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Towards the production of fungal biocontrol candidates using inert supports: a case of study of Trichoderma asperellum in a pilot fixed bed fermenter

Barrera, Mauricio Cruz, Gómez, Martha Isabel, Serrato Bermúdez, Juan Carlos
Biocontrol science and technology 2019 v.29 no.2 pp. 162-184
Trichoderma asperellum, air flow, biological control, biological control agents, carbon nitrogen ratio, conidia, fermenters, foams, fungi, graphs, mathematical models, polyurethanes, response surface methodology, rice hulls, solid state fermentation, specific growth rate, temperature
The production of fungal biocontrol agents by solid-state fermentation (SSF) processes in inert supports demands deeper studies in SSF-modelling and SSF-optimisation to cope with scale-up issues. Here, we report the systematic application of fractional factorial and central composite designs to optimise the conidia productivity and maximum specific growth rate of the biological control candidate Trichoderma asperellum strain Th204 using two inert supports: polyurethane foam (PUF) and rice husk (RH), in a pilot 16 L fixed bed fermenter. By using response surface methodology, 2D contour graphs and Spearman’s correlation coefficients, axial temperature, conidia concentration, bed moisture and pressure drop gradients were modelled. C:N ratio and airflow rate were identified as significant factors. Optimal conditions using PUF a C:N ratio of 18.1 and airflow of 0.8 m³ h⁻¹ were found, with the highest productivity of 3.09 × 10⁷conidia g⁻¹ initial dry matter h¹. Polynomial models and response surfaces found in this study are advantageous to design strategies to scale-up the SSF process in fixed bed fermenters for fungal biological control candidates.