Antifungal activity of lactic acid bacteria to control table olive production

It is well known that sourdough lactic acid bacteria can produce compounds able to inhibit moulds related to bread spoilage [1]. Consequently, the addition of antifungal sourdough in the bakery industry is now a common practice having the potential to ensure the microbiological safety of bread [2,3]. Moreover, antifungal lactobacilli can be find in raw milk that appears to be a productive reservoir [4]. In table olive fermentation, fungal growth is a big problem and, at present, no biological control is adopted. Natamycin was proposed as a fungal control agent having, also, the potential to enhance the process by favouring the growth of the indigenous population of lactic acid bacteria against other competing microorganisms [5]. It has been reported that table olives act a suitable substrate for the production of citrinin mycotoxin; high hydrostatic pressure effects on citrinin and mould microflora has been evaluated [6]. Considering this state of the art, aim of the present work was to find antifungal strains of lactic acid bacteria among the almost 400 autochthonous strains present in the Collection of the Laboratory of Microbiology in order to control table olive fermentation. The strains were tested in Petri plates against two strains of moulds prevailing in two different olive brines. The strains exhibiting antifungal activity derived from olive brines, cheeses, and sourdoughs. Since each of them was able to inhibit only one of the tested moulds, the next step will be to carry out fermentation trials coupling the best strains as adjunct culture together with starter cultures. This study constitute a step towards the main goal to solve the problem of the fungal growth and the potential mycotoxin accumulation during the table olive fermentation.This work was supported by PON 03 PE_00090_2 - Modelli sostenibili e nuove tecnologie per la valorizzazione delle olive e dell’olio extra vergine di oliva prodotto in Calabria.Keywords: antifungal activity; lactic acid bacteria; table olive.References[1] Corsetti A, Gobbetti M, Rossi J, Damiani P (1998) Antimould activity of sourdough lactic acid bacteria: identification of a mixture of organic acids produced by Lactobacillus sanfrancisco CB1. Appl Microbiol Biotechnol 50:253-256.[2] Ryan LAM, Dal Bello F, Arendt EK (2008) The use of sourdough fermented by antifungal LAB to reduce the amount of calcium propionate in bread. Int J Food Microbiol 125:274-278.[3] Gerez CL, Torino MI, Rollán G, Font de Valdez G (2009) Prevention of bread mould spoilage by using lactic acid bacteria with antifungal properties. Food Control 20:144-148.[4] Delavenne E, Mounier J, Déniel F, Barbier G, Le Blay G (2012) Biodiversity of antifungal lactic acid bacteria isolated from raw milk samples from cow, ewe and goat over one-year period. Int J Food Microbiol 155:185-190.[5] Hondrodimou O, Kourkoutas Y, Panagou EZ (2011) Efficacy of natamycin to control fungal growth in natural black olive fermentation. Food Microbiol 28:621-627.[6] Tokuşoğlu Ö, Alpas H, Bozoğlu F (2010) High hydrostatic pressure effects on mold flora, citrinin mycotoxin, hydroxytyrosol, oleuropein phenolics and antioxidant activity of black table olives. Inn Food Sci Emerg Technol 11:250-258.