Kinetic and Thermodynamic Characterization of Lysine Production Process in Brevibacterium lactofermentum

Expression and characterization of a novel organic solvent tolerant protease from Bacillus sphaericus DS11

Organic solvent-tolerant proteases have many applications in the synthesis of peptides. In this study, we have developed a low-cost and convenient method to produce highly concentrated organic solvent-tolerant protease. Organic solvent tolerant protease (OSP) gene from Bacillus sphaericus DS11 was cloned and expressed in Bacillus subtilis WB800. The optimum pH of the recombinant protease was 9.0. The optimum temperature of the recombinant protease was 40 °C. The recombinant protease was purified by ethanol with the yield of (87.33%). The yield of OSP enriched by ethanol was higher than that of by Ni-chelating affinity chromatography, which indicated that precipitation of the recombinant OSP with ethanol is a relatively low-cost and fast method for organic solvent -tolerant protease preparation. These results showed that this enzyme could be very useful in different industrial applications.

Fungal Biomass Protein Production from Trichoderma harzianum Using Rice Polishing

Industrially important enzymes and microbial biomass proteins have been produced from fungi for more than 50 years. High levels of crude protein as much as 45% are present in fungal biomass with balanced essential amino acids. The aim of this study was to access the potential of Trichoderma harzianum to produce fungal biomass protein from rice polishings. Maximum biomass yield was obtained at 5% (w/v) rice polishings after 72 h of incubation at 28°C at pH 4. Carbon and nitrogen ratio of 20 : 1 gave significantly higher production of fungal biomass protein. The FBP in the 75 L fermenter contained 49.50% crude protein, 32.00% true protein, 19.45% crude fiber, 9.62% ash, 11.5% cellulose content, and 0.325% RNA content. The profile of amino acids of final FBP exhibited that all essential amino acids were present in great quantities. The FBP produced by this fungus has been shown to be of good nutritional value for supplementation to poultry. The results presented in this study have practical implications in that the fungus T. harzianum could be used successfully to produce fungal biomass protein using rice polishings.

Kinetics and thermodynamics of ethanol production by Saccharomyces cerevisiae MLD10 using molasses

In this study, we have used ultraviolet (UV) and γ-ray induction to get a catabolite repression resistant and thermotolerant mutant with enhanced ethanol production along with optimization of sugar concentration and temperature of fermentation. Classical mutagenesis in two consecutive cycles of UV- and γ-ray-induced mutations evolved one best catabolite-resistant and thermotolerant mutant Saccharomyces cerevisiae MLD10 which showed improved ethanol yield (0.48 ± 0.02 g g(-1)), theoretical yield (93 ± 3%), and extracellular invertase productivity (1,430 ± 50 IU l(-1) h(-1)), respectively, when fermenting 180 g sugars l(-1) in molasses medium at 43 °C in 300 m(3) working volume fermenter. Ethanol production was highly dependent on invertase production. Enthalpy (ΔH*) (32.27 kJ M(-1)) and entropy (ΔS*) (-202.88 J M(-1) K(-1)) values at 43 °C by the mutant MLD10 were significantly lower than those of β-glucosidase production by a thermophilic mutant derivative of Thermomyces lanuginosus. These results confirmed the enhanced production of ethanol and invertase by this mutant derivative. These studies proved that mutant was significantly improved for ethanol production and was thermostable in nature. Lower fermentation time for ethanol production and maintenance of ethanol production rates (3.1 g l(-1) h(-1)) at higher temperature (43 °C) by this mutant could decrease the overall cost of fermentation process and increase the quality of ethanol production.