Community Composition In Water Research Articles

Characterization of Microplastic Surface Bacterial Community Structure and Prediction of Ecological Risk in Poyang Lake, China

In recent years, the environmental pollution of microplastics in Poyang Lake has received increasing attention. Baisha Lake of Poyang Lake was selected as the study area, and samples of water and sediments of Baisha Lake and the microplastics therein were collected, and the polymer types of microplastics were identified as polyethylene (PE), polyester (PET), polypropylene (PP), and polystyrene (PS) using Fourier infrared spectroscopy. We also analyzed the structural composition of bacterial communities in water, in sediments, and on microplastic surfaces using 16S high-throughput sequencing. The species richness and diversity of bacteria on the microplastic surfaces were lower than those in the surrounding water and sediments. The results of NMDS analysis showed that the bacterial community structures on the microplastic surfaces differed greatly from those in the surrounding sediments and water. The bacterial community composition in water and sediment differed from that on the microplastic surfaces, and the dominant bacterial phyla on the microplastic surfaces were Proteobacteria and Bacteroidota, and their relative abundance on the microplastic surfaces was higher than that in sediment. The relative abundance of Proteobacteria was higher than that in water. The relative abundances of Bacteroidota and Actinobacteriota were significantly lower than that of water. Massilia and Pseudomonas were the dominant genera on the microplastic surfaces, and their relative abundances were significantly higher than those in the surrounding water and sediments. BugBase phenotype prediction revealed that the relative abundance of contains mobile elements, biofilm formation, potential pathogenicity, and stress tolerance phenotypes of microplastic bacterial communities were significantly higher than those of the surrounding water and sediments. The results revealed that microplastics may have contributed to the spread of harmful bacteria, including pathogenic bacteria, and increased the potential pathogenicity of bacterial communities. Additionally, microplastic surface bacterial communities had higher phenotypes of mobile gene element content. Revealing the potential harm of microplastic pollution to wetland ecology at the micro level may provide a scientific reference for maintaining the ecological stability of wetlands.

The Effect of Artificial Substrate and Carbon Source Addition on Bacterial Diversity and Community Composition in Water in a Pond Polyculture System

The use of artificial substrates and biofloc technology can favor fish culture and improve water quality. The aim of this study was to evaluate whether artificial substrates and carbon source additions modify the microbial activity of water bodies. The diversity and structure of microflora in the water after adding artificial substrates and carbon sources to the ponds were analyzed using high-throughput sequencing based on the V3-V4 region of 16S rRNA genes. The results showed that there was no difference in the richness and diversity of intestinal microflora between the control and experimental groups. Principal coordinate analysis (PCoA) and nonmetric multidimensional scaling (NMDS) showed that artificial substrate and carbon source addition changed the structure of the microflora. The results of a linear discriminant analysis (LDA) effect size (LefSe) indicated 11 biomarkers in the EGˍst group. Spearman correlation heatmap analysis showed that environmental factors affected the bacterial communities, and the results of a redundancy analysis indicated that chemical oxygen demand was a critical factor in controlling the bacterial communities in the water. These results provide an understanding of the effect of artificial substrate and carbon source addition on bacterial diversity and community composition in water.

Microbial community dynamics and assembly mechanisms across different stages of cyanobacterial bloom in a large freshwater lake

Cyanobacterial bloom caused by eutrophication in lakes has become one of the significant environmental problems worldwide. However, a notable research gap persists in understanding the environmental adaptation and community assembly of microbial dynamics in response to different blooming stages. Therefore, metagenomic sequencing was employed in this study to investigate alterations in the microbial community composition in water and sediment during different stages of cyanobacterial blooms in Lake Taihu. The results indicated significant spatiotemporal variations in physicochemical parameters across the early, medium, and late stages of a complete cyanobacteria bloom cycle. Diversity analysis further revealed that the temporal differences in the microbial community were substantially greater than spatial variations. Notably, during the medium-blooming stages in water, Microcystis emerged as the predominant detected cyanobacteria genus. Interestingly, the content of superoxide dismutase (SOD), malondialdehyde (MDA), and catalase (CAT) in sediment exceeded those in water by over 10 times, indicating that sediment-dwelling Cyanobacteria might constitute a crucial source of water blooms. Moreover, dissolved oxygen, pH, and water temperature were identified as the most influential environmental variables shaping the microbial community in the water. Stochasticity emerged as a prominent factor governing microbial community assembly across different bloom periods. Meanwhile, co-occurrence patterns suggested fewer interactions and instability between species in medium-blooming stages. Notably, the potential keystone phyla occupied crucial ecological niches. This research carries significant theoretical implications for managing cyanobacterial blooms in freshwater ecosystems.

Wastewater treatment effectiveness is facilitated by crucial bacterial communities in the wetland ecosystem.

Microorganisms play essential roles in nutrient removal and biogeochemical cycling during wastewater treatment. However, little is known about the main roles of key functional bacterial communities in wastewater treatment processes. We collected 18 water samples and 15 sediment samples from the six operational subsystems of the constructed wetland, among which the contact oxidation pond, enhanced hybrid biofilm reactor, and central stabilization pond are the main wastewater treatment units in the constructed wetland, and then investigated the bacterial communities using 16S rRNA gene targeting and sequencing to address this knowledge gap. The results indicated that the composition of the bacterial community is closely related to the efficiency of pollutant removal. The abundant carbon metabolism function increased the removal of nitrate‑nitrogen (NO3--N) and total nitrogen (TN) by the contact oxidation pond by 89.84 % and 38.91 %, respectively. The overlap of ecological niches and the presence of pathogenic bacteria substantially affect effluent wastewater treatment. Second, NO3--N (p < 0.001) was the most important factor driving the bacterial community composition in water and sediments. Furthermore, the positive structure was prevalent in the cooccurrence network of water samples (87.24 %) and sediments (76.53 %) of the wetland, and this positive structure with keystone species was critical for the adaptation of the bacterial community to environmental filtration. In summary, this study reveals the distribution patterns of bacterial communities in different wastewater treatment processes and their driving factors and provides new perspectives on the link between the bacterial community composition and wastewater treatment.

Microcosm experiment to test bacterial responses to perfluorooctanoate exposure

The impact of perfluoroalkyl and polyfluoroalkyl substances on microbial communities is challenging to investigate in situ because of the complexity and dynamics of natural ecosystems. In the present study, four microcosms were established to explore the impact of perfluorooctanoate (PFOA) on bacterial communities in riverine and marine settings. PFOA distribution between the aqueous and sedimentary phases fluctuated in both PFOA-amended and unamended control systems. PFOA was more rapidly partitioned into the sediment in marine than in riverine microcosms. Differences in iron concentration and salinity may influence PFOA exchange between water and sediment. In marine microcosms, the alpha diversity of bacterial communities was significantly correlated to PFOA concentration. PFOA tended to correlate more strongly with bacterial community composition in water than in sediment. At the whole system level, Lefse's analysis indicated Algoriphagus halophilus as biomarkers for PFOA exposure in both riverine and marine systems, and the family Flavobacteriaceae were also more abundant in the exposed systems. In terms of temporal variation (comparison between three time points in the systems), metastat analysis showed great variability of potential PFOA-sensitive bacteria at the genus level. As such, most PFOA-sensitive genera were transitory and variable and existed for a short term in different systems (river, sea, blank, and experiment) and phases. Compared with other PFOA-sensitive genera, we suggest that further research is carried out to explore the use of Limnobacter as a bioindicator for temporal monitoring of PFOA pollution.

Bacterial diversity and community composition in lake water and sediment of Lake Daihai

采用高通量测序技术，研究了内蒙古岱海流域入湖河流、湖水及沉积物细菌多样性及群落组成.结果显示，细菌多样性从高到低依次为：沉积物>河流>湖泊.聚类分析表明入湖河流、湖水和沉积物细菌群落可分为明显不同的3支，说明这3种生境中细菌群落结构有较大差异.物种注释结果表明，河流中优势细菌菌群为髌骨细菌（Patescibacteria）、变形菌门（Proteobacteria）、拟杆菌门（Bacteroidetes）和放线菌门（Actinobacteria）；湖水中优势细菌菌群为放线菌门（Actinobacteria）；而沉积物中优势细菌菌群为变形菌门和绿弯菌门（Chloroflexi）.典范对应分析及Monte Carlo检验表明，电导率和悬浮物含量对水体中（河流与湖泊）细菌群落影响显著，二者共解释了细菌群落变化的86.5%；而冗余分析及Monte Carlo检验表明，泥深、磁化率和总有机碳对沉积物中细菌群落影响显著，三者共解释了细菌群落变化的47.9%.近30年来，岱海地区气候变化和人类活动导致湖水咸化，沉积物碳氮指标显著增长.岱海水体及沉积物细菌多样性及群落组成的差异及其主要驱动因子，反映了细菌对这种气候变化和人类活动共同作用的响应.;Bacterial diversity and community composition was investigated in the Lake Daihai Basin, Inner Mongolia using high-throughput sequencing technology. The results showed that bacterial diversity was highest in sediments, followed by river and lake water. Cluster analysis showed that bacterial community compositions in the inflowing river, lake water and sediments were separated into three distinct groups, indicating great differences in bacterial community compositions among the three habitats. Taxonomic annotation showed that the dominant bacterial flora in the river was Patescibacteria, Proteobacteria, Bacteroidetes and Actinobacteria. Actinobacteria was the most dominant bacteria phylum in the lake water, while the dominant bacterial flora in sediments were Proteobacteria and Chloroflexi. Canonical correspondence analysis and Monte Carlo permutation test revealed that the variations of bacterial community compositions in the river and lake were significantly explained by conductivity and suspended solids, which explained 86.5% of the variation. Redundant analysis and Monte Carlo permutation test revealed that the variations of bacterial community compositions in sediment were significantly explained by depth, magnetic susceptibility and total organic carbon, which explained 47.9% of the variation in total. During the past 30 years, Lake Daihai has experienced salinization in lake water and a remarkable increase of carbon and nitrogen in the sediment due to climate change and anthropogenic activities. The variations of bacterial diversity and community composition in the water and sediments, as well as their main driving environmental factors, highlight the responses of bacteria to the combined effects of climate change and anthropogenic activities on Lake Daihai.

Contrasting Analysis of Microbial Community Composition in the Water and Sediments of the North Canal Based on 16S rRNA High-Throughput Sequencing

As the bridge of pollutant exchange between sediments and aquatic ecosystems, microorganisms play an important role in material circulation. However, there are few comparative studies of microorganisms in water and sediment of urban rivers with unconventional water supply, sluice dam, and lining closure. The highly artificial area of Beijing-Tianjin-Hebei section of the North Canal was chosen for this study. We analyze the differences of microbial community composition in water and sediment using high-throughput sequencing. The results show that the microbial communities in the sediments of the North Canal have higher α-diversity than those in the water. With regards to β-diversity, the similarity of microbial communities in the water is higher than that in the sediment. There is no significant difference in the abundance of Proteobacteria between water and sediments. The abundance of α-Proteobacteria, Actinobacteria, Cyanobacteria, and Verrucomicrobia was higher in water than that of sediment, while the abundance of γ-Proteobacteria, δ-Proteobacteria, Chloroflexi, Firmicutes, and Acidobacteria was higher in sediments than that of water. Aerobic or facultative anaerobes dominated the microbial aquatic system, while anaerobes dominated the sediments. The risk of bacteria releasing pathogens from the sediment into the water habitat is high. The research results provide a scientific basis for revealing the mechanism of microbial community change under river pollution risk in highly artificial reclaimed water.

Response of sediment and water microbial communities to submerged vegetations restoration in a shallow eutrophic lake

Submerged macrophytes are the main primary producers in shallow lakes and play an important role in structuring communities. Aquatic microbes are also an important component of aquatic ecosystems and play important roles in maintaining the health and stability of ecosystems. However, little is known about the interactions between macrophytes and microbes during the reintroduction of submerged vegetation. Here, we chose restored zones dominated by four different submerged vegetations and a bare zone in a shallow eutrophic lake to unveil the microbial diversity, composition and structure changes in sediment and water samples after submerged macrophytes were recovered for one and a half years (July 2019) and two years (April 2020). We found that the recovery of submerged vegetations decreased phosphorus content in water and sediments but increased nitrogen and carbon content in sediments. We observed that the transparency of water in the restored zones was significantly higher than that in the bare zone in July. The recovery of submerged vegetations significantly influenced the alpha diversity of bacterial communities in sediments, with higher values observed in restored zones than in bare zones, whereas no significant influence was found in the water samples. In July, the macrophyte species showed strong effects on the bacterial community composition in water and relatively little effect in sediment. However, a strong effect of the macrophyte species on the composition of bacterial communities in sediments was observed in April, which may be related to the decomposition of plant litter and the decay of detritus. Additionally, the dissimilarity of the sedimentary bacterial community may increase more slowly with environmental changes than the planktonic bacterial community dissimilarity. These results suggest that the large-scale restoration of aquatic macrophytes can not only improve water quality and change sediment characteristics but can also affect the diversity and compositions of bacterial communities, and these effects seem to be very long-lasting.

Influence of pipe materials on the microbial community in unchlorinated drinking water and biofilm

Biodegradable compounds can cause undesired microbial growth in drinking water systems and these compounds can originate from the water or pipe materials used in drinking water systems. The aim of our study was to determine the influence of different pipe materials on the microbial populations in water and biofilm under semi-stagnant conditions. The microbial communities in biofilm and water, which were in contact with seven different materials, were characterized by determining ATP concentrations, microbial composition gene copy numbers of some specific microbial groups. The ATP concentration in water and biofilm varied between the different materials with glass (negative control) < copper < PVCC < PE-Xc < PE-Xb < PE-100 < PVC-P. Gene copy numbers of Legionella spp., Mycobacterium spp., Pseudomonas spp., Aeromonas spp., fungi and Vermamoeba vermiformis were also higher for PVC-P and PE than for glass, copper and PVCC. The bacterial community composition in water and biofilm varied between materials as well. PERMANOVA and CAP analysis demonstrated that copper and PVC-P are different when compared to the other materials. Furthermore, bacterial community composition and ATP concentrations in water and biofilm were similar after eight and 16 weeks incubation, but differed from results obtained after one week. Finally, the ATP, the specific microbial groups and the bacterial community composition also differed between water and biofilm on each material. We conclude from our study that pipe material is an important factor that influences the biomass concentration, abundance of specific microorganisms and the bacterial community composition in distribution systems with unchlorinated drinking water.

Bacterial Diversity in a Dynamic and Extreme Sub-Arctic Watercourse (Pasvik River, Norwegian Arctic)

Microbial communities promptly respond to the environmental perturbations, especially in the Arctic and sub-Arctic systems that are highly impacted by climate change, and fluctuations in the diversity level of microbial assemblages could give insights on their expected response. 16S rRNA gene amplicon sequencing was applied to describe the bacterial community composition in water and sediment through the sub-Arctic Pasvik River. Our results showed that river water and sediment harbored distinct communities in terms of diversity and composition at genus level. The distribution of the bacterial communities was mainly affected by both salinity and temperature in sediment samples, and by oxygen in water samples. Glacial meltwaters and runoff waters from melting ice probably influenced the composition of the bacterial community at upper and middle river sites. Interestingly, marine-derived bacteria consistently accounted for a small proportion of the total sequences and were also more prominent in the inner part of the river. Results evidenced that particular conditions occurring at sampling sites (such as algal blooms, heavy metal contamination and anaerobiosis) may select species at local scale from a shared bacterial pool, thus favoring certain bacterial taxa. Conversely, the few phylotypes specifically detected in some sites are probably due to localized external inputs introducing allochthonous microbial groups.

Bacterial community rather than metals shaping metal resistance genes in water, sediment and biofilm in lakes from arid northwestern China

Lakes in arid northwestern China are valuable freshwater resources that drive socioeconomic development. Environmental pollution can significantly influence the composition of microbial communities and the distribution of functional genes in lakes. This study investigated heavy metal pollution to identify possible correlations with metal resistance genes (MRGs) and bacterial community composition in water, sediment and biofilm samples from Bosten Lake and Ebi Lake in northwestern China. High levels of zinc were detected in all samples. However, the metals detected in the sediment samples of both lakes were determined to be at low risk levels according to an ecological index. The mercury resistance gene subtype merP had the greatest average abundance (4.61 × 10−3 copies per 16S rRNA) among all the samples, followed by merA and merC. The high abundance of merA in the pelagic zone rather than in benthic sediment suggests that the pelagic microbial community was important in mercury reduction. Proteobacteria were the main phylum found in the microbial communities in all samples. However, microbial communities in most of the water, sediment and biofilm samples had different compositions, indicating that the habitat niche plays an important role in shaping the bacterial communities in lakes. The microbial community, rather than the heavy metals, was the main driver of MRG distribution. The abundances of some bacterial genera involved in the decomposition of organic matter and the terrestrial nitrogen cycle were negatively correlated with heavy metals. This result suggests that metal pollution can adversely affect the biogeochemical processes that occur in lakes.

Characterization of the bacterial community composition in water of drinking water production and distribution systems in Flanders, Belgium.

The quality of drinking water is influenced by its chemical and microbial composition which in turn may be affected by the source water and the different processes applied in drinking water purification systems. In this study, we investigated the bacterial diversity in different water samples from the production and distribution chain of thirteen drinking water production and distribution systems from Flanders (Belgium) that use surface water or groundwater as source water. Water samples were collected over two seasons from the source water, the processed drinking water within the production facility and out of the tap in houses along its distribution network. 454‐pyrosequencing of 16S ribosomal RNA gene sequences revealed a total of 1,570 species‐level bacterial operational taxonomic units. Strong differences in community composition were found between processed drinking water samples originating from companies that use surface water and other that use groundwater as source water. Proteobacteria was the most abundant phylum in all samples. Yet, several phyla including Actinobacteria were significantly more abundant in surface water while Cyanobacteria were more abundant in surface water and processed water originating from surface water. Gallionella, Acinetobacter, and Pseudomonas were the three most abundant genera detected. Members of the Acinetobacter genus were even found at a relative read abundance of up to 47.5% in processed water samples, indicating a general occurrence of Acinetobacter in drinking water (systems).

Clay Flocculation Effect on Microbial Community Composition in Water and Sediment

Clay-based flocculation techniques have been developed to mitigate harmful algal blooms; however, the potential ecological impacts on the microbial community are poorly understood. In this study, chemical measurements were combined with 16S rRNA sequencing to characterize the microbial community response to different flocculation techniques, including controls, clay flocculation, clay flocculation with zeolite, and clay flocculation with O2 added zeolite capping. Sediment bacterial biomass measured by PLFA were not significantly altered by the various flocculation techniques used. However, 16S rRNA sequencing revealed differences in water microbial community structure between treatments with and without zeolite capping. The differences were related to significant reductions of total nitrogen (TN), total phosphorus (TP) and ammonia (NH4+) concentration and increase of nitrate (NO3-) concentration in zeolite and O2 loaded zeolite capping. The relative abundance of ammonia oxidizing bacteria increased fourfold in zeolite capping microcosms, suggesting zeolite promoted absorbed ammonia removal in the benthic zone. Zeolite-capping promoted bacteria nitrogen cycling activities at the water-sediment interface. Potential pathogens that are usually adapted to eutrophic water bodies were reduced after clay flocculation. This study demonstrated clay flocculation did not decrease bacterial populations overall and may reduce regulatory indicators and pathogenic contaminants in water. Zeolite capping may also help prevent nutrients from being released back into the water thus preventing additional algal blooms.

Variation of bacterial communities in water and sediments during the decomposition of Microcystis biomass.

The bacterial community composition in water and sediment samples during the decomposition of Microcystis biomass were analyzed using the 454 pyrosequencing technique. We found dramatic shifts in the bacterial community composition of water and sediments after the addition of Microcystis biomass. Among all the detected phyla, only Firmicutes was found to be dominant in both water and sediment samples. The genus Clostridium sensu stricto was the absolutely dominant group in Firmicutes and showed drastic variations with incubation time during the decomposition process. Peak values in relative abundance of Clostridium sensu stricto appeared in the first few days for water and sediment samples. Environmental factors such as pH, dissolved oxygen (DO), and dissolved organic carbon (DOC) in water samples showed drastic variations during the decomposing process, which might be the prominent forces driving the variation of bacterial communities. The abundant genus, Clostridium sensu stricto, were thought to be well adapted to higher DOC and turbidity and lower pH and DO conditions. Compared with the sediment samples, the decomposition of Microcystis biomass had greater influence on the bacterial community composition in water and Clostridium sensu stricto might play important roles in the process of Microcystis biomass decomposition.

RAS and microbial maturation as tools for K-selection of microbial communities improve survival in cod larvae

Abstract A high share of opportunistic and fast-growing microbes is generally negative for the performance of marine fish larvae. It is hypothesised that larvae that are reared in water dominated by K-strategists (mature microbial communities) will perform better, because they are less likely to encounter opportunistic (r-selected) microbes and develop detrimental host–microbe interactions. K-selection can be set up by securing competition for resources by maintaining a low nutrient supply per microbe in a maturing biofilter in a flow through system or in a recirculation system without disinfection. In an experiment with Atlantic cod larvae (Gadus morhua L.) the development of the microbial community in the inflowing water to tanks as well as in the tank water was studied in a conventional flow through system (FTS) and two hypothesised K-selective systems: a microbially matured flow through system (MMS) and a recirculation aquaculture system (RAS). As predicted, the K-selective treatments resulted in a significantly more mature and stable microbial community composition in the water going in to the fish tanks compared to the FTS. The larvae in the K-selective treatments showed 72% higher survival than the larvae in the FTS. In K-selective systems where the inflowing water to the fish tanks is matured at a microbial carrying capacity that is significantly lower than the carrying capacity in the rearing tank (i.e. MMS) there is hypothetically an opening for proliferation of opportunists to match the higher carrying capacity in the tank water. As predicted, the RAS showed K-selection of the incoming water at a carrying capacity similar to that of the tank water, which resulted in a significantly more stable microbial community composition in the tank water of the RAS than in the MMS and FTS. The results of this experiment showed a high potential for increasing fish survival by using K-selection of bacteria, which is a cheap and easy method that can be used in all kinds of new or existing aquaculture systems.

Characterization of bacterial community composition in rotifer cultures under unexpected growth suppression

Unexpected growth suppression is common in rotifer mass culturing, and bacteria present in culture tanks are believed to be one of the main causes. We used a polymerase chain reaction (PCR)-amplified 16S ribosomal RNA (rRNA) gene finger-printing method to determine the bacterial community composition in water and that in association with rotifers present in tanks when rotifer growth was suppressed. Bacterial 16S rRNA genes representing Nautella sp. and Marinomonas sp. were identified as dominant in control tanks with good rotifer growth. In contrast, the bacterial community composition was more diverse at start-up in tanks where rotifer growth was suppressed. The community composition changed during rotifer cultivation, and bacterial sequences representative of Ruegeria sp. and Hyphomonas sp. were dominant when rotifer growth recovered. These findings indicate that the bacterial community composition varied according to the rotifer growth conditions and suggest that the initial microbial flora present in the culture water may cause rotifer growth suppression.