【目的】根际促生菌对促进植物生长发育、改善土壤微生态环境、实现林业可持续发展有重要作用,研究浙江地区毛竹(Phyllostachys edulis)根际土壤功能细菌,考察菌株对毛竹幼苗生长的影响,为开发利用新的竹类植物微生物资源,提升竹林生产力和生态系统服务功能提供依据。【方法】以毛竹根际土壤为对象,利用传统稀释培养的方法分离根际细菌,基于16S rRNA基因序列利用最大似然法构建系统发育树,依托功能平板和特异性颜色变化进行体外功能评价,最后通过回接试验考察功能菌株对毛竹种子萌发和幼苗生长的影响。【结果】①共分离获得根际细菌39株,分属于3门12科23属。其中,放线菌门(Actinomycetota)为优势菌门,占38.5%;优势菌科为芽孢杆菌科(Bacillaceae),占25.6%。②对39株细菌进行功能评价发现,其中20株具有产吲哚乙酸(IAA)的功能,3株具有产铁载体功能,3株具有溶解无机磷能力,7株具有矿化有机磷能力,5株具有解钾能力。③菌株SD2N7同时具有产IAA、无机磷溶解、有机磷矿化以及解钾功能。生理生化指标测定及16s rRNA基因序列比对结果表明,菌株SD2N7为伍尔贝丁拉恩氏菌(Rahnella woolbedingensis)。通过回接试验发现,菌株SD2N7能够显著缩短毛竹种子的萌发时间,并促进毛竹幼苗根和叶片的伸长。【结论】毛竹根际土壤中功能微生物资源丰富,筛选获得了多株具有产IAA和铁载体,以及溶磷和解钾功能的菌株,且回接试验明确了菌株SD2N7对毛竹种子萌发和幼苗生长具有明显的促进作用。

【Objective】 Plant growth-promoting rhizobacteria play an important role in promoting plant growth and development, improving the soil microenvironment, and aiding the development of sustainable forestry practices. The functional bacteria in the rhizospheric soil of Phyllostachys edulis, and their effects on seedling growth were investigated to provide a scientific basis for the development and utilization of new microbial resources from bamboo, improving the productivity of bamboo forests, and enhancing the functions of ecosystem services.【Method】The rhizosphere soil of P. edulis was selected as the research object, and the rhizosphere bacteria were isolated using traditional dilution culture methods. A phylogenetic tree based on the 16S rRNA gene sequences was constructed using the maximum-likelihood method. In vitro functional evaluation was performed based on the functional plates and specific color changes. The effects of the functional strains on the germination of P. edulis seeds and the growth of seedlings were finally investigated with re-inoculation experiments.【Result】 A total of 39 rhizosphere bacterial strains from 23 genera belonging to 12 families under three phyla, were isolated and cultured. Actinomycetota and Bacillaceae were the dominant phylum and family with relative abundances of 41.0% and 25.6%, respectively. Functional analysis of the 39 bacterial strains revealed that 20 and three strains were capable of producing IAA (indole-3-acetic acid) and siderophores, while five and three strains were capable of dissolving potassium and inorganic phosphorus, respectively, and seven strains were capable of mineralizing organic phosphorus. The strain SD2N7 was capable of simultaneously producing IAA, dissolving inorganic phosphorus and potassium, and mineralizing organic phosphorus. Based on the physiological and biochemical characteristics and the 16S rRNA gene alignment, strain SD2N7 was identified as Rahnella woolbedensis. The re-inoculation experiments revealed that strain SD2N7 could significantly shorten the germination period of P. edulis seeds and promote the elongation of the roots and leaves of P. edulis seedlings.【Conclusion】 There were abundant functional microbial resources in the rhizosphere soil of P. edulis, which were capable of producing IAA or siderophores, dissolving phosphorus and potassium, and performing other functions. The back-grafting test additionally demonstrated that strain SD2N7 significantly promoted seed germination and the growth of P. edulis seedlings.