Impact of Nutrients on Protozoa Community Diversity and Structure in Litter of Two Natural Grass Species in a Copper Tailings Dam, China.

Tong Jia,Baofeng Chai,Tingyan Guo,Xiaoxia Liang

doi:10.3390/microorganisms9112250

Abstract

In nature, protists directly participate in litter decomposition and indirectly affect litter decomposition processes by means of their influence on litter microbial communities. To date, relevant studies on litter microbial communities have primarily focused on bacteria and fungi, while relatively little attention has been paid to the characteristics of protozoan communities within damaged ecosystems. Two dominant grass species (Bothriochloa ischaemum and Imperata cylindrica) were selected from China’s “Eighteenth” River tailings dam to explore protozoan community composition and diversity in a degraded mining area and to clarify the influence among key ecological factors and protozoan community characteristics in litter. High-throughput sequencing was used to analyze protozoan community composition and diversity, while correlation analysis was used to explore the relationships between protozoan communities and litter nutrient characteristics, including associative enzyme degradation. Although protozoan communities in litter shared a dominant group at an order level (Colpodida), they differed at a genus level (i.e., Hausmanniella and Tychosporium). Moreover, although the order Cryomonadida positively correlated to total nitrogen (TN) and sucrose, it exhibited an extreme negative correlation to total carbon (TC) and cellulase. Colpodida and Oomycota_X significantly and negatively correlated to litter urease activity. Nutrient characteristics of grass litter in copper tailing dams are important ecological factors that affect protozoan community characteristics. Notable differences were observed among protozoan communities of these two grass species, while litter enzyme activities were closely correlated to protozoan community diversity. The results suggested that Colpodida may play important roles in litter decomposition and nutrient cycling in mining areas.

Highlights

Litter acts as a pathway for plants to transfer nutrients to the soil within terrestrial ecosystems [1]
The litter protist communities of B. ischaemum was mainly affected by the total carbon (TC) of the litter, while the total nitrogen (TN), urease activity and sucrase activity were the important ecological factors affecting the protist communities of I. cylindrica litter (Figure 5)
Many protists reside in both plant leaves, as well as in a variety of species [18], which has an effect on bacterial community characteristics and which alter microbial community functionality [7]

Summary

Introduction

Litter acts as a pathway for plants to transfer nutrients to the soil within terrestrial ecosystems [1]. The carbon (C) released through litter decomposition is an important source of soil organic matter conversion into humus, which is highly significant for material circulation. Protists are an integral constituent of soil microbial communities [2]. Autotrophic protists provide vital C inputs to soil [3], and certain protists participate in organic matter degradation processes [4]. Protists are major consumers within soil food webs, which regulate microbial communities through phagocytosis or the secretion of metabolites [5], affecting microbial functions and subsequently ecological C and nitrogen (N) cycling processes [6]. In addition to directly participating in litter degradation, protist communities may indirectly regulate litter degradation processes by influencing litter microbial communities

Methods

Results

Conclusion