SCREENING, ISOLATION, CHARACTERIZATION AND IDENTIFICATION OF ALKALINE PROTEASE PRODUCING BACTERIA

Proteases are an

important group of industrial enzymes and they make up the largest portion of

the entire global enzyme sales. They hydrolyze complex proteins to amino acids

and peptides. Proteases have numerous applications in many industries such as

detergent industry, leather industry, food industry, paper and pulp, silver

recovery from photographic films and bioremediation processes. Although

protease enzymes are widespread in nature and synthesized by plants, animals,

and microorganisms, the preferred protease sources are microbial sources

because they can grow and reproduce quickly and easily, produce enzymes with

high efficiency in simple nutrient media, can be easily manipulated

genetically, can grow in extreme heat, cold, acidic and basic conditions, and

can produce enzymes that can work under these conditions.<o:p></o:p>

The aims of the

present study were isolation, screening, and identification of alkaline

protease producing novel bacteria from water samples of Van Lake. For

prescreening of protease producer bacteria, nutrient agar medium containing 10%

skim milk was used. Among 60 isolates growing at pH 8 and higher, 9 isolates

were chosen as potent alkaline protease producers. These isolates were

identified based on their 16S rDNA sequence analyses, morphological and

biochemical characteristics. Identified strains were further subjected to

quantitative protease activity assay using casein as the substrate. Most potent

isolate was alkaliphilic Exiguobacterium

alkaliphilum strain VLP1 (GenBank Acc No: ON853834.1). Exiguobacterium is a genus of firmicute in the order Bacillales. E. alkaliphilum VLP1 has orange-colored and round colony form with

bacillus cell shape. It is an alkaliphilic, non-motile, Gram (+), catalase (+),

urease (-), hemolysis (-), lipase (-), amilase (-), celulase (-) bacterium.<o:p></o:p>