The Structure and Species Co-Occurrence Networks of Soil Denitrifying Bacterial Communities Differ Between A Coniferous and A Broadleaved Forests

• Main Authors: Jie Chen, Jiajia Li, Weijun Shen, Han Xu, Yide Li, Tushou Luo
• Format: Article
• Language: English
• Published: MDPI AG 2019-09-01
• Series: Microorganisms
• Subjects: Soil N cycling; functional gene; microbial network; artificial plantation; forest degradation
• Online Access: https://www.mdpi.com/2076-2607/7/9/361

<i>Acacia mangium</i> (AM) and <i>Pinus massoniana</i> (PM) are widely planted in tropical regions, whereas their effects on soil microbial communities remain unclear. We did a comprehensive investigation of soil denitrifying bacterial communities in AM and PM monoculture plantations in Southern China based on the high throughput sequencing data of their functional genes: <i>nirK</i>, <i>nirS</i>, and <i>nosZ</i>. The average abundance of <i>nosZ</i> (1.3 &#215; 10⁷) was significantly higher than <i>nirS</i> (5.6 &#215; 10⁶) and <i>nirK</i> (4.9 &#215; 10⁵). Shannon estimator revealed a markedly higher &#945;-diversity of <i>nirS</i> and <i>nosZ</i> communities in PM than in AM plantations. The AM and PM plantations were dominated by different <i>nirS</i> and <i>nosZ</i> taxa belonging to proteobacteria, actinobacteria, thermoleophilia, chloroflexia, and acidobacteria, while the dominant <i>nirK</i> taxa were mainly categorized into proteobacteria in both types of plantations. The structure of <i>nirS</i> and <i>nosZ</i> communities shifted substantially from AM to PM plantations with changes in soil moisture, NH₄⁺, and microbial biomass nitrogen content. The species co-occurrence network of <i>nirK</i> community was better organized in a more modular manner compared to <i>nirS</i> and <i>nosZ</i> communities, and the network keystone species mostly occurred in PM plantations. These results indicated a highly species corporation of <i>nirK</i> community in response to environmental changes, especially in PM plantations. AM and PM plantations can form different soil denitrifying microbial communities via altering soil physicochemical properties, which may further affect soil N transformations.