摘要：Amylases are extracellular enzymes of great industrial interest. Present study was planned with the objectives- comparison and screening of best α-amylase producer bacteria, effect of PEG 4000 in different concentrations on α-amylase production and, recovery of α-amylase from crude extract, concentrate and ultra-filtrate. It was found that Bacillus amyloliquefaceins had 39.5 mm and Bacillus subtilis 29.5 mm diameter of zone of clearance on starch agar medium, while the isolate from soil showed much lesser (5.5 mm) zone of clearance. Therefore, Bacillus amyloliquefaceins strain was best α-amylase producer than others. Medium with 7 and 2% PEG concentration showed 30 times higher alpha amylase activity than medium without PEG. Furthermore lower concentration of PEG 2% showed promising results as compared to PEG 7%. The highest concentration of α-amylase (2690 U mL-1 of cf) was found in sample concentrate, which is nearly ten times higher than the original sample (260 U mL-1). Theoretically ultra filtrate should not have any amylase activity but in our result it was 89 U mL-1. Present study suggests that B. amyloliquefaceins is the best bacterial strain to produce maximum quantity of α-amylase in the medium containing PEG 2%.
