Plant growth-promoting bacteria such as Streptomyces are an attractive alternative for increasing the sustainability of agricultural systems. In this study, Streptomyces isolates obtained from rhizosphere soil of plants in the family Fabaceae were characterized for their plant growth-promoting traits, including the production of siderophores, 1-aminocyclopropane-1-carboxylate (ACC) deaminase, indole-3-acetic acid (IAA), and phenazines. Soybean seeds were bacterized with selected isolates to test growth promotion. All isolates produced IAA, and the isolate CLV45 was the most efficient, reaching 398.53 mg of IAA per gram of cells. CLV41, CLV45, and CLV46 showed high activity for ACC deaminase whereas CLV42, CLV44, and CLV46 were efficient in siderophore production. Pyocyanin was detected in all isolates; CLV41, CLV43, and CLV45 produced phenazine-carboxylic acid as well. Selected for IAA and ACC deaminase production combined with production of siderophores and phenazines, CLV42, CLV44, and CLV45 were tested for their growth promotion potential. Seed bacterization with CLV45 resulted in plants with increased shoot growth (36.63%) and dry mass (17.97%) compared to control plants. Results suggest that moderate or high levels of auxin and ACC deaminase production by the isolate CLV45 positively affected the growth of soybean plants, making it a strong candidate for further studies on biofertilizer formulation.

中文翻译：

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链霉菌属 来自豆科植物根际的 CLV45 有利于大豆植物的生长

链霉菌等促进植物生长的细菌是提高农业系统可持续性的有吸引力的替代品。在这项研究中，从豆科植物根际土壤中获得的链霉菌分离物具有促进植物生长的特性，包括产生铁载体、1-氨基环丙烷-1-羧酸 (ACC) 脱氨酶、吲哚-3-乙酸(IAA) 和吩嗪。用选定的分离株对大豆种子进行杀菌以测试生长促进作用。所有分离株均产生 IAA，其中分离株 CLV45 最有效，每克细胞可产生 398.53 毫克 IAA。CLV41、CLV45 和 CLV46 对 ACC 脱氨酶显示出高活性，而 CLV42、CLV44 和 CLV46 在铁载体生产中是有效的。在所有分离株中均检测到绿脓素；CLV41, CLV43, CLV45 也产生吩嗪羧酸。CLV42、CLV44 和 CLV45 被选择用于 IAA 和 ACC 脱氨酶生产以及铁载体和吩嗪的生产，测试了它们的生长促进潜力。与对照植物相比，用 CLV45 进行种子杀菌导致植物的芽生长 (36.63%) 和干重 (17.97%) 增加。结果表明，分离株 CLV45 产生的中等或高水平的生长素和 ACC 脱氨酶对大豆植物的生长产生积极影响，使其成为进一步研究生物肥料配方的有力候选者。与对照植物相比，用 CLV45 进行种子杀菌导致植物的芽生长 (36.63%) 和干重 (17.97%) 增加。结果表明，分离株 CLV45 产生的中等或高水平的生长素和 ACC 脱氨酶对大豆植物的生长产生积极影响，使其成为进一步研究生物肥料配方的有力候选者。与对照植物相比，用 CLV45 进行种子杀菌导致植物的芽生长 (36.63%) 和干重 (17.97%) 增加。结果表明，分离株 CLV45 产生的中等或高水平的生长素和 ACC 脱氨酶对大豆植物的生长产生积极影响，使其成为进一步研究生物肥料配方的有力候选者。