<i>Bacillus amyloliquefaciens</i>: a versatile antimicrobial Firmicute for the suppression of wilt caused by <i>Ralstonia pseudosolanacearum</i> in tomato
Creators: name: Balamurugan, Alexander
name: Ashajyothi, Mushineni
name: Velmurugan, Shanmugam
name: Charishma, Krishnappa
name: Sakthivel, Krishnan
name: Muthamilan, Malaiyandi
name: Kumar, Aundy
Publisher: name: Taylor & Francis
Year: 2024
Subjects: subject: Microbiology
subject: FOS: Biological sciences
subject: Genetics
subject: Molecular Biology
subject: Environmental Sciences not elsewhere classified
subject: Ecology
subject: Biological Sciences not elsewhere classified
subject: Plant Biology

description: Rhizosphere bacteria based biological control strategy is an eco-friendly approach to protect crops from various plant diseases. Among these, spore-forming <i>Bacillus</i>, abundant in the rhizosphere, provide unique advantages for plant health. This study focused on characterising two tomato rhizosphere-associated <i>Bacillus amyloliquefaciens</i> strains (Trb7 and Trb11), highly effective against the bacterial wilt pathogen <i>Ralstonia pseudosolanacearum in vitro</i>. Species identification was based on partial 16S rRNA gene sequencing, supported by phylogenetic analysis. Five antimicrobial peptide (AMP) genes (surfactin, fengycin, bacilysin, subtilin, and spore protein) were detected in both the isolates of <i>B. amyloliquefqciens</i> using specific molecular markers. Greenhouse trials showed that prophylactic application of these isolates led to an 83.4% reduction in tomato bacterial wilt, with only 16.6% wilt incidence compared to the 100% in the <i>R. pseudosolanacearum</i>-inoculated control. Moreover, these <i>B. amyloliquefaciens</i> isolates exhibited plant-growth-promoting traits <i>in vitro</i>. Interestingly, they also showed significant inhibition of mycelial growth against <i>Sclerotium rolfsii</i> and <i>Alternaria alternata</i>, major fungal pathogens in tomatoes. Overall, our findings highlight the potent bactericidal role of <i>B. amyloliquefaciens</i> isolates in suppressing <i>R. pseudosolanacearum</i> in tomatoes. Two among the 100 <i>Bacillus</i> displayed antibacterial activity against <i>Ralstonia pseudosolanacearum.</i>Antibacterial firmicutes was identified as <i>Bacillus amyloliquefaciens</i> through the 16S rRNA gene sequence analysis.Five AMP genes (<i>srfAA, fenD, bacA, spas,</i> and <i>spoVG</i>) were identified in the isolates.Delivery of <i>B. amyloliquefaciens</i> drenching on rhizosphere significantly reduced wilt.Additionally, <i>B. amyloliquefaciens</i> showed the antifungal activity on <i>Sclerotium rolfsii</i> and <i>Alternaria alternata</i>. Two among the 100 <i>Bacillus</i> displayed antibacterial activity against <i>Ralstonia pseudosolanacearum.</i> Antibacterial firmicutes was identified as <i>Bacillus amyloliquefaciens</i> through the 16S rRNA gene sequence analysis. Five AMP genes (<i>srfAA, fenD, bacA, spas,</i> and <i>spoVG</i>) were identified in the isolates. Delivery of <i>B. amyloliquefaciens</i> drenching on rhizosphere significantly reduced wilt. Additionally, <i>B. amyloliquefaciens</i> showed the antifungal activity on <i>Sclerotium rolfsii</i> and <i>Alternaria alternata</i>. Graphical abstract depicting the isolation and characterisation of Bacillus amyloliquefaciens for the suppression of wilt caused by Ralstonia pseudosolanacearum in tomato. Figures was created and manually edited in Biorender.com.