Effect of Agitation Speed and Incubation Time on Amylase Production by Bacillus Species Isolated from Malted and Fermented Maize (Zea mays)

Abstract

Aims: The effect of agitation speed and incubation time on Bacillus species growth and amylase production isolated from malted and fermented maize were investigated. Study Design: An experimental study. Methodology: Bacillus species were screened for amylase production using starch hydrolysis method on starch agar. Bacillus sp.IBM21 was observed to exhibit highest hydrolytic activity with zone of clearance of diameter 41.6mm. Process parameters optimizations were evaluated using submerge fermentation techniques. Results: The effect of agitation speed on growth and amylase production was varied from 100-250 rpm. It was observed that, the amylolytic Bacillus species were able to grow optimally at agitation speed of 100 rpm while their highest amylase activities were recorded at speed of 150 rpm for Bacillus sp.IBM22, 10.16Um-1 and 200 rpm for Bacillus sp.IBM21, 5.59Um-1. The effect of incubation time was varied from 12-72h, amylase activities as well as bacterial growth increases with increase in incubation time until peaks were attained at 36h (10.16Uml-1, OD540nm, 2.98) for Bacillus sp.IBM22 and 48h ( 5.5Uml-1, OD540nm 1.55) for Bacillus sp.IBM21. Conclusion: The results of this study indicate that Bacillus species isolated from malted/fermented maize produced amylase maximally at optimal agitation speed and incubation time ranges of 150-200rpm and 36-48h respectively.