Occurrence of antimicrobial activities of bacteria from soybean leaf spots

Abstract

Bacteria were isolated from leaf spots of field grown soybeans during two growing seasons. The leaf spots yielded up to 4 different species and a total population size of about 10(7)-10(8) bacteria/cm2. The majority of the 192 isolates belonged to the species Pseudomonas syringae pv. glycinea (55%), causing leaf spots of bacterial blight on soybeans, and Erwinia herbicola (22%). The remaining isolates included bacteria from other genera, but occurred occasionally. The determination of biological activity of the isolates demonstrated that a high percentage of strains from the group Erwinia/Enterobacter produced biological active substances against Escherichia coli (69%) and against Chlorella pyrenoidosa (88%). The majority of P. syringae pv. glycinea strains failed to do so. None of the isolates affected the growth of Geotrichum candidum. The E. herbicola strains showed clear antagonistic properties against a wide range of isolated bacteria. Four E. herbicola strains inhibited the growth of nearly all other E. herbicola isolates and 6 other strains were active against most of the P. syringae pv. glycinea isolates. However, antagonistic interactions among strains isolated from a distinct leaf spot were very rarely.

The bacterial lipopeptide iturins induce Verticillium dahliae cell death by affecting fungal signalling pathways and mediate plant defence responses involved in pathogen‐associated molecular pattern‐triggered immunity

“…The antagonistic activity of strain 41B‐1 against V. dahliae was tested in vitro using a modified agar diffusion assay described by Völksch and colleagues (), with some additional modifications. Conidia of V. dahliae were obtained by culturing the strain in PDB for 3 days at 25°C at 150 rpm, and the resultant concentration was approximately 10 7 conidia per millilitre of the suspension.…”

Toxin production by pathovars ofPseudomonas syringae and their antagonistic activities against epiphytic microorganisms

“…The tabtoxin-producers inhibited the growth of all tested Gram-negative bacteria including E. herbicola which was insensitive against all other toxigenic strains. On the contrary to that, E. herbicola strains which were described as common phylloplane bacteria on different plant species can inhibit plant-pathogenic bacteria (VÖLKSCH et al 1993, MAY et al 1997.…”

Characterization of plant growth-promoting traits and antagonistic potentials of endophytic bacteria from bean plants against Pseudomonas syringae pv. phaseolicola

“…The different species belonging Bacillus and Pseudomonas have been reported to inhibit several fungal and bacterial plant pathogens (Beer et al 1984, El-Goorani and Beer 1991, Völksch et al 1993 and it is an effective competitor in biological prevention of frost injury (Lindow et al 1983). Different species of Pseudomonas were reported to produce a variety of metabolites (Leisinger and Margaff 1979), some of which were implicated in the biological control of plant pathogenic fungal and bacterial disease agents (Dowling and O'Gara 1994).…”