Mycofumigation of postharvest blueberries with volatile compounds from Trichoderma atroviride IC-11 is a promising tool to control rots caused by Botrytis cinerea.

Botrytis cinerea, the causal agent of the gray mold, is a filamentous fungus that infects blueberries and can cause important production losses in postharvest storage. Considering that the use of synthetic fungicides is not allowed on blueberries in postharvest conditions, alternative and natural strategies are needed to control gray mold. The objective of this work was to evaluate the capability of volatile organic compounds (VOCs) produced by Trichoderma atroviride IC-11 to control B. cinerea growth in blueberries after harvest. These VOCs inhibited almost completely B. cinerea growth in vitro. The most abundant volatile compound was 6-pentyl-α-pyrone (6PP). In vitro assays with pure 6PP confirmed its antifungal activity. The incidence of gray mold was evaluated in blueberries inoculated with B. cinerea and exposed to volatiles of T. atroviride IC-11. Gray mold incidence among those stored in air at 20 °C for 14 days was 100%, while the incidence among the volatile-treated fruit was 17%. Gray mold incidence among those stored in air at 4 °C for 31 days was 82%, while the incidence among the volatile-treated fruit was 11%. T. atroviride IC-11 VOCs inhibited mycelial growth and conidia germination of B. cinerea. The binding of VOCs to the surface of hyphae caused their vacuolation and deterioration. Selective cytotoxicity of 6PP on B. cinerea was observed but not on human intestinal cells at specific concentrations that controlled gray mold. The postharvest mycofumigation of blueberries with T. atroviride IC-11 VOCs is a promising approach to protect these fruits from gray mold.

Production of 6-pentyl--pyrone by trichoderma harzianum in solid-state fermentation

Many Trichoderma species are able to produce 6-pentyl--pyrone (6-PP), a lactone with coconut-like aroma. In the present work, several culture parameters were studied to enhance the production of 6-PP by Trichoderma harzianum 4040 in solid-state fermentation. Green coir powder added to a nutrient solution was used as support material for fermentation. A Plackett-Burman screening technique was applied, followed by a fractionary factorial design. The best culture conditions within the experimental domain studied were (100 g support)-1: sucrose, 3 g; NaNO3, 0.24 g; (NH4)2SO4, 0.18 g; KH2PO4, 0.1 g; inoculum concentration, 2.2 x 10(6) spores; moisture level, 55%. The temperature established was 28ºC. The fermentation under the selected conditions led to a 6-PP production six times higher (5.0 mg/g dry matter) than the initial one (0.8 mg/g dry matter) after seven days of cultivation.

Muitas espécies do gênero Trichoderma são capazes de produzir a substância 6-pentil--pirona (6-PP), uma lactona com aroma característico de coco. No presente trabalho, vários parâmetros de cultura foram estudados para aumentar a produção de 6-PP por Trichoderma harzianum 4040 em fermentação em estado sólido. Pó da casca de coco verde adicionado à uma solução nutriente foi usado como material de suporte para a fermentação. Um planejamento experimental de varredura segundo a técnica de Plackett-Burman foi aplicado, seguido de um planejamento fatorial fracionário. No domínio experimental estudado, as melhores condições de cultura foram (100 g suporte)-1: sacarose, 3 g; NaNO3, 0,24 g; (NH4)2SO4, 0,18 g; KH2PO4, 0,1 g; produção do inóculo, 2,2 x 10(6) esporos; umidade, 55%. A temperatura estabelecida foi de 28ºC. Esse estudo conduziu à concentração de 6-PP seis vezes maior (5,0 mg/g de matéria seca) do que a inicial (0,8 mg/g de matéria seca) após sete dias de cultivo.