The fitness of microbes and their colonization efficiency in plants is significant for promotion of plant growth, but the mechanism between plants and bacteria in rhizospheric region is not clearly explained. This study focused on identification and characterization of some plant growth promoting biocontrol bacteria. A total of 94 bacteria strains were isolated and tested for different plant growth promotion activities and their antagonistic behaviors towards different pathogenic fungi. The isolated bacteria were categorized into 23 bacterial genera, using 16S rRNA. The most predominant genera of bacterial isolates were Pseudomonas (4 species) and Bacillus (6 species). The isolates (Qassim University Saudi Arabia (QUSA) 52 and 45) and their transposon mutagenesis mutants inhibited mycelium growth of Rhizoctonia solani, Alternria sp., and Colletotrichum sp. Isolates 52 and 45 of P. fluorescens and their mutants’ 52-M12, 45-M19, and 45-M20 yielded the highest dry weight and shoot, and root length in alfalfa plants. Furthermore, the efficiency of these bacterial isolates and mutants against R. solani was considerably higher than the control treatment. Therefore, application of biocontrol agents can significantly control the soil-born fungal pathogen in alfalfa plants.

中文翻译：

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的影响荧光假单胞菌的体外和体内生物控制和植物生长促进通过转座子诱变上产生的突变体

微生物的适应性及其在植物中的定殖效率对于促进植物生长具有重要意义，但根际区中植物与细菌之间的机制尚不清楚。这项研究的重点是鉴定和表征一些促进植物生长的生物防治细菌。总共分离出94个细菌菌株，并测试其不同的植物生长促进活性及其对不同病原真菌的拮抗行为。使用16S rRNA将分离的细菌分为23个细菌属。细菌分离株的最主要属是假单胞菌（4种）和芽孢杆菌（6种）。分离株（沙特阿拉伯卡西姆大学（QUSA）52和45）及其转座子诱变突变体可抑制茄红假单胞菌菌丝体的菌丝体生长，和Colletotrichum sp。在苜蓿植物中，荧光假单胞菌的52和45及其突变体52-M12、45-M19和45-M20的分离产生了最高的干重，枝条和根长。此外，这些细菌分离株和突变体对抗茄根瘤菌的效率大大高于对照处理。因此，施用生物防治剂可以显着控制苜蓿植物中土壤出生的真菌病原体。