Antagonistic potential of Bacillus spp. isolates against bacterial pathogens of tomato and fungal pathogen of pepper

Abstract

In vitro antagonistic potential of eleven isolates of Bacillus spp. against two phytopathogenic bacteria and one fungus was tested in order to identify potential biocontrol agents in vegetable crops. The Bacillus spp. isolates demonstrated different levels of antagonistic effect against the tested pathogenic microorganisms. Data in the study proved Xanthomonas vesicatoria to be more sensitive to Bacillus spp. strains than Clavibacter michiganensis subsp. michiganensis. Ten B. subtilis strains induced growth inhibition of X. vesicatoria, while a strain of B. pumilus did not affect the growth of that bacterium. The largest inhibition zones against X. vesicatoria were induced by strains B-319, B-325 and B-358. The pathogenic strain C. michiganensis subsp. michiganensis was most inhibited by two B. subtilis strains (B-338 and B-348) with mean inhibition zone diameters of up to 20 mm. B. subtilis strain B-319 which was the best in inhibiting X. vesicatoria, showed the lowest inhibitory effect on C. michiganensis subsp. michiganensis. The largest growth inhibition percentage of Verticillium sp. (PGI approximately 70%) was induced by B. subtilis strains B-310 and B-322. The other B. subtilis strains showed PGI values ranging from 45% to 68%, while B. pumilus strain B-335 had the least antagonistic potential (PGI =34.43%) against the pathogen. This study identified at least one suitable biocontrol candidate, B. subtilis strain B-358, as effective in vitro against all three vegetable pathogens.

A Novel Isolate of Bacillus cereus Promotes Growth in Tomato and Inhibits Clavibacter michiganensis Infection under Greenhouse Conditions

“…This type of knowledge might be important for future industrial application purposes of B.c-A, because it is important to search for cheaper culture mediums, in order to diminish costs of large-scale production of PGPBs. Moreover, it has been reported that strains of B. subtilis and Pseudomonas sp display antagonistic activity in vitro and in vivo , respectively, against Cmm and the bacterial canker in tomato [ 24 ] and [ 25 ]. To our knowledge, the results of the present work are the first report showing that a strain of Bacillus cereus (as B.c-A) displays in vitro and in vivo antagonistic activity against Cmm and the canker disease provoked by this pathogen in tomato.…”

Skin bacteria of rainbow trout antagonistic to the fish pathogen Flavobacterium psychrophilum

“…Based on the sequence identity of > 99% (considered to belong to the same species), the isolates were assigned to 20 groups spanning 18 genera and five phyla. Previous reports 35 , 36 showed that closely related strains (including those shared > 99.2% of 16S rRNA gene similarity 36 ) similarly exhibited antagonistic activities. In this study, a representative strain was selected from each group assuming that strains of each group exhibit similar antagonistic characteristics.…”

“…The production of siderophores 10 , bacteriocins 41 , lipoprotein 17 , hydrogen peroxide 35 , and blocking quorum-sensing 16 are considered as the mechanisms underlying the antagonistic ability of bacteria. Among these, GL7 produced siderophores, whereas OX14 was also weakly positive.…”

The Use of Interactions Between Microorganisms in Strawberry Cultivation (Fragaria x ananassa Duch.)

“…Research indicates that P. polymyxa ( Zhang et al, 2018 ), Bacillus sp. ( Milijasevic-Marcic et al, 2018 ), and Streptomyces sp. ( Olanrewaju and Babalola, 2019 ) are disease-inhibiting bacteria.…”