罗布麻内生与根际细菌多样性及脱胶功能菌株的挖掘

Diversity of endophytic and rhizospheric bacteria of Apocynum venetum and isolation of degumming bacteria

摘要:

目的 探明新疆北部罗布麻内生细菌和根际细菌的多样性及群落组成，筛选具有高效、专一性脱胶潜力的菌株资源。方法 采集克拉玛依、阜康、乌鲁木齐及吐鲁番4个地区的罗布麻样品，利用16S rRNA基因高通量测序技术分析细菌群落结构；采用纯培养技术分离菌株，并通过刚果红染色与酶活力测定筛选具有木聚糖酶和果胶酶活性，而无纤维素酶活性的功能菌株。结果 高通量测序共鉴定出38门345科872属的细菌。其中假单胞菌门(Pseudomonadota)和放线菌门(Actinomycetota)为优势菌门。细菌丰度与多样性表现为根际土壤>根部>叶>茎；吐鲁番样地微生物丰度和多样性低于其他三地。从样品中分离获得361株纯培养细菌，分属于4门47科86属。从中筛选出9株专性脱胶功能菌，其中7株(77.78%)为来源于茎和叶的内生菌。功能最优菌株Bacillus rugosus (VFS.M1.04)的木聚糖酶与果胶酶活力分别为2 237 U/mL和1 002 U/mL。结论 罗布麻内生细菌与根际细菌群落结构受所处生境和植物部位影响。Bacillus是其中的优势功能菌属，采用“同源筛选”策略从其茎、叶内生菌中能有效获得脱胶能力强且不损伤纤维素的优良菌株，为开发罗布麻绿色生物脱胶工艺提供了宝贵的菌种资源与理论基础。

Abstract:

Objective To elucidate the diversity and community composition of endophytic and rhizospheric bacteria associated with Apocynum venetum in northern Xinjiang and to screen the strains with efficient and specific degumming potential.Methods Samples of A. venetum were collected from four regions: Karamay, Fukang, Urumqi, and Turpan. The bacterial community structure was analyzed by 16S rRNA gene high-throughput sequencing. Pure-culture techniques were employed for strain isolation, and functional strains exhibiting xylanase and pectinase activities but lacking cellulase activity were screened by Congo red staining and enzyme activity assays.Results High-throughput sequencing identified 872 genera of bacteria belonging to 345 families of 38 phyla, among which Pseudomonadota and Actinomycetota were the dominant phyla. Bacterial abundance and diversity followed the order: rhizospheric soil>root>leaf>stem. Microbial abundance and diversity at the Turpan site were lower than those at the other sampling sites. A total of 361 bacterial strains were isolated in pure culture, belonging to 86 genera, 47 families of 4 phyla. Nine specific degumming strains were screened out, of which seven (77.78%) strains were endophytes derived from stems and leaves. The optimal functional strain, Bacillus rugosus (VFS.M1.04), showed xylanase and pectinase activities of 2 237 U/mL and 1 002 U/mL, respectively.Conclusion The community structures of endophytic and rhizospheric bacteria associated with A. venetum are significantly influenced by habitats and plant parts. Bacillus is the dominant functional genus, and the homologous screening strategy effectively enables the acquisition of elite strains with strong degumming capacity and no cellulose degradation from stem and leaf endophytes. This study provides valuable microbial resources and a theoretical basis for developing a green biological degumming process for A. venetum. These findings support the targeted exploitation of plant-associated microbial strains for sustainable fiber processing.