Production of protease from biodiesel waste derived semipurified glycerol

Abstract

Glycerol generated as the by-product of biodiesel production from vegetable oil or animal fat, has increased the availability of crude glycerol in the market. New strategies need to be developed for the utilization of this abundant carbon source. Using biodiesel waste derived semipurified glycerol as the carbon source, <em>Bacillus</em> <em>amyloliquefaciens</em>, <em>Bacillus</em> <em>megaterium</em> and <em>Bacillus</em> <em>cereus</em> were compared for the production of protease, an industrially important enzyme. Results showed that the medium with 1% semipurified glycerol was an effective carbon source for protease production by these organisms. In addition to glycerol concentration, the parameters such as temperature, pH, incubation period and volume of the inoculum were optimized to increase the protease production. Among the three <em>Bacillus</em> <em>species</em> studied, <em>B. amyloliquefaciens </em> was found to be the best producer of protease. A maximum protease production of 543.95 ± 1.84 U/mL occurred at 48 h with the pH of the medium 9.0, and an inoculum density of 2.6 × 10⁸ cells mL^-1 at 45°C by <em>B. amyloliquefaciens.</em>