Biocide effects of volatile organic compounds produced by potential biocontrol rhizobacteria on Sclerotinia sclerotiorum

Abstract

Six rhizobacteria isolated from common bean and able to protect bean plants from the common bacterial blight (CBB) causal agent, were in vitro evaluated for their potential antifungal effects toward different plant pathogenic fungi, mostly soil-borne. By dual culture assays, the above bacteria resulted producing diffusible and volatile metabolites which inhibited the growth of the majority of the pathogens under study. In particular, the latter substances highly affected the mycelium growth of Sclerotinia sclerotiorum strains, one of which was selected for further studies either on mycelium or sclerotia. Gas chromatographic analysis of the bacterial volatiles led to the identification of an array of volatile organic compounds (VOCs). Time course studies showed the modification of the VOCs profile along a period of 5 days. In order to evaluate the single detected VOC effects on fungal growth, some of the pure compounds were tested on S. sclerotiorum mycelium and their minimal inhibitory quantities were determined. Similarly, the minimal inhibitory quantities on sclerotia germination were also defined. Moreover, observations by light and transmission electron microscopes highlighted hyphae cytoplasm granulation and ultrastructural alterations at cell organelles, mostly membranes, mitochondria, and endoplasmic reticulum. The membranes appeared one of the primary targets of bacterial volatiles, as confirmed by hemolytic activity observed for the majority of pure VOCs. However, of interest is the alteration observed on mitochondria as well.

Identification of a Potential ISR Determinant from Pseudomonas aeruginosa PM12 against Fusarium Wilt in Tomato

“…Similarly elicitor benzothiazole isolated from Pseudomonas sp. has shown inhibition of mycelial growth and germination from ascospores and sclerotia of Sclerotinia sclerotiorum (Fernando et al, 2005). Aldehydes, ketones and benzenes from Bacillus amyloliquefaciens have been known to restrict mycelial growth and spore germination of F. oxysporum (Yuan et al, 2012).…”

Breath metabolome of mice infected with Pseudomonas aeruginosa

“…Only one compound remained completely unknown (similarity match < 600), though it was reproducibly present. Cyclohexanol has been previously reported to be produced by Pseudomonas strains (Giorgio et al 2015), and 2-hexanone was previously reported in the headspace of sputum from patients infected with P. aeruginosa (Goeminne et al 2012). …”

“…Only two compounds that we identified were previously reported in relation to Pseudomonas , namely cyclohexanol and 2-hexanone (Giorgio et al 2015; Goeminne et al 2012). The latter was significantly more abundant in the breath of UV-killed and PBS infected mice compared to the Live-group, suggesting that the molecule may be metabolized by the pathogen.…”

Biological Management of Vascular Wilt of Chickpea (Cicer arietinum L.) Incited by Fusarium oxysporum f. sp. ciceris by Antagonistic Rhizobacteria Co-Inoculated with Native Mesorhizobium

“…However among Bacillus isolates, Ba11 was found to be most efficient in pathogen inhibition i.e. 76.3% followed by Ba19 (74.5±0.21%) ( (Giorgio et al, 2015).…”