UV Induced Increase in Activity of Subtilisin from Bacillus subtilis MTCC441

Abstract

Microorganisms are constantly exposed to varying physical, chemical and biological conditions which induce morphological, biochemical and genetic changes in them. These changes may be deleterious to some organisms whereas others develop mechanisms to overcome such stresses. This study was conducted to understand the microbiological and biochemical changes in bacteria under conditions of UV stress. Bacillus subtilis MTCC441, a ubiquitous, spore forming bacterium was chosen as the model organism for this study as it is a very hardy organism and can resist several environmental stresses. It has developed several mechanisms to overcome stress. One such mechanism is the production of Subtilisin protein. Subtilisin, a biosurfactant and serine endopeptidase helps to counter stress in several ways by inhibiting the growth of competing organisms, regulating cell number in its colonies and also acting as an antioxidant. On exposure to UV stress, growth and viability of the culture is found to reduce. It is observed that the organism tries to overcome these stresses by sporulation and production of Subtilisin. As far as our knowledge goes, this is the first report on UV triggering the production of Subtilisin in Bacillus subtilis. With increase in time of UV exposure a corresponding increase in the specific activity of Subtilisin was observed. It is to be concluded that UV acts as a stressor for Bacillus subtilis and it in turn tries to counter stress by producing Subtilisin.
Key words: Bacillus subtilis, Subtilisin, UV, Specific activity, Stress, Sporulation