Understanding the Linkage between Elevation and the Activated-Sludge Bacterial Community along a 3,600-Meter Elevation Gradient in China

Abstract

To understand the relationship between elevation and bacterial communities in wastewater treatment plants (WWTPs), bacterial communities in 21 municipal WWTPs across China, located 9 to 3,660 m above sea level (masl), were investigated by 454 pyrosequencing. A threshold for the association of elevation with bacterial community richness and evenness was observed at approximately 1,200 masl. At lower elevations, both richness and evenness were not significantly associated with elevation. At higher elevations, significant declines with increased elevations were observed for community richness and evenness. The declining evenness trend at the phylum level was reflected by distinct trends in relative abundance for individual bacterial phyla. Betaproteobacteria, Bacteroidetes, and Firmicutes displayed significant increases, while most other phyla showed declines. Spearman correlation analysis indicated that the community richness and evenness at high elevations were more correlated with elevation than with any other single environmental variable. Redundancy analysis indicated that the contribution of elevation to community composition variances increased from 3% at lower elevations to 11% at higher elevations whereas the community composition variance at higher elevations remained much more explained by operational variables (39.2%) than by elevation. The influent total phosphorus concentration, food/microorganism ratio, and treatment process were the three shared dominant contributors to the community composition variance across the whole elevation gradient, followed by effluent ammonia nitrogen and temperature at higher elevations. W astewater treatment plants (WWTPs) are broadly applied for the efficient removal of contaminants from wastewater before its discharge into the natural environment. A complex microbial community is the most dominant contributor to the removal of contaminants in WWTPs. A better understanding of the microbial community structure and its relationship to influential variables could provide important guidance for the improvement of wastewater treatment efficiency (1). Multiple studies have investigated the significant associations between WWTP microbial community structures and operational parameters or wastewater characteristics, such as dissolved oxygen concentration (2), temperature (3), treatment process (4), influent ammonia nitrogen concentration (5), biological oxygen demand (6), and total phosphorus (TP) concentration (7). However, regardless of the weakly neutral assembly of bacterial communities (8), there is still a large part of the bacterial community variance that cannot be explained by these well-known variables. Thus, it is presumed that there are still other environmental variables that potentially influence the variance of WWTP microbial communities.In recent years, a few studies were performed to explore the relationship between microbial communities and geographical locations of WWTPs. Zhang et al. (9) found significant geographical differences in bacterial communities amo...

Shifts in the Microbial Community of Activated Sludge with Different COD/N Ratios or Dissolved Oxygen Levels in Tibet, China

“…The difference in our reported richness and evenness of microbial community to those reported by Chandra Yadav et al [16] may be related to elevational gradient. As reported by Niu [27], a significant change in the evenness of the bacterial community was observed at around 1200 m of elevation with a linear decline as elevation increased to 3660 m. The microbial abundance at the phylum level was clearly lower when the DO concentration was 0.5-1, 1-2, and 2.5-3.5 mg/L than when the DO was 2-2.5 mg/L, indicating that the bio-community proportions in the sludge vary with the DO concentration. Figure 6 summarizes the relative abundances of the fungi community on the phylum level of activated sludge with different COD/N ratios or DO concentrations.…”

“…The treatment performance can be explained by the relative OTU richness and evenness of microbial communities of activated sludge [19,27]. The community richness and evenness were two important factors that influenced the functional stability and general performance of WWTPs [37].…”

Disentangling the Drivers of Diversity and Distribution of Fungal Community Composition in Wastewater Treatment Plants Across Spatial Scales

“…Moreover, Evans et al (2014) suggested that the observed differences in the fungal community structures was due to the different wastewater characteristics or operational parameters in the WWTPs. It is therefore that the specific operational parameters [e.g., retention time, plant dimension, temperature, food to microorganisms (F/M) ratio] can be regulated to achieve the desired treatment performance aims ( Niu et al, 2015 ).…”

Ignored fungal community in activated sludge wastewater treatment plants: diversity and altitudinal characteristics

“…Pyrosequencing was performed on a Roche 454 FLX Titanium sequencer (Roche, Nutley, USA) at the Chinese National Human Genome Center (SinoGenoMax). The raw reads were processed using Mothur as described by Niu et al (2015). The obtained raw reads were deposited in the NCBI short-read archive database (accession number SRR3344414).…”