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Cow dung: a potential biomass substrate for the production of detergent-stable dehairing protease by alkaliphilic Bacillus subtilis strain VV

Ponnuswamy Vijayaraghavan1*, Aija Vijayan2, Arumugaperumal Arun3, John Kennady Jenisha3 and Samuel Gnana Prakash Vincent1

Author Affiliations

1 International Centre for Nanobiotechnology, Centre for Marine Science and Technology, Manonmaniam Sundaranar University, Rajakkamangalam–629 502, Kanyakumari District, Tamil Nadu, India

2 Centre for Marine Science and Technology, Manonmaniam Sundaranar University, Rajakkamangalam–629 502, Kanyakumari District, Tamil Nadu, India

3 Department of Biotechnology, Kalasalingam University, Virudhunagar, Srivilliputtur, 626 126, Tamilnadu, India

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SpringerPlus 2012, 1:76  doi:10.1186/2193-1801-1-76

Published: 22 December 2012

Abstract

Cow dung, a cheap and easily available source of energy, was used as the substrate for the production of alkaline protease by solid-state fermentation using the Bacillus subtilis strain VV. In order to achieve the maximum yield of this enzyme, the following optimum process parameters are needed: fermentation period (72 h), pH (10.0), moisture content (140%), inoculum (25%), temperature (30–40°C), carbon source (2% (w/w) maltose) and nitrogen source (1% (w/w) urea). The protease was stable over a broad temperature range (30–50°C) and pH (8.0-10.0), with maximum activity at 50°C and pH 10.0. Among the divalent ions tested, Ca2+ (0.01 M) increased enzyme activity. The purified protease, after being subjected to sodium dodecyl sulphate-polyacrylamide gel electrophoresis, was found to have a molecular mass of 38.5 kDa. The enzyme was solvent-and surfactant-stable and showed activity even after 24 h incubation along with various commercially available detergents. This enzyme possessed dehairing properties for animal hide after 16 h of incubation at room temperature. From these results it is evident that cow dung is a potential substrate for the production of a detergent-stable, dehairing protease by B. subtilis. This enzyme has a lot of potential applications in the detergent and leather-processing industries.

Keywords:
Cow dung; Solid-state fermentation; Bacillus subtilis strain VV; Alkaline protease; Detergent-stable