Biofilm production by Aureobasidium pullulans improves biocontrol against sour rot in citrus

Abstract

The biocontrol efficiency of Aureobasidium pullulans strain ACBL-77 against Geotrichum citri-aurantii, causal agent of sour rot in citrus, and their interactions were evaluated. For this, were evaluated the incorporation of nutrients in optimizing the antagonistic activity of the yeast, the competition for nutrients between microorganisms, the effect of nutrients on yeast cell and biofilm production and their correlation in the biocontrol of disease, the survival of yeast in citrus fruits and the interaction between microorganisms using scanning electron microscopy. Micronutrients (boric acid, cobalt chloride and ammonium molybdate) favoured the antagonistic action of A. pullulans. Ammonium sulfate 1% and sucrose 0.5% favoured the yeast during the competition between the microorganisms. The addition of ammonium sulfate (1%) in the yeast culture stimulated biofilm production and increased the antagonistic activity against the disease, as also allowed the better survival of yeast in wounded sites of citrus fruit. The yeast was found to be able to form biofilms on citrus, deforming the pathogen hyphae. These results showed the importance of the addition of nutrients in A. pullulans based-formulations when aiming for their use on a commercial scale. This is the first report of a positive correlation between the increase in the quantity of biofilm produced by A. pullulans, with increased antagonistic activity.

Stress-Tolerant Yeasts: Opportunistic Pathogenicity Versus Biocontrol Potential

“…On the other hand, formation of a biofilm is of benefit when a microorganism is used as a biocontrol agent, as this brings several advantages over planktonic lifestyle: higher stress tolerance, antagonism by niche exclusion due to intensive competition for space and nutrients, and antibiosis via production of antimicrobials (reviewed in [115]). It has been shown that A. pullulans can live on plant surfaces in the form of biofilms [116,117] and that this biofilm formation improves the biocontrol activity against sour rot on citruses [116]. The previously reported biofilm production for D. hansenii [118], albeit not in the context of biocontrol, was also seen here, but not for M. fructicola strains.…”

Fifty Aureobasidium pullulans genomes reveal a recombining polyextremotolerant generalist

“…The ability of A. pullulans to survive in such unconventional habitats and to outcompete other species has been linked to its great adaptability to novel environments, to its polyextremotolerancethe ability to tolerate a plethora of different stresses (Gostin car et al, 2011) and to its nutritional versatility, which is associated with its wide enzymatic profile (Di Francesco et al, 2017). Its production of antimicrobial compounds and siderophores, and its biofilm formation and other factors are also likely to contribute to its adaptability (Takesako et al, 1993;Wang et al, 2009;Klein and Kupper, 2018).…”

Athelia (Sclerotium) rolfsii in Allium sativum: potential biocontrol agents and their effects on plant metabolites

“…Biofilms are morphologically more resistant to high temperatures and oxidative stress, and can be involved in biological control activity. Klein and Kupper (2018) between an increase in antagonistic activity and a rise in biofilm production. They emphasized that biofilm formation was an important biological control mechanism because the antagonist rapidly colonized the lesions and the film protected the plant against attack from phytopathogens.…”