Optimization of xylanase production by filamentous fungi in solid state fermentation and scale-up to horizontal tube bioreactor

Five microorganisms, namely Aspergillus niger CECT 2700, A. niger CECT 2915, A. niger CECT 2088, Aspergillus terreus CECT 2808, and Rhizopus stolonifer CECT 2344, were grown on corncob to produce cell wall polysaccharide-degrading enzymes, mainly xylanases, by solid-state fermentation (SSF). A. niger CECT 2700 produced the highest amount of xylanases of 504±7 U/g dry corncob (dcc) after 3 days of fermentation. The optimization of the culture broth (5.0 g/L NaNO3, 1.3 g/L (NH4)2SO4, 4.5 g/L KH2PO4, and 3 g/L yeast extract) and operational conditions (5 g of bed loading, using an initial substrate to moistening medium of 1:3.6 (w/v)) allowed increasing the predicted maximal xylanase activity up to 2,452.7 U/g dcc. However, different pretreatments of materials, including destarching, autoclaving, microwave, and alkaline treatments, were detrimental. Finally, the process was successfully established in a laboratory-scale horizontal tube biore- actor, achieving the highest xylanase activity (2,926 U/g dcc) at a flow rate of 0.2 L/min. The result showed an overall 5.8-fold increase in xylanase activity after optimization of culture media, operational conditions, and scale-up.We are grateful to the Spanish Ministry of Science and Innovation for the financial support of this work (project CTQ2011-28967), which has partial financial support from the FEDER funds of the European Union; to the Leonardo da Vinci Programme for founding the stay of Felisbela Oliveira in Vigo University; to MAEC-AECID (Spanish Government) for the financial support for Perez-Bibbins, B. and to Spanish Ministry of Education, Culture and Sports for Perez-Rodriguez's FPU; and to Solla E. and Mendez J. (CACTI-University of Vigo) for their excellent technical assistance in microscopy

Characterization Of Beta-Galactosidase From Alternaria Alternata On Solid-State Cultivation

The effects of orange peel, lemon peel, apple peel, wheat-bran and watermelon peel on beta-galactosidase production from Alternaria alternata were studied. Beta-galactosidase (EC-3.2.1.23) was produced best by solid-state fermentation of A. alternata on wheat bran. The effects of pH and incubation temperature were studied. The highest enzyme activity was obtained at 50 degrees C and pH 5.0. The enzyme was relatively stable in the pH range 3.0-5.0 and between 20 degrees-50 degrees C. The enzyme maintained 85% of its activity at 20 degrees-30 degrees C and 70% at 50 degrees C. Activity was more than 92% between pH 3.0-5.0 and 42% in 40 min and 50% in 30 min at 60 degrees C. In addition, glucose did not have an inhibitory effect, and galactose had only a slight inhibitory effect.Wo

Comparison of live and dead biomass of fungi on decolorization of methyl orange

Decolorization of methyl orange with live and autoclaved biomass fungi were studied. Sixteen different fungi including Fusarium, Trichoderma, Humicola, Aspergillus, Penicillium, Paecilomyces, Alternaria and Beauveria were evaluated. The highest decolorization activity was observed with Fusarium acuminatum and Humicola fuscoatra. Decolorization efficiencies of live and autoclaved biomasses were compared. In addition, spores of eight fungi showing high decolorization efficiency were inoculated fordecolorization ability. The most successful fungi were Penicillium sp. and Fusarium sp. For adsorption studies, methyl orange decolorization with live and autoclaved biomasses were found most suitable with malt extract compared to yeast extract peptone medium