Sunday, April 29, 2007

Screening and optimization of medium composition for alkaline protease production by Bacillus sp. RKY3 through statistical approaches

Lebaka Veeranjaneya Reddy1, Young-Jung Wee2, and Hwa-Won Ryu2. (1) Higher Education Center for Bioregulator Research, Chonnam National University, Gwangju 500-757, South Korea, (2) School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, South Korea

Proteases, also known as peptidyl-peptide hydrolases were important industrial enzymes occupying 60% of enzyme sales and extensively used in industries like detergents, meat tenderization, cheese making, dehairing, baking, brewery, production of digestive aids and silver recovery from photographic film. Due to its increased economic importance research is being extensively carried out throughout the world to isolate strains for the efficient production of protease and also to optimize the various fermentation parameters, including medium composition and culture conditions for maximizing its production.

In view of this we isolated one microorganism from the soil and that was identified to be closely related to Bacillus subtilis subsp. subtilis ATCC 6051 on the basis of partial 16S rRNA gene sequence homology. We applied statistical method, Plackett-Burman design to screen and select the best carbon and nitrogen sources for the production of alkaline protease. From these experiments we selected four components as significant factors, starch, corn steep liquor, yeast extract and inoculum size. From the preliminary experiments 550 U/ml protease could be obtained. In the next stage we are planning to enhance the protease production by optimizing the culture conditions and medium composition through a central composite design of response surface methodology.