Zhang Jianyun, Liao Siyu, Gao Weiping, Qubie Axing, He Dongmei, Wang Hai, Yan Zhuyun
State Key Laboratory of Characteristic Chinese Medicine Resources in Southwest China, Chengdu University of Traditional Chinese Medicine, Chengdu, 611137, China.
School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, 611137, China.
Int Microbiol. 2025 Jan 22. doi: 10.1007/s10123-025-00633-y.
Cultivable microbial communities associated with plants inhabiting extreme environments have great potential in biotechnological applications. However, there is a lack of knowledge about these microorganisms from Bryophyllum pinnatum (which survives in severely barren soil) and their ability to promote plant growth. The present study focused on the isolation, identification, biochemical characterization, and potential applications of root endophytic bacteria and rhizosphere bacteria. A total of 73 bacterial isolates were obtained, with 50 derived from rhizospheric soil and 23 from root tissue. The identified strains were categorized into 16 genera, with Bacillus, Priestia, Pseudarthrobacter, Neobacillus, Mesobacillus, and Arthrobacter being the most species-rich genera. Heat stress experiments indicated that almost half (50.7%) of the selected isolates were tolerant to heat stress. Furthermore, most strains present diverse capabilities for biotechnological applications, including the potential for indole-3-acetic acid (IAA) production, organic phosphorus solubilization, inorganic phosphorus solubilization, and nitrogen fixation. Some isolates (21.92%) exhibited broad-spectrum antagonistic activity against various phytopathogenic fungi, including Fusarium spp. Agar plate assays revealed that the Cellulomonas hominis strain LS43 and Bacillus inaquosorum strain LS77 significantly increased the total fresh weight of Arabidopsis (P < 0.05), yet these strains did not significantly affect the primary root length or the number of leaves. Notably, a subset of the strains tested did not significantly increase the growth of Arabidopsis and, in fact, had inhibitory effects on certain growth parameters. This is the first investigation highlighting the potential of root endophytic bacteria and rhizosphere bacteria in association with B. pinnatum in barren soils. Thus, these isolated strains positively influence plant nutrient uptake, stress resilience, and biocontrol to reduce chemical inputs in conventional agricultural practices, highlighting the importance of their development as biofertilizers for improving the quality of barren soil.
与生长在极端环境中的植物相关的可培养微生物群落，在生物技术应用方面具有巨大潜力。然而，对于落地生根（能在极度贫瘠的土壤中存活）中的这些微生物及其促进植物生长的能力，我们了解不足。本研究聚焦于根内生细菌和根际细菌的分离、鉴定、生化特性及潜在应用。共获得73株细菌分离物，其中50株来自根际土壤，23株来自根组织。鉴定出的菌株分为16个属，芽孢杆菌属、Priestia属、假节杆菌属、新芽孢杆菌属、中芽孢杆菌属和节杆菌属是物种最丰富的属。热胁迫实验表明，近一半（50.7%）的所选分离物耐受热胁迫。此外，大多数菌株在生物技术应用方面具有多种能力，包括产生吲哚 - 3 - 乙酸（IAA）、溶解有机磷、溶解无机磷和固氮的潜力。一些分离物（21.92%）对包括镰刀菌属在内 的多种植物病原真菌表现出广谱拮抗活性。琼脂平板试验表明，人栖纤维单胞菌菌株LS43和水生芽孢杆菌菌株LS77显著增加了拟南芥的总鲜重（P < 0.05）然而，这些菌株对主根长度或叶片数量没有显著影响。值得注意的是，测试的一部分菌株并未显著增加拟南芥的生长，实际上，对某些生长参数有抑制作用。这是首次强调根内生细菌和根际细菌与贫瘠土壤中的落地生根相关的潜力的研究。因此，这些分离菌株对植物养分吸收、抗逆性和生物防治有积极影响，可减少传统农业实践中的化学投入，凸显了将其开发为生物肥料以改善贫瘠土壤质量的重要性。
