Biocontrol Ability of Strain <i>Bacillus amyloliquefaciens</i> SQ-2 against Table Grape Rot Caused by <i>Aspergillus tubingensis</i>

<i>Bacillus amyloliquefaciens</i> strain SQ-2, isolated from a cured product, has been demonstrated to exhibit a highly efficacious performance against phytopathogens, including <i>Stemphylium solani</i>, <i>Fusarium moniliforme</i>, <i>Fusarium graminearum</i>, and <i>Aspergillus tubingensis</i>. In particular, with regard to <i>A. tubingensis</i>, which causes summer bunch rot, SQ-2 has been observed to suppress the mycelial growth of all tested grape cultivars by over 40%. Especially on Kyoho grapes, it has the highest inhibition rate of 53%. Scanning electron microscopy (SEM) confirms that SQ-2 is an effective agent for suppressing the mycelia proliferation, differentiation, and spore formation of <i>A. tubingensis</i>. Furthermore, an LC/MS analysis revealed that SQ-2 produces two principal lipopeptides, namely, bacillibactin and surfactin, in addition to a polyketide, bacillaene. Further analysis through gas chromatography-mass spectrometry (GC/MS) identified 41 distinct volatile organic compounds secreted by SQ-2. Transcriptomic analysis indicated that exposure to the metabolite of SQ-2 induced substantial gene expression alterations in <i>A. tubingensis</i>. These data suggest that <i>B. amyloliquefaciens</i> strain SQ-2 exhibits promising crop protection potential of inhibiting plant pathogens through the secretion of bacillibactin, surfactin, bacillaene, and VOCs.