Full Length Research Paper

Some properties of extracellular protease from Bacillus licheniformis LBBL-11 isolated from “iru”, a traditionally fermented African locust bean condiment

Folasade M.  Olajuyigbe* and Joshua O. Ajele

Department of Biochemistry, Federal University of Technology, P. M. B.704 Akure 340001, Nigeria.

*Corresponding author. E-mail: sadeolaj@yahoo.com.

Accepted  20 August 2008

   Abstract

Twelve strains of Bacillus licheniformis isolated from traditionally fermented African locust bean (iru) were evaluated in respect to production of protease on skim milk agar. B. licheniformis LBBL-11 exhibited the highest proteolytic activity with a diameter of clear zone measuring 35.0 mm. Production of protease from B. licheniformis LBBL-11 was further studied by growing the strain on nutrient broth. Maximum protease production was 18.4 U/ml  at 48 hour of growth which coincided with the end of exponential phase. The protease from this Bacillus sp had optimum pH of 8.0 and was stable over a wide pH range of 5.0 - 11.0. The optimum temperature for the protease activity was 60^oC. The enzyme was 95% stable at 60^oC after 60 min of incubation. These properties indicate possible application of B. licheniformis LBBL-11 as potential starter culture for the fermentation of African locust bean under controlled conditions of temperature and pH.

Key words: Fermented locust bean, iru, protease, thermostable, Bacillus licheniformis