BACTERIAL ISOLATES OF MARINE COAST AS COMMERCIAL PRODUCER OF PROTEASE

Abstract

The objective of this work was to explore and exploit the extracellular protease secreting marine microbial biodiversity of the eastern coastal region of India. Culture dependent method was applied for isolation of microbes from the marine coast of West Bengal (Digha and Mandarmani) and Andhra Pradesh (Vizag) in India. Six protease secreting isolates were screened using casein hydrolysing property as well as azocasein assay and characterized on the basis of their morphological, biochemical, physiological and 16S rDNA based molecular properties. The enzymes were used for various commercial applications at a laboratory scale. Besides milk media and Luria Bertini broth, all the isolates grew in carbon minimal salt medium with jaggeri or tamarind as the carbon source (0.3% w/v). They showed intracellular metal accumulation when grown in presence of metal salts in the medium as evident from Energy Dispersive X-ray Fluorescense Analysis (EDXRF) data. Maximum accumulation of lead was found in case of Bacillus cereus SM2. It showed equal efficiency of metal removal from solid strip at zero valent state. The isolates were also capable of complete removal of silver from exposed X-ray film after 48 hrs of incubation except for Escherichia coli SD1. Bacillus cereus SM2, isolate SD2 (closest to Bacillus pumilus) and isolate SV1 (closest to Bacillus cibi) were able to enhance the cleaning efficiency of detergent when used as additive. Use of tamarind and jaggeri as carbon source in minimal medium would make the process cost effective during large scale application. The ability to grow in a wide range of temperature and pH and accumulation of heavy metals revealed that these isolates would be potential candidates for bioremediation. Thus the marine diversity for protease production is extremely rich with immense commercial applications.