E. S. Nam and J. K. Ahn
The cold-adapted bacteria producing lactose hydrolyzing enzyme were isolated from the soils of Nome area in Alaska. The strain KNOUC601was rod, stained negatively in Gram stain. It grew optimally at 30â�?�? and pH 8.0-8.5, and utilized glucose, maltose, sucrose, mannose, galactose, lactose as carbon source. This strain was aerobic asporogenic bacilli, immobile, catalase positive and oxidase negative. Based on physiological and biochemical properties, the strain could be presumably identified as Rahnella sp., finally as Rahnella aquatilis by phylogenetic analysis based on 16S rDNA sequence, and the strain was named as Rahnella aquatilis KNOUC601. The optimal conditions for ONPG hydrolysis of cell free extract from the strain were 15â�?�? and pH 7.8. It retained activity higher than 90% of maximum activity at refrigerate temperature. Zymogram assay of cell free extract from the strain in nondenaturing polyacrylamide gel showed a distinct band of X-gal hydrolysis. The strain Rahnella aquatilis KNOUC601 has high possibility to produce lactase available for practical use at refrigerate temperature.
Share this article