黄河滩地和稻田土中铁还原菌、不产氧光合细菌分布机制

Distribution of ferric reducing bacteria and anoxygenic phototrophic bacteria in the Yellow River beach and paddy soil

摘要:

【目的】探讨沿黄流域土壤中铁还原菌(ferric reducing bacteria, FeRB)、不产氧光合细菌(anoxygenic phototrophic bacteria, AnPB)的分布机制。【方法】以沿黄流域(原阳段)为研究对象，采集黄河滩地和稻田土样，利用16S rRNA基因高通量测序和实时荧光定量分析技术，结合统计学分析，揭示FeRB、AnPB菌群结构、丰度和主要环境影响因子。【结果】二者中的优势FeRB在科(属)水平为Hydrogenophilaceae (Thiobacillus)、Bacillaceae (Bacillus)、Clostridiaceae、Rhodobactereace (Rhodobacter)、Geobacteraceae (Geobacter)，优势AnPB为Rhodobactereace (Rhodobacter)、Chloroflexaceae (Chloronema)、Acetobacteraceae (Roseomonas)。AnPB中Rhodobacteraceae与FeRB中Bacillaceae、Clostridiaceae的相对丰度负相关；AnPB中Sphingomonadaceae与Hydrogenophilaceae、Clostridiaceae的相对丰度亦负相关。土壤硝酸盐氮(NO₃^--N)与Rhodobactereace相对丰度负相关，与Geobacteraceae相对丰度正相关。二价铁(Fe²⁺)对FeRB、AnPB菌群组成的差异分别可解释13.5%、41.8%，pH对FeRB、AnPB菌群组成的差异分别可解释65.7%、42.8%。黄河滩地总细菌(total bacteria, BAC)、地(热)杆菌[Geo(thermo)bacter，GEO]、光合紫细菌(phototrophic purple bacteria, PPB)的拷贝数分别为2.52 (±3.43)×10⁹ 、5.21 (±7.58)×10⁷、2.9 (±3.70)×10⁷ copies/g干土。稻田土中BAC、GEO、PPB拷贝数依次为3.82 (±1.29)×10¹⁰、3.05 (±2.44)× 10⁸、4.31 (±0.90)×10⁸ copies/g干土。0-1 cm土层中PPB拷贝数显著高于1-2 cm、2-3cm土层。Fe²⁺对BAC、GEO、PPB数量分布变异的解释度为81.5%。【结论】土壤类型不同，潜在FeRB、AnPB物种组成不同，GEO、PPB丰度也不同。Fe²⁺对FeRB、AnPB分布起关键驱动作用。

关键词:铁还原菌;不产氧光合细菌;稻田土;黄河滩地

Abstract:

[Objective] To explore the distribution of ferric reducing bacteria (FeRB) and anoxygenic phototrophic bacteria (AnPB) in the soil along the Yellow River. [Methods] Soil samples were collected from the beach and paddy fields at the Yuanyang section of the Yellow River. High-throughput sequencing of 16S rRNA gene and quantitative real-time PCR were combined with statistical analysis to reveal the structure and abundance of FeRB and AnPB and the main environmental factors affecting the bacteria. [Results] The dominant FeRB families (genera) were Hydrogenophilaceae (Thiobacillus), Bacillaceae (Bacillus), Clostridiaceae, Rhodobactereace (Rhodobacter) and Geobacteraceae (Geobacter). The dominant AnPB families (genera) were Rhodobactereace (Rhodobacter), Chloroflexaceae (Chloronema) and Acetobacteraceae (Roseomonas). The relative abundance of Rhodobacteraceae (AnPB) was negatively correlated with that of Bacillaceae and Clostridiaceae (FeRB). The relative abundance of Sphingomonadaceae (AnPB) was negatively correlated with that of Hydrogenophilaceae and Clostridiaceae (FeRB). Soil nitrate nitrogen (NO₃^--N) was negatively correlated with the relative abundance of Rhodobacteraceae but positively correlated with that of Geobacteraceae. Ferrous ions (Fe²⁺) explained 13.5% and 41.8% of the community variations of FeRB and AnPB, respectively; pH explained 65.7% and 42.8%, respectively. The number of total bacteria (BAC), Geo(thermo)bacter (GEO) and phototrophic purple bacteria (PPB) in the Yellow River beach was 2.52 (±3.43)×10⁹, 5.21 (±7.58)×10⁷ and 2.9 (±3.70)× 10⁷ copies/g dry soil, respectively, and that in the paddy soil was 3.82 (±1.29)×10¹⁰, 3.05 (±2.44)×10⁸ and 4.31 (±0.90)×10⁸ copies/g dry soil, respectively. Moreover, the PPB in the upmost soil layer (0-1 cm) were significantly more than those in the 1-2 cm and 2-3 cm soil layers. Fe²⁺ explained 81.5% variations in the absolute abundance of BAC, GEO and PPB. [Conclusion] The potential community of FeRB and AnPB and the abundance of GEO and PPB varied between different soil types. Overall, Fe²⁺ played a key role in shaping the distribution pattern of FeRB and AnPB.

Key words:ferric reducing bacteria;anoxygenic phototrophic bacteria;paddy soil;the Yellow River beach