γ-聚谷氨酸配施化肥对新疆棉田土壤微生物群落结构及功能的影响

Effects of γ-polyglutamic acid combined with chemical fertilizer on soil microbial community structure and function in Xinjiang cotton fields

摘要:

【目的】长期大量施用化肥导致土壤退化及土壤微生物群落结构失衡。采用有机活性物质配施化肥，被认为是阻控土壤退化并维系微生物群落稳定性的重要策略。【方法】以棉花为供试作物，采用宏基因组学方法研究生物活性物质γ-聚谷氨酸(γ-polyglutamic acid,γ-PGA)与化肥配施对棉田土壤微生物群落结构和功能的影响，试验共设计3个施肥处理组和1个不施肥对照组：单施化肥(NK)、化肥添加γ-PGA水溶液(YT)、化肥添加γ-PGA颗粒(GT)和不施肥(CK)。【结果】GT和YT处理的棉花生长状况和土壤养分含量显著高于NK和CK。微生物群落分析结果表明，γ-PGA配施化肥显著提高土壤微生物的丰度和多样性，而单施化肥处理对微生物多样性提高并不显著，同时γ-PGA的施加也改变了棉田土壤微生物群落组成，与NK相比，YT与GT的变形菌门的相对丰度减少9.70%−12.72%，拟杆菌门的相对丰度增加13.33%−20.90%，放线菌门的相对丰度增加8.09%−13.01%。此外，YT处理中丛植菌根真菌Rhizophagus的相对丰度增加了19.71%。功能基因分析表明，GT和YT处理显著提高了氨基酸生物合成、次生代谢生物合成和ABC转运蛋白等相关功能基因的丰度。【结论】施用γ-PGA对新疆棉田土壤微生物多样性及生态系统稳定性具有应用潜力。

关键词:棉花;γ-聚谷氨酸;宏基因组学;微生物群落;功能基因

Abstract:

[Objective] Long-term and excessive application of chemical fertilizers leads to soil degradation and an imbalanced microbial community structure in soil.The combination of organic active substances with chemical fertilizers is considered an important approach for controlling soil degradation and maintaining microbial community stability.[Methods] Metagenomics was employed to study the effects of combining the bioactive substance γ-polyglutamic acid (γ-PGA) with chemical fertilizer on soil microbial community and function in cotton fields.Four fertilization groups were designed:chemical fertilizer (NK),chemical fertilizer combined with γ-PGA aqueous solution (YT),chemical fertilizer combined with γ-PGA granules (GT),and no fertilizer (CK).[Results] GT and YT groups outperformed NK and CK groups in terms of cotton growth and soil nutrient content.The combination of γ-PGA with chemical fertilizer significantly increased the microbial abundance and diversity in soil,while chemical fertilizer alone did not improve soil microbial diversity.In addition,the application of γ-PGA changed soil microbial community composition.Compared with the NK group,YT and GT groups showed a 9.70%–12.72% decrease in the relative abundance of Proteobacteria and 13.33%–20.90% and 8.09%–13.01% increases in the relative abundance of Bacteroidetes and Actinobacteria,respectively.In addition,the relative abundance of Rhizophagus(a genus of mycorrhiza fungi) increased by 19.71% in the YT group.The functional gene analysis showed that GT and YT significantly increased the abundance of functional genes related to amino acid biosynthesis,secondary metabolite biosynthesis,and ABC transporters.[Conclusion] The application of γ-PGA has the potential of improving soil microbial diversity and ecosystem stability in Xinjiang cotton fields.

Key words:cotton;γ-polyglutamic acid;metagenomics;microbial community;functional gene