Enhancement of laccase production by Cerrena unicolor through fungal interspecies interaction and optimum conditions determination.

The present study aimed to identify a pair of fungal strains that promote laccase production in the co-cultivation of white-rot basidiomycetes and to determine the optimum conditions to enhance enzyme synthesis under co-fermentation of mandarin peels. Co-cultivation of Cerrena unicolor with Trametes versicolor, Lenzites betulina, and Panus lecomtei led to up-regulation of laccase activity. Moreover, interspecific interaction of Cerrena unicolor and Trametes versicolor induced the production of two new laccase isoenzymes. By contrast, interactions of Cerrena unicolor with Trametes coccineus and Trametes hirsuta resulted in a multiple decreased ability of Cerrena unicolor to produce laccase. Co-cultivation of Cerrena unicolor with other fungi 3- to 12-fold down-regulated manganese peroxidase (MnP) activity. The outcomes of these fungal interactions are closely related to the initial concentration and availability of the nutrients, the partners' inoculum ratio, time, and sequence of their inoculation. Co-cultivation of Cerrena unicolor and Trametes versicolor in fermenter resulted in the accumulation of 476 U/mL laccase and 1.12 U/mL MnP.

Bacillus amyloliquefaciens Spore Production Under Solid-State Fermentation of Lignocellulosic Residues.

This study was conducted to elucidate cultivation conditions determining Bacillus amyloliquefaciens B-1895 growth and enhanced spore formation during the solid-state fermentation (SSF) of agro-industrial lignocellulosic biomasses. Among the tested growth substrates, corncobs provided the highest yield of spores (47 × 1010 spores g-1 biomass) while the mushroom spent substrate and sunflower oil mill appeared to be poor growth substrates for spore formation. Maximum spore yield (82 × 1010 spores g-1 biomass) was achieved when 15 g corncobs were moistened with 60 ml of the optimized nutrient medium containing 10 g peptone, 2 g KH2PO4, 1 g MgSO4·7H2O, and 1 g NaCl per 1 l of distilled water. The cheese whey usage for wetting of lignocellulosic substrate instead water promoted spore formation and increased the spore number to 105 × 1010 spores g-1. Addition to the cheese whey of optimized medium components favored sporulation process. The feasibility of developed medium and strategy was shown in scaled up SSF of corncobs in polypropylene bags since yield of 10 × 1011 spores per gram of dry biomass was achieved. In the SSF of lignocellulose, B. amyloliquefaciens B-1895 secreted comparatively high cellulase and xylanase activities to ensure good growth of the bacterial culture.