Vieira G, Purić J, Morão L G, Dos Santos J A, Inforsato F J, Sette L D, Ferreira H, Sass D C
Department of Biochemistry and Microbiology, Institute of Biosciences, São Paulo State University (UNESP) "Júlio de Mesquita Filho", Rio Claro, São Paulo, Brazil.
Lett Appl Microbiol. 2018 Jul;67(1):64-71. doi: 10.1111/lam.12890. Epub 2018 May 7.
This study aims to obtain secondary metabolites extracts from filamentous fungi isolated from soil and marine sediments from Antarctica and assess its potential antibacterial activity on Xanthomonas citri subsp. citri, the agent of citrus canker. Metabolites production was conducted in Malt 2% broth at 15°C for 20 days after which intracellular and extracellular extracts were obtained. The extracts were evaluated by cell viability assays through Resazurin Microtitre Assay. From 158 fungal extracts, 33 hampered bacterial growth in vitro. The average inhibition of the extracts obtained from terrestrial (soil) and marine (sediments) fungi was 94 and 97% respectively. These inhibition values were close to the average of 90% cell death for the positive control. MIC90 and MBC for the bioactive extracts were established. Isolates that produced active metabolites against the phytopathogen were identified using molecular taxonomy (ITS-rRNA sequencing) as: Pseudogymnoascus, Penicillium, Cadophora, Paraconiothyrium and Toxicocladosporium. Antarctic fungal strains isolated from terrestrial and marine sediments were able to produce secondary metabolites with antimicrobial activity against X. citri subsp. citri, highlighting the importance of these microbial genetic resources. These metabolites have potential to be used as alternatives for the control of this plant pathogen.
This manuscript makes an impact on the study of micro-organisms from extreme habitats and their possible contribution in discovering new active molecules against pathogens of agricultural interest. Studies on the Antarctic continent and its communities have attracted the scientific community due to the long period of isolation and low levels of disturbance that surrounds the region. Knowing the potential of fungi in this region to produce active secondary metabolites, we aim to contribute to the discovery of compounds with antibacterial action in Xanthomonas citri subsp. citri, a plant pathogen present in several regions around the globe.
本研究旨在从南极洲土壤和海洋沉积物中分离出的丝状真菌中获取次生代谢产物提取物，并评估其对柑橘溃疡病菌——柑橘黄龙病菌亚种的潜在抗菌活性。在2%麦芽肉汤中于15°C培养20天以产生代谢产物，之后获得细胞内和细胞外提取物。通过刃天青微量滴定法进行细胞活力测定来评估提取物。从158种真菌提取物中，有33种在体外抑制了细菌生长。从陆地（土壤）和海洋（沉积物）真菌中获得的提取物的平均抑制率分别为94%和97%。这些抑制值接近阳性对照90%细胞死亡的平均值。确定了生物活性提取物的MIC90和MBC。使用分子分类学（ITS-rRNA测序）鉴定出对植物病原体产生活性代谢产物的分离株为：假裸囊菌属、青霉属、卡多孢属、拟茎点霉属和毒枝孢属。从陆地和海洋沉积物中分离出的南极真菌菌株能够产生对柑橘黄龙病菌亚种具有抗菌活性的次生代谢产物，突出了这些微生物遗传资源的重要性。这些代谢产物有潜力用作控制这种植物病原体的替代品。
本手稿对来自极端栖息地的微生物研究及其在发现针对农业相关病原体的新活性分子方面的可能贡献产生了影响。由于该地区长期隔离和低干扰水平，对南极大陆及其群落的研究吸引了科学界。了解该地区真菌产生活性次生代谢产物的潜力，我们旨在为发现对柑橘黄龙病菌亚种具有抗菌作用的化合物做出贡献，该病菌是全球多个地区存在的一种植物病原体。
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