Endophytic Microbiome Is a Unique Repository of Bio-Foes Against Toxigenic Fungi Harming Peanut Productivity
The major objective was to investigate the protective capabilities of endophytic bacterial strains isolated from a number of medicinal plant species towards <i>Aspergillus</i> spp. secured from the internal tissues of fungi-infected peanuts. Among 32 fungal isolates surveyed for mycotoxi...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-07-01
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| Series: | Microbiology Research |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2036-7481/16/7/141 |
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| Summary: | The major objective was to investigate the protective capabilities of endophytic bacterial strains isolated from a number of medicinal plant species towards <i>Aspergillus</i> spp. secured from the internal tissues of fungi-infected peanuts. Among 32 fungal isolates surveyed for mycotoxin production in various culture media (PDA, RBCA, YES, CA), 10 isolates qualitatively producing AFB<sub>1</sub>, besides 10 OTA-producers, were assayed by HPLC for quantitative toxin production. <i>Aspergillus</i> spp. isolate Be 13 produced an extraordinary quantity of 1859.18 μg mL<sup>−1</sup> AFB<sub>1</sub>, against the lowest toxin level of 280.40 μg mL<sup>−1</sup> produced by the fungus isolate IS 4. The estimated amounts of OTA were considerably lower and fell in the range 0.88–6.00 μg mL<sup>−1</sup>; isolate Sa 1 was superior, while isolate Be 7 seemed inferior. Based on ITS gene sequencing, the highly toxigenic <i>Aspergillus</i> spp. isolates Be 13 and Sa 1 matched the description of <i>A. novoparasiticus</i> and <i>A. ochraceus</i>, respectively, <i>ochraceus</i>, respectively, which are present in GenBank with identity exceeding 99%. According to 16S rRNA gene sequencing, these antagonists labeled Ar6, Ma27 and So34 showed the typical characteristics of <i>Pseudomonas aeruginosa</i>, <i>Bacillus subtilis</i> and <i>Bacillus velezensis</i>, respectively, with similarity percentages of 99–100. The plant growth-promoting activity measurements of the identified endophytes indicated the production of 16.96–80.00 μg/100 mL culture medium of IAA. Phosphate-solubilizing capacity varied among endophytes from 2.50 to 21.38 μg/100 mL. The polysaccharide production pool of bacterial strains ranged between 2.74 and 6.57 mg mL<sup>−1</sup>. <i>P. aeruginosa</i> Ar6 and <i>B. velezensis</i> successfully produced HCN, but <i>B. subtilis</i> failed. The in vitro mycotoxin biodegradation potential of tested bacterial endophytes indicated the superiority of <i>B. velezensis</i> in degrading both mycotoxins (AFB<sub>1</sub>-OTA) with average percentage of 88.7; <i>B. subtilis</i> ranked thereafter (85.6%). The 30-day old peanut (cv. Giza 6) seedlings grown in gnotobiotic system severely injured due to infection with AFB<sub>1</sub>/OTA-producing fungi, an effect expressed in significant reductions in shoot and root growth traits. Simultaneous treatment with the endophytic antagonists greatly diminished the harmful impact of the pathogens; <i>B. velezensis</i> was the pioneer, not <i>P. aeruginosa</i> Ar6. In conclusion, these findings proved that several endophytic bacterial species have the potential as alternative tools to chemical fungicides for protecting agricultural commodities against mycotoxin-producing fungi. |
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| ISSN: | 2036-7481 |