Influence of Cultural and Nutritional Factors on β-Mannanase Production by Penicillium italicum under Submerged State Fermentation

Abstract

Aims: The process parameters influencing enzyme production were optimized to ascertain the optimal cultural and nutritional conditions for β-mannanase production by Penicillium italicum in submerged state fermentation. Study Design: Five stages of experimental processes were designed for this study. The first stage, samples were withdrawn after 24, 48, 72, 96, 120, 144,168 and 192 h incubation. The second experiment, different agricultural wastes were screened as substitute to Locust Bean Gum. In third experiment, the effect of different pH values on β-mannanase production was evaluated, while the fermentation media were incubated at different temperatures in the fourth experiment. In fifth experiment, the effect of different surfactants on β-mannanase activity was evaluated. Place and Duration of Study: Microbiology Research Laboratory, Federal University of Technology, Akure Nigeria between September 2011 and March 2012. Methodology: Beta-Mannanase production was conducted in mineral salt medium and enzyme activity determined by dinitrosalicylic acid method, while protein content was determined by Lowry method. Results: Maximum β-mannanase activity (41.667 U/ml) was observed after 120 h of incubation. Different agricultural wastes were screened as carbon substrates for β-mannanase production. Among tested carbon sources, orange peels proved to the best for β-mannanase production with an activity of 50.000 U/ml. Initial pH of the culture medium was optimized and a pH of 6.0 (130.556 U/ml) was found to be the best pH for β-mannanase activity. The optimum temperature was 30°C with an activity of 136.418 U/ml. Of all surfactants screened, Tween 20 (67.500 U/ml) gave the highest β-mannanase activity. Conclusion: The nutritional and cultural factors obtained to be optimal from this study will help to design an experiment for maximum mannanase biosynthesis using cheaper substrates in place of commercial substrates known to be expensive for enzyme production.