Structural and Predicted Functional Diversities of Bacterial Microbiome in Response to Sewage Sludge Amendment in Coastal Mudflat Soil

Abstract

The study investigated the influence of sewage sludge application at rates of 0 (CK), 30 (ST), 75 (MT), and 150 (HT) t ha−1 to mudflats on bacterial community diversity and predicted functions using amplicon-based sequencing. Soils under sewage sludge treatments, especially the HT treatment, exhibited lower pH, salinity and higher nutrient contents (C, N, and P). Moreover, restructured bacterial communities with significantly higher diversities and distinct core and unique microbiomes were observed in all sewage sludge-amended soils as compared to the control. Specifically, core bacterial families, such as Hyphomicrobiaceae, Cytophagaceae, Pirellulaceae Microbacteriaceae, and Phyllobacteriaceae, were significantly enriched in sewage sludge-amended soils. In addition, sewage sludge amendment significantly improved predicted functional diversities of core microbiomes, with significantly higher accumulative relative abundances of functions related to carbon and nitrogen cycling processes compared to the unamended treatment. Correlation analyses showed that modified soil physicochemical properties were conducive for the improvement of diversities of bacterial communities and predicted functionalities. These outcomes demonstrated that sewage sludge amendment not only alleviated saline–sodic and nutrient deficiency conditions, but also restructured bacterial communities with higher diversities and versatile functions, which may be particularly important for the fertility formation and development of mudflat soils.

Intercropping and nitrogen enhance eucalyptus productivity through the positive interaction between soil fertility factors and bacterial communities along with the maintenance of soil enzyme activities

“…More bacteria in the EI group suggest that bacteria may play a key role in promoting N metabolism in the rhizosphere (Hacquard et al, 2015; Näsholm et al, 2009). This process, in turn, may increase the plant nutrient supply (Li, Wang, et al, 2021; Zhao et al, 2016). Although N application altered soil fertility, only the Chao1 index was significantly altered by N; the structural compositions at the bacterial phylum and genus levels did not differ significantly (Tables S2 and S3).…”

Alleviated environmental constraints and restructured fungal microbiome facilitate aggregate formation and stabilization in coastal mudflat saline soil amended by sewage sludge

“…This result was similar to the improvement of soil macroaggregates by exogenous organic inputs in saline‐sodic soils, such as sewage sludge, manure, and vermicompost amendments (Bai, Zuo, et al, 2018; Hanay et al, 2004). Sewage sludge‐induced amelioration of soil chemical properties (i.e., pH, salinity, and SOC) and shift of soil microbial community diversity (especially the fungal microbiome) might be most responsible for the improvement of soil aggregation, as they have been widely demonstrated to be pivotal factors involved in soil aggregate formation (Li et al, 2021; Xiao et al, 2020). Additionally, enhanced aggregate stability with higher MWD and GMD but lower fractal dimension D and erodibility K were observed in the sludge‐amended saline soil (Figure 1b–e).…”

“…In terms of soil pH and salinity, lower values were observed in reclaimed coastal saline soils, which was in accordance with previous literature that found that sewage sludge can efficiently alleviate the saline‐sodic condition in coastal areas (Bai et al, 2017). Compared with CK (8.91), lower pH values in LT (8.59), MT (8.53), and HT (8.28) soils (Table 1) were partially explained by the neutralization caused by sewage sludge with a lower pH (Table S1) and acid compounds derived from OM‐rich sewage sludge degradation (Li et al, 2021), while significantly improved soil aggregation status might be the primary reason for blocking the capillary rise of upward‐moving salt.…”

“…Soil chemical characteristics determinations were referenced by Li et al (2021). Soil water‐stable aggregates were separated using an agglomerate apparatus according to an established procedure adapted from Elliott (1986) and Zhang et al (2007).…”

“…In this study, the fungal ITS2 region was amplified using primer pairs ITS3F/ITS4R, with the PCR processes described by Zhao et al (2014). Sequencing was conducted on an Illumina Miseq instrument following the manufacturer's instructions (Li et al, 2021). Raw sequences obtained from Illumina Miseq sequencing were quality‐controlled, merged, and analyzed according to the established procedures of Li et al (2020).…”