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Glucocorticoids in sewage treatment plant effluent discharged into rivers could influence microbial community structure in river-based aquifer media and affect groundwater quality. The effect of representative natural and synthetic glucocorticoids, namely, hydrocortisone (CRL) and dexamethasone (DEX), on the microbial communities in three types of river-based aquifer media was evaluated. The aquifer media was taken from the Beijing Chaobai River (BJ), Hebei Hutuo River (HB), and Tianjin Duliujian River (TJ) and they exhibited different physicochemical and biological properties. The attenuation rates of CRL were 0.175, 0.119, and 0.096 day−1 and for DEX were 0.222, 0.151, and 0.113 day−1 in the media from BJ, HB, and TJ, respectively. All the attenuation rates followed first-order kinetics. The biodiversity decreased significantly with CRL and DEX amendment. The microbial community composition differed in relation to the type of aquifer media and glucocorticoids, especially for BJ at the phylum level. In BJ, the major bacterial genus was Bacillus and in HB it was Rhodobacter. However, in TJ, three bacterial genera (Methylophilus, Methylobacillus, and Methylotenera) and Candidatus_Nitrososphaera were predominant in the microflora. All these genera were able to degrade both CRL and DEX. Distance-based redundancy analysis revealed that total organic carbon (TOC), the type of glucocorticoid, and the pH were the main factors explaining the variations in microbial community composition. [ABSTRACT FROM AUTHOR]

This study evaluated the effectiveness of external electron donors on the bio-reductive degradation enhancement of fluoroglucocorticoids (FGCs) in the groundwater fluctuation zone during the wet season when reverse upward fluctuation of the groundwater table occurs and the dry season after the groundwater table declines. The results showed that the external electron donors, provided by the addition of nano zero-valent iron-modified biochar (nZVI@BC), inhibited the migration and enhanced the reductive defluorination of triamcinolone acetonide (TA), a representative FGC. The accumulation rate constant with temporal fluctuation depth and the attenuation rate constant with vertical fluctuation depth were −2.55 × 10−3 and 4.20 × 10−2, respectively, in the groundwater of the natural groundwater fluctuation zone (N-FZ). In contrast, the accumulation and attenuation rate constants were, respectively, 35.6% and 2.64 times higher in the groundwater fluctuation zone amended with nZVI@BC (nZVI@BC-FZ) as compared with those observed in the N-FZ. Furthermore, the decay rate constant of the TA residue in the dry season was 0.843 × 10−2 μg/d in N-FZ and was 2.19 times higher in nZVI@BC-FZ. This enhancement effect, caused by the addition of external electrons, was positively correlated with the evolution of the microbial community and the expression of functional genes. The microbes evolved into functional genera with reductive dehalogenation (Xylophilus and Hydrogenophaga) and iron-oxidizing (Lysobacter , Pseudoxanthomonas , and Sphingomonas) abilities in the nZVI@BC-FZ system, which increased dehalogenation and iron oxide genes by a 4–5 order of magnitude. The utilization proportion of external electrons for TA metabolism was 50.04%, of which 30.82%, 10.26%, and 8.96% were utilized for defluorination, hydrogenation, and ring-opening, respectively. This study provides an effective method to reduce pollutant diffusion and enhance the bio-reductive degradation caused by groundwater table fluctuation. [Display omitted] • Migration rate of TA decreased by 2.81 times with the amendment of nZVI@BC. • Biodegradation of TA increased by 2.2 times with the amendment of nZVI@BC. • External electrons were used for defluorination, hydrogenation, and ring-opening. • Defluorination improved by 2.1 times with the expression of dehalogenation gene. • Defluorination/electron transfer related microbes were enriched by 2.38 times. [ABSTRACT FROM AUTHOR]

In this long-term field study, to restore a dried river ecosystem, reclaimed water was used as a supplementary water source. The main aim of this study was to investigate the accumulation and migration potential of EDCs in groundwater during long-term utilization of reclaimed water and the changes in microbial community during the removal of EDCs. A long-term field study was conducted in order to ascertain the temporal and spatial distribution of four selected endocrine-disrupting chemicals (EDCs) in an underground aquifer in the Chaobai watershed, where reclaimed water is the primary water source. Anew, the microbial community structure at different groundwater depths, along with related environmental factors were also determined. Based on the results obtained from this long-term study, it was found that the EDCs in the surface water of the Chaobai river have entered a depth of 80 m in the groundwater aquifers, within a distance of 360 m from the river. The vertical profiles of the concentrations of bisphenol A (BPA), 4-nonylphenol (NP), estrone (E1), and estriol (E3) decreased significantly from the surface to different groundwater depths with first-order attenuation rates of 0.0416, 0.0343, 0.0498, and 0.0173 m-1. The aquifer depth, water temperature, conductivity, and coexisting anions correlated well with the distribution of EDCs in groundwater. • Spatiotemporal variation of 4 endocrine disrupting chemicals (EDCs) was ascertained. • Analysis of variance (ANOVA) were used to perform statistical analysis of the data. • EDCs in groundwater depends on aquifer depth, temperature, competing ions, etc. • Microbial communities and their clustering affected the degradation of EDCs. • Microorganisms affected by: temperature > depth > EDC concentration > pH > TOC. [ABSTRACT FROM AUTHOR]

Ruminant rumen is a biological fermentation system that can efficiently degrade lignocellulosic biomass. The knowledge about mechanisms of efficient lignocellulose degradation with rumen microorganisms is still limited. In this study, composition and succession of bacteria and fungi, carbohydrate-active enzymes (CAZymes), and functional genes involved in hydrolysis and acidogenesis were revealed during fermentation in Angus bull rumen via metagenomic sequencing. Results showed that degradation efficiency of hemicellulose and cellulose reached 61.2% and 50.4% at 72 h fermentation, respectively. Main bacterial genera were composed of Prevotella , Butyrivibrio , Ruminococcus , Eubacterium , and Fibrobacter , and main fungal genera were composed of Piromyces , Neocallimastix , Anaeromyces , Aspergillus , and Orpinomyces. Principal coordinates analysis indicated that community structure of bacteria and fungi dynamically changed during 72 h fermentation. Bacterial networks with higher complexity had stronger stability than fungal networks. Most CAZyme families showed a significant decrease trend after 48 h fermentation. Functional genes related to hydrolysis decreased at 72 h, while functional genes involved in acidogenesis did not change significantly. These findings provide a in-depth understanding of mechanisms of lignocellulose degradation in Angus bull rumen, and may guide the construction and enrichment of rumen microorganisms in anaerobic fermentation of waste biomass. [Display omitted] • Corn stover was efficiently hydrolyzed during rumen fermentation. • Rumen bacterial and fungal community composition dynamically changed. • Synergism was greater than competition among rumen bacteria and fungi. • Efficient hydrolysis efficiency was attributed to the complex CAZyme families. • Hydrolysis capacity decreased, while acidogenesis capacity remained unchanged. [ABSTRACT FROM AUTHOR]

During groundwater recharge with reclaimed water, pentabromodiphenyl ether (BDE-99) might contaminate the underground aquifers. In order to understand the effects of elevated sulfate concentrations on the biodegradation of BDE-99, lab-scale column experiments were performed to study the changes in bacterial and archaeal communities. The results confirmed that the biodegradation rate of BDE-99 improved significantly with the addition of sulfate. Oxygen was replaced by sulfate as the predominant electron acceptor, and the major biodebromination metabolites of BDE-99 were BDE-28 and BDE-47, respectively, The results from 454 pyrosequencing of 16s rRNA genes showed that the microbial community structure shifted toward communities with BDE-99 co-metabolism ability. At the bacterial genus level, Geothrix , Thiobacillus , Sphingomonas , Paenibacillus and Desulforhabdus were the five most abundant genera, wherein, Thiobacillus was able to treat the toxic products generated during polybrominated diphenyl ethers (PBDE) biodegradation. In the case of archaea at the genus level, Methanobrevibacter , Methanomethylovorans , DHVEG-6, Candidatus Nitrososphaera and Methanosphaera were the predominant groups, of which Methanobrevibacter and Methanosphaera showed good ability to metabolize BDE-99 with sulfate amendment. [ABSTRACT FROM AUTHOR]

The main aim of this study was to remove nitrogen compounds from reclaimed water and reuse the water in semi-arid riverine lake systems. In order to assess the nitrogen removal efficiencies in different natural environments, laboratory scale column experiments were performed using sterilized soil (SS), silty clay (SC), soil with submerged plant (SSP) and biochar amendment soil (BCS). The initial concentration of NO 3 − -N and the flow rate was maintained constant at 15 mg L −1 and 0.6 ± 0.1 m d −1 , respectively. Among the tested columns, both SSP and BCS were able to achieve NO 3 − -N levels <0.2 mg L −1 in the treated reclaimed water. The results from bacterial community structure analysis, using 454 pyrosequencing of 16s rRNA genes, showed that the dominant denitrifier was Bacillus at the genera level. [ABSTRACT FROM AUTHOR]

The biodegradation characteristics and primary metabolic pathway of hydrocortisone were investigated in different aquifer media-water systems. The aquifer media from Beijing Chaobai river (BJ), Hebei Hutuo river (HB), and Tianjin Duliujian river (TJ), having different properties were used. The results showed that the attenuation rates of hydrocortisone were 0.175, 0.119 and 0.096 d −1 in BJ, HB, TJ respectively and all of them followed the first-order rate kinetics. The main metabolic pathway of hydrocortisone in the BJ system began with the hydration of C-4 and C-5 double bond on ring A, and the A-ring was subsequently cleaved. In the case of the HB system, the primary biotransformation pathway started from the side chain degradation and oxidation of C-12 on ring D to form a ketone group, and the D-ring was subsequently carboxylated and cleaved. The differences in attenuation rates and metabolic pathways were associated with community structures of bacteria and archaea in different systems. The biodegradation of A-ring had a greater influence on the decay rate than D-ring. The results from microbial community structure analysis using 454 pyrosequencing of 16s rRNA genes showed that the microbial community structure transformed to microflora with good degrading capacity towards hydrocortisone by hydrocortisone amendment. The potential bio-transformers were seven major bacterial genera ( Methylophilus , Sphingopyxis , Arenimonas , hgcI_clade , Methylobacillus , Methylotenera and Fluviicola ) and two major archaeal genera ( Candidatus_Nitrososphaera and Woesearchaeota_DHVEG-6 ), respectively. [ABSTRACT FROM AUTHOR]

The use of tertiary-treated municipal wastewater for groundwater recharge through river utilization may cause pentabromodiphenyl ether (BDE-99) pollution, which poses a potential risk to groundwater aquifers. Elevated nitrate levels may change the structure of microbial communities, thus influencing the biodegradation of BDE-99. To investigate the influence of elevated nitrate levels on the changes in microbial communities and associated biodegradation of BDE-99 appropriately, a laboratory-scale column was designed to simulate the percolation process. The results showed that the attenuation rate of BDE-99 increased with nitrate concentrations. The lower-brominated ether congeners were the primary debrominated metabolites, while high-brominated diphenyl ethers and isomers of BDE-100 also emerged, and their concentrations decreased with reduced nitrate concentrations. The microbial community composition and structure significantly changed with elevated nitrate levels and relative abundance of nitrate-reducing bacteria with diverse metabolic capabilities increased. The order of the relative abundance of the largest five classes, as well as the relative abundances of the largest five families and genera, changed with increasing nitrate concentrations. The diversity of microorganisms with universal aromatics-degrading abilities related to nitrogen transformation played an important role in mitigating the infiltration of BDE-99 to groundwater. [ABSTRACT FROM AUTHOR]