% (w/w) was found to stimulate α-amylase production. Thus, B. cereus produced a high titre of α-amylase in solid state fermentation using inexpensive agro-residue under optimized conditions. Key words: α-Amylase, Bacillus cereus, solid-state fermentation, optimization.
Highlights
Α-Amylases (α-1,4-glucanohydrolases,E.C.3.2.1.1) are endo-amylases that catalyze the hydrolysis of α-D-(1,4) glycosidic linkages in starch components or related carbohydrates, releasing malto-oligosaccharides and glucose in the α-anomeric form (Nazmi et al, 2006)
Many agro-industrial by-products such as wheat bran, rice bran, molasses, barley bran, maize meal, soybean meal, potato peel and coconut oil cake have been screened as low cost solid substrates for microbial production of α-amylase in solid-state fermentation (Shukla and Kar, 2006)
The bacterial isolates were grown in liquid broth and the amount of α-amylase production was determined in cell free supernatant
Summary
Α-Amylases (α-1,4-glucanohydrolases,E.C.3.2.1.1) are endo-amylases that catalyze the hydrolysis of α-D-(1,4) glycosidic linkages in starch components or related carbohydrates, releasing malto-oligosaccharides and glucose in the α-anomeric form (Nazmi et al, 2006). The potential for commercial application of α-amylases is enormous It is a key enzyme in the conversion of starch to sugar syrups, production of cyclodextrins, preparation of digestive aids, production of chocolates, cakes and fruit juices. They are very extensively used in beverages, baby foods and pharmaceutical industries. Many agro-industrial by-products such as wheat bran, rice bran, molasses, barley bran, maize meal, soybean meal, potato peel and coconut oil cake have been screened as low cost solid substrates for microbial production of α-amylase in solid-state fermentation (Shukla and Kar, 2006). In this paper we have reported the factors that influence maximization of α-amylase production by B. cereus
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