中文摘要：

【目的】为了鉴定从沙糖橘果实表面分离得到的拮抗放线菌株MY-4，并确定该菌株对果蔬病原菌的拮抗作用，【方法】采用分析MY-4形态学、生理生化特性及16SrDNA序列相似性方法以确定其分类地位，并采用平板对峙培养法和生长速率法测定了其抑菌活性。【结果】结果显示，菌株MY-4为小白链霉菌（Streptomyces albus Routien），菌株MY-4及其无菌发酵液对供试16种果蔬病原真菌均具有拮抗作用，其中菌株MY-4对香蕉炭疽病菌的拮抗作用最强．平板抑菌带宽度达17．08mm，无菌发酵液对柑橘绿霉病菌的拮抗作用最强，菌丝生长抑制率高达98．82％，【结论】小自链霉菌菌株MY-4具有活性高、抑菌谱广的特点，有望继续研究开发成新的生防剂。

英文摘要：

[Objective] The purpose of the study is to identify the antagonistic actinomyce strain MY-4 isolated from the surface of Shatang mandarin, and to evaluate the application potential of the strain for the biocontrol of fruit and vegetable diseases. [Method] The taxonomic identification of the strain was carried out based on the morphology, physio-biochemical characteristics and the 16S rDNA sequence analysis, and the antagonistic activity of strain MY-4 was determined by confronting incubation on the PDA plates and the mycelium growth rate method. [Result] Strain MY-4 was identified as Streptomyces albtdus. The results showed that strain MY-4 and its cell-free fermentation filtrate exhibited extensive antagonistic ef- fect on 16 fruit and vegetable pathogenic fungi. The strain exhibited the strongest antibiosis capacity with an inhibitory zone up to 17.08 mm against mycelia growth of Colletotrichum musae. Meanwhile, its culture filtrate showed the strongest antibiosis capacity against Penicillium digitatum and reduced mycelium growth by up to 98.82%. [Conclusion] These findings show that Streptomyces albulus strain MY-4 has high activity, broad antifungal spectrum, and is expected to develop into a new biocontrol agent.