Archaeal Communities In Sediments Research Articles

Differential insights into the distribution characteristics of archaeal communities and their response to typical pollutants in the sediments and soils of deep-water reservoir

This study focused on the Fengshuba deep-water reservoir in South China, and systematically explored the distribution characteristics of archaeal communities in the sediment and soil in water level fluctuation zones and their response mechanisms to typical pollutants. The results show that Euryarchaeota and Bathyarchaeota are the dominant phyla in sediment archaeal communities, while Thaumarchaeota dominates in soil. The absolute abundance of archaea in the sediments was lower than that in the soils, but the diversity and richness of archaeal communities were higher than those in the soils. Seasonal changes affected the composition of sediment archaeal communities, and the archaeal compositions in the two habitats also showed significant differences. The neutral community model indicates that the assembly of archaeal communities in sediments is mainly governed by stochastic processes, while deterministic processes dominate in soils. The responses of archaeal communities to pollutants in the two habitats were significantly different. Among them, the carbon-nitrogen ratio and tetracycline concentration are the key factors driving seasonal changes in the archaeal communities in the sediment. Structural equation modeling further showed that the archaeal community in the sediment was positively correlated with organochlorine pesticides and antibiotics, while the archaeal community in the soil showed an opposite trend. This study provides new insights into the complexity of interactions between archaeal communities and typical contaminants in reservoir systems.

Archaeal communities in natural and artificially restored mangrove sediments in Tieshan Bay, China

Mangrove forests are crucial wetland ecosystems located in tropical and subtropical intertidal zones, but they have become extensively degraded. As a viable ecological restoration strategy, the cultivation of native mangrove vegetation in these degraded areas has gained considerable attention. Mangroves’ unique environmental conditions make them suitable habitats for diverse microbial communities, including Archaea - one of the main microbial communities in mangrove sediments - which plays a pivotal role in biogeochemical cycles. However, little is known about the dynamics of archaeal communities during mangrove restoration through phytoremediation. In this study, we investigated the physicochemical properties of sediment profiles from natural and artificially restored mangrove ecosystems in Tieshan Bay. We utilized quantitative polymerase chain reaction (qPCR) and 16S rRNA gene sequencing techniques to explore differences in abundance, community structure, and composition of archaeal communities between sediment profiles in natural and artificially restored mangrove ecosystems. We also examined correlations between archaeal communities and environmental factors. Our results revealed that Crenarchaeota, Thermoplasmatota, Asgardarchaeota, Nanoarchaeota, and Euryarchaeota were the predominant archaeal phyla, with significant variation in sediment composition observed for Crenarchaeota and Thermoplasmatota in different depths. We also found significant differences in archaeal abundance and community composition between natural and restored mangrove sediments. Furthermore, C/N ratio and pH emerged as primary drivers of archaeal communities in wet and dry season sediments, respectively. Additionally, the study revealed seasonal disparities in seasonal differences in the relative abundance of certain archaeal groups (such as Asgardarchaeota, Nanoarchaeota). Network analysis demonstrated stronger interconnections among archaeal communities in sediments from natural mangroves than from artificially restored ones. These findings enhance our knowledge of archaeal community succession patterns in mangrove restoration, as well as provide fresh perspectives for the sustainable management of mangrove ecosystems.

Spatial-temporal dynamics and influencing factors of archaeal communities in the sediments of Lancang River cascade reservoirs (LRCR), China.

The spatial and temporal distribution of the archaeal community and its driving factors in the sediments of large-scale regulated rivers, especially in rivers with cascade hydropower development rivers, remain poorly understood. Quantitative PCR (qPCR) and Illumina MiSeq sequencing of the 16S rRNA archaeal gene were used to comprehensively investigate the spatiotemporal diversity and structure of archaeal community in the sediments of the Lancang River cascade reservoirs (LRCR). The archaeal abundance ranged from 5.11×104 to 1.03×106 16S rRNA gene copies per gram dry sediment and presented no temporal variation. The richness, diversity, and community structure of the archaeal community illustrated a drastic spatial change. Thaumarchaeota and Euryyarchaeota were the dominant archaeal phyla in the sediments of the cascade rivers, and Bathyarchaeota was also an advantage in the sediments. PICRUSt metabolic inference analysis revealed a growing number of genes associated with xenobiotic metabolism and carbon and nitrogen metabolism in downstream reservoirs, indicating that anthropogenic pollution discharges might act as the dominant selective force to alter the archaeal communities. Nitrate and C/N ratio were found to play important roles in the formation of the archaeal community composition. In addition, the sediment archaeal community structure was also closely related to the age of the cascade reservoir and hydraulic retention time (HRT). This finding indicates that the engineering factors of the reservoir might be the greatest contributor to the archaeal community structure in the LRCR.

Identifying Microbial Distribution Drivers of Archaeal Community in Sediments from a Black-Odorous Urban River—A Case Study of the Zhang River Basin

Rapid urbanization has destroyed urban water systems and led to blackened and odorous rivers. The heavily polluted rivers are always facing eutrophication and heavy metal pollution, while the combined effects of these environmental factors on the microbial diversity and distribution of the river microbial communities have not been adequately reported, especially the archaeal communities. In this study, we investigated the community structure and microbial distribution of sediment archaeal communities from an urban blackened and odorous river basin of the Zhang river, in Nanling, China. Results showed that the archaeal community from the eight sediment sites have average values of Shannon and Chao1 at 3.4921 and 232.7202, respectively. The community diversity and richness were different among samples. Halobacterota and Euryarchaeota were the most abundant phylum and Crenarchaeota also took up a considerable amount of the archaeal community. To reveal the main environmental drivers of the distribution of archaeal communities in sediment, the environmental physicochemical factors (total nitrogen, total phosphorus, oxidation/reduction potential, nitrate nitrogen, ammonia nitrogen, pH and total organic carbon) and heavy metals (Cr, Ni, Cu, Zn, As, Cd, Pb and Hg) in sediment were determined. A redundancy analysis (RDA) revealed that Eh was the most prominent influencing factor, and As was the most influential heavy metal on the microbial distribution of archaeal communities. Furthermore, a variance partitioning analysis (VPA) was used to identify the impacts of physicochemical factors and heavy metals on the archaeal community distribution. Results showed that heavy metals have higher effects on archaeal community distribution than physicochemical factors. The present study suggested that the heavy metal pollution should be paid more attention in the microbial distribution in heavily polluted urban rivers, and also should be taken into consideration for improving the efficacies of ecological evaluation and remediation.

Identifying ecological processes driving vertical and horizontal archaeal community assemblages in a contaminated urban river.

Understanding environmental factors driving ecological processes of archaeal communities in heavily contaminated rivers is crucial for improvements in river ecological monitoring and indication. However, succession mechanisms underlying vertical and horizontal archaeal community assemblages in contaminated rivers remains largely unstudied. Here, to investigate ecological processes controlling archaeal community succession in a contaminated urban river, multivariate statistics approaches were applied to fields samples collected from locations representing vertical and horizontal assemblages of archaeal community. Our results revealed that archaeal community in the river showed distinct vertical and horizontal distribution patterns and the differences between water and sediment samples were most significant. Beta-diversity patterns in the vertical and horizontal assemblages are both almost completely caused by species replacement between sampling points (horizontal βSIM=0.60±0.09, βNES=0.09±0.05; vertical βSIM=0.40±0.07, βNES=0.10±0.06). Considering phylogenetic turnover deviation, homogenizing dispersal was the most crucial process dominating archaeal community assemblages in water samples while main ecological process in sediment samples was variable selection. Euryarchaeota and Thaumarchaeota were found to prefer high-nutrients and low-nutrients environments, respectively. Analysis of environmental drivers of archaeal phyla distribution and community assemblages indicated that nutrients played a decisive role in driving the sediment archaeal community. Dissolved oxygen (DO) explained the most variation in phylogenetic turnover deviation within all water archaeal community while oxidation reduction potential (ORP) contributed most for horizontal sediment archaeal community assemblages. These findings help to indicate the pollution situation of the river and provide information to predict how archaeal communities would respond to different environmental variations.

Bacterial and Archaeal Communities in Sediments from the Adjacent Waters of Rushan Bay (China) Revealed by Illumina Sequencing

In this study, bacterial and archaeal communities in sediments from the adjacent waters of Rushan Bay were studied based on 16S ribosomal RNA (rRNA) gene. Illumina sequencing and quantitative PCR (qPCR) analyses were used to analyze the bacterial and archaeal community characteristics. The ecological analyses of sequences revealed that the diversity of bacterial communities was higher than that of archaeal communities. The abundance of bacterial 16S rRNA genes was observed to be greater than that of archaeal 16S rRNA genes. Proteobacteria and Piscirickettsiaceae were the most abundant bacterial phylum and family; Thaumarchaeota dominated the archaeal communities, and MGI in Thaumarchaeota and Halobacteria in Euryarchaeota were prevalent and the predominant archaeal class in this study. Temperature and ammonium concentration were related to the bacterial communities, whereas the nitrite concentration and ammonium concentration had a correlation with the archaeal communities; meanwhile, a complex combination of environmental factors might shape the bacterial and archaeal communities in this dynamic environment. Functional Annotation of Prokaryotic Taxa (FAPROTAX) analysis showed that most bacterial sequences were involved in chemoheterotrophy, sulfate respiration, respiration of sulfur compounds, aerobic nitrite oxidation and nitrification; for the archaeal communities, the essential ecological functions were chemoheterotrophy, other ecological functions such as aerobic ammonia oxidation and methanogenesis, were also predicted to be present in this study. The comparison of bacterial and archaeal communities in different environments suggest that similar conditions are hypothesized to give rise to similar microbial communities, and environmental conditions may contribute significantly to the bacterial and archaeal community structure.

Variations of Sediment Archaea Communities in Different Distribution Areas of Bruguiera gymnoihiza Mangrove in Dongzhaigang, China

Archaea communities widely exist in mangrove forest sediments, but their spatial variations among different distribution areas with salinity gradient in mangrove forest sediments is not well understood. This study used 16S rRNA Miseq sequence to investigate the sediment archaeal community structure and diversity of Bruguiera gymnoihiza mangrove forest in China along three different distribution areas. The results showed rich methanogen and ammonia-oxidizing archaea resources in the study site, with Methanobacterium, Methanothrix, Methanomassiliicoccus, Nitrosopumilus and Nitrososphaera (>1%) as the dominant genera. Mantel test and Redundancy analysis (RDA) results revealed that pH was the determinant for archaeal community structure in our study. The RDA result showed that the available K also contributed to archaeal community structure. There was a significant and positive relationship between pH and available P; in addition, the two values were significantly and negatively related to the observed OTU number. These results suggested that pH is the main determinant of the archaeal community structure and diversity in distribution areas of Bruguiera gymnoihiza in Dongzhaigang.

Patterns of bacterial and archaeal communities in sediments in response to dam construction and sewage discharge in Lhasa River

The increased anthropogenic activities in the Tibetan Plateau may threaten the river environmental safety. However, limited information is available on the Lhasa River in the Tibetan Plateau, which is known as the remaining pure land on Earth. Here, we firstly investigated the distribution patterns of bacterial and archaeal communities in sediments in response to dam construction and sewage discharge along the reaches of the Lhasa River. The total organic carbon, total Nitrogen (N), nitrate and ammonium contents and the relative abundance of bacteria and archaea significantly increased in reservoir sites in comparison with sites below dam, and they also gradually increased from upstream to downstream in sewage discharge sites. By contrast, the diversity of sediment bacteria and archaea in reservoir sites were significantly less than that in sites below dam and sewage discharge sites at Operational Taxonomic Units (OTUs) level. The dominant species were water-bloom cyanobacteria in the reservoir area of Zhikong Dam and Proteobacteria in the sewage discharge sites, which were significantly correlated with the nutrient concentration. The abundance of nitrogen functional genes significantly also increased in reservoir sites and the downstream of sewage discharge areas. These results suggested that dam construction and sewage discharge caused the increase of sediment bacterial communities and nutrient levels and potentially induced eutrophication in the Lhasa River.

Response of freshwater sediment archaeal community to metal spill

Archaea play an important role in the biogeochemical cycling of elements in the environment. Heavy metals are ubiquitous pollutants in the environment. Previous studies have revealed a considerable influence of metal pollution on the archaeal community, but the short-term response of the archaeal community to metal pollution remains unclear. Hence, the present study investigated the short versus long-term responses of overall archaeal communities in freshwater sediments after exposure to accidental metal pollution caused by the discharge of heavy metal-containing wastewater from an indium-producing factory. Quantitative PCR was used to determine the archaeal abundance, while Illumina MiSeq sequencing was applied to characterize the diversity and structure of the archaeal community. The abundance (2.47 × 105–1.55 × 108 archaeal 16S rRNA gene copies per gram dry sediment), diversity (Shannon diversity index = 2.49–4.45) and structure of overall archaeal community illustrated a drastic temporal change. The archaeal communities mainly comprised the phyla Euryarchaeota, Thaumarchaeota and Bathyarchaeota. The exposure to metal pollution induced an increase in the proportion of Euryarchaeota but lowered the proportion of Thaumarchaeota. The accidental metal pollution exerted a profound impact on the archaeal community in freshwater sediment. This study could contribute our understanding of the short versus long-term response of archaeal communities to metal pollution.

Metal contaminations impact archaeal community composition, abundance and function in remote alpine lakes.

Using the 16S rRNA and mcrA genes, we investigated the composition, abundance and activity of sediment archaeal communities within 18 high-mountain lakes under contrasted metal levels from different origins (bedrock erosion, past-mining activities and atmospheric depositions). Bathyarchaeota, Euryarchaeota and Woesearchaeota were the major phyla found at the meta-community scale, representing 48%, 18.3% and 15.2% of the archaeal community respectively. Metals were equally important as physicochemical variables in explaining the assemblage of archaeal communities and their abundance. Methanogenesis appeared as a process of central importance in the carbon cycle within sediments of alpine lakes as indicated by the absolute abundance of methanogen 16S rRNA and mcrA gene transcripts (105 to 109 copies g-1 ). We showed that methanogen abundance and activity were significantly reduced with increasing concentrations of Pb and Cd, two indicators of airborne metal contaminations. Considering the ecological importance of methanogenesis in sediment habitats, these metal contaminations may have system wide implications even in remote area such as alpine lakes. Overall, this work was pioneer in integrating the effect of long-range atmospheric depositions on archaeal communities and indicated that metal contamination might significantly compromise the contribution of Archaea to the carbon cycling of the mountain lake sediments.

Spatiotemporal variation of bacterial and archaeal communities in sediments of a drinking reservoir, Beijing, China

Bacterial and archaeal assemblages are one of the most important contributors to the recycling of nutrients and the decomposition of organic matter in aquatic sediments. However, their spatiotemporal variation and its driving factors remain unclear, especially for drinking reservoirs, which are strongly affected by human consumption. Using quantitative PCR and Illumina MiSeq sequencing, we investigated the bacterial and archaeal communities in the sediments of a drinking reservoir, the Miyun Reservoir, one of the most important drinking sources for Beijing City. The abundance of bacteria and archaea presented no spatiotemporal variation. With respect to community diversity, visible spatial and temporal differences were observed in archaea, whereas the bacterial community showed minor variation. The bacterial communities in the reservoir sediment mainly included Proteobacteria, Bacteroidetes, Nitrospirae, Acidobacteria, and Verrucomicrobia. The bacterial community structure showed obvious spatial variation. The composition of the bacterial operational taxonomic units (OTUs) and main phyla were dam-specific; the composition of samples in front of the dam were significantly different from the composition of the other samples. The archaeal communities were mainly represented by Woesearchaeota and Euryarchaeota. Distinctly spatial and seasonal variation was observed in the archaeal community structure. The sediment NH4+-N, pH, and water depth were identified as the key driving factors of changes in the composition of the bacterial and archaeal communities. Water depth might have the greatest influence on the microbial community structure. The dam-specific community structure may be related to the greater water depth in front of the dam. This finding indicates that water depth might be the greatest contributor to the microbial community structure in the Miyun Reservoir.

Differences in the Composition of Archaeal Communities in Sediments from Contrasting Zones of Lake Taihu.

In shallow lakes, different primary producers might impact the physiochemical characteristics of the sediment and the associated microbial communities. Until now, little was known about the features of sediment Archaea and their variation across different primary producer-dominated ecosystems. Lake Taihu provides a suitable study area with cyanobacteria- and macrophyte-dominated zones co-occurring in one ecosystem. The composition of the sediment archaeal community was assessed using 16S rRNA gene amplicon sequencing technology, based on which the potential variation with respect to the physiochemical characteristics of the sediment was analyzed. Euryarchaeota (30.19% of total archaeal sequences) and Bathyarchaeota (28.00%) were the two most abundant phyla, followed by Crenarchaeota (11.37%), Aigarchaeota (10.24%) and Thaumarchaeota (5.98%). The differences found in the composition of the archaeal communities between the two zones was significant (p = 0.005). Sediment from macrophyte-dominated zones had high TOC and TN content and an abundance of archaeal lineages potentially involved in the degradation of complex organic compounds, such as the order Thermoplasmatales. In the area dominated by Cyanobacteria, archaeal lineages related to sulfur metabolism, for example, Sulfolobales and Desulfurococcales, were significantly enriched. Among Bathyarchaeota, subgroups MCG-6 and MCG-15 were significantly accumulated in the sediment of areas dominated by macrophytes whereas MCG-4 was consistently dominant in both type of sediments. The present study contributes to the knowledge of sediment archaeal communities with different primary producers and their possible biogeochemical functions in sediment habitats.

Multitaxon activity profiling reveals differential microbial response to reduced seawater pH and oil pollution.

There is growing concern that predicted changes to global ocean chemistry will interact with anthropogenic pollution to significantly alter marine microbial composition and function. However, knowledge of the compounding effects of climate change stressors and anthropogenic pollution is limited. Here, we used 16S and 18S rRNA (cDNA)-based activity profiling to investigate the differential responses of selected microbial taxa to ocean acidification and oil hydrocarbon contamination under controlled laboratory conditions. Our results revealed that a lower relative abundance of sulphate-reducing bacteria (Desulfosarcina/Desulfococcus clade) due to an adverse effect of seawater acidification and oil hydrocarbon contamination (reduced pH-oil treatment) may be coupled to changes in sediment archaeal communities. In particular, we observed a pronounced compositional shift and marked reduction in the prevalence of otherwise abundant operational taxonomic units (OTUs) belonging to the archaeal Marine Benthic Group B and Marine Hydrothermal Vent Group (MHVG) in the reduced pH-oil treatment. Conversely, the abundance of several putative hydrocarbonoclastic fungal OTUs was higher in the reduced pH-oil treatment. Sediment hydrocarbon profiling, furthermore, revealed higher concentrations of several alkanes in the reduced pH-oil treatment, corroborating the functional implications of the structural changes to microbial community composition. Collectively, our results advance the understanding of the response of a complex microbial community to the interaction between reduced pH and anthropogenic pollution. In future acidified marine environments, oil hydrocarbon contamination may alter the typical mixotrophic and k-/r-strategist composition of surface sediment microbiomes towards a more heterotrophic state with lower doubling rates, thereby impairing the ability of the ecosystem to recover from acute oil contamination events.

Archaeal communities in the sediments of different mangrove stands at Dongzhaigang, China

Purpose Knowledge of archaeal communities is essential for understanding of the mechanism of carbon and nitrogen cycle in the mangrove sediment ecosystem. Presently, little is known about archaeal communities in the Dongzhaigang mangrove sediments. This study aimed to characterize the archaeal communities in sediments of different mangrove stands and to find out the correlations between archaeal communities and the environmental factors of sediments.

Temporal and Spatial Dynamics of Archaeal Communities in Two Freshwater Lakes at Different Trophic Status.

In either eutrophic Dianchi Lake or mesotrophic Erhai Lake, the abundance, diversity, and structure of archaeaplankton communities in spring were different from those in summer. In summer, archaeaplankton abundance generally decreased in Dianchi Lake but increased in Erhai Lake, while archaeaplankton diversity increased in both lakes. These two lakes had distinct archaeaplankton community structure. Archaeaplankton abundance was influenced by organic content, while trophic status determined archaeaplankton diversity and structure. Moreover, in summer, lake sediment archaeal abundance considerably decreased. Sediment archaeal abundance showed a remarkable spatial change in spring but only a slight one in summer. The evident spatial change of sediment archaeal diversity occurred in both seasons. In Dianchi Lake, sediment archaeal community structure in summer was remarkably different from that in spring. Compared to Erhai Lake, Dianchi Lake had relatively high sediment archaeal abundance but low diversity. These two lakes differed remarkably in sediment archaeal community structure. Trophic status determined sediment archaeal abundance, diversity and structure. Archaeal diversity in sediment was much higher than that in water. Water and sediment habitats differed greatly in archaeal community structure. Euryarchaeota predominated in water column, but showed much lower proportion in sediment. Bathyarchaeota was an important component of sediment archaeal community.

Vertical distribution of archaeal communities in cold seep sediments from the jiulong methane reef area in the south China sea

Jiulong methane reef, a large cold seep area on the continental slope of the South China Sea (SCS), was characterized by chemosynthetic fauna, bacterial mats, methane-derived carbonate structures, and a shallow depth of sulfate-methane transition zone (SMTZ) in gravity cores. To characterize the microbial diversity and variation in correlation to methane venting in the cold seep area, the archaeal community in sediments of the gravity Core CL11 was analyzed, using the Illumina MiSeq sequencing system. A total of 96,917 valid sequences were obtained and classified into 275 OTUs. Taxonomic analysis showed that all the archaeal sequences belonged to the phyla of Crenarchaeota (69.41%) and Eurarchaeota (25.26%). Vertical distribution of the archaeal communities showed that the Marine Benthic Group B (MBG-B) was the predominant group (58.92%) in the topmost sediment of the core, while percentages of the South African Gold Mine Euryarchaeotal Group (SAGMEG) sequences increased with depth. Our findings indicate that the archaeal community in the cold seep of Jiulong Methane Reef is unique and provides us new insights into the archaeal community composition of the cold seep area.

Differences in the Composition of Archaeal Communities in Sediments from Contrasting Zones of Lake Taihu

Differences in the Composition of Archaeal Communities in Sediments from Contrasting Zones of Lake Taihu

The Vertical Distribution of Sediment Archaeal Community in the "Black Bloom" Disturbing Zhushan Bay of Lake Taihu.

Using the Illumina sequencing technology, we investigated the vertical distribution of archaeal community in the sediment of Zhushan Bay of Lake Taihu, where the black bloom frequently occurred in summer. Overall, the Miscellaneous Crenarchaeotal Group (MCG), Deep Sea Hydrothermal Vent Group 6 (DHVEG-6), and Methanobacterium dominated the archaeal community. However, we observed significant difference in composition of archaeal community among different depths of the sediment. DHVEG-6 dominated in the surface layer (0–3 cm) sediment. Methanobacterium was the dominating archaeal taxa in the L2 (3–6 cm) and L3 (6–10) sediment. MCG was most abundant in the L4 (10–15 cm) and L5 (15–20 cm) sediment. Besides, DHVEG-6 was significantly affected by the concentration of total phosphorus (TP). And loss on ignition (LOI) was an important environmental factor for Methanobacterium. As the typical archaeal taxa in the surface layer sediment, DHVEG-6 and Methanobacterium might be more adapted to abundant substrate supply from cyanobacterial blooms and take active part in the biomass transformation. We propose that DHVEG-6 and Methanobacterium could be the key archaeal taxa correlated with the “black bloom” formation in Zhushan Bay.

The putative functional ecology and distribution of archaeal communities in sponges, sediment and seawater in a coral reef environment.

Archaea play crucial roles in a number of key ecological processes including nitrification and methanogenesis. Although several studies have been conducted on these organisms, the roles and dynamics of coral reef archaeal communities are still poorly understood, particularly in host and nonhost biotopes and in high (HMA) and low microbial abundance (LMA) sponges. Here, archaeal communities detected in six distinct biotopes, namely, sediment, seawater and four different sponge species Stylissa carteri, Stylissa massa, Xestospongia testudinaria and Hyrtios erectus from the Spermonde Archipelago, SW Sulawesi, Indonesia were investigated using 454-pyrosequencing of 16S rRNA genes (OTU cut-off 97%). Archaeal communities from sediment and sponges were dominated by Crenarchaeota, while the seawater community was dominated by Euryarchaeota. The biotope explained almost 75% of the variation in archaeal composition, with clear separation between microbial assemblages from sediment, X.testudinaria and H.erectus (HMA). In contrast, samples from seawater and both Stylissa species (LMA) showed considerable overlap in the ordination and, furthermore, shared most abundant OTUs with the exception of a single dominant OTU specifically enriched in both Stylissa species. Predicted functional gene content in archaeal assemblages also revealed significant differences among biotopes. Different ammonia assimilation strategies were exhibited by the archaeal communities: X.testudinaria, H.erectus and sediment archaeal communities were enriched for glutamate dehydrogenase with mixed specificity (NAD(P)(+) ) pathways, while archaeal planktonic communities were enriched for specific glutamate dehydrogenase (NADP(+) ) and glutamate synthase pathways. Archaeal communities in Stylissa had intermediate levels of enrichment. Our results indicate that archaeal communities in different biotopes have distinct ecophysiological roles.

Diversity and Distribution of Archaea in the Mangrove Sediment of Sundarbans.

Mangroves are among the most diverse and productive coastal ecosystems in the tropical and subtropical regions. Environmental conditions particular to this biome make mangroves hotspots for microbial diversity, and the resident microbial communities play essential roles in maintenance of the ecosystem. Recently, there has been increasing interest to understand the composition and contribution of microorganisms in mangroves. In the present study, we have analyzed the diversity and distribution of archaea in the tropical mangrove sediments of Sundarbans using 16S rRNA gene amplicon sequencing. The extraction of DNA from sediment samples and the direct application of 16S rRNA gene amplicon sequencing resulted in approximately 142 Mb of data from three distinct mangrove areas (Godkhali, Bonnie camp, and Dhulibhashani). The taxonomic analysis revealed the dominance of phyla Euryarchaeota and Thaumarchaeota (Marine Group I) within our dataset. The distribution of different archaeal taxa and respective statistical analysis (SIMPER, NMDS) revealed a clear community shift along the sampling stations. The sampling stations (Godkhali and Bonnie camp) with history of higher hydrocarbon/oil pollution showed different archaeal community pattern (dominated by haloarchaea) compared to station (Dhulibhashani) with nearly pristine environment (dominated by methanogens). It is indicated that sediment archaeal community patterns were influenced by environmental conditions.