In vitro suppression of fungi caused by combinations of apparently non-antagonistic soil bacteria

TY - JOUR

T1 - In vitro suppression of fungi caused by combinations of apparently non-antagonistic soil bacteria

AU - De Boer, W.

AU - Wagenaar, A.M.

AU - Klein Gunnewiek, P.J.A.

AU - Van Veen, J.A.

N1 - Reporting year: 2007 Metis note: 3873;CTE; TME; file:///C:/pdfs/Pdfs2007/DeBoer_ea_3873.pdf

PY - 2007

Y1 - 2007

N2 - We hypothesized that apparently non-antagonistic soil bacteria may contribute to suppression of fungi during competitive interactions with other bacteria. Four soil bacteria (Brevundimonas sp., Luteibacter sp., Pedobacter sp. and Pseudomonas sp.) that exhibited little or no visible antifungal activity on different agar media were prescribed. Single and mixed strains of these species were tested for antagonism on a nutrient-poor agar medium against the plant pathogenic fungi Fusarium culmorum and Rhizoctonia solani and the saprotrophic fungus Trichoderma harzianum. Single bacterial strains caused little to moderate growth reduction of fungi (quantified as ergosterol), most probably due to nutrient withdrawal from the media. Growth reduction of fungi by the bacterial mixture was much stronger than that by the single strains. This appeared to be mostly due to competitive interactions between the Pseudomonas and Pedobacter strains. We argue that cohabitation of these strains triggered antibiotic production via interspecific interactions and that the growth reduction of fungi was a side-effect caused by the sensitivity of the fungi to bacterial secondary metabolites. Induction of gliding behavior in the Pedobacter strain by other strains was also observed. Our results indicate that apparently non-antagonistic soil bacteria may be important contributors to soil suppressiveness and fungistasis when in a community context. [KEYWORDS: antagonistic bacteria ; competition ; ergosterol ; fungistasis ; gliding ; interspecific interaction]

AB - We hypothesized that apparently non-antagonistic soil bacteria may contribute to suppression of fungi during competitive interactions with other bacteria. Four soil bacteria (Brevundimonas sp., Luteibacter sp., Pedobacter sp. and Pseudomonas sp.) that exhibited little or no visible antifungal activity on different agar media were prescribed. Single and mixed strains of these species were tested for antagonism on a nutrient-poor agar medium against the plant pathogenic fungi Fusarium culmorum and Rhizoctonia solani and the saprotrophic fungus Trichoderma harzianum. Single bacterial strains caused little to moderate growth reduction of fungi (quantified as ergosterol), most probably due to nutrient withdrawal from the media. Growth reduction of fungi by the bacterial mixture was much stronger than that by the single strains. This appeared to be mostly due to competitive interactions between the Pseudomonas and Pedobacter strains. We argue that cohabitation of these strains triggered antibiotic production via interspecific interactions and that the growth reduction of fungi was a side-effect caused by the sensitivity of the fungi to bacterial secondary metabolites. Induction of gliding behavior in the Pedobacter strain by other strains was also observed. Our results indicate that apparently non-antagonistic soil bacteria may be important contributors to soil suppressiveness and fungistasis when in a community context. [KEYWORDS: antagonistic bacteria ; competition ; ergosterol ; fungistasis ; gliding ; interspecific interaction]

U2 - 10.1111/j.1574-6941.2006.00197.x

DO - 10.1111/j.1574-6941.2006.00197.x

M3 - Article

SN - 0168-6496

VL - 59

SP - 177

EP - 185

JO - FEMS Microbiology Ecology

JF - FEMS Microbiology Ecology

IS - 1

ER -