AUTHOR=Pandey Chitra , Prabha Deepti , Negi Yogesh Kumar , Maheshwari Dinesh Kumar , Dheeman Shrivardhan , Gupta Monika 

TITLE=Macrolactin A mediated biocontrol of Fusarium oxysporum and Rhizoctonia solani infestation on Amaranthus hypochondriacus by Bacillus subtilis BS-58

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1105849

DOI=10.3389/fmicb.2023.1105849

ISSN=1664-302X

ABSTRACT=<p>Plant diseases are one of the main hurdles for successful crop production and sustainable agriculture development world-wide. Though several chemical measures are available to manage crop diseases, many of them have serious side effects on humans, animals and the environment. Therefore, the use of such chemicals must be limited by using effective and eco-friendly alternatives. In view of the same, we found a <italic>Bacillus subtilis</italic> BS-58 as a good antagonist towards the two most devastating phytopathogens, i.e., <italic>Fusarium oxysporum</italic> and <italic>Rhizoctonia solani</italic>. Both the pathogens attack several agricultural crops (including <italic>amaranth</italic>) and induce a variety of infections in them. The findings of scanning electron microscopy (SEM) in this study suggested that <italic>B. subtilis</italic> BS-58 could inhibit the growth of both the pathogenic fungi by various means such as perforation, cell wall lysis, and cytoplasmic disintegration in the fungal hyphae. Thin-layer chromatography, LC–MS and FT-IR data revealed the antifungal metabolite to be macrolactin A with a molecular weight of 402 Da. Presence of the <italic>mln</italic> gene in the bacterial genome further endorsed that the antifungal metabolite produced by BS-58 was macrolactin A. Pot trial conducted in the present study showed that seed treatment by BS-58 effectively reduced seedling mortality (54.00 and 43.76%) in <italic>amaranth</italic>, when grown in pathogen infested soil (<italic>F. oxysporum</italic> and <italic>R. solani</italic>, respectively), when compared to their respective negative controls. Data also revealed that the disease suppression ability of BS-58 was almost equivalent to the recommended fungicide, carbendazim. SEM analysis of roots of the seedlings recovered from pathogenic attack substantiated the hyphal disintegration by BS-58 and prevention of <italic>amaranth</italic> crop. The findings of this study conclude that macrolactin A produced by <italic>B. subtilis</italic> BS-58 is responsible for the inhibition of both the phytopathogens and the suppression of the diseases caused by them. Being native and target specific, such strains under suitable conditions, may result in ample production of antibiotic and better suppression of the disease.</p>