Isolation and Characterization of an Antagonistic Endophytic Bacterium Bacillus velezensis CB3 the Control of Citrus Green Mold Pathogen Penicillium digitatum

Abstract

In order to develop environment friendly fungicide for the control of citrus green mold (Penicillium digitatum) using endophytic bacteria, the 21 bacterial isolates were isolated from citrus leaves in seven different orchards in Jeju Province. Among the 21 bacterial isolates, 5 bacterial isolates presented antifungal activity against green mold pathogen P. digitatum. The CB3 isolate, which showed the most strong antagonistic effect, was selected through opposite culture against the pathogen. The rod-shaped, gram-positive bacterium CB3 was identified as Bacillus velezensis based on morphological, physiological characteristics, 16S rDNA, and gyr A gene sequence analysis. The isolate CB3 showed strong antifungal activity against two citrus postharvest pathogen P. digitatum. Citrus fruits were treated by wound inoculation with P. digitatum pathogen, and the control efficacy of CB3 culture broth was 66.7% (1 × 10 8 cfu/ml). In conclusion, The stability of CB3 and its strong antifungal activity also lead us to believe that it has potential for application as an environment friendly biological control agent.

Biocontrol Ability of the Bacillus amyloliquefaciens Group, B. amyloliquefaciens, B. velezensis, B. nakamurai, and B. siamensis, for the Management of Fungal Postharvest Diseases: A Review

“…97 Application of B. velezensis CB3 cells (1 × 10 6 CFU/mL, 58% disease incidence inhibition; 1 × 10 7 CFU/mL, 58% disease incidence inhibition; 1 × 10 8 CFU/mL, 67% disease incidence inhibition) and supernatant (56% disease incidence inhibition) provided similar efficacies. 98 A suitable explanation for these differences is that not all strains can successfully colonize different hosts, which is in agreement with the conclusion achieved in the Isolation Sources and Colonization Ability section after analyzing the connections between the isolation source and studied host. For example, B. amyloliquefaciens B4 supernatant reduced the disease incidence of P. expansum by 77−85%.…”

“…In contrast with the mentioned results, Chen et al indicated that the control of B. cinerea with B. amyloliquefaciens RS-25 was slightly more effective when using cells (61%–87%) than when applying the culture supernatant (55%–87%) and extracts (57%–76%) . Application of B. velezensis CB3 cells (1 × 10 6 CFU/mL, 58% disease incidence inhibition; 1 × 10 7 CFU/mL, 58% disease incidence inhibition; 1 × 10 8 CFU/mL, 67% disease incidence inhibition) and supernatant (56% disease incidence inhibition) provided similar efficacies …”

Complete Genome Sequence of Bacillus velezensis GQJK49, a Plant Growth-Promoting Rhizobacterium with Antifungal Activity

“…Bacillus velezensis is widely used as a biocontrol strain ( 1 – 3 ). Chang et al ( 4 ) reported that B. velezensis SSH100-10 produces iturin A against fungi.…”

Plant-microbial interactions in agriculture and the use of farming systems to improve diversity and productivity

“…For example, the bacteria Bacillus amyloliquefaciens reduced the growth of 12 fungal species (including Alternaria panax , Botrytis cinera , Colletotrichum orbiculare , Penicillium digitatum , Pyricularia grisea , and Sclerotinia sclerotiorum ), in vitro and in trials with cucumber and pumpkin plants [70]. Bacillus amyloliquefaciens also reduced fungal rot in citrus [71], strawberries [72], and soybeans [73], and B. velenzensis reduced the infection of citrus green mold by the fungus Penicillium digitatum [74]. In field conditions, where continuously mono-cropped tobacco plants had eventually become infected with Fusarium due to pathogen build-up in soil, large-scale treatment of bacteria native to the soil habitat showed a reduction in fungal infection [75].…”