Abstract

Bertrand Tatsinkou Fossi*, Frédéric Tavea, Celine Jiwoua and Robert Ndjouenkeu

One hundred and nineteen amylases producing strains (29 yeasts and 90 bacteria) were isolated from some Cameroonian soils contaminated by starchy residues and screened for thermostable amylases production. Phenotypic characterization of these amylases producing strains revealed the prominence of ascomycetous yeasts and two kinds of bacteria; the aerobic endospore forming dominated by Bacillus spp and aero-anaerobic non spore forming bacteria dominated by lactic acid bacteria of Lactobacillus spp. Among yeasts, one designated 04LBA3 produced high title of very high thermostable amylase. It was able to provoke starch hydrolysis halo of 33.7???1.5 mm on starch agar plate, and produced 80 ???0.5 U/ml of amylase in starch broth after 48 h of incubation at 30°C. Concerning amylases producing bacteria, two isolates designated 04BBA15 and 04BBA19 showed very high amylolytic power, the values were 55.0???3.2 mm and 45.3???1.5 mm of starch hydrolysis halo respectively for 04BBA15 and 04BBA19. Amylase production in starch broth were 131.0 and 107.7 U/ml respectively for 04BBA15 and 04BBA19 after 48 h of incubation at 40°C, on the other hand, their crude amylase extract remained 100% of original activity after been heated at 80°C for 30 min. The strain 04LBA3, 04BBA15, 04BBA19 were respectively identified as strain of Schwanniomyces alluvius, Bacillus amyloliquefaciens and Lactobacillus fermentum. Cluster analysis on the basis of amylolytic activity and thermostability of crude amylase extract showed similarities between strains of same geographic origin, this observation allows us to suggest that amylase activity and thermostabilty can serve as indicators for micro-organisms traceability.