High Salinity Inhibits Soil Bacterial Community Mediating Nitrogen Cycling

Abstract

Salinization is considered as a major threat to soil fertility and agricultural productivity throughout the world. Soil microbes play a crucial role in maintaining ecosystem stability and function (e.g., nitrogen cycling). However, the response of bacterial community composition and community-level function to soil salinity remains uncertain. Herein, we used multiple statistical analyses to assess the effect of high salinity on bacterial community composition and potential metabolism function in the agricultural ecosystem. Results showed that high salinity significantly altered bacterial both alpha (Shannon-Wiener index and phylogenetic diversity) and beta diversity. Salinity, TN, and SOM were the vital environmental factors shaping bacterial community composition. The relative abundance of Actinobacteria , Chloroflexi , Acidobacteria , and Planctomycetes decreased with salinity, whereas Proteobacteria and Bacteroidetes increased with salinity. The modularity and the ratio of negative to positive links remarkedly decreased indicated that high salinity destabilized bacterial networks. Variable selection, which belongs to deterministic processes, mediated bacterial community assembly within the saline soils. Function prediction results showed that the key nitrogen metabolism (e.g., ammonification, nitrogen fixation, nitrification, and denitrification processes) was inhibited in high salinity habitats. Miseq sequencing of 16S rRNA genes revealed that the abundance and composition of nitrifying community were influenced by high salinity. The consistency of function prediction and experimental verification demonstrated that high salinity inhibited soil bacterial community mediating nitrogen cycling. Our study provides strong evidence for salinity effect on the bacterial community composition and key metabolism function, which could help us understand how soil microbe responds to ongoing environment perturbation. IMPORTANCE Revealing the response of the soil bacterial community to external environmental disturbances is an important but poorly understood topic in microbial ecology. In this study, we evaluated the effect of high salinity on the bacterial community composition and key biogeochemical processes in salinized agricultural soils (0.22 to 19.98 dS m −1 ). Our results showed that high salinity significantly decreased bacterial diversity, altered bacterial community composition, and destabilized bacterial network. Moreover, variable selection (61-66%) mediated bacterial community assembly within the saline soils. Functional prediction combined with microbiological verification proved that high salinity inhibited soil bacterial community mediating nitrogen turnover. Understanding the impact of salinity on soil bacterial community is of great significance in managing saline soils and maintaining a healthy ecosystem.

Insights of Host Physiological Parameters and Gut Microbiome of Indian Type 2 Diabetic Patients Visualized via Metagenomics and Machine Learning Approaches

“…Interestingly co-occurrence network analysis also revealed that there are significant differences present in the proportion of taxonomic abundance of Firmicutes and Bacteroidota phylum in T2D compared to the NGT group which is also in line with the previously reported data (Turnbaugh et al, 2006 ; Ley et al, 2008 ; Zhang et al, 2013 ; Ahmad et al, 2019 ). The same trend was also observed in identified keystone taxa from the two co-occurrence networks and they might play an essential role in maintaining the microbial structure links, information transmission, and ecological function of the entire ecological communities in the gastrointestinal tract (Li et al, 2020a , b , 2021 ).…”

“…We used Spearman's rank correlation to assess the association among microbial OTUs from each group. Moreover, p = ≤0.05 and a Spearman's rank correlation coefficient, ρ = ≥0.6 were selected as the thresholds between two OTUs (Jiao et al, 2016 ; Li et al, 2021 ). Two co-occurrence networks were built, the T2D co-occurrence network (TCN), and NGT co-occurrence network (NCN).…”

Irrigation water salinity structures the bacterial communities of date palm (Phoenix dactylifera)-associated bulk soil

“…Apart from soil salinity, irrigation water salinity also affect the Shannon diversity index, both negatively ( Zheng et al, 2017 ; Chen et al, 2019 ; Hou et al, 2021 ) and positively ( Chen et al, 2017 ) in arid soil. Soil salinity is also reported to structure bacterial communities ( O’Brien et al, 2019 ; Rath et al, 2019 ; Guo et al, 2021 ; Li et al, 2021a ; Nan et al, 2022 ), with soil pH and EC being major predictors of bacterial communities ( O’Brien et al, 2019 ; Rath et al, 2019 ; Nan et al, 2022 ) in arid ecosystems. Despite gaining limited knowledge on the impact of groundwater irrigation-induced salinity on bacterial communities, the responsible structuring factor has not been identified yet ( Chen et al, 2017 ).…”

“…The resiliency of soil-inhabiting bacteria against increasing salinity is dependent on the filtration of specific bacterial taxa and capable of withstanding the stress. Based on previous studies, soil salinity increase is known to correlate with an increase in abundance of Proteobacteria ( Nan et al, 2022 ) and its classes, Gamma and Alphaproteobacteria ( Zhang et al, 2019 ), and a reduction in Actinobacteriota, Chloroflexi, Acidobacteria, and Planctomycetes ( Li et al, 2021a ). In cotton field soil, Chen et al (2019) found a reduction in the abundance of Actinobacteriota, Gemmatimonadetes, and Acidobacteria after irrigation with saline groundwater.…”

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“…We used Spearman's rank correlation to assess the association among microbial OTUs from each group. Moreover, p = ≤0.05 and a Spearman's rank correlation coefficient, ρ = ≥0.6 were selected as the thresholds between two OTUs (Jiao et al, 2016;Li et al, 2021). Two co-occurrence networks were built, the T2D cooccurrence network (TCN), and NGT co-occurrence network (NCN).…”