Evaluation of the biofungicide effects of LAB against Penicillium digitatum (citrus green mould)

GEREZ C.L.; CARBAJO M.S.,; ROLLÁN G.; FONT DE VALDEZ, G; TORRES LEAL, G

Wuhan, China

Congreso; 11th International Citrus Congress organizado por International Society of Citriculture (ICC 2008); 2008

The citrus industry in Tucumán has placed Argentina among the main lemon producers in the world. Lemons are sensible to infections caused by fungi, mainly Penicillium digitatum which is responsible for severe economic losses worldwide. Currently, this postharvest disease is controlled for chemicals fungicides. The use of these fungicides is restricted because its negative effects on environment, health and the development of fungicide resistance. World trends are moving toward the reduction of pesticide use, thus; several physical and biological treatments have been evaluated. In previous studies, eight lactic acid bacteria (LAB) were able to inhibit the growth of P. digitatum strains isolated from decayed lemon. The aim of this work was to characterize the antifungal effect of LAB and to evaluate its biofungicide effectiveness by the response surface methodology. The antifungal activity of LAB was not changed after either heating (100ºC, 20 min.) or treatment with Proteinase K, while it was removed after neutralization indicating the acidic nature of the metabolites involved in antifungal activity. Lactic (LA), acetic (AC) phenyllactic (PLA) acids were related to the antifungal effect of the LAB cultures. A central composite design and response surface methodology was used to evaluate the antifungal effectiveness of the organic acids. The activity of the organic acids was comparable with imazalil, guazatine and Serenade® (commercial biofungicide) in high concentrations as 100 ppm, 100 ppm and 6.0 ppm, respectively.The results show the potential use of antifungal LAB and/or biofungicide as a novel biocontrol strategy of postharvest diseases as contribution to maintain the quality, and shelf life of citrus fruit as well as alternative of chemical fungicides use.