Hydrothermal processing and enzymatic hydrolysis of sorghum bagasse for fermentable carbohydrates production.

Untreated and hydrothermally treated sorghum bagasse (SB) was hydrolyzed to simple sugars by the synergistic action of cellulases and hemicellulases produced by the fungi Fusarium oxysporum and Neurospora crassa. Synergism between the two lignocellulolytic systems was maximized with the application of higher fraction of N. crassa enzymes. Hydrothermolysis of SB was studied at a wide range of treatment times and temperatures. At intense pretreatment conditions (210 degrees C for 20 min; logR(0)=4.54), the residual hemicellulose percentage was 17.45%, while formation of inhibitory products, 5-hydromethyl-furfural (HMF), furfural, acetic and formic acid, (0.21, 0.51, 3.36 and 1.80 g/l, respectively) remained in acceptable levels. Maximum conversion of cellulose and total polysaccharides of the untreated SB were 23.18% and 18.79%, respectively. Combining hydrothermal treatment and enzymatic hydrolysis of released oligosaccharides and insoluble solids resulted in improvement of cellulose (approximately 15% increase) and total polysaccharides (two fold) hydrolysis compared to that of untreated SB.

Improving the catalytic performance of fungal laccases in monoterpene-based reaction systems.

Ternary systems consisting of monoterpenes (alpha-pinene or D-limonene), tert-butanol and water were used as reaction media to enhance the catalytic performance of laccases from various fungi sources (Trametes versicolor, T. hirsuta and Botrytis cinerea). The enzymes had improved catalytic efficiency (5- to 10-fold) in alpha-pinene-rich environment, while optimal reaction rates were in high-water content systems (15.5% v/v). The stability of laccases was significantly improved in monoterpene-based systems (up to 90% residual enzyme activity after 24 h at 30 degrees C) in comparison with other non-conventional media. The results indicate that these ternary systems can increase the potential of laccases as catalysts for various oxidations.

Biodegradation of phenol by acclimatized Pseudomonas putida cells using glucose as an added growth substrate.

Biodegradation of phenol, a pollutant derived from many industrial processes, was achieved through acclimatized Pseudomonas putida cells. The strategy to overcome the inhibitory effect of phenol on microbial growth involved the addition of glucose, a conventional carbon source. A factorial experimental design was employed in order to optimize the initial phenol and glucose concentrations. The optimum conditions found were applied in 2-lt bioreactors. The development of acclimatized cells and the use of glucose as an added growth substrate resulted in a significant phenol degradation rate of 60.7 mg L(-1) h(-1) with a complete removal of 1200 mg L(-1) phenol.