Qi Dengfeng, Zou Liangping, Zhou Dengbo, Chen Yufeng, Gao Zhufen, Feng Renjun, Zhang Miaoyi, Li Kan, Xie Jianghui, Wang Wei
Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, China.
Front Microbiol. 2019 Jun 28;10:1390. doi: 10.3389/fmicb.2019.01390. eCollection 2019.
Actinobacteria are important producers of bioactive compounds. Extreme ecosystems cause evolution of novel secondary metabolic pathways of Actinobacteria and increase the possible discovery of new biological functions of bioactive compounds. Here, we isolated 65 Actinobacteria from rhizosphere soil samples of . An Actinobacteria strain (named SCA3-4) was screened against f. sp. Tropical Race 4 ( TR4, ATCC 76255). The strain produced pink-white aerial mycelia and brown substrate mycelium on Gause No. 1 agar. Biverticillate chains of cylindrical spores were observed by scanning electron microscopy (SEM). Based on alignment of 16 rRNA sequences, a constructed phylogenetic tree showed that strain SCA3-4 shared a 99.54% similarity with NRRL B-1968T. The morphological, biochemical, physiological, and molecular characteristics further indicated that strain SCA3-4 belongs to the sp. It can grow well on medium with the following antibiotics chloramphenicol, streptomycin, penicillin-G, gentamicin, erythromycin, nystatin or neomycin sulfate. The polymerase chain reaction (PCR) amplification of types I and II polyketide synthase genes ( and ) suggested its bioactive potential. Under treatment with 100 μg/ml of ethyl acetate extracts isolated from sp. SCA3-4, growth of TR4 was inhibited and cell membrane was destroyed. Crude extracts also showed a broad-spectrum antifungal activity against 13 phytopathogenic fungi including TR4 and displayed the lowest minimum inhibitory concentration (MIC) (0.781 μg/ml) against (ATCC 58718). A total of 21 different compounds identified by gas chromatography-mass spectrometry (GC-MS) were composed of phenolic compound, pyrrolizidine, hydrocarbons, esters, and acids. Besides the known active compounds, sp. SCA3-4 possesses antimicrobial or other biological activities. Further attention will be paid on other compounds with no functional annotation, aiming at the discovery of new bioactive substances.
放线菌是生物活性化合物的重要生产者。极端生态系统促使放线菌新的次生代谢途径进化，并增加了发现生物活性化合物新生物学功能的可能性。在此，我们从……的根际土壤样本中分离出65株放线菌。筛选了一株放线菌菌株（命名为SCA3 - 4）对抗香蕉枯萎病菌4号生理小种（TR4，ATCC 76255）。该菌株在改良高氏一号培养基上产生粉白色气生菌丝体和褐色基内菌丝体。通过扫描电子显微镜（SEM）观察到圆柱形孢子的双轮生链。基于16 rRNA序列比对构建的系统发育树表明，菌株SCA3 - 4与野野村放线菌NRRL B - 1968T的相似度为99.54%。形态学、生化、生理和分子特征进一步表明菌株SCA3 - 4属于野野村放线菌。它能在含有氯霉素、链霉素、青霉素 - G、庆大霉素、红霉素、制霉菌素或硫酸新霉素的培养基上良好生长。I型和II型聚酮合酶基因（pks1和pks2）的聚合酶链反应（PCR）扩增表明其具有生物活性潜力。在用100μg/ml从野野村放线菌SCA3 - 4中分离的乙酸乙酯提取物处理下，香蕉枯萎病菌TR4的生长受到抑制且细胞膜被破坏。粗提物还对包括香蕉枯萎病菌TR4在内的13种植物病原真菌表现出广谱抗真菌活性，并且对尖孢镰刀菌（ATCC 58718）显示出最低最小抑菌浓度（MIC）（0.781μg/ml）。通过气相色谱 - 质谱联用（GC - MS）鉴定出的总共21种不同化合物由酚类化合物、吡咯里西啶、烃类、酯类和酸类组成。除了已知的活性化合物外，野野村放线菌SCA3 - 4还具有抗菌或其他生物活性。将进一步关注其他无功能注释的化合物，旨在发现新的生物活性物质。
