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Shewanella putrefaciens CN32对粘土附着态铵氮释放的影响
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国家自然科学基金(41602347)


Effects of Shewanella putrefaciens CN32 on the release of clay-sorbed NH4+
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    摘要:

    [目的] 研究产胞外分泌物微生物Shewanella putrefaciens CN32对土壤中常见粘土矿物附着态NH4+的释放效果及影响机制。[方法] 以吸附NH4+的蒙脱石、蛭石、伊蒙混层矿物和黑云母为对象,通过监测S.putrefaciens CN32作用下不同粘土释放的NH4+含量及过程,以及监测微生物量及释放的胞外聚合物(Extracellular Polymeric Substances,EPS)的含量变化,研究S.putrefaciens CN32作用下不同粘土矿物类型附着态NH4+释放的差异性。[结果] 粘土矿物附着态NH4+含量从高到低依次为蒙脱石 > 蛭石 > 伊蒙混层矿物 > 黑云母(黑云母NH4+吸附量极低,会在非生物作用下几乎完全释放),CN32作用下粘土附着态NH4+相对释放量依次为蒙脱石 > 伊蒙混层矿物 > 蛭石;然而,尽管CN32有效促进了粘土附着态NH4+释放,但释放的NH4+并未在溶液中大量累积,而是多被微生物同化吸收转化为生物有机氮(EPS为主)并吸附在粘土表面,且粘土对EPS的吸附能力表现为蒙脱石 > 伊蒙混层矿物 > 蛭石 > 黑云母;由于粘土吸附NH4+及EPS都与矿物中的羟基(结构水或层间水)关系密切,推测EPS对矿物羟基的竞争吸附可能是CN32促进NH4+释放的重要原因之一。[结论] 以上结果表明,产EPS微生物S.putrefaciens CN32能够促进各类粘土矿物的附着态NH4+释放,但释放的NH4+可以通过微生物作用转化为有机氮,从而在减少NH4+流失的同时增加土壤氮肥的生物可利用性,因此微生物在降低土壤氮肥流失、转化土壤氮肥污染过程中可能起到了重要作用,也揭示了深入系统地分析不同类型土壤(粘土类型不同)中粘土附着态NH4+在不同功能微生物作用下的迁移转化过程,是精准评估土壤氮肥施用效率及流失风险的前提之一。

    Abstract:

    [Objective] This study was conducted to explore the effect and mechanism of Shewanella putrefaciens CN32, a typical bacterium secretes extracellular polymeric substances (EPS), on the release of clay-sorbed NH4+ in soils. [Methods] The common clay minerals in soil, including smectite, vermiculite, smectite-illite mixlayer mineral and biotite were used for NH4+ sorption and then was inoculated by S. putrefaciens CN32. The contents of clay-sorbed N, dissolved NH4+, the microbial biomass and EPS were monitored to understand the variation of NH4+ release from different types of the clay minerals. [Results] The content of clay-sorbed NH4+ was dependent on clay types, with high to low in smectite > vermiculite > smectite-illite mixlayer mineral (in biotite was too low). With the activity of S. putrefaciens CN32, the percentage of released NH4+ was highest in smectite, followed by in smectite-illite mixlayer mineral and lowest in vermiculite. Although CN32 effectively promoted the release of clay-sorbed NH4+, the released NH4+ did not accumulate in the solution but assimilated by the bacterial cells, which was transformed into bio-organic nitrogen (mainly EPS) and attached on the clay surface. The adsorption of EPS was highest on smectite, followed by smectite-illite mixlayer mineral and vermiculite. FTIR analysis revealed that the adsorption of both NH4+ and EPS on clays were closely associated with the hydroxyl groups in minerals (structural or interlayer water), thus, it is speculated that the competitive adsorption on mineral hydroxyl may be one of the important reasons for stimulated release of NH4+ by CN32. [Conclusion] The results of the present study demonstrated that the EPS-producing S. putrefaciens CN32 can promote the release of clay-sorbed NH4+ from all kinds of clay minerals. The released NH4+ does not necessary to be leached from the soil profile but instead to be transformed into organic nitrogen and increases the bioavailability of nitrogen fertilizer. Therefore, microorganisms may play an important role in reducing nitrogen loss and easing ammonia pollution from soils. It is important to systematically understand the microbial effects on the migration and transformation of clay-sorbed NH4+ in different types of soils (with different assemble of clay minerals), which serves for the precise prediction of the efficiency and loss risk of nitrogen fertilizers in soils.

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马晓田,常保璇,黄柳琴,蒋宏忱. Shewanella putrefaciens CN32对粘土附着态铵氮释放的影响. 微生物学报, 2020, 60(6): 1192-1205

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  • 收稿日期:2020-03-28
  • 最后修改日期:2020-05-15
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  • 在线发布日期: 2020-06-10
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