Antimicrobial and plant growth-promoting properties of the cacao endophyte Bacillus subtilis  ALB629

Abstract

Aims: To investigate the effects of the endophyte Bacillus subtilis ALB629 on the growth of cacao seedlings at early developmental stage and to evaluate its antimicrobial properties. Methods and Results: Germinating cacao seeds were inoculated with ALB629, and seedlings growth was evaluated 30 days later. Significant increase (P < 0Á05) was observed in the root system (up to 30%), leaf area (14%) and stem height (7Á6%). ALB629 colonized the entire plant, prevailing over indigenous micro-organisms. In addition, it was tested in vitro, by pairing assays, and showed antagonistic effect against the phytopathogenic fungi Moniliophthora perniciosa, Colletotrichum sp. and C. gossypii. When tested in cacao-grafting procedure in the field, ALB629 increased the grafting success rate (24%), indicating its protective effect. In addition, this Bacillus secretes an antagonist compound, as shown by the antifungal activity of the cell-free culture. Conclusions: Bacillus subtilis ALB629 promotes cacao root growth, besides promoting growth of the aerial part of cacao seedlings. It has antimicrobial properties and produces an antifungal compound. Significance and Impact of the Study: ALB629 presented beneficial characteristics for cacao cultivation, being a good biological control agent candidate. Furthermore, it is a potential source of antifungal compound with potential for commercial exploitation.

Diversity of food-borne Bacillus volatile compounds and influence on fungal growth

“…; Falcao et al . ) reported the in vitro antagonistic activity of endophytic B. subtilis, B. amyloliquefaciens, B. mycoides and B. cereus towards M. perniciosa , however, they did not identify the compounds responsible for the inhibition. To the best of our knowledge, this is the first report on the antifungal activity of Bacillus VOCs against M. perniciosa .…”

Bacillus species (BT42) isolated from Coffea arabica L. rhizosphere antagonizes Colletotrichum gloeosporioides and Fusarium oxysporum and also exhibits multiple plant growth promoting activity

“…The test for antifungal activity of the culture filtrate was done as described elsewhere with modifications [50, 51]. Briefly, to check the antifungal activity of culture filtrate from strain BT42, a single colony of the isolate inoculated into Luria-Bertani (LB) broth and incubated for 120 h under shaking condition of 150 rpm at 30 °C.…”

Biocontrol of Bacterial Leaf Blight of Rice and Profiling of Secondary Metabolites Produced by Rhizospheric Pseudomonas aeruginosa BRp3

“…Similarly, different endophytic strains of B. subtilis have been reported to have plant growth promoting activity on cacao and biocontrol activity against phytopathogens like Moniliophthora perniciosa and Colletotrichum spp. but the antifungal metabolites were not investigated (Kumar et al, 2012; Nain et al, 2012; Falcao et al, 2014). The use of Pseudomonas and Bacillus strains have been reported for the biocontrol of rice pathogens such as Xoo, M. oryzae , and R. solani (Ji et al, 2008; Helene et al, 2011; Spence et al, 2014).…”