Production of microsclerotia by Trichoderma asperellum through submerged liquid fermentation using low-cost nitrogen and carbon sources

Abstract

The aim of this work is to optimize the nutritional conditions using low-cost carbon and nitrogen sources for microsclerotia (MS) production of two Brazilian Trichoderma asperellum strains (BRM-29576 and BRM-29104). A fractional factorial design was used to investigate five variables: carbon source, carbon concentration, nitrogen source, C:N ratio and fungal strain. In this study, the optimal nutritional conditions for improving MS yield were achieved using sucrose and autolyzed yeast, carbon concentration at 20 g L−1 and C:N ratio of 10:1 for the BRM-29104 strain, which outperformed the other strain and yielded up to 2.5 (±0.9) × 104 MS mL−1 within 7 days of fermentation. Sucrose and autolyzed yeast are two economically available carbon and nitrogen sources in Brazil that are suitable for MS production by T. asperellum BRM-29104. Vacuum filtration of MS biomass through nylon filter (200 mesh/74 μm) increased MS concentration, resulting in up to 1.8 (±0.2) × 105 MS g−1. Our results support a cost-efficient liquid medium to achieve high MS yields by strain BRM-29104 in combination with an easy method to harvest and concentrate MS from culture broth for further formulation development.