A new bioorganic fertilizer can effectively control banana wilt by strong colonization with Bacillus subtilis N11

202

138

cBacillus amyloliquefaciens strains are capable of suppressing soilborne pathogens through the secretion of an array of lipopeptides and root colonization, and biofilm formation ability is considered a prerequisite for efficient root colonization. In this study, we report that one of the lipopeptide compounds (bacillomycin D) produced by the rhizosphere strain Bacillus amyloliquefaciens SQR9 not only plays a vital role in the antagonistic activity against Fusarium oxysporum but also affects the expression of the genes involved in biofilm formation. When the bacillomycin D and fengycin synthesis pathways were individually disrupted, mutant SQR9M1, which was deficient in the production of bacillomycin D, only showed minor antagonistic activity against F. oxysporum, but another mutant, SQR9M2, which was deficient in production of fengycin, showed antagonistic activity equivalent to that of the wild-type strain of B. amyloliquefaciens SQR9. The results from in vitro, root in situ, and quantitative reverse transcription-PCR studies demonstrated that bacillomycin D contributes to the establishment of biofilms. Interestingly, the addition of bacillomycin D could significantly increase the expression levels of kinC gene, but KinC activation is not triggered by leaking of potassium. These findings suggest that bacillomycin D contributes not only to biocontrol activity but also to biofilm formation in strain B. amyloliquefaciens SQR9.

Section: Methodsmentioning

confidence: 99%

“…Colonization of root is a prerequisite for successful control of soilborne pathogen by BCAs (17), which depend on the capability of biofilm formation. It is now widely recognized that most bacteria found in natural, clinical, and industrial settings persist in association with surfaces by forming biofilms (18).…”

mentioning

confidence: 99%

Contribution of Bacillomycin D in Bacillus amyloliquefaciens SQR9 to Antifungal Activity and Biofilm Formation

Shao

et al. 2013

202

138

“…The shuttle plasmid pHAPII was used to introduce plasmid-borne GFP genes into B. amyloliquefaciens SQR9 and its derivative strains by electroporation (20). To study root colonization, B. amyloliquefaciens strains were labeled with GFP to enable the monitoring.…”

Section: Methodsmentioning

confidence: 99%

Enhanced Control of Cucumber Wilt Disease by Bacillus amyloliquefaciens SQR9 by Altering the Regulation of Its DegU Phosphorylation

Zhang

Wang

et al. 2014

Self Cite

109

Bacillus amyloliquefaciens strain SQR9, isolated from the cucumber rhizosphere, suppresses the growth of Fusarium oxysporum in the cucumber rhizosphere and protects the host plant from pathogen invasion through efficient root colonization. In the Gram-positive bacterium Bacillus, the response regulator DegU regulates genetic competence, swarming motility, biofilm formation, complex colony architecture, and protease production. In this study, we report that stepwise phosphorylation of DegU in B. amyloliquefaciens SQR9 can influence biocontrol activity by coordinating multicellular behavior and regulating the synthesis of antibiotics. Results from in vitro and in situ experiments and quantitative PCR (qPCR) studies demonstrate the following: (i) that the lowest level of phosphorylated DegU (DegUϳP) (the degQ mutation) impairs complex colony architecture, biofilm formation, colonization activities, and biocontrol efficiency of Fusarium wilt disease but increases the production of macrolactin and bacillaene, and (ii) that increasing the level of DegUϳP by degQ and degSU overexpression significantly improves complex colony architecture, biofilm formation, colonization activities, production of the antibiotics bacillomycin D and difficidin, and efficiency of biocontrol of Fusarium wilt disease. The results offer a new strategy to enhance the biocontrol efficacy of Bacillus amyloliquefaciens SQR9.

“…Representative isolates of B. subtilis XY11 were selected for colonization analysis. The protocol for electroporation of the isolate was carried out as described previously by Zhang et al (19). GFP-tagged XY11 was inoculated into LB medium containing 20 g/ml kanamycin and grown to stationary phase.…”

Section: Methodsmentioning

confidence: 99%

Involvement of Colonizing Bacillus Isolates in Glucovanillin Hydrolysis during the Curing of Vanilla planifolia Andrews

Yong-gan

et al. 2015

Vanilla beans were analyzed using biochemical methods, which revealed that glucovanillin disperses from the inner part to the outer part of the vanilla bean during the curing process and is simultaneously hydrolyzed by ␤-D-glucosidase. Enzymatic hydrolysis was found to occur on the surface of the vanilla beans. Transcripts of the ␤-D-glucosidase gene (bgl) of colonizing microorganisms were detected. The results directly indicate that colonizing microorganisms are involved in glucovanillin hydrolysis. Phylogenetic analysis based on 16S rRNA gene sequences showed that the colonizing microorganisms mainly belonged to the Bacillus genus. bgl was detected in all the isolates and presented clustering similar to that of the isolate taxonomy. Furthermore, inoculation of green fluorescent protein-tagged isolates showed that the Bacillus isolates can colonize vanilla beans. Glucovanillin was metabolized as the sole source of carbon in a culture of the isolates within 24 h. These isolates presented unique glucovanillin degradation capabilities. Vanillin was the major volatile compound in the culture. Other compounds, such as ␣-cubebene, ␤-pinene, and guaiacol, were detected in some isolate cultures. Colonizing Bacillus isolates were found to hydrolyze glucovanillin in culture, indirectly demonstrating the involvement of colonizing Bacillus isolates in glucovanillin hydrolysis during the vanilla curing process. Based on these results, we conclude that colonizing Bacillus isolates produce ␤-D-glucosidase, which mediates glucovanillin hydrolysis and influences flavor formation. V anilla flavoring obtained from cured Vanilla planifolia beans is widely used in food, beverages, and cosmetics, such that the total worldwide consumption is markedly increasing (1, 2). The characteristics of the vanilla flavor are formed only during a careful curing process that yields the main aromatic constituent, vanillin, and over 200 other volatile compounds with delicate sweet fragrances (3).The conventional curing process starts with a blanching step in which the mature green vanilla bean is immersed in hot water for 3 to 5 min. The vanilla beans are then subjected to a process that involves periodic sweating and drying. During the remaining part of the day, the vanilla beans are allowed to acclimate on wooden racks in a well-ventilated room and are then stored in small bundles in plastic vacuum bags at room temperature (4, 5).In fresh vanilla beans, vanillin is exclusively present in a conjugated form, principally as glucovanillin. At this stage, the beans display no trace of vanilla flavor (6, 7). One of the most important aspects of curing is when glucovanillin comes into contact with ␤-D-glucosidase, thus releasing free vanillin (8). Thermal treatment, plant enzyme reactions, and microbial activity are all important in vanillin flavor generation (9). Röling et al. (10) reported that differences in microbial abundance, communities, and strain characteristics result in variations in vanilla flavor. These results show that colonizing microorg...