Bacillus isolates from the spermosphere of peas and dwarf French beans with antifungal activity against Botrytis cinerea and Pythium species

Abstract

A range of isolation procedures including washing, sonication and incubation in nutrient broth were used separately and in combination to obtain potential bacterial antagonists to Botrytis cinerea and Pythium mamillatum from the testae and cotyledons of peas and dwarf French beans. Heat treatment was also used to bias this selection towards spore-forming bacteria. Ninety-two bacterial isolates were obtained, 72 of which were provisionally characterized as species of Bacillus. Four of these Bacillus isolates (B3, C1, D4 and J7) displayed distinct antagonism in vitro against Botrytis cinerea and P. mamillatum when screened using dual culture analysis. Further characterization of these antagonists using API 50CHB biochemical profiling identified isolate D4 as Bacillus polymyxa and isolates B3, C1 and J7 as strains of B. subtilis. In vitro screening techniques, using cell-free and heat-killed extracts of liquid cultures against Botrytis cinerea, demonstrated the production of antifungal compounds by these four Bacillus antagonists. With each isolate the antifungal activity was found not to be either exclusively spore-bound nor released entirely into the medium but present in both fractions. The antifungal compounds produced by these isolates were shown to be heat-stable. Their identification, production and release require further study for exploitation as biocontrol systems.

Antibiosis and dark-pigments secretion by the phytopathogenic and environmental fungal species after interaction in vitro with a Bacillus subtilis isolate

“…Antagonism in vitro varies according to culture media, bacterial antagonist and fungal species (Walker et al, 1998). The pH might be crucial for inducing the enzyme production by Bacillus spp from an intestinal source.…”

Integrated Management of Damping-off, Root and/or Stem Rot Diseases of Chickpea and Efficacy of the Suggested Formula

“…Their action could be through antibiosis (Walker et al, 1998), mycoparasitism (Haran et al, 1996). The competition for nutrients and/or space (Inbar et al, 1994).…”

Amazing Multiple Function Properties of Plant Growth Promoting Rhizobacteria in the Rhizosphere Soil

“…Some authors have suggested that the use of antimicrobially active species and strains of the genus Bacillus, or the use of their metabolites, may be an alternative or supplementary method to chemical plant protection (Berger et al, 1996;Handelsman et al, 1990;Klich et al, 1994;Sharga and Lyon, 1998). Many of these bacilli are generally soil-inhabiting bacteria or exist as epiphytes and endophytes in the spermosphere (Walker et al, 1998) and rhizosphere (Handelsman et al, 1990;Kajimura et al, 1995;McKeen et al, 1986). For this reason, Bacillus species are ideal candidates for use as biocontrol agents in seed treatment programs against soil-borne pathogens (Walker et al, 1998).…”

“…Many of these bacilli are generally soil-inhabiting bacteria or exist as epiphytes and endophytes in the spermosphere (Walker et al, 1998) and rhizosphere (Handelsman et al, 1990;Kajimura et al, 1995;McKeen et al, 1986). For this reason, Bacillus species are ideal candidates for use as biocontrol agents in seed treatment programs against soil-borne pathogens (Walker et al, 1998).…”