Meloidogyne spp. are microscopic, obligatory endoparasites with worldwide distribution which cause severe damage to agricultural crops. The present study revealed the nematicidal activity of Streptomyces antibioticus strain M7 against Meloidogyne incognita. The culture supernatant of the isolate caused 100% J2 mortality after 24 h and inhibited egg hatching (only 3%). In addition, the nematicidal activity of actinomycins V, X₂ and D purified from strain M7 was also checked. In vitro studies displayed 97.0–99.0% juvenile mortality and 28.0–44.0% egg hatching after 168 h at 240 µg/ml of actinomycin, with LD₅₀ (lethal dose) values of 28–120 µg/ml. In vivo study further validated the nematicidal activity of strain M7, where nematode infested tomato plants treated with culture supernatant/cells/solvent extract showed reduction in root galls and egg masses per plant by 50.0–62.06% and 53.48–76.74%, respectively, and significantly enhanced the shoot length (54.67–76.39%), root length (36.45–64.88%), shoot fresh weight (111–171.77%), root fresh weight (120–163.33%), shoot dry weight (54.45–145.45%), and root dry weight (100–133.3%) over the nematode infested plants treated with water. Furthermore, tomato plants treated with cells/culture supernatant/extract of strain M7 without nematode infestation also showed significant increase in various plant growth parameters. Thus, the outcome of the study revealed the potential of S. antibioticus strain M7 and actinomycins produced from it to be developed as safe nematicidal agents to control the root knot nematodes, and to increase the crop yield.

中文翻译：

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链霉菌M7菌株对根结线虫的杀线虫潜力。

根结线虫属 是在世界范围内分布的微观必不可少的内寄生物，会对农作物造成严重破坏。本研究揭示了链霉菌M7菌株对根结线虫的杀线虫活性。分离物的培养物上清液在24小时后导致100％的J2死亡，并抑制卵孵化（仅3％）。另外，还检查了从菌株M7纯化的放线菌素V，X ₂和D的杀线虫活性。体外研究显示放线霉素为240 µg / ml 168小时后，幼虫死亡率为97.0–99.0％，卵孵化率为28.0–44.0％，LD ₅₀（致命剂量）值在28–120 µg / ml之间。体内研究进一步验证了菌株M7的杀线虫活性，其中用培养上清液/细胞/溶剂提取物处理过的线虫侵染的番茄植株，每株植株的根root和卵量分别减少了50.0–62.06％和53.48–76.74％，并且显着提高了枝长（54.67–76.39％），根长（36.45–64.88％），枝鲜重（111–171.77％），根鲜重（120–163.33％），枝干重（54.45–145.45％） ，以及用水处理的线虫侵染植物的根干重（100-133.3％）。此外，用没有线虫侵染的细胞/培养上清液/菌株M7的提取物处理的番茄植物也显示出各种植物生长参数的显着增加。因此，研究结果显示了抗生素链球菌M7菌株和由此产生的放线菌素将被开发为安全的杀线虫剂，以控制根结线虫并增加农作物的产量。