Regulating soil bacterial diversity, community structure and enzyme activity using residues from golden apple snails

Jiaen Zhang,Yue Xiong,Guangchang Wei,Xuening Lu,Jiaxin Wang

doi:10.1038/s41598-020-73184-z

Abstract

It has been shown that the golden apple snail (GAS, Pomacea canaliculata), which is a serious agricultural pest in Southeast Asia, can provide a soil amendment for the reversal of soil acidification and degradation. However, the impact of GAS residue (i.e., crushed, whole GAS) on soil bacterial diversity and community structure remains largely unknown. Here, a greenhouse pot experiment was conducted and 16S rRNA gene sequencing was used to measure bacterial abundance and community structure in soils amended with GAS residue and lime. The results suggest that adding GAS residue resulted in a significant variation in soil pH and nutrients (all P < 0.05), and resulted in a slightly alkaline (pH = 7.28–7.75) and nutrient-enriched soil, with amendment of 2.5–100 g kg−1 GAS residue. Soil nutrients (i.e., NO3-N and TN) and TOC contents were increased (by 132–912%), and some soil exocellular enzyme activities were enhanced (by 2–98%) in GAS residue amended soil, with amendment of 1.0–100 g kg−1 GAS residue. Bacterial OTU richness was 19% greater at the 2.5 g kg−1 GAS residue treatment than the control, while it was 40% and 53% lower at 100 g kg−1 of GAS residue and 50 g kg−1 of lime amended soils, respectively. Firmicutes (15–35%) was the most abundant phylum while Bacterioidetes (1–6%) was the lowest abundant one in GAS residue amended soils. RDA results suggest that the contents of soil nutrients (i.e., NO3-N and TN) and soil TOC explained much more of the variations of bacterial community than pH in GAS residue amended soil. Overuse of GAS residue would induce an anaerobic soil environment and reduce bacterial OTU richness. Soil nutrients and TOC rather than pH might be the main factors that are responsible for the changes of bacterial OTU richness and bacterial community structure in GAS residue amended soil.

Highlights

The paddy fields were proposed[16,17], the low effectiveness or high cost of these methods limited the possibility for their practical application
The total organic carbon (TOC) and N H4-N progressively increased as more GAS residue was added, the levels rose by 134% (TOC) and 168% (NH4-N) from the control to the amendment of 100 g kg−1 GAS residue
The contents of NO3-N and total nitrogen (TN) significantly increased by 912% and 132% at 25 g kg−1 GAS residue amendment compared with the control, but they significantly decreased by 27% and 32% at 100 mg kg−1 GAS residue amendment compared with that of 25 g kg−1 GAS residue amendment (Fig. 1b,e)

Summary

Introduction

The paddy fields were proposed[16,17], the low effectiveness or high cost of these methods limited the possibility for their practical application. What remains largely unknown is the effect that GAS residue has on soil microbial properties, especially bacterial community and diversity. Some studies have suggested that forest soils with lower pH support greater microbial diversity than agricultural soils with higher pH values[27] Soil microbes, such as bacteria and fungi, generate extracellular enzymes to release assimilable C, N and phosphorus (P) from organic compounds[28]. Β-1,4-glucosidase (BG), β-d-cellobiosidase (CB), β-1,4-Nacetylglucosaminidase (NAG) and acid phosphatase (ACP) were reported as the key enzymes associated with the recycling of nutrients related to C, N, and P28,30 Numerous environmental factors, such as water31, salinity31, pollution[32], soil nutrients33, temperature[34] and soil pH, can affect the activities of extracellular enzymes directly or indirectly. Elevated soil pH and soil nutrients induced by the amendment of GAS residue may be the major factors that are responsible for the changes of bacterial community structure and bacterial diversity

Objectives

Methods

Results

Discussion

Conclusion