SCREENING THERMOPHILIC BACTERIA PRODUCING THERMOSTABLE α-AMYLASE ISOLATED IN VIETNAM
Nguyễn Thế Trang
Nguyễn Thị Đà
Trần Đình Mấn
Abstract
Strains ML04, ML05, ML06, ML07, ML08, ML09, LP09, LP10 and LP11 were isolated from My Lam hotspring in Tuyen Quang province and La Phu hotspring in Phu Tho. All these trains were cultured in mineral - starch medium. LP09 strain has showed the largest α-amylase activity in this medium. LP09 is a Gram positive, non - motived bacterium and could grew in high temperature (75oC). API 50 CHB Kit was used for classification LP09strain. According result of Nazina’s morphology and API Kit, LP09 belongs to Geobacillus genus and has called Geobacillus sp. LP09. The strain was cultured in liquid mineralmedia with 1 % soluble starch to produce α-amylase. The influence of the carbon source on α-amylase production by Geobacillus sp. LP09 was investigated using different carbon sources: soluble starch, rice flour, corn meal and tapioca. It showed maximum activity with 2 % soluble starch (14,6 UI/ml). Studies the enzyme production conditions of the newly isolatedGeobacillus revealed that the maximum enzyme production after 48 h of cultivation at pH 7, 65oC