Screening and Analysis of Antifungal Strains Bacillus subtilis JF-4 and B. amylum JF-5 for the Biological Control of Fusarium Wilt of Banana

Abstract

Purpose: This study aimed to identify the antagonistic bacteria from the rhizosphere of healthy bananas that can effectively suppress the Fusarium wilt of banana, and to further investigate the inhibitory mechanism. Method: The primary and secondary screening techniques were implemented using the double-plate and fermentation antagonism methods. The strain was identified based on physiological and biochemical tests, 16S rRNA gene sequencing, and specific gene amplification. The effects of crude extract on the protein content, lipid peroxidation, and pectinase activity of mycelia were determined from the identified isolates. Results: Two antagonistic bacteria, JF-4 and JF-5, were screened and initially identified as Bacillus subtilis (GenBank: OR125631) and B. amylum (GenBank: OR125632). The greenhouse experiment showed that the biological control efficiency of the two antagonists against the Fusarium wilt of banana was 48.3% and 40.3%, respectively. The catalase content produced by lipid peroxidation increased significantly after treatment with the crude extracts of JF-4 and JF-5 at concentrations of 0.69 μmol/L and 0.59 μmol/L, respectively. The protein and ergosterol content and pectinase activity decreased significantly. The two antagonistic bacteria might inhibit the growth of pathogens by enhancing lipid peroxidation and decreasing the synthesis of cell metabolites. Twenty compounds were identified by gas chromatography–mass spectrometry (GC-MS). B. subtilis JF-4 was further sequenced and assembled to obtain a complete circular chromosome genome of 681,804,824 bp. The genome consisted of a 4,310,825-bp-long scaffold. Conclusion: The findings of this study may help elucidate the mechanism behind this biocontrol isolate.

Biological control of the native endophytic fungus Pochonia chlamydosporia from the root nodule of Dolichos lablab on Fusarium wilt of banana TR4

“…Therefore, this strain will be an important biocontrol strain resource for the green control of FWB. YNF2217 could be used as an additional and new biocontrol strain resource along with the previously discovered strains such as Pseudomonas (Xie et al, 2023 ), Bacillus (Fan et al, 2021 , 2023 ; Duan et al, 2023 ), Trichoderma (Thukkaram et al, 2020 ) and Streptomyces (Lu et al, 2022 ). The prevention and control mechanisms of biocontrol fungi mainly include competition (Alwathnani et al, 2012 ), mycoparasitism (Amira et al, 2017 ), antibiosis (Vinale et al, 2014 ), induced resistance (Chemical et al, 2012 ), growth promotion (López-Bucio et al, 2015 ), and synergistic antagonism (Schulz et al, 2013 ).…”