Integrated control of penicillium digitatum by the predacious yeast Saccharomycopsis crataegensis and sodium bicarbonate on oranges

Our investigation of integrated biological control (IBC) started with an assay testing activity of the predacious yeast Saccharomycopsis crataegensis UFMG-DC19.2 against Penicillium digitatum LCP 4354, a very aggressive fungus that causes postharvest decay in oranges. Under unfavourable environmental conditions, the yeast showed a high potential for control (39.9 percent disease severity reduction) of this fungus. This result was decisive for the next step, in which S. crataegensis was tested in association with sodium bicarbonate salt, a generally regarded as safe (GRAS) substance. The yeast was able to survive at different concentrations of the salt (1 percent, 2 percent and 5 percent), and continued to grow for a week at the wound site, remaining viable at high population for 14 days on the fruit surface. The yeast alone reduced the severity of decay by 41.7 percent and sodium bicarbonate alone reduced severity of decay by 19.8 percent, whereas the application of both led to a delay in the development of symptoms from 2 to 10 days. Ingredients of the formulations were not aggressive to fruits since no lesions were produced in control experiments.

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.