Production of β-Mannanase by Penicillium italicum Subjected to Different Growth Conditions

Aims: The process parameters affecting enzyme production were optimized to ascertain the best optimal conditions for β-mannanase production by Penicillium italicum in solid state fermentation. Study Design: Four stages of experimental processes were designed for this study. The first experiment, samples were withdrawn after 24, 48, 72, 96, 120, 144,168 and 192 h incubation. In second experiment, the fermentation media were incubated at different temperatures. In third experiment, the effect of different pH values on β-mannanase production was evaluated, while the fourth experiment described the supplementation of surfactants in mineral salt solution for β-mannanase production. Place and Duration of Study: Microbiology Research Laboratory, Federal University of Technology, Akure Nigeria between September 2011 and March 2012. Methodology: β-mannanase production was conducted using Locust Bean Gum (LBG) as the sole carbon source; moisten with mineral salt solution, and enzyme activity determined by dinitrosalicylic acid method, while protein content was determined by Lowry method. Results: Maximum enzyme activity (146.389 U/ml) was observed after 72 h of incubation. Different surfactants were supplemented in the basal medium, and Sodium Dodecyl Sulfate (SDS) was observed to give the highest β-mannanase activity of 53.335 U/ml. Initial pH of the culture medium was optimized and a pH of 6.0 was found to support maximum enzyme activity (173.241 U/mg protein). The optimum incubation temperature was achieved at 35°C. Conclusion: The results obtained provide information on optimal process parameters that might improve the yield of β-mannanase by P. italicum for better fish feed formulation, especially in the larval stages of fish fingerlings when the enzyme system is not efficient.

Volatile metabolites produced from agro-industrial wastes by Na-alginate entrapped Kluyveromyces marxianus

Abstract The aim of this study was to evaluate the effects of alginate entrapment on fermentation metabolites of Kluyveromyces marxianus grown in agrowastes that served as the liquid culture media. K. marxianus cells entrapped in Na-alginate were prepared using the traditional liquid-droplet-forming method. Whey and pomaces from processed tomatoes, peppers, and grapes were used as the culture media. The changes in the concentrations of sugar, alcohol, organic acids, and flavor compounds were analyzed using gas chromatography-mass spectrometry (GC-MS) and high pressure liquid chromatography (HPLC). Both free and entrapped, K. marxianus were used individually to metabolize sugars, organic acids, alcohols, and flavor compounds in the tomato, pepper, grape, and acid whey based media. Marked changes in the fermentation behaviors of entrapped and free K. marxianus were observed in each culture. A 1.45-log increase was observed in the cell numbers of free K. marxianus during fermentation. On the contrary, the cell numbers of entrapped K. marxianus remained the same. Both free and entrapped K. marxianus brought about the fermentation of sugars such as glucose, fructose, and lactose in the agrowaste cultures. The highest volume of ethanol was produced by K. marxianus in the whey based media. The concentrations of flavor compounds such as ethyl acetate, isoamyl alcohol, isoamyl acetate, 2-phenylethyl isobutyrate, phenylethyl acetate, and phenylethyl alcohol were higher in fermented agrowaste based media compared to the control.

Biodegradation of agro-industrial wastes by a edible mushroom Pleurotus tuber-regium (Fr.).

When Pleurotus tuber-regium was cultivated on cotton waste , rice straw, cocoyam peels and sawdusts of Mansonia altissima, Boscia angustifolia and Khaya ivorensis, the highest crude protein, crude fat and carbohydrate contents in sporophores were 29.4 (M. altissima) , 1.4 (rice straw) and 61.3% (cocoyam peels), respectively. Sporophores produced on rice straw had the greatest energy value and those on B. angustifolia the least i.e. 3147.6 and1709.1 kcal g-1 substrates, respectively. The greatest degradation of the components of the substrates as a result of the cultivation was 62.4 and 71.5% for cellulose and hemicellulose in cotton wastes and 60.2% for lignin in K. ivorensis , with the greatest reduction in energy value of the substrate being 2667.9 kcal g-1 substrate in K. ivorensis. There was no correlation between the extent of the degradation of these components and the yield of of sporophores, while the energy recovery of substrate in the mushroom was highest for cocoyam peels and least for sawdust of B. angustifolia, 3.7 and 0.5%, respectively.