Variations in Soil Bacterial Composition and Diversity in Newly Formed Coastal Wetlands

Abstract

Coastal ecosystems experience some of the most active land–ocean interactions in the world, and they are characterized by high primary productivity and biological diversity in the sediment. Given the roles of microorganisms in soil biogeochemical cycling and their multifaceted influence on soil ecosystems, it is critical to understand the variations and drivers of soil microbial communities across coastal ecosystems. Here, we studied soil bacterial community dynamics at different sites (from seawater to freshwater) in the Yellow River Delta, China. Bacterial community composition and diversity over four seasons were analyzed through 16S rRNA genes. Notably, the bacterial community near the ocean had the lowest alpha-diversity when compared with the other sites. No significant differences in bacterial communities among seasons were found, indicating that seasonal variation in temperature had little influence on bacterial community in the newly formed wetlands in the Yellow River Delta. Bacterial community structure changed substantially along the salinity gradient, revealing a clear ecological replacement along the gradual transformation gradient from freshwater to seawater environment. Redundancy analysis revealed that salinity was the main driver of variations in bacterial community structure and explained 17.5% of the variability. Our study provides a better understanding of spatiotemporally determined bacterial community dynamics in coastal ecosystems.

Shifts in the Bacterial Population and Ecosystem Functions in Response to Vegetation in the Yellow River Delta Wetlands

“…There were 46 phyla, 188 classes, 237 orders, 404 families, and 697 genera in the total of 3,896 OTUs. Consistent with previous results (12,29), the most predominant phylum was Proteobacteria, followed by Bacteroidetes, in each of the five wetland plots (Fig. 2a).…”

“…S3), pH and soil water content and salinity were the major factors influencing community composition. The results were rather similar to those reported from previous studies conducted in the Yellow River Delta (12,29,30); i.e., the bacterial community near the ocean had the lowest alpha-diversity among the sites, and salinity had an important effect on the microbial community structure.…”

“…Microbes in the Yellow River Delta have been widely investigated, for example, in studies of the bacterial distribution patterns between water and sediment (23,24), the effects of soil salinity and petroleum contamination on soil bacterial community structures (25,26), the diversity and distribution of nirK-harboring denitrifying bacteria in the water column (27), and nitrite-dependent anaerobic methane-oxidizing bacteria in sediments (28). The bacterial community structures in wetland soil, from saline bare land to the marshy grassland of P. australis (12,29), as well as in different tidal flats (30) have also been investigated. Those previous studies revealed that the bacterial compositions differed significantly along vegetative succession regions, and the dominant phyla across all samples were Proteobacteria, Bacteroidetes, and Firmicutes.…”

Fresh Compost Tea Application Does Not Change Rhizosphere Soil Bacterial Community Structure, and Has No Effects on Soybean Growth or Yield

“…Surprisingly, both the control and treated soil samples were largely dominated by Planctobacteria ( Figure 1 a), a result contrasting with several studies identifying Proteobacteria as the dominant bacterial phylum in soils, followed by Chloroflexi, Bacteroidetes, Actinobacteria and Acidobacteria [ 43 , 44 , 45 , 46 , 47 ]. Planctobacteria are a unique divergent phylum of aquatic bacteria [ 48 , 49 , 50 , 51 , 52 , 53 ], that can be isolated from nonaquatic environments such as soil [ 52 , 54 ].…”

Fresh Compost Tea Application Does Not Change Soil Bacterial Community Structure, and Has No Effects on Soybean Growth or Yield

“…Surprisingly, both the control and treated soil samples were largely dominated by Planctobacteria (Fig. 1.a), a result contrasting with several studies identifying Proteobacteria as the dominant bacterial phylum in soils, followed by Chloroflexi, Bacteroidetes, Actinobacteria, and Acidobacteria [43][44][45][46][47]. Planctobacteria are a unique divergent phylum of aquatic bacteria [48][49][50][51][52][53], that can be isolated from nonaquatic environments such as soil [52,54].…”