Biological control of Penicillium italicum, P. digitatum and P. expansum by the predacious yeast Saccharomycopsis schoenii on oranges

In this study we evaluated the ability of Saccharomycopsis schoenii Nadson and Krassiln (UWO-PS 80-91) as biocontrol agent against plant pathogenic filamentous fungi P. expansum Link (UFMG 01-2002), P. italicum Wehmer (LCP 61.1199), and P. digitatum (Pers.: Fr.) (LCP 984263, LCP 68175 and LCP 4354). S. schoenii was able to reduce disease severity in oranges inoculated with all fungi. Among the phytopathogens, P. digitatum LCP4354 was the most virulent whereas P. digitatum LCP 68175 was the most susceptible to predation. The yeast was able to survive for 21 days on the fruit surface and did not produce lesions on oranges. Production of antagonistic substances by S. schoenii was not detected using standard techniques. Our results point to the potential use of S. schoenii to control postharvest phytopathogens in fruits.

Este estudo avaliou a capacidade de levedura Saccharomycopsis schoenii Nadson & Krassiln (UWO-PS 80-91) em controlar o crescimento dos fungos fitopatogênicos Penicillium expansum Link (UFMG 01-2002), P. italicum Wehmer (LCP 61.1199), e P. digitatum (Pers.: Fr.) (LCP 984263, LCP 68175 e LCP 4354). S. schoenii reduziu a severidade da doença em laranjas inoculadas com todos os fitopatógenos testados. Entre estes fitopatógenos, P. digitatum LCP4354 apresentou a maior virulência enquanto que P. digitatum LCP 68175 foi o mais suscetível à predação. A levedura foi capaz de permanecer viável, sem produzir lesões na superfície dos frutos por 21 dias. Outra característica desejável observada foi a ausência de produção de substâncias antagonistas. Sendo assim, este trabalho evidência o potencial de utilização da levedura S. schoenii em protocolos de controle biológico de doenças pós-colheita em laranjas.

Biological control of Penicillium italicum, P. digitatum and P. expansum by the predacious yeast Saccharomycopsis schoenii on oranges.

In this study we evaluated the ability of Saccharomycopsis schoenii Nadson and Krassiln (UWO-PS 80-91) as biocontrol agent against plant pathogenic filamentous fungi P. expansum Link (UFMG 01-2002), P. italicum Wehmer (LCP 61.1199), and P. digitatum (Pers.: Fr.) (LCP 984263, LCP 68175 and LCP 4354). S. schoenii was able to reduce disease severity in oranges inoculated with all fungi. Among the phytopathogens, P. digitatum LCP4354 was the most virulent whereas P. digitatum LCP 68175 was the most susceptible to predation. The yeast was able to survive for 21 days on the fruit surface and did not produce lesions on oranges. Production of antagonistic substances by S. schoenii was not detected using standard techniques. Our results point to the potential use of S. schoenii to control postharvest phytopathogens in fruits.

Phenol degradation by a Graphium sp. FIB4 isolated from industrial effluents.

In this work, we show that the fungal strain Graphium sp. FIB4 was able to use phenol as the sole carbon source. Higher degradation of phenol was accomplished by alginate-immobilized mycelial mass than by mycelial suspensions of Graphium sp. FIB4. Free mycelium exhibited higher degradation rates when compared with the alginate-immobilized mycelium in the presence of 14 mM of phenol or less. Above this concentration, degradation rates by free mycelium decreased and the immobilized mycelium showed higher values. The maximum degradation rate for 8 mM phenol was found to be 20.13 mg/l x h by free mycelia and 16.24 mg/l x h by immobilized mycelial mass in the presence of 18 mM phenol. When the fungus was grown on medium without phenol, catechol 1,2-dioxygenase activity was not detected. This enzyme activity was induced at phenol concentrations as low as 0.05 mM and up to 6 mM at 24 h incubation at 30 degrees C, suggesting that catechol was oxidized by the ortho type of ring fission. Addition of glucose reduced phenol consumption rate, and both substrates were used simultaneously. Glucose concentrations higher than 0.075% repressed the induction of phenol oxidation by Graphium sp. FIB4 grown on glucose. But glucose did not fully repress utilization of phenol by phenol-pre-induced cells. Immobilization and addition of calcium and barium ions were detrimental to the stability of catechol 1,2-dioxygenase activity and phenol degradation by Graphium sp. FIB4.