Mass Production of Conidia of Penicillium frequentans , a Biocontrol Agent Against Brown Rot of Stone Fruits

Abstract

Conidial production of Penicillium frequentans, a biocontrol agent of the fungal pathogen Monilinia laxa, was tested in liquid and solid-state fermentation. Conidial production of P. frequentans in solid-state fermentation was higher than in liquid-state fermentation. Solid-state fermentation was made in specially designed plastic bags (VALMIC®) containing peatvermiculite (11 w/w). Addition of nutrients to the peatvermiculite increased conidial production of P. frequentans, especially when lentil meal was added. The number of conidia obtained in this solid-state fermentation was maintained in the range of 108-109 conidia g-1 from 5 to 120 days after inoculation. Germinability of these conidia was > 90% until 90 days of incubation and declined at 120 days. Optimal initial moisture content in the substrate was 30-40% (v/w). At lower moisture contents, significant reductions in conidial production and germinability were observed, particularly at 10% (v/w). Conidial production was similar when the substrate was inoculated with 105, 106 or 107 conidia g-1 dry substrate. Fresh conidia produced by solid-state fermentation reduced the incidence of brown rot on plums by 75%.