BACKGROUND Production of antibiotics to inhibit competitors affects soil microbial community composition and contributes to disease suppression. In this work, we characterized whether Streptomyces bacteria, prolific antibiotics producers, inhibit a soil borne human pathogenic microorganism, Streptomyces sudanensis. S. sudanensis represents the major causal agent of actinomycetoma - a largely under-studied and dreadful subcutaneous disease of humans in the tropics and subtropics. The objective of this study was to evaluate the in vitro S. sudanensis inhibitory potential of soil streptomycetes isolated from different sites in Sudan, including areas with frequent (mycetoma belt) and rare actinomycetoma cases of illness. RESULTS Using selective media, 173 Streptomyces isolates were recovered from 17 sites representing three ecoregions and different vegetation and ecological subdivisions in Sudan. In total, 115 strains of the 173 (66.5%) displayed antagonism against S. sudanensis with different levels of inhibition. Strains isolated from the South Saharan steppe and woodlands ecoregion (Northern Sudan) exhibited higher inhibitory potential than those strains isolated from the East Sudanian savanna ecoregion located in the south and southeastern Sudan, or the strains isolated from the Sahelian Acacia savanna ecoregion located in central and western Sudan. According to 16S rRNA gene sequence analysis, isolates were predominantly related to Streptomyces werraensis, S. enissocaesilis, S. griseostramineus and S. prasinosporus. Three clusters of isolates were related to strains that have previously been isolated from human and animal actinomycetoma cases: SD524 (Streptomyces sp. subclade 6), SD528 (Streptomyces griseostramineus) and SD552 (Streptomyces werraensis). CONCLUSION The in vitro inhibitory potential against S. sudanensis was proven for more than half of the soil streptomycetes isolates in this study and this potential may contribute to suppressing the abundance and virulence of S. sudanensis. The streptomycetes isolated from the mycetoma free South Saharan steppe ecoregion show the highest average inhibitory potential. Further analyses suggest that mainly soil properties and rainfall modulate the structure and function of Streptomyces species, including their antagonistic activity against S. sudanensis.

中文翻译：

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在苏丹和南苏丹，土壤链霉菌的多样性和地理分布对引起放线菌的苏丹链霉菌具有拮抗作用。

背景技术抑制竞争者的抗生素的生产影响土壤微生物群落组成并有助于疾病抑制。在这项工作中，我们表征了多产抗生素生产者链霉菌细菌是否抑制土壤传播的人类病原微生物苏丹链霉菌。苏丹链球菌是放线菌病的主要病原体。放线菌是一种在热带和亚热带地区被广泛研究的可怕的皮下疾病。这项研究的目的是评估苏丹链球菌从苏丹不同地区分离的土壤链霉菌的体外抑制潜力，这些地区包括频繁（霉菌瘤带）和罕见放线菌病病例的地区。结果使用选择性介质，从苏丹的三个生态区域和不同植被和生态分区的17个站点中回收了173株链霉菌。总共173株中的115株（66.5％）显示出对苏丹链霉菌的拮抗作用，并具有不同程度的抑制作用。从南撒哈拉草原和林地生态区（苏丹北部）分离出的菌株比从位于苏丹南部和东南部的东苏丹大草原生态区或从位于中部和南部的萨赫勒相思大草原生态区分离出的菌株显示更高的抑制潜力。苏丹西部。根据16S rRNA基因序列分析，分离物主要与链霉菌，链霉菌，灰质链霉菌和prasinosporus关联。三个分离株群与以前从人和动物放线菌病病例中分离出的菌株有关：SD524（链霉菌属第6小节），SD528（灰链霉菌属）和SD552（Werraensis链霉菌）。结论在本研究中，对半数以上土壤链霉菌分离株的体外抑菌潜力均得到了证实，该潜力可能有助于抑制苏丹草的丰度和毒力。从无真菌病的南撒哈拉草原生态区分离的链霉菌具有最高的平均抑制潜力。进一步的分析表明，土壤性质和降雨主要调节链霉菌的结构和功能，包括它们对苏丹链球菌的拮抗活性。SD524（链霉菌属第6小节），SD528（灰链霉菌属）和SD552（紫菜链霉菌）。结论在本研究中，对半数以上土壤链霉菌分离株的体外抑菌潜力均得到了证实，该潜力可能有助于抑制苏丹草的丰度和毒力。从无真菌病的南撒哈拉草原生态区分离的链霉菌具有最高的平均抑制潜力。进一步的分析表明，土壤性质和降雨主要调节链霉菌的结构和功能，包括它们对苏丹链球菌的拮抗活性。SD524（链霉菌属第6小节），SD528（灰链霉菌属）和SD552（紫菜链霉菌）。结论在本研究中，对半数以上土壤链霉菌分离株的体外抑菌潜力均得到了证实，该潜力可能有助于抑制苏丹草的丰度和毒力。从无真菌病的南撒哈拉草原生态区分离的链霉菌具有最高的平均抑制潜力。进一步的分析表明，土壤性质和降雨主要调节链霉菌的结构和功能，包括它们对苏丹链球菌的拮抗活性。在这项研究中，超过一半的土壤链霉菌分离株都被证明有苏丹红，而这种潜力可能有助于抑制苏丹红的丰度和毒力。从无真菌病的南撒哈拉草原生态区分离的链霉菌具有最高的平均抑制潜力。进一步的分析表明，土壤性质和降雨主要调节链霉菌的结构和功能，包括它们对苏丹链球菌的拮抗活性。在这项研究中，超过一半的土壤链霉菌分离株都被证明有苏丹红，而这种潜力可能有助于抑制苏丹红的丰度和毒力。从无真菌病的南撒哈拉草原生态区分离的链霉菌具有最高的平均抑制潜力。进一步的分析表明，土壤性质和降雨主要调节链霉菌的结构和功能，包括它们对苏丹链球菌的拮抗活性。