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. Solidstate fermentation was made in specially designed plastic bags (VALMIC ® ) containing peat:vermiculite (1:1 w/w). Addition of nutrients to the peat:vermiculite 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 10 8 -10 9 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 10 5 , 10 6 or 10 7 conidia g -1 dry substrate. Fresh conidia produced by solid-state fermentation reduced the incidence of brown rot on plums by 75%.