RESUMO
Bacterial communities in drinking water provide a gauge to measure quality and confer insights into public health. In contrast to urban systems, water treatment in rural areas is not adequately monitored and could become a health risk. We performed 16S rRNA amplicon sequencing to analyze the microbiome present in the water treatment plants at two rural communities, one city, and the downstream water for human consumption in schools and reservoirs in the Andean highlands of Ecuador. We tested the effect of water treatment on the diversity and composition of bacterial communities. A set of physicochemical variables in the sampled water was evaluated and correlated with the structure of the observed bacterial communities. Predominant bacteria in the analyzed communities belonged to Proteobacteria and Actinobacteria. The Sphingobium genus, a chlorine resistance group, was particularly abundant. Of health concern in drinking water reservoirs were Fusobacteriaceae, Lachnospiraceae, and Ruminococcaceae; these families are associated with human and poultry fecal contamination. We propose the latter families as relevant biomarkers for establishing local standards for the monitoring of potable water systems in highlands of Ecuador. Our assessment of bacterial community composition in water systems in the Ecuadorian highlands provides a technical background to inform management decisions.
Assuntos
Água Potável , Humanos , Equador , RNA Ribossômico 16S/genética , Bactérias , Proteobactérias/genética , Microbiologia da ÁguaRESUMO
AIM: To analyse the physiological response of Sphingobium sp. 22B to water stress. METHODS AND RESULTS: The strain was grown under excess of carbon source and then subjected to low (60RH) and high (18RH) water stress conditions for 96 h. Quantification of trehalose, glycogen, polyhydroxybutyrate (PHB) and transmission electron microscopy (TEM) was studied. Genes linked with desiccation were searched in Sphingobium sp. 22B and Sphingomonas 'sensu latu' genomes and their transcripts were quantified by real-time PCR. Results showed that, in the absence of water stress, strain 22B accumulated 4·76 ± 1·41% of glycogen, 0·84 ± 1·62% of trehalose and 44·9 ± 6·4% of PHB per cellular dry weight. Glycogen and trehalose were mobilized under water stressed conditions, this mobilization was significantly higher in 60RH in comparison to 18RH. Gene treY was upregulated sixfold in 60RH relative to control condition. TEM and quantification of PHB revealed that PHB was mobilized under 60RH condition accompanied by the downregulation of the phbB gene. TEM images showed an extracellular amorphous matrix in 18RH and 60RH. Major differences were found in the presence of aqpZ and trehalose genes between strain 22B and Sphingomonas genomes. CONCLUSION: Strain 22B showed a carbon conservative metabolism capable of accumulation of three types of endogenous carbon sources. The strain responds to water stress by changing the expression pattern of genes related to desiccation, formation of an extracellular amorphous matrix and mobilization of the carbon sources according to the degree of water stress. Trehalose, glycogen and PHB may have multiple functions in different degrees of desiccation. The robust endowment of molecular responses to desiccation shown in Sphingobium sp. 22B could explain its survival in semi-arid soil. SIGNIFICANCE AND IMPACT OF THE STUDY: Understanding the physiology implicated in the toleration of the PAH-degrading strain Sphingobium sp 22B to environmental desiccation may improve the bioaugmentation technologies in semi-arid hydrocarbon-contaminated soils.
Assuntos
Adaptação Fisiológica/fisiologia , Viabilidade Microbiana , Sphingomonadaceae/fisiologia , Água/metabolismo , Argentina , Chile , Glicogênio/metabolismo , Umidade , Microbiologia do Solo , Sphingomonadaceae/genética , Sphingomonadaceae/metabolismo , Trealose/metabolismoRESUMO
Toxic compounds, such as 4-chlorophenol (4-CP), which is a common pollutant in wastewater, are removed efficiently from sequencing batch reactors (SBRs) by microorganisms. The bacterial community in aerobic granules formed during the removal of 4-CP in a SBR was monitored for 63days. The SBR reactor was operated with a constant filling and withdrawal time of 7 and 8min and decreasing settling time (30, 5, 3 and 2min) to induce the formation of aerobic granules. During the acclimation period lasting 15days (30min settling time) had a strong effect on the bacterial community. From day 18 onwards, Sphingobium and Comamonadaceae were detected. Rhizobiaceae were dominant from day 24 to day 28 when stable aerobic granules were formed. At day 35, fluffy granules were formed, but the bacterial community structure did not change, despite the changes in the reactor operation to inhibit filamentous bacteria growth. This is the first report on changes in the bacterial community structure of aerobic and fluffy granules during granulation process in a reactor fed with 4-CP and the prediction of its metabolic pathways.
Assuntos
Bactérias/metabolismo , Reatores Biológicos/microbiologia , Clorofenóis/química , Águas ResiduáriasRESUMO
The effect of bioaugmentation with Sphingobium sp. AM strain on different soils microbiomes, pristine soil (PS), chronically contaminated soil (IPK) and recently contaminated soil (Phe) and their implications in bioremediation efficiency was studied by focusing on the ecology that drives bacterial communities in response to inoculation. AM strain draft genome codifies genes for metabolism of aromatic and aliphatic hydrocarbons. In Phe, the inoculation improved the elimination of phenanthrene during the whole treatment, whereas in IPK no improvement of degradation of any PAH was observed. Through the pyrosequencing analysis, we observed that inoculation managed to increase the richness and diversity in both contaminated microbiomes, therefore, independently of PAH degradation improvement, we observed clues of inoculant establishment, suggesting it may use other resources to survive. On the other hand, the inoculation did not influence the bacterial community of PS. On both contaminated microbiomes, incubation conditions produced a sharp increase on Actinomycetales and Sphingomonadales orders, while inoculation caused a relative decline of Actinomycetales. Inoculation of most diverse microbiomes, PS and Phe, produced a coupled increase of Sphingomonadales, Burkholderiales and Rhizobiales orders, although it may exist a synergy between those genera; our results suggest that this would not be directly related to PAH degradation.
Assuntos
Actinomycetales/metabolismo , Burkholderiaceae/metabolismo , Poluição Ambiental/análise , Hidrocarbonetos Policíclicos Aromáticos/metabolismo , Rhizobiaceae/metabolismo , Poluentes do Solo/metabolismo , Sphingomonadaceae/metabolismo , Actinomycetales/crescimento & desenvolvimento , Sequência de Bases , Biodegradação Ambiental , Burkholderiaceae/crescimento & desenvolvimento , Genoma Bacteriano/genética , Microbiota , Fenantrenos/metabolismo , RNA Ribossômico 16S/genética , Rhizobiaceae/crescimento & desenvolvimento , Análise de Sequência de DNA , Solo , Microbiologia do Solo , Sphingomonadaceae/crescimento & desenvolvimentoRESUMO
Banana has been a main agricultural product in the French West Indies (Guadeloupe and Martinique) since the 1960s. This crop requires the intensive use of pesticides to prevent attacks by insect pests. Chlorinated pesticides, such as hexachlorocyclohexane (HCH), chlordecone and dieldrin, were used until the beginning of the 1990s, resulting in a generalized diffuse contamination of the soil and water in the areas of banana production, hence the need to develop solutions for cleanup of the polluted sites. The aims of this work were (i) to assess lindane degradation in soil slurry microcosms treated with lindane at 10 mg/L and (ii) to detect the catabolic genes involved in the HCH degradation pathway. The soil slurry microcosm system showed a 40% lindane degradation efficiency at the end of a 30-day experiment. Lower lindane removal was also detected in the abiotic controls, probably caused by pesticide adsorption to soil particles. Indeed, the lindane concentration decreased from 6000 to 1330 ng/mL and from 800 to 340 ng/mL for the biotic and abiotic soils, respectively. Nevertheless, some of the genes involved in the HCH degradation pathway were amplified by polymerase chain reaction (PCR) from crude deoxyribonucleic acid (DNA) extracted from the Guadeloupe agricultural soil, suggesting that HCH degradation is probably mediated by bacteria closely related to the family Sphingomonadaceae.