AUTHOR=Tang Tao , Wang Fanfan , Huang Houyun , Guo Jie , Guo Xiaoliang , Duan Yuanyuan , Wang Xiaoyue , Wang Qingfang , You Jingmao 

TITLE=Bacillus velezensis LT1: a potential biocontrol agent for southern blight on Coptis chinensis

JOURNAL=Frontiers in Microbiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1337655

DOI=10.3389/fmicb.2024.1337655

ISSN=1664-302X

ABSTRACT=<sec id="sec1001"><title>Introduction</title><p>Southern blight, caused by <italic>Sclerotium rolfsii</italic>, poses a serious threat to the cultivation of <italic>Coptis chinensis</italic>, a plant with significant medicinal value. The overreliance on fungicides for controlling this pathogen has led to environmental concerns and resistance issues. There is an urgent need for alternative, sustainable disease management strategies.</p></sec><sec id="sec2001"><title>Methods</title><p>In this study, <italic>Bacillus velezensis</italic> LT1 was isolated from the rhizosphere soil of diseased <italic>C. chinensis</italic> plants. Its biocontrol efficacy against <italic>S. rolfsii</italic> LC1 was evaluated through a confrontation assay. The antimicrobial lipopeptides in the fermentation liquid of <italic>B. velezensis</italic> LT1 were identified using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF-MS). The effects of <italic>B. velezensis</italic> LT1 on the mycelial morphology of <italic>S. rolfsii</italic> LC1 were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).</p></sec><sec id="sec3001"><title>Results</title><p>The confrontation assay indicated that <italic>B. velezensis</italic> LT1 significantly inhibited the growth of <italic>S. rolfsii</italic> LC1, with an inhibition efficiency of 78.41%. MALDI-TOF-MS analysis detected the presence of bacillomycin, surfactin, iturin, and fengycin in the fermentation liquid, all known for their antifungal properties. SEM and TEM observations revealed that the mycelial and cellular structures of <italic>S. rolfsii</italic> LC1 were markedly distorted when exposed to <italic>B. velezensis</italic> LT1.</p></sec><sec id="sec4001"><title>Discussion</title><p>The findings demonstrate that <italic>B. velezensis</italic> LT1 has considerable potential as a biocontrol agent against <italic>S. rolfsii</italic> LC1. The identified lipopeptides likely contribute to the antifungal activity, and the morphological damage to <italic>S. rolfsii</italic> LC1 suggests a mechanism of action. This study underscores the importance of exploring microbial biocontrol agents as a sustainable alternative to chemical fungicides in the management of plant diseases. Further research into the genetic and functional aspects of <italic>B. velezensis</italic> LT1 could provide deeper insights into its biocontrol mechanisms and facilitate its application in agriculture.</p></sec>