Endospore biocontrol activity of two Bacillus strains against brown rot of stone fruits caused by Monilinia laxa

• Published in: Journal of plant pathology 2003-12, Vol.85 (4), p.278-278
• Main Authors: Casalini, L, Mari, M, Pratella, G C
• Format: Article
• Language: English
• Subjects: Bacillus; Monilinia laxa
• ISSN: 1125-4653

As biological control agent, Gram-positive bacteria have a natural advantage over their Gram-negative counterparts; i.e. the presence of spores which are resistant to heat and desiccation. Sporulating Gram-positive micro-organisms, such as non-pathogenic species belonging to the genus Bacillus, can be formulated into stable products due to the ability, under certain condition such as nutrient depletion, to undergo a differentiation process resulting in the formation of a highly resistant dormant endospore. These spores can then persist in the environment for prolonged periods until a sensitive response mechanism detects specific environmental conditions, initiating the process of germination and outgrowth. Post-harvest fruit treatments with sporulating Gram-positive microorganisms could be supplemented with various formulation additives in order to enhance their viability and performance and to increase the number of propagules applied to the wound surface. The activity of laboratory-produced endospores of two Bacillus spp. strains on M. laxa was investigated. Treatment with pure spore suspensions did not prevent the growth of the pathogen. Heat activation of spores followed by the contact with nutrient and non nutrient germinants such as L-alanine, AGFK (L-asparagine, D-glucose, D-fructose and KCl) and Calcium Dipicolinate (CaDPA) enhanced spore germination in in vitro spectrophotometer assay; only heat-activated spores mixed with CaDPA (50 mM) reduced significantly (P less than or equal to 0.05) the incidence of M. laxa on peaches cv Flaminia by 30% (2ORB strain) and 43% (7ORC strain) with respect to the untreated control.