Forced Aeration Influence on the Production of Spores by Trichoderma strains

Abstract

The main purpose of the present study was to evaluate the effect of an initial aeration rate on the sporulation of six Trichoderma strains under solid state fermentation conditions and to evaluate the behavior of the lytic enzymes involved in the process at laboratory scale. A mixture of sugarcane bagasse, wheat bran, chitin, potato flour and olive oil were used as a substrate. Cultures were carried out using glass columns applying an initial aeration rate of 50 ml min−1 (2 mL min−1g−1). Under the present culture conditions, chitinase and amylase activities were enhanced by the aeration with values of 30.74 and 44.54 U g−1 with T. longibranchiatum. These vales represent an increase of 226 and 167%, respectively compared with the system without air supply. For most of the strains, the forced aeration increased the endoglucanase activity, but the best value was observed with T. yunnanense (38.32 U g−1). All strains showed low values of exoglucanase and lipase when the aeration was applied. Trichoderma spp. was the strain most affected negatively by the aerated process, showing the lowest enzyme activities. The forced air supply into solid-state fermentation did not improve the production of spores from Trichoderma since similar results were obtained in the process without forced aeration. On this report, we reach concentrations greater than 1 × 109 spores per gram of substrate at 96–120 h of culture, indicating a feasible approach of agro-industrial wastes as a substrate for the biomass production.