Bioprocess Development Department, Genetic Engineering and Biotechnology Research Institute (GEBRI), City of Scientific Research and Technological Applications (SRTA-City), New Borg El-Arab City, Alexandria, 21934, Egypt.
Botany and Microbiology Department, Faculty of Science, Alexandria University, Alexandria, 21526, Egypt.
BMC Plant Biol. 2024 Aug 9;24(1):760. doi: 10.1186/s12870-024-05441-6.
Soil-borne plant diseases represent a severe problem that negatively impacts the production of food crops. Actinobacteria play a vital role in biocontrolling soil-borne fungi.
The target of the present study is to test the antagonistic activity of chitinase-producing Streptomyces cellulosae Actino 48 (accession number, MT573878) against Rhizoctonia solani. Subsequently, maximization of Actino 48 production using different fermentation processes in a stirred tank bioreactor. Finally, preparation of bio-friendly formulations prepared from the culture broth of Actino 48 using talc powder (TP) and bentonite in a natural as well as nano forms as carriers. Meanwhile, investigating their activities in reducing the damping-off and root rot diseases of peanut plants, infected by R. solani under greenhouse conditions.
Actino 48 was found to be the most significant antagonistic isolate strain at p ≤ 0.05 and showed the highest inhibition percentage of fungal mycelium growth, which reached 97%. The results of scanning electron microscope (SEM) images analysis showed a large reduction in R. solani mycelia mass. Additionally, many aberrations changes and fungal hypha damages were found. Batch fermentation No. 2, which was performed using agitation speed of 200 rpm, achieved high chitinase activity of 0.1163 U mL min with a yield coefficient of 0.004 U mL min chitinase activity/g chitin. Nano-talc formulation of Actino 48 had more a significant effect compared to the other formulations in reducing percentages of damping-off and root rot diseases that equal to 19.05% and 4.76% with reduction percentages of 60% and 80%, respectively. The healthy survival percentage of peanut plants recorded 76.19%. Furthermore, the nano-talc formulation of Actino 48 was sufficient in increasing the dry weight of the peanut plants shoot, root systems, and the total number of peanut pods with increasing percentages of 47.62%, 55.62%, and 38.07%, respectively.
The bio-friendly formulations of actinobacteria resulting from this investigation may play an active role in managing soil-borne diseases.
土传植物病害是粮食作物生产的严重问题，放线菌在防治土传真菌方面具有重要作用。
本研究的目的是测试产壳聚糖的链霉菌 Actino 48（登录号 MT573878）对茄丝核菌的拮抗活性。随后，使用搅拌罐生物反应器中的不同发酵工艺来最大化 Actino 48 的产量。最后，使用滑石粉（TP）和膨润土制备生物友好型制剂，这些制剂来自 Actino 48 的发酵液，既可以是天然形式，也可以是纳米形式作为载体。同时，研究它们在温室条件下减轻花生植株感染茄丝核菌引起的猝倒病和根腐病的活性。
Actino 48 是最显著的拮抗分离株，p≤0.05，对真菌菌丝生长的抑制率最高，达到 97%。扫描电子显微镜（SEM）图像分析结果表明，茄丝核菌菌丝体质量大量减少。此外，还发现了许多异常变化和真菌菌丝损伤。在搅拌速度为 200 rpm 的条件下进行的批发酵 2 号，获得了 0.1163 U mL min 的高壳聚糖活性，产率系数为 0.004 U mL min 壳聚糖活性/g 壳聚糖。与其他制剂相比，纳米滑石粉制剂的 Actino 48 对降低猝倒病和根腐病的百分率有更显著的效果，分别为 19.05%和 4.76%，降幅分别为 60%和 80%。花生植株的健康存活率记录为 76.19%。此外，Actino 48 的纳米滑石粉制剂足以增加花生植株地上部分、根系和花生总荚数的干重，分别增加 47.62%、55.62%和 38.07%。
本研究中产生的生物友好型放线菌制剂可能在防治土传病害方面发挥积极作用。
