Black rot, caused by Xanthomonas campestris pv. campestris (Xcc) is a devastating disease that poses a significant threat to the cultivation of cabbage (Brassica oleracea var. capitata) worldwide, resulting in substantial economic losses. In this study, antagonistic bacteria were isolated from cabbage leaves and identified, and their biological control potential against Xcc was investigated through in vitro and in vivo experiments. For this purpose, candidate antagonistic bacteria were initially screened using hypersensitivity reaction, pectolytic activity and cabbage pathogenicity tests. To ensure taxonomic precision, isolates were identified by 16s rRNA sequencing and further validated through Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS). According to comparative results, isolate A1b was identified as Bacillus thuringiensis, isolate A4d as Bacillus licheniformis, isolate A16c as Bacillus subtilis subsp. subtilis, and isolate A19b as Bacillus pumilus, respectively. Preliminary in vitro assays confirmed the antagonistic potential of the tested Bacillus isolates against Xcc, producing inhibition zones ranging from 10.20 to 20.90 cm. Subsequent in vivo pot experiments demonstrated that disease suppression was significantly influenced by the timing of foliar applications, resulting in substantial biological control efficacies ranging from 51.2% to 98.5% under the evaluated conditions. Pearson correlation analysis revealed a time-dependent dynamic between in vitro inhibition zones and biocontrol efficacy, showing a significant positive correlation for applications 4, which shifted to a negative correlation for applications 5 and 6. Considering the synergistic potential of microbial communities, we propose that this approach may enhance black rot disease suppression and offer a sustainable strategy for integrated pest management, directly aligning with the European Green Deal by supporting the reduction of chemical pesticide dependency through eco-friendly alternatives. This study confirms the effectiveness of B. thuringiensis and B. pumilus and, to the best of our knowledge, represents the first report documenting the efficacy of B. subtilis subsp. subtilis and B. licheniformis against Xcc in cabbage, thereby providing a promising alternative for sustainable agriculture, with B. subtilis subsp. subtilis exhibiting comparatively greater in vivo efficacy than the other isolates tested.

Biocontrol Potential of Bacillus Species Against Black Rot Disease (Xanthomonas campestris pv. campestris) in Cabbage

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发表日期：

2026年7月17日

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Tuğba Eroğlu,
Nida Uysal,
Eminur Elçi

摘要

Black rot, caused by Xanthomonas campestris pv. campestris (Xcc) is a devastating disease that poses a significant threat to the cultivation of cabbage (Brassica oleracea var. capitata) worldwide, resulting in substantial economic losses. In this study, antagonistic bacteria were isolated from cabbage leaves and identified, and their biological control potential against Xcc was investigated through in vitro and in vivo experiments. For this purpose, candidate antagonistic bacteria were initially screened using hypersensitivity reaction, pectolytic activity and cabbage pathogenicity tests. To ensure taxonomic precision, isolates were identified by 16s rRNA sequencing and further validated through Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS). According to comparative results, isolate A1b was identified as Bacillus thuringiensis, isolate A4d as Bacillus licheniformis, isolate A16c as Bacillus subtilis subsp. subtilis, and isolate A19b as Bacillus pumilus, respectively. Preliminary in vitro assays confirmed the antagonistic potential of the tested Bacillus isolates against Xcc, producing inhibition zones ranging from 10.20 to 20.90 cm. Subsequent in vivo pot experiments demonstrated that disease suppression was significantly influenced by the timing of foliar applications, resulting in substantial biological control efficacies ranging from 51.2% to 98.5% under the evaluated conditions. Pearson correlation analysis revealed a time-dependent dynamic between in vitro inhibition zones and biocontrol efficacy, showing a significant positive correlation for applications 4, which shifted to a negative correlation for applications 5 and 6. Considering the synergistic potential of microbial communities, we propose that this approach may enhance black rot disease suppression and offer a sustainable strategy for integrated pest management, directly aligning with the European Green Deal by supporting the reduction of chemical pesticide dependency through eco-friendly alternatives. This study confirms the effectiveness of B. thuringiensis and B. pumilus and, to the best of our knowledge, represents the first report documenting the efficacy of B. subtilis subsp. subtilis and B. licheniformis against Xcc in cabbage, thereby providing a promising alternative for sustainable agriculture, with B. subtilis subsp. subtilis exhibiting comparatively greater in vivo efficacy than the other isolates tested.