Structural and Functional Changes of Groundwater Bacterial Community During Temperature and pH Disturbances

Phycospheric bacteria limits the effect of nitrogen and phosphorus imbalance on diatom bloom

Human activities have caused an imbalance in the input nitrogen and phosphorus (N/P) in the biosphere. The imbalance of N/P is one of the characteristics of water eutrophication, which is the fundamental factor responsible for the blooms. The effects of the N/P imbalance on diatom and phycospheric bacteria in blooms are poorly understood. In this study, the N/P molar ratio in real water (14:1) and the predicted N/P molar ratio in future water (65:1) were simulated to analyze the response of Cyclotella sp. and phycospheric bacteria to the N/P imbalance. The results showed that the N/P imbalance inhibited the growth of Cyclotella sp., but prolonged diatom bloom duration. The resistance of Cyclotella sp. to the N/P imbalance is related to phycospheric bacteria, and there are dynamic regulatory mechanisms within the phycospheric bacteria community to resist the N/P imbalance: (1) the increase of HNA bacterial density, the decrease of LNA bacterial density, (2) the increase of phycospheric bacterial diversity and eutrophic bacteria abundance, and the change of denitrifying bacteria abundance, (3) the activity of nitrogen and phosphorus metabolism of HNA bacteria enhanced, while that of LNA bacteria decreased. And the gene hosts of nitrogen and phosphorus metabolism were most enriched in Proteobacteria, indicating that Proteobacteria played an important role in maintaining the stability of phycospheric bacteria and was the dominant phylum resistant to the N/P imbalance. This study clarified that the algal-bacteria system was resistant to the N/P imbalance and implied that the N/P imbalance had little effect on the occurrence of diatom bloom events due to the presence of phycospheric bacteria.

Low serum lipase levels in mothers of children with stunted growth indicate the possibility of low calcium absorption during pregnancy: A cross-sectional study in North Sumatra, Indonesia

Stunting is caused by various factors, including low nutritional intake in the first two years of life. This study aimed to investigate the differences in sociodemographic factors and mineral, vitamin, and enzyme parameters in mothers associated with the occurrence of stunting in children. We conducted a cross-sectional study from September to November 2020 on North Sumatra Island, Indonesia. The data collected included sociodemographic characteristics, pregnancy history, birth history, food intake, and laboratory examinations, including measurements of calcium, iron, zinc, vitamin D, pancreatic amylase, and serum lipase levels. This study included 50 healthy mothers aged 18-50 years old with children aged 2 to 60 months. There was a significant difference in serum calcium levels between the groups of mothers of children with normal and stunted growth (p = 0.03, mean difference±standard error (SE) = 0.23±0.12, 95% CI: 0.19-0.45). All of the study subjects were categorized as vitamin D deficient. The mean lipase level in the group of mothers of children with stunted growth was significantly lower than that in the group of mothers of children with normal growth (p = 0.02, mean difference±SE = 4.34±1.83, 95% CI: 0.62-8.06). The conclusion was that serum lipase levels were significantly lower in mothers of children with stunted growth compared to mothers of children with normal growth. Serum lipase levels this low are likely to indicate that a mother is unable to meet her child's calcium needs during pregnancy, increasing the child's risk of stunted growth.

Experimental research on the transport-transformation of organic contaminants under the influence of multi-field coupling at a site scale

Organic-contaminated shallow aquifers have become a global concern of groundwater contamination, yet little is known about the coupled effects of hydrodynamic-thermal-chemical-microbial (HTCM) multi-field on organic contaminant transport and transformation over a short time in aquifers. Therefore, this study proposed a quick and efficient field experimental method for the transport-transformation of contaminants under multi-field coupling to explore the relationship between organic contaminants (total petroleum hydrocarbon (TPH), polycyclic aromatic hydrocarbons (PAHs), benzene-toluene-ethylbenzene-xylene (BTEX) and phthalates acid esters (PAEs)) and multi-field factors. The results showed that hydrodynamics (affecting pH, p < 0.001) and temperature (affecting dissolved oxygen, pH and HCO3-, p < 0.05) mainly affected the organic contaminants indirectly by influencing the hydrochemistry to regulate redox conditions in the aquifer. The main degradation reactions of the petroleum hydrocarbons (TPH, PAHs and BTEX) and PAEs in the aquifer were sulfate reduction and nitrate reduction, respectively. Furthermore, the organic contamination was directly influenced by microbial communities, whose spatial patterns were shaped by the combined effects of the spatial pattern of hydrochemistry (induced by the organic contamination pressure) and other multi-field factors. Overall, our findings imply that the spatiotemporal patterns of organic contaminants are synergistically regulated by HTCM, with distinct mechanisms for petroleum hydrocarbons and PAEs.

Characteristics of microbial community structure and influencing factors of Yangcheng Lake and rivers entering Yangcheng Lake during the wet season

Yangcheng Lake, a typical fishery lake in the middle and lower reaches of the Yangtze River, is threatened by eutrophication. As the main performers of biogeochemical cycles, microorganisms affect the ecological stability of the lake. To study the structural characteristics of the microbial community in Yangcheng Lake and rivers entering Yangcheng Lake and the response relationship with environmental factors, the microbial community was categorized based on the contour of Yangcheng Lake, the major rivers entering Yangcheng Lake, and the pollution sources. The distribution characteristics of seven physicochemical indices were analyzed, including total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), water temperature (WT), pH, dissolved oxygen (DO), and ratio of total nitrogen to total phosphorus (TN/TP). Characterization of microbial community structure based on 16S rRNA high-flux sequencing technology and ANOSIM analysis were used to explore the differences in the relative abundance of microorganisms at each sampling point in the lake and rivers, and redundancy analysis (RDA) was used to analyze the relationship between the microbial community and physicochemical factors. The results showed that the dominant phyla, genera of microorganisms, and the total number of OTUs in the lake and rivers were similar. The dominant phyla included Proteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, and Verrucomicrobia; the dominant genera included the hgcI clade, CL500-29 marine group, Microcystis PCC-7914, Chloroplast_norank, Clade III_norank, and Flavobacterium. ANOSIM analyses revealed that the microbial community of Yangcheng Lake exhibited an association with geographical space, while the microbial community in the rivers that was linked to the type of pollution source. Redundancy analysis (RDA) indicated that dissolved oxygen (DO), total nitrogen (TN), and pH were significantly correlated with the dominant phyla in Yangcheng Lake (p < 0.05), while total nitrogen (TN), water temperature(WT), and the ratio of total nitrogen to total phosphorus (TN/TP) were significantly related with the dominant genera in Yangcheng Lake (p < 0.05). Total nitrogen (TN) was also significantly linked to the dominant phyla and genera of the tributaries (p < 0.05). Despite the structural similarities in microbial communities between Yangcheng Lake and its inflowing rivers, environmental factors demonstrated significant associations with these communities, providing crucial data support for pollution prevention and the ecological restoration of Yangcheng Lake.

Anthropogenic original DOM is a critical factor affecting LNA bacterial community assembly

We investigated the geographical and environmental distance-decay relationships for both of the two bacteria in the Haihe River, Tianjin, China. HNA bacteria exhibited a stronger geographical variation-dependent pattern while LNA bacteria exhibited a stronger environmental variation-dependent pattern. Variance partition analysis (VPA), Mantel test, and partial mantel test validated the discrepant impacts of geographical distance and environmental factors on their two communities. The heterogeneous selection dominated community assembly of LNA bacteria demonstrates their greater sensitivity to environmental conditions. As the deterministic environmental factor, anthropogenic original dissolved organic matter (DOM) functions exclusively on LNA bacteria, and it is the critical factor leading to the discrepant biogeographical patterns of LNA and HNA bacteria. LNA bacteria interact with HNA bacteria and mediate the DOM driving total bacteria assembly. The LNA keystone taxa, Pseudomonas, Rheinheimera, Candidatus Aquiluna, and hgcl clade are capable to compete with HNA bacteria for anthropogenic original DOM, and are potential indicators of anthropogenic pollution. Our research reveals the non-negligible effect of the LNA bacteria in regulating the ecological response of total bacteria.

Low and high nucleic acid content bacteria play discrepant roles in response to various carbon supply modes

Planktonic bacteria can be grouped into 'high nucleic acid content (HNA) bacteria' and 'low nucleic acid content (LNA) bacteria.' Nutrient input modes vary in environments, causing nutrient availability heterogeneity. We incubated them with equal amounts of total glucose added in a continuous/pulsed mode. The pulse-treated LNA bacteria exhibited twice the cell abundance and four times the viability of the continuous-treated LNA, while HNA did not show an adaptation to pulsed treatment. In structural equation modelling, LNA bacteria had higher path coefficients than HNA, between growth and carbon-saving metabolic pathways, intracellular ATP and the inorganic energy storage polymer, polyphosphate, indicating their low-cost growth, and flexible energy storage and utilisation. After incubation, the pulse-treated LNA bacteria contained more proteins and polysaccharides (0.00064, 0.0012 ng cell-1 ) than the continuous-treated LNA (0.00014, 0.00014 ng cell-1 ), conferring endurance and rapid response to pulses. Compared to LNA, HNA keystone taxa had stronger correlations with the primary glucose metabolism step, glycolysis, and occupied leading positions to explain the random forest model. They are essential to introduce glucose into the element cycling of the whole community under both treatments. Our work outlines a systematic bacterial response to carbon input.

Spatiotemporal dynamics of high and low nucleic acid-content bacterial communities in Chinese coastal seawater: assembly process, co-occurrence relationship and the ecological functions

Studies of high nucleic acid-content (HNA) and low nucleic acid-content (LNA) bacterial communities are updating our view of their distributions and taxonomic composition. However, there are still large gaps in our knowledge of the composition, assembly processes, co-occurrence relationships and ecological functions of HNA and LNA bacterial communities. Here, using 16S rRNA gene amplicon sequencing, we investigated the spatiotemporal dynamics, assembly processes, co-occurrence relationships and ecological functions of HNA and LNA bacterial communities in the samples collected in summer and winter in Chinese coastal seas. The communities of HNA and LNA bacteria had clear spatiotemporal patterns and LNA bacteria was phylogenetically less diverse than HNA bacteria in both seasons. The distribution of HNA and LNA bacteria were significantly affected by the environmental factors and a significant seasonal-consistent distance-decay patterns were found in HNA and LNA bacteria. Furthermore, a quantitative assessment of ecological processes revealed that dispersal limitation, homogeneous selection exerted important roles in the community assembly of HNA and LNA bacteria. More importantly, we observed seasonality in the co-occurrence relationships: closer inter-taxa connections of HNA bacterial communities in winter than in summer and the opposite is true in the LNA bacterial communities. Some ecological functions, such as: phototrophy, photoautotrophy, oxygenic photoautotrophy, were different between HNA and LNA bacteria. These results provide a better understanding of spatiotemporal patterns, processes, and the ecological functions of HNA and LNA bacterial communities in Chinese coastal seawater.

Potamogeton crispus restoration increased the epiphytic microbial diversity and improved water quality in a micro-polluted urban river

Special characterization and assembly of epiphytic microbial communities remain unclear in micro-polluted water column during submersed macrophytes restoration. In this study, an in-situ enclosure area sowing with turions of Potamogeton crispus (P. crispus) was conducted in a micro-polluted urban river to investigate the characterization of P. crispus and epiphytic microbial communities and their response to water environment under different water depths. Turions completely germinated in water column with <90 cm water depth and the germination speed decreased with increasing water depth within 18 days. There were obvious differences in morphological characteristics of P. crispus between deep and shallow water layers. P. crispus restoration decreased by 12-32%, 13-36%, 9-43% and 5-36% of COD, NH₄⁺-N, TN and TP concentration, respectively, in enclosed overlying water compared to the river (P < 0.05) during 5 months of experiment. Illumina sequencing was employed to explore the epiphytic bacterial and microeukayotic communities at water depth 25-35 cm (shallow area) and 80-90 cm (deep area). A total of 9 bacterial and 12 microeukayotic dominant phyla were obtained in eight samples. It should be noted that the algae abundances were higher in shallow area than deep area but a reverse trend was observed for methanotrophs. Null model analysis revealed that dispersal limitation and undominated process was the most important assembly process, whereas stochastic processes gained more importance in shallow area than deep one. According to cooccurrence analysis (|r| > 0.6, P < 0.05), there were more strongly correlated edges in shallow area (456 edges) than deep area (340 edges). These results highlight that submerged macrophytes restoration can increase microbial diversity and improve water quality, and provide a "summer disease cured in winter" way by using could-resistant P. crispus for water purification in micro-polluted rivers in low-temperature season.

Research on microbial community structure and treatment of dye wastewater with the enhancement of activated sludge by magnetic field at low temperature

This study characterized the effect of different magnetic field (MF) intensities (10-40 mT) on the degradation of dye wastewater by activated sludge and the diversity of the microbial community at a low temperature (5 °C). The examined MF range promoted the degradation of dye wastewater by the microorganisms in the activated sludge at a low temperature. It was found that the optimal degradation performance was achieved at 30 mT. Additionally, the maximum degradation efficiency of COD and chromaticity (66.30% and 60.87%, respectively) were also achieved at 30 mT and the peak TTC-dehydrogenase activity (TTC-DHA) was 9.44 mg TF g^-1 SS. Furthermore, it was revealed that MF enhancement increased the richness and diversity of activated sludge microorganisms, thus promoting the growth and reproduction of activated sludge microorganisms at low temperatures. Bacterial taxa known to effectively participate in the degradation of pollutants by activated sludge were enriched at 30 mT. The dominant bacteria under 30 mT were Flavobacterium, Hydrogenophaga, Gemmatimonadaceae, Zoogloea, Saprospiraceae, Pseudomonas, and Geothrix.

Elevated antimony concentration stimulates rare taxa of potential autotrophic bacteria in the Xikuangshan groundwater

Microbial communities composed of few abundant and many rare species are widely involved in the biogeochemical cycles of elements. Yet little is known about the ecological roles of rare taxa in antimony (Sb) contaminated groundwater. Groundwater samples were collected along an Sb concentration gradient in the Xikuangshan antimony mine area and subjected to high through-put sequencing of 16S rRNA genes to investigate the bacterial communities. Results suggested that both abundant and rare sub-communities were dominated by Betaproteobacteria, Gammaproteobacteria, and Alphaproteobacteria, whereas rare sub-communities showed higher alpha-diversities. Multivariate analysis showed that both the abundant and rare taxa were under the stress of Sb, but the impact on rare taxa was greater. Nitrate explained a large part for the variation of the abundant sub-communities, indicating the critical role of nitrate for their activities under anoxic conditions. In contrast, bicarbonate significantly impacted rare sub-communities, suggesting their potential autotrophic characteristics. To further explore the role of rare taxa in the communities and the mechanism of affecting the community composition, a network was constructed to display the co-occurrence pattern of bacterial communities. The rare taxa contributed most of the network nodes and served as keystone species to maintain the stability of community. Abiotic factors (mainly Sb and pH) and bacterial interspecific interactions (interactions between keystone species and other bacterial groups) jointly affect the community dynamics. Functional prediction was performed to further reveal the ecological function of rare taxa in the Sb-disturbed groundwater environment. The results indicated that the rare taxa harbored much more diverse functions than their abundant counterparts. Notably, elevated Sb concentration promoted some potential autotrophic functions in rare taxa such as the oxidation of S-, N-, and Fe(II)-compounds. These results offer new insights into the roles of rare species in elemental cycles in the Sb-impacted groundwater.

Characteristics, Biodiversity, and Cultivation Strategy of Low Nucleic Acid Content Bacteria

Low nucleic acid content (LNA) bacteria are ubiquitous and estimated to constitute 20%–90% of the total bacterial community in marine and freshwater environment. LNA bacteria with unique physiological characteristics, including small cell size and small genomes, can pass through 0.45-μm filtration. The researchers came up with different terminologies for low nucleic acid content bacteria based on different research backgrounds, such as: filterable bacteria, oligotrophic bacteria, and low-DNA bacteria. LNA bacteria have an extremely high level of genetic diversity and play an important role in material circulation in oligotrophic environment. However, the majority of LNA bacteria in the environment remain uncultivated. Thus, an important challenge now is to isolate more LNA bacteria from oligotrophic environments and gain insights into their unique metabolic mechanisms and ecological functions. Here, we reviewed LNA bacteria in aquatic environments, focusing on their characteristics, community structure and diversity, functions, and cultivation strategies. Exciting future prospects for LNA bacteria are also discussed.

The biogeochemical responses of hyporheic groundwater to the long-run managed aquifer recharge: Linking microbial communities to hydrochemistry and micropollutants

Interactions of surface water and groundwater (SW-GW) in hyporheic zones produce biogeochemical hotspots. However, response patterns of hyporheic groundwater to external influences remain unclear. In this study, three datasets (hydrochemistry, antibiotics, and microbiome) were collected over a hydrological year to explore the influence of a 12-year managed aquifer recharge (MAR) project. We observed that the long-term MAR practice elevated nutrient and antibiotic levels while reduced redox potential in hyporheic groundwater, and these impacts depended on decreasing SW-GW interaction intensity with aquifer depth. In contrast, the long-term MAR practice increased community dissimilarity of 30-m groundwater but had little impact on 50-m or 80-m groundwater. Moreover, hyporheic community assembly was dominated by dispersal limitation, and thereby co-varied hydrochemistry and antibiotics only attributed to small community variability. The long-term MAR practice decreased species-interaction intensity and changed the abundance of metabolic functions in hyporheic groundwater. Furthermore, predicted community functions involving carbon, nitrogen, sulfur, and manganese cycles for 30-m groundwater showed higher abundances than those for 50- and 80-m groundwater. Collectively, we showed that hyporheic groundwater was sensitive to the SW-GW interaction and human activities, with the interactions of hydrochemistry, contaminants, and microbiome linking to hyporheic groundwater quality and ecosystem functioning.

Potential threat of antibiotics resistance genes in bioleaching of heavy metals from sediment

Bioleaching is considered a promising technology for remediating heavy metals pollution in sediments. During bioleaching, the pressure from the metals bioleached is more likely to cause the spread of antibiotic resistance genes (ARGs). The changes in abundance of ARGs in two typical heavy metal bioleaching treatments using indigenous bacteria or functional bacteria agent were compared in this study. Results showed that both treatments successfully bioleached heavy metals, with a higher removal ratio of Cu with functional bacteria agent. The absolute abundances of most ARGs decreased by one log unit after bioleaching, particularly tetR (p = 0.02) and tetX (p = 0.04), and intI1 decreased from 10⁶ to 10⁴ copies/g. As for the relative abundance, ARGs in the non-agent treatment increased from 3.90 × 10^-4 to 1.67 × 10^-3 copies/16S rRNA gene copies (p = 0.01), and in the treatment with agent, it reached 6.65 × 10^-2 copies/16S rRNA gene copies, and intI1 relative abundance was maintained at 10^-3 copies/16S rRNA gene copies. The relative abundance of ARGs associated with efflux pump mechanism and ribosomal protection mechanism increased the most. The co-occurrence network indicated that Cu bioleached was the environmental factor determining the distribution of ARGs, Firmicutes might be the potential hosts of ARGs. Compared to bioleaching with indigenous bacteria, the addition of functional bacteria agent engendered a decrease in microbial alpha diversity and an increase in the amount of Cu bioleached, resulting in a higher relative abundance of ARGs. Heavy metal pollution can be effectively removed from sediments using the two bioleaching treatments, however, the risk of ARGs propagation posed by those procedures should be considered, especially the treatment with functional bacteria agents. In the future, an economical and efficient green technology that simultaneously reduces both the absolute abundance and relative abundance of ARGs should be developed.

When FLOW-FISH met FACS: Combining multiparametric, dynamic approaches for microbial single-cell research in the total environment

In environmental microbiology, the ability to assess, in a high-throughput way, single-cells within microbial communities is key to understand their heterogeneity. Fluorescence in situ hybridization (FISH) uses fluorescently labeled oligonucleotide probes to detect, identify, and quantify single cells of specific taxonomic groups. The combination of Flow Cytometry (FLOW) with FISH (FLOW-FISH) enables high-throughput quantification of complex whole cell populations, which when associated with fluorescence-activated cell sorting (FACS) enables sorting of target microorganisms. These sorted cells may be investigated in many ways, for instance opening new avenues for cytomics at a single-cell scale. In this review, an overview of FISH and FLOW methodologies is provided, addressing conventional methods, signal amplification approaches, common fluorophores for cell physiology parameters evaluation, and model variation techniques as well. The coupling of FLOW-FISH-FACS is explored in the context of different downstream applications of sorted cells. Current and emerging applications in environmental microbiology to outline the interactions and processes of complex microbial communities within soil, water, animal microbiota, polymicrobial biofilms, and food samples, are described.

Comparison of planktonic bacterial communities indoor and outdoor of aquaculture greenhouses

AIMS

Greenhouses are widely used in agriculture systems to shield crops from unfavourable weather to achieve a year-round food supply. In recent years, aquaculture ponds have been placed in greenhouses in many regions. The impacts of the greenhouses on planktonic bacterial communities should be uncovered.

METHODS AND RESULTS

In this study, two polyolefin film greenhouses accommodating aquaculture ponds were established and planktonic bacterial communities were compared from samples taken in aquaculture ponds inside and outside the greenhouses, using Illumina 16S rRNA sequencing.

CONCLUSIONS

The results showed there were significant variations in bacterial community structure between indoor and outdoor samples. Obvious differences were also found between two greenhouses, whereas the differences in indoor samples were weaker than outdoor samples. Significantly higher temperature (in summer), pH and permanganate index were found in the outdoor pond samples. Results of redundancy analysis showed that Proteobacteria and Bacteroidota were positively related to the dissolved oxygen, total nitrogen and total phosphorus, and Actinobacteriota were positively related to pH, temperature and permanganate index, whereas Cyanobacteria were positively related to the salinity, conductivity, total dissolved solids and ammonia nitrogen.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results of this study revealed that greenhouses significantly influenced planktonic bacterial communities in aquaculture ponds. This study is expected to provide a scientific basis for aquaculture in greenhouses.

Survivability of Alcaligenaceae and Chromatiaceae as palm oil mill effluent pollution bioindicators under fluctuations of temperature, pH and total suspended solid

Alcaligenaceae and Chromatiaceae were previously reported as the specific pollution bioindicators in the receiving river water contaminated by palm oil mill effluent (POME) final discharge. Considering the inevitable sensitivity of bacteria under environmental stresses, it is crucial to assess the survivability of both bacteria in the fluctuated environmental factors, proving their credibility as POME pollution bioindicators in the environment. In this study, the survivability of Alcaligenaceae and Chromatiaceae from facultative pond, algae (aerobic) pond and final discharge were evaluated under varying sets of temperature (25-40°C), pH (pH 7-9) and low/high total suspended solid (TSS) contents of POME collected during low/high crop seasons of oil palm, respectively. Following treatment, the viability status and compositions of the bacterial community were assessed using flow cytometry-based assay and high-throughput Illumina MiSeq, respectively, in correlation with the changes of physicochemical properties. The changes in temperature, pH and TSS indeed changed the physicochemical properties of POME. The functionality of bacterial cells was also shifted where the viable cells and high nucleic acid contents reduced at elevated levels of temperature and pH but increased at high TSS content. Interestingly, the Alcaligenaceae and Chromatiaceae continuously detected in the samples which accounted for more than 0.5% of relative abundance, with a positive correlation with biological oxygen demand (BOD₅) concentration. Therefore, either Alcaligenaceae or Chromatiaceae or both could be regarded as the reliable and specific bacterial indicators to indicate the pollution in river water due to POME final discharge despite the fluctuations in temperature, pH and TSS.

Physiological Profiling and Functional Diversity of Groundwater Microbial Communities in a Municipal Solid Waste Landfill Area

The disposal of municipal solid wastes in landfills represents a major threat for aquifer environments at the global scale. The aim of this study was to explore how groundwater geochemical characteristics can influence the microbial community functioning and the potential degradation patterns of selected organic substrates in response to different levels of landfill-induced alterations. Groundwaters collected from a landfill area were monitored by assessing major physical-chemical parameters and the microbiological contamination levels (total coliforms and fecal indicators—Colilert-18). The aquatic microbial community was further characterized by flow cytometry and Biolog EcoPlatesTM assay. Three groundwater conditions (i.e., pristine, mixed, and altered) were identified according to their distinct geochemical profiles. The altered groundwaters showed relatively higher values of organic matter concentration and total cell counts, along with the presence of fecal indicator bacteria, in comparison to samples from pristine and mixed conditions. The kinetic profiles of the Biolog substrate degradation showed that the microbial community thriving in altered conditions was relatively more efficient in metabolizing a larger number of organic substrates, including those with complex molecular structures. We concluded that the assessment of physiological profiling and functional diversity at the microbial community level could represent a supportive tool to understand the potential consequences of the organic contamination of impacted aquifers, thus complementing the current strategies for groundwater management.