Kaur Talwinder, Manhas Rajesh Kumari
Department of Microbiology, Guru Nanak Dev University, Amritsar, India.
J Basic Microbiol. 2014 Nov;54(11):1175-85. doi: 10.1002/jobm.201300086. Epub 2013 Jun 14.
In the present study, an actinobacterium strain, possessing antagonistic activity against different fungal phytopathogens viz. Colletotrichum acutatum, Cladosporium herbarum, Alternaria brassicicola, Exserohilum sp., Alternaria mali, Colletotrichum gleospoiroides, Alternaria alternata, Cercospora sp., Fusarium oxysporum f.sp. dianthi and Fusarium moniliformae, was isolated from soil and identified as Streptomyces hydrogenans DH16. Application of culture supernatant (5%)/cells (10(7) cfu ml(-1) ), 2 h post inoculation with A. brassicicola (10(5) spores ml(-1) ), resulted in 85.95 and 93.75% suppression of black leaf spot of Raphanus sativus, respectively on detached leaves. Whereas cells/culture supernatant (above 5%) completely suppressed the disease incidence when co inoculated with fungal pathogen. The crude extract containing antifungal components was completely stable at 70 °C for 1 h retaining 90 and 67.67% activity after boiling (for 1 h) and autoclaving (121 °C for 30 min), respectively. No loss in activity was observed when treated with proteinase K and on exposure to sun and UV light and found to be active over a wide range of pH (2 to 14). Bioautography of the solvent extract against test phytopathogens revealed the presence of three active components. Ethyl acetate extract of DH16 also demonstrated insecticidal activity against Spodoptera litura, causing 40% larval mortality and extension of larval period. In addition, it produced 30 µg ml(-1) of Indole Acetic Acid (IAA) in a medium containing tryptophan which promoted lateral root formation in Vigna radiata (green gram). These results indicate that Streptomyces hydrogenans holds the potential to be used as antifungal, insecticidal, and plant growth promoting agent.
在本研究中，从土壤中分离出一株对不同真菌植物病原体具有拮抗活性的放线菌菌株，这些病原体包括尖孢炭疽菌、草本枝孢菌、芸苔链格孢、突脐孢属、苹果链格孢、胶孢炭疽菌、链格孢、尾孢属、尖孢镰刀菌黄瓜专化型和串珠镰刀菌，该菌株被鉴定为嗜氢链霉菌DH16。在接种芸苔链格孢（10⁵ 个孢子/毫升）2小时后，施用培养上清液（5%）/细胞（10⁷ 个菌落形成单位/毫升），在离体叶片上分别导致萝卜黑斑病抑制率达85.95%和93.75%。而当细胞/培养上清液浓度高于5%时，与真菌病原体共同接种可完全抑制发病率。含有抗真菌成分的粗提物在70℃下1小时完全稳定，煮沸（1小时）和高压灭菌（121℃ 30分钟）后分别保留90%和67.67%的活性。用蛋白酶K处理、暴露于阳光和紫外光下时未观察到活性损失，且在广泛的pH范围（2至14）内均有活性。溶剂提取物对测试植物病原体的生物自显影显示存在三种活性成分。DH16的乙酸乙酯提取物对斜纹夜蛾也表现出杀虫活性，导致40%的幼虫死亡率并延长幼虫期。此外，它在含有色氨酸的培养基中产生30微克/毫升的吲哚乙酸（IAA），促进绿豆侧根形成。这些结果表明嗜氢链霉菌有潜力用作抗真菌、杀虫和促进植物生长的制剂。
