P80: Brewer’s spent grain as substrate for xylanolytic enzyme production by Penicillium janczewskii

Brewers’ spent grain (BSG) is the major by-product of the brewing industry, representing around 85% of the total by-products generated. Despite it is available in large quantities in many countries throughout the year, it has been mainly used as cattle feed. Recently, there have been several attempts to use BSG in biotechnological processes, such as for enzyme production. The production of xylanase, β-xylosidase and α-arabinofuranosidase by a Penicillium janczewskii strain, isolated from soil of an Atlantic Rainforest region (Estação Ecológica Juréia-Itatins, SP, Brazil), was optimized in solid cultures with BSG as substrate. The cultures were performed in 250 mL Erlenmeyer flasks containing 5g of BSG. The cultures were inoculated with 1 mL of a 10⁷ conidia mL^-1 suspension. Moisture of the substrate (provided by tap water, distilled water or salt solution), period and temperature of cultivation were the parameters investigated in order to improve the production of the enzymes by this fungal strain. Highest enzymatic production was observed in 100% (v/w) moisturized cultures. The production was still higher when the moisture was provided by Vogel’s salt solution. The highest xylanase and α-arabinofuranosidase production was observed in seven days-old cultures, while the highest β-xylosidase production was observed in eight days-old cultures. Temperatures of 20, 25 and 30 °C were selected for optimized production of β-xylosidases, xylanases and α-arabinofuranosidases, respectively. In cultures carried out at 35 °C, only very low xylanase production was observed and the production of the other enzymes was not detected.