Aureobasidium pullulans (LS-30) an antagonist of postharvest pathogens of fruits: study on its modes of action

In vitro and in situ study of postharvest apple blue mold biocontrol by Aureobasidium pullulans: Evidence for the involvement of competition for nutrients

“…1 and 2) or in situ by the addition of exogenous apple nutrients (Figs. 3, 4, 7 and 8), which constitute supporting evidence for a possible involvement of competition for nutrients in the biocontrol activity of strain Ach1-1 against blue mold caused by P. expansum on stored apple fruit (Droby et al, 1989;Janisiewicz et al, 2000;Castoria et al, 2001;Meziane et al, 2006). If this is the case, strain Ach1-1 applied on apple surfaces will exert a fungistatic rather than fungicidal activity on P. expansum as it will deplete (limiting) nutrients available at the infection site (wounds) and inhibit conidia germination that depends on exogenous nutrients without affecting their viability.…”

“…In this way, competition for nutrients may be particularly effective as a sole mode of action or it may weaken the pathogen and predispose it to other mechanisms. In fact, other modes of action, including elicitation of host defence responses or production of lytic enzymes, might contribute simultaneously or sequentially with competition for nutrients to the biocontrol activity of strain Ach1-1 as was reported for other strains of the same species (Ippolito et al, 2000;Castoria et al, 2001).…”

“…In this context, several strains of the yeast-like fungus Aureobasidium pullulans (de Bary) Arnaud, one of the most widespread and well adapted saprophytes (Blakeman and Fokkema, 1982), have been isolated and appear to be potential biocontrol agents based on their great effectiveness in controlling the main postharvest pathogens (e.g. Botrytis cinerea and P. expansum) on several important crops including apple, table grape and strawberry (Lima et al, 1999(Lima et al, , 2003Ippolito et al, 2000Ippolito et al, , 2005Castoria et al, 2001;Adikaram et al, 2002).…”

“…Although several possible mechanisms have been reported (Droby and Chalutz, 1994;Janisiewicz and Korsten, 2002;Massart and Jijakli, 2007), the main mode of action of yeast(-like) biocontrol agents is believed to be competition for nutrients and space (Droby and Chalutz, 1994;Lima et al, 1997;Janisiewicz et al, 2000;Castoria et al, 2001). According to the literature dealing with competition for nutrients and space using different antagonist/pathogen(/host) systems (Castoria et al, 1997(Castoria et al, , 2001Lima et al, 1997;Janisiewicz et al, 2000;Guetsky et al, 2002;Vero et al, 2002): (i) most studies have considered either the in vitro or the in situ approach but not both, (ii) the contribution of the competition for nutrients and competition for space has rarely been considered separately, and (iii) in situ assays have been often performed using the Nutrient Yeast Dextrose Broth medium whose composition is not comparable with that of host tissues. In the present study, competition for nutrients as a mode of action of A. pullulans strain Ach1-1 against P. expansum was first examined in vitro using a system that allows discrimination between competition for nutrients and that for space (Janisiewicz et al, 2000) using increasing concentrations of apple juice.…”

Antagonistic interactions between Aureobasidium pullulans and Fusarium culmorum, a fungal pathogen of winter wheat

“…The biotechnological potential of A. pullulans is also associated with its high enzymatic activity. Depending on temperature, type of fermentation, carbon source, pH and water availability, the isolates of A. pullulans produce endoglucanase, xylanase, beta-glucosidase (Leite et al 2008), polygalacturonases (Stratilová et al 2006), amylase (Li et al 2007;Manitchotpisit et al 2011) and chitinases (endochtinase, chitobiosidase) and beta-1,3-glucanase that is produced in culture and apple wounds (Castoria et al 2001). The enzymes produced by A. pullulans are involved in mode of action of this microrganism and play a key role in the biological control of plant diseases, suppressing the growth of phytopathogens.…”