Exploring Pediococcus sp. M21F004 for Biocontrol of Bacterial and Fungal Phytopathogens

This study explores the biocontrol potential of <i>Pediococcus</i> sp. M21F004, a lactic acid bacteria (LAB) isolated from marine environments, against several bacterial and fungal phytopathogens. Out of 50 marine bacterial isolates, <i>Pediococcus</i> sp. M21F004 was selected for its exceptional antimicrobial activity. The strain, isolated from the intestine of a starry flounder, was identified as <i>Pediococcus</i> sp. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that oleic acid (OA) is a key antimicrobial compound produced by <i>Pediococcus</i> sp. M21F004. In vitro assays showed that the culture broth (CB) of <i>Pediococcus</i> sp. M21F004, as well as OA, exhibited significant inhibitory effects against pathogens such as <i>Fusarium oxysporum</i>, <i>Clarireedia homoeocarpa</i>, and <i>Pectobacterium carotovorum</i> subsp. <i>carotovorum</i>. In vivo tests on cucumber <i>Fusarium</i> wilt, creeping bentgrass dollar spot, tomato bacterial wilt, and kimchi cabbage soft rot further demonstrated the strain's efficacy in reducing disease severity. Moreover, OA had the highest control value of 74% against tomato bacterial wilt, followed by 64.1% against cucumber fusarium wilt, 42.5% against kimchi cabbage soft rot, and 16.5% against creeping bentgrass dollar spot. These findings suggest that <i>Pediococcus</i> sp. M21F004 and its metabolite OA offer promising alternatives to chemical pesticides, contributing to sustainable plant disease management by promoting resistance induction and providing an eco-friendly approach to agriculture.