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1.
J Environ Manage ; 301: 113802, 2021 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-34638039

RESUMO

The ability to detect human fecal pollution in water is of great importance when assessing the associated health risks. Many microbial source tracking (MST) markers have been proposed to determine the origin of fecal pollution, but their application remains challenging. A range of factors, not yet sufficiently analyzed, may affect MST markers in the environment, such as dilution and inactivation processes. In this work, a statistical framework based on Monte Carlo simulations and non-linear regression was used to develop a classification procedure for use in MST studies. The predictive model tested uses only two parameters: somatic coliphages (SOMCPH), as an index of general fecal pollution, and human host-specific bacteriophages that infect Bacteroides thetaiotaomicron strain GA17 (GA17PH). Taking into account bacteriophage dilution and differential inactivation, the threshold concentration of SOMCPH was calculated to be around 500 PFU/100 mL for a limit of detection of 10 PFU/100 mL. However, this threshold can be lowered by increasing the analyzed volume sample, which in turn lowers the limit of detection. The resulting model is sufficiently accurate for application in practical cases involving MST and could be easily used with markers other than those tested here.

2.
Water Res ; 203: 117543, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34433109

RESUMO

According to the European Directives (UE) 2020/2184 and 2009/54/EC, which establishes the sanitary criteria for water intended for human consumption in Europe, water suitable for human consumption must be free of the bacterial indicators Escherichia coli, Clostridium perfringens and Enterococcus spp. Drinking water is also monitored for heterotrophic bacteria, which are not a human health risk, but can serve as an index of bacteriological water quality. Therefore, a rapid, accurate, and cost-effective method for the identification of these colonies would improve our understanding of the culturable bacteria of drinking water and facilitate the task of water management by treatment facilities. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is potentially such a method, although most of the currently available mass spectral libraries have been developed in a clinical setting and have limited environmental applicability. In this work, a MALDI-TOF MS drinking water library (DWL) was defined and developed by targeting bacteria present in water intended for human consumption. This database, made up of 319 different bacterial strains, can contribute to the routine microbiological control of either treated drinking water or mineral bottled water carried out by water treatment and distribution operators, offering a faster identification rate compared to a clinical sample-based library. The DWL, made up of 96 bacterial genera, 44 of which are not represented in the MALDI-TOF MS bacterial Bruker Daltonics (BDAL) database, was found to significantly improve the identification of bacteria present in drinking water.


Assuntos
Água Potável , Purificação da Água , Bactérias , Bases de Dados Factuais , Humanos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
3.
Sci Total Environ ; 789: 147828, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34052479

RESUMO

Bathing water quality may be negatively impacted by diffuse pollution arising from urban and agricultural activities and wildlife, it is therefore important to be able to differentiate between biological and geographical sources of faecal pollution. crAssphage was recently described as a novel human-associated microbial source tracking marker. This study aimed to evaluate the performance of the crAssphage marker in designated bathing waters. The sensitivity and specificity of the crAss_2 marker was evaluated using faecal samples from herring gulls, dogs, sewage and a stream impacted by human pollution (n = 80), which showed that all human impacted samples tested positive for the marker while none of the animal samples did. The crAss_2 marker was field tested in an urban marine bathing water close to the discharge point of human impacted streams. In addition, the bathing water is affected by dog and gull fouling. Analysis of water samples taken at the compliance point every 30 min during a tidal cycle following a rain event showed that the crAss_2 and HF183 markers performed equally well (Spearman correlation ρ = 0.84). The levels of these marker and faecal indicators (Escherichia coli, intestinal enterococci, somatic coliphages) varied by up to 2.5 log10 during the day. Analysis of a high-tide transect perpendicular to the shoreline revealed high levels of localised faecal contamination 1 km offshore, with a concomitant spike in the gull marker. In contrast, both the crAss_2 and HF183 markers remained at a constant level, showing that human faecal contamination is homogenously distributed, while gull pollution is localised. Performance of the crAss_2 and HF183 assay was further evaluated in bimonthly compliance point samples over an 18-month period. The co-occurrence between the crAss_2 and HF183 markers in compliance sampling was 76%. A combination of both markers should be applied in low pollution impacted environments to obtain a high confidence level.


Assuntos
Monitoramento Ambiental , Microbiologia da Água , Animais , Cães , Fezes , Humanos , Rios , Esgotos , Poluição da Água/análise
4.
Int J Hyg Environ Health ; 230: 113628, 2020 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-33038613

RESUMO

A safe water supply requires distinct treatments and monitoring to guarantee the absence of pathogens and substances potentially hazardous for human health. In this study we assessed the efficiency of the dead-end ultrafiltration (DEUF) method to concentrate faecal indicator organisms (FIO) and pathogens in water samples with different physicochemical characteristics. Water samples were collected at the treatment stages of two drinking water treatment plants to analyse the concentration of a variety of 7 FIO and 4 reference microbes which have some species that are pathogenic to humans: Campylobacter spp., enteroviruses, Cryptosporidium spp. and Giardia spp. The samples were analysed before and after concentration by DEUF, detecting FIO concentrations about 1 log10 higher in non-concentrated samples from both catchments. Percent recoveries were highly variable with a mean of 43.8 ± 17.5%, depending on the FIO and inherent sample characteristics. However, DEUF enabled FIO concentration in high volumes of water (100-500 l), allowing a reduction in the detection limit compared to the non-concentrated samples due to the high volume processing capabilities of the method. As a consequence, the detection of FIO removal from water in the drinking water treatment process was 1.0-1.5 logarithms greater in DEUF-treated water compared to unfiltered samples. The DEUF method improved the detection of target indicators and allowed for the detection of pathogens in low concentrations in water after the treatment stages, confirming the suitability of DEUF to concentrate high volumes of different types of water. This method could be useful for microbial analysis in water treatment monitoring and risk assessment, allowing the identification of critical points during the water treatment process and potential hazards in water destined for several uses.

5.
Int J Food Microbiol ; 334: 108850, 2020 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-32919261

RESUMO

The complex and highly diverse microbial environment of drinking water, consisting mainly of bacteria at different metabolic states, is still underexplored. The aim of this work was to characterize the bacterial communities in tap water and bottled mineral water, the two predominant sources of drinking water in modern societies. A total of 11 tap water samples from a range of locations and distribution networks and 10 brands of bottled natural mineral water were analysed using two approaches: a) heterotrophic plate counts by matrix-assisted laser desorption/ionization time of flight mass-spectrometry (MALDI-TOF MS) for the culturable heterotrophic communities, and b) Illumina amplicon sequencing for total bacteria including non-culturable bacteria. Culturable heterotrophic bacteria were isolated in WPCA (ISO) agar at 22 ± 2 °C for 72 h and 2046 isolates were identified using MALDI-TOF MS. The Bruker Daltonics Library and a previously customized library (Drinking Water Library) were used as reference databases. For the total bacteria fraction, DNA was extracted from 6 L of water and submitted to Illumina 16S rRNA sequencing of the v4 region. Significant differences were observed between mineral and tap water, with a general dominance of Alphaproteobacteria (mainly the genus Blastomonas) in tap water and Gammaproteobacteria in mineral water with Acidovorax being the dominant genus in 3 out of 7 mineral water brands. The bacterial communities in the different brands of mineral water were highly diverse and characteristic of each one. Moreover, the season in which the water was bottled also affected the species distribution, with some of them identified in only one season. Among the culturable bacteria, the most abundant phylum was Proteobacteria (around 85% of the isolates), followed by Actinobacteria, Firmicutes and Bacteroidetes. Proteobacteria was also the most abundant phylum detected with Illumina sequencing (>99% of the reads). The two methods gave distinct results at the different taxonomic levels and could therefore have a complimentary application in the study of microbiota in mineral water environments. MALDI-TOF MS is a promising method for the rapid identification of heterotrophic bacteria in routine water analysis in the bottling industry. SIGNIFICANCE AND IMPACT OF THE STUDY: The complementarity of MALDI-TOF MS and NGS in the assessment of bacterial community diversity has been demonstrated in water intended for human consumption. The two methods are suitable for routine use in the water industry for water quality management.


Assuntos
Técnicas Bacteriológicas , Água Potável/microbiologia , Microbiota , Águas Minerais/microbiologia , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Bactérias/metabolismo , Técnicas Bacteriológicas/métodos , Meios de Cultura/metabolismo , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , RNA Ribossômico 16S/genética , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
6.
Environ Pollut ; 266(Pt 1): 115254, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32721842

RESUMO

Water quality monitoring is essential to safeguard human and environmental health. The advent of next-generation sequencing techniques in recent years, which allow a more in-depth study of environmental microbial communities in the environment, could broaden the perspective of water quality monitoring to include impact of faecal pollution bacteria on ecosystem. In this study, 16 S rRNA amplicon sequencing was used to evaluate the impact of wastewater treatment plant (WWTP) effluent on autochthonous microbial communities of a temporary Mediterranean stream characterized by high flow seasonality (from 0.02 m3/s in winter to 0.006 m3/s in summer). Seven sampling campaigns were performed under different temperatures and streamflow conditions (winter and summer). Water samples were collected upstream (Upper) of the WWTP, the secondary effluent (EF) discharge and 75 m (P75) and 1000 m (P1000) downstream of the WWTP. A total of 5,593,724 sequences were obtained, giving rise to 20,650 amplicon sequence variants (ASV), which were further analysed and classified into phylum, class, family and genus. Each sample presented different distribution and abundance of taxa. Although taxon distribution and abundance differed in each sample, the microbial community structure of P75 resembled that of EF samples, and Upper and P1000 samples mostly clustered together. Alpha diversity showed the highest values for Upper and P1000 samples and presented seasonal differences, being higher in winter conditions of high streamflow and low temperature. Our results suggest the microbial ecology re-establishment, since autochthonous bacterial communities were able to recover from the impact of the WWTP effluent in 1 km. Alpha diversity results indicates a possible influence of environmental factors on the bacterial community structure. This study shows the potential of next-generation sequencing techniques as useful tools in water quality monitoring and management within the climate change scenario.


Assuntos
Microbiota , Esgotos , Bactérias/genética , Humanos , RNA Ribossômico 16S , Águas Residuárias
7.
Food Microbiol ; 82: 1-10, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31027761

RESUMO

Natural mineral waters contain indigenous bacteria characteristic of each spring source. Once bottled, these communities change over time until the water is consumed. Bottle material is believed to play a major role in the succession of these populations, but very few studies to date have evaluated the effect of this material on bacterial communities. In this study, we examined the microbial community structure of three natural mineral waters over 3 months after bottling in glass and polyethylene terephthalate (PET) bottles. To this end, we used culture-dependent (heterotrophic plate count) and culture-independent methods (16S rRNA massive gene sequencing, denaturing gradient gel electrophoresis (DGGE) and fluorescent microscopy with vital dyes). Total and viable cell counts increased by around 1-2 log10 units between 1 and 2 weeks after bottling and then remained constant over 3 months for all waters regardless of the bottle material. DGGE fingerprints and 16S rRNA massive sequencing analysis both indicated that different communities were established in the waters two weeks after bottling in the different bottle materials. In conclusion, no differences in total, viable and culturable bacteria counts were observed between mineral waters bottled with PET or glass during shelf life storage. Nevertheless, in spite of changes in the communities, each water brand and material presented a distinct microbial community structure clearly distinguishable from the others, which could be interesting for traceability purposes.


Assuntos
Bactérias/isolamento & purificação , Água Potável/microbiologia , Armazenamento de Alimentos , Águas Minerais/microbiologia , Microbiologia da Água , Bactérias/classificação , Contagem de Colônia Microbiana , Variação Genética , Vidro , Sequenciamento de Nucleotídeos em Larga Escala , Metagenômica , Polietilenotereftalatos , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/genética
8.
Methods Mol Biol ; 1693: 11-22, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29119428

RESUMO

Here we describe the detection, enumeration, and isolation of bacteriophages infecting Bacteroides. The method is based on the infection of Bacteroides host strains and the production of visible plaques in a confluent lawn of the host strain using the double-layer agar method. This is a straightforward methodology that can be applied for the detection, enumeration and isolation of bacteriophages for other anaerobic bacteria, using an appropriate host strain and culture conditions. In the case of bacteriophages of Bacteroides the results can be obtained in less than 24 h, although the time could vary depending on the growth rate of the host strain.


Assuntos
Bacteriófagos/isolamento & purificação , Bacteroides/virologia , Animais , Bacteriófagos/crescimento & desenvolvimento , Bacteroides/classificação , Fezes/microbiologia , Humanos
9.
J Water Health ; 15(6): 885-897, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29215353

RESUMO

The aim of this work was to assess the suitability of matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) for routine heterotrophic monitoring in a drinking water treatment plant. Water samples were collected from raw surface water and after different treatments during two campaigns over a 1-year period. Heterotrophic bacteria were studied and isolates were identified by MALDI-TOF MS. Moreover, the diversity index and the coefficient of population similarity were also calculated using biochemical fingerprinting of the populations studied. MALDI-TOF MS enabled us to characterize and detect changes in the bacterial community composition throughout the water treatment plant. Raw water showed a large and diverse population which was slightly modified after initial treatment steps (sand filtration and ultrafiltration). Reverse osmosis had a significant impact on the microbial diversity, while the final chlorination step produced a shift in the composition of the bacterial community. Although MALDI-TOF MS could not identify all the isolates since the available MALDI-TOF MS database does not cover all the bacterial diversity in water, this technique could be used to monitor bacterial changes in drinking water treatment plants by creating a specific protein profile database for tracking purposes.


Assuntos
Bactérias/isolamento & purificação , Água Potável/microbiologia , Monitoramento Ambiental/métodos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Purificação da Água/normas
10.
Microb Biotechnol ; 10(6): 1775-1780, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28925595

RESUMO

In recent decades, considerable effort has been devoted to finding microbial source-tracking (MST) markers that are suitable to assess the health risks of faecally polluted waters, with no universal marker reported so far. In this study, the abundance and prevalence of a crAssphage-derived DNA marker in wastewaters of human and animal origins were studied by a new qPCR assay with the ultimate aim of assessing its potential as an MST marker. crAssphage showed up to 106 GC/ml in the sewage samples of human origin, in both the total DNA and the viral DNA fraction. In wastewaters containing animal faecal remains, 39% of the samples were negative for the presence of the crAssphage sequence, while those showing positive results (41% of the samples) were at least 1 log10 unit lower than the samples of human origin. Noteworthy, the log10 values of the ratio (R) crAssphage (GC/ml)/Escherichia coli (CFU/ml) varied significantly depending on the human or animal origin (R > 1.5 for human samples and R < -1.5 for animal wastewater samples. This study opens the way for further research to explore if different specific animal variants of crAssphage exist and whether other zones of the crAssphage genome are better suited to source discrimination.


Assuntos
Bacteriófagos/isolamento & purificação , Fezes/virologia , Esgotos/virologia , Águas Residuárias/virologia , Animais , Bacteriófagos/classificação , Bacteriófagos/genética , Escherichia coli/genética , Escherichia coli/isolamento & purificação , Fezes/microbiologia , Humanos , Esgotos/microbiologia , Águas Residuárias/microbiologia , Poluição da Água
11.
Water Res ; 123: 623-631, 2017 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-28709106

RESUMO

Mediterranean rivers, which are subject to long, dry periods and heavy rainfall events, could be particularly useful for understanding future climate scenarios. This study generated microcosms that mimicked riverbank sediment resuspension into the water of a typical Mediterranean river as a consequence of heavy rainfall. The mobilization and inactivation of six fecal pollution indicators and microbial source tracking markers were evaluated. The T90 values in the sediments were: 4 days for sorbitol-fermenting Bifidobacterium, 11 days for culturable E. coli, 36 days for bacteriophages infecting Bacteroides thetaiotaomicron strain GA17 and more than 42 days for qPCR-detected E. coli, somatic coliphages and sulfite-reducing clostridia spores. Bacteriophages and bacteria showed different resuspension and sedimentation patterns. The data obtained could be used in predictive models to assess the effects of climate change on surface water quality. Pathogen mobilization into the water column poses a risk for humans, animals and the natural environment, and breaches the One Health approach.


Assuntos
Mudança Climática , Rios , Microbiologia da Água , Animais , Colífagos , Escherichia coli , Fezes , Humanos
12.
Curr Opin Microbiol ; 38: 95-105, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28600959

RESUMO

Efforts to identify and characterize strategies for horizontal gene transfer (HGT) in prokaryotes could have overlooked some mechanisms that do not entirely fit in with the canonical ones most often described (conjugation of plasmids, phage transduction and transformation). The difficulty in distinguishing the different HGT strategies could have contributed to underestimate their real extent. Here we review non classical HGT strategies: some that require mobile genetic elements (MGEs) and others independent of MGE. Among those strategies that require MGEs, there is a range of newly reported, hybrid and intermediate MGEs mobilizing only their own DNA, others that mobilize preferentially bacterial DNA, or both. Considering HGT strategies independent of MGE, a few are even not restricted to DNA transfer, but can also mobilize other molecules. This review considers those HGT strategies that are less commonly dealt with in the literature. The real impact of these elements could, in some conditions, be more relevant than previously thought.


Assuntos
Bactérias/genética , Transferência Genética Horizontal , Células Procarióticas , Sequências Repetitivas Dispersas
13.
Mar Environ Res ; 129: 68-75, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28487162

RESUMO

Bryozoans are among the most abundant and diverse members of the Antarctic benthos, however the role of bioactive metabolites in ecological interactions has been scarcely studied. To extend our knowledge about the chemical ecology of Antarctic bryozoans, crude ether extracts (EE) and butanol extracts (BE) obtained from two Antarctic common species (Cornucopina pectogemma and Nematoflustra flagellata), were tested for antibacterial and repellent activities. The extracts were screened for quorum quenching and antibacterial activities against four Antarctic bacterial strains (Bacillus aquimaris, Micrococcus sp., Oceanobacillus sp. and Paracoccus sp.). The Antarctic amphipod Cheirimedon femoratus and the sea star Odontaster validus were selected as sympatric predators to perform anti-predatory and substrate preference assays. No quorum quenching activity was detected in any of the extracts, while all EE exhibited growth inhibition towards at least one bacterium strain. Although the species were not repellent against the sea star, they caused repellence to the amphipods in both extracts, suggesting that defence activities against predation derive from both lipophilic and hydrophilic metabolites. In the substrate preference assays, one EE and one BE deriving from different specimens of the species C. pectogemma were active. This study reveals intraspecific variability of chemical defences and supports the fact that chemically mediated interactions are common in Antarctic bryozoans as means of protection against fouling and predation.


Assuntos
Briozoários/fisiologia , Adaptação Fisiológica , Anfípodes , Animais , Regiões Antárticas , Antibacterianos/metabolismo , Antibacterianos/farmacologia , Produtos Biológicos/metabolismo , Produtos Biológicos/farmacologia , Comportamento Alimentar , Comportamento Predatório , Estrelas-do-Mar
14.
Water Res ; 112: 248-253, 2017 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-28171819

RESUMO

Climate change is expected to affect the Mediterranean region by causing an increase in the number of heavy rainfall events. The aim of this study was to assess the effect of extreme river flow variations due to rainfall on the persistence and mobilisation of various microorganisms. These included faecal pollution indicators (Escherichia coli (EC), somatic coliphages (SOMCPH) and sulphite reducing clostridia spores (SRC)), microbial source tracking indicators (Bacteroides thetaiotaomicron GA17 strain phages (GA17PH) and sorbitol fermenting bifidobacteria (SFBIF)), and two pathogens (Salmonella spp and Enterovirus). Water and sediment samples were taken at different distances from the river before and after heavy rainfall events. The microbial load was higher in sediment samples closer to the river course. The concentration of some faecal indicators (EC and SFBIF) increased in sediments and river water after rainfall events, whereas the most conservative parameter (SRC) showed almost no variation. After rainfall, the indicators persisted at a different rate. Salmonella spp and Enterovirus were detected in some samples but always at lower concentrations than the microbial indicators. In conclusion, sediments are reservoirs of faecal and MST indicators and pathogens and could therefore pose a risk of pathogen dissemination.


Assuntos
Mudança Climática , Microbiologia da Água , Colífagos , Fezes/microbiologia , Rios/microbiologia
15.
FEMS Microbiol Lett ; 363(17)2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27481701

RESUMO

Bacteriophages are increasingly being used as water quality indicators. Two groups of phages infecting Escherichia coli, somatic and F-specific coliphages, are being considered as indicators of fecal and viral contamination for several types of water around the world. However, some uncertainties remain regarding which coliphages to assess. Recently, E. coli strain CB390 has been reported to be suitable for simultaneous detection of both groups, which seems to be more informative than determining only one of the groups. Here, a significant number of samples from different settings, mostly those where F-specific phages have been reported to outnumber somatic coliphages, are analyzed for somatic coliphages, F-specific RNA phages by standardized methods and coliphages detected by host strain CB390. The results presented here confirm that the numbers of phages counted using CB390 are equivalent to the sum of the somatic and F-specific coliphages counted independently in all settings. Hence the usefulness of this strain for simultaneous detection of somatic and F-specific coliphages is confirmed. Also, sets of data on the presence of coliphages in reclaimed and groundwater are reported.


Assuntos
Colífagos/isolamento & purificação , Escherichia coli/virologia , Microbiologia da Água , Fezes/virologia , Esgotos/virologia , Qualidade da Água
16.
J Environ Manage ; 182: 335-341, 2016 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-27497310

RESUMO

Reverse osmosis membrane filtration technology (RO) is used to treat drinking water. After RO treatment, bacterial growth is still observed in water. However, it is not clear whether those microorganisms belong to species that can pose a health risk, such as Pseudomonas spp. The goal of this study is to characterize the bacterial isolates from a medium that is selective for Pseudomonas and Aeromonas which were present in the water fraction before and after the RO. To this end, isolates were recovered over two years and were identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry. They were then biochemically phenotyped and the population similarity indexes were calculated. The isolates were analysed for their capacity to form biofilms in vitro and antimicrobial susceptibility. There were significant differences between the microbial populations in water before and after RO. Furthermore, the structures of the populations analysed at the same sampling point were similar in different sampling campaigns. Some of the isolates had the capacity to form a biofilm and showed resistance to different antibiotics. A successful level filtration via RO and subsequent recolonization of the membrane with different species from those in the feed water was found. Pseudomonas aeruginosa was not recovered from among the isolates. This study increases the knowledge on the microorganisms present in water after RO treatment, with focus in one of the genus causing problems in RO systems associated with human health risk, Pseudomonas.


Assuntos
Pseudomonas/fisiologia , Microbiologia da Água , Purificação da Água/métodos , Biofilmes , Filtração , Humanos , Membranas Artificiais , Osmose
17.
Water Sci Technol ; 73(9): 2182-8, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27148720

RESUMO

Conventional bacterial indicators present serious drawbacks giving information about viral pathogens persistence during sludge hygienization treatments. This calls for the search of alternative viral indicators. Somatic coliphages' (SOMCPH) ability for acting as surrogates for enteroviruses was assessed in 47 sludge samples subjected to novel treatment processes. SOMCPH, infectious enteroviruses and genome copies of enteroviruses were monitored. Only one of these groups, the bacteriophages, was present in the sludge at concentrations that allowed the evaluation of treatment's performance. An indicator/pathogen relationship of 4 log10 (PFU/g dw) was found between SOMCPH and infective enteroviruses and their detection accuracy was assessed. The obtained results and the existence of rapid and standardized methods encourage the inclusion of SOMCPH quantification in future sludge directives. In addition, an existing real-time quantitative polymerase chain reaction (RT-qPCR) for enteroviruses was adapted and applied.


Assuntos
Colífagos/fisiologia , Enterovirus/fisiologia , Esgotos/microbiologia , Eliminação de Resíduos Líquidos/métodos , Microbiologia da Água
18.
Int J Hyg Environ Health ; 219(7 Pt A): 577-584, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-26809219

RESUMO

The study of bacterial communities throughout a drinking water treatment plant could provide a basic understanding of the effects of water processing that could then be used to improve the management of such plants. However, it is necessary to develop new analytical techniques that are sufficiently efficient, robust and fast for their effective and useful application in routine analysis. The aim of this study is therefore to assess the performance of matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS), as compared to the PhenePlate™ system, for routine analysis in a drinking water treatment plant. To this end we studied a total of 277 colonies isolated in different seasons and from different points throughout the water treatment process, including: raw water, sand filtration, ultrafiltration, reverse osmosis and chlorination. The colonies were analysed using MALDI-TOF MS by direct deposition of the cells on the plate. The colonies were also biochemically fingerprinted using the PhenePlate™ system, clustered according to their similarity and a representative strain was selected for 16S rRNA gene sequencing and API® gallery-based identification. The use of MALDI-TOF MS was reliable compared to the PhenePlate™ system and has the advantage of being faster and relatively cheap. Bacteria typing by MALDI-TOF MS is therefore a promising method to replace conventional routine phenotypic methods for the identification of bacteria in drinking water laboratories, thanks to its robustness. The major limiting factor for MALDI-TOF MS is the lack of a suitable mass spectra database; although each laboratory can develop its own library. This methodology will provide a tracking tool for companies to use in risk management and the detection of possible failures in both the water treatment processes and the distribution network, as well as offering characterization of the intrinsic microbial populations.


Assuntos
Bactérias/isolamento & purificação , Monitoramento Ambiental/métodos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Poluentes da Água/isolamento & purificação , Bactérias/classificação , Bactérias/genética , Técnicas de Tipagem Bacteriana , Água Potável , RNA Bacteriano/genética , RNA Ribossômico 16S/genética , Poluentes da Água/classificação , Purificação da Água
19.
Environ Microbiol ; 18(3): 957-69, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26626855

RESUMO

Lysogeny by temperate phages provides novel functions for bacteria and shelter for phages. However, under conditions that activate the phage lytic cycle, the benefit of lysogeny becomes a paradox that poses a threat for bacterial population survival. Using Escherichia coli lysogens for Shiga toxin (Stx) phages as model, we demonstrate how lysogenic bacterial populations circumvent extinction after phage induction. A fraction of cells maintains lysogeny, allowing population survival, whereas the other fraction of cells lyse, increasing Stx production and spreading Stx phages. The uninduced cells were still lysogenic for the Stx phage and equally able to induce phages as the original cells, suggesting heterogeneity of the E. coli lysogenic population. The bacterial population can modulate phage induction under stress conditions by the stress regulator RpoS. Cells overexpressing RpoS reduce Stx phage induction and compete with and survive better than cells with baseline RpoS levels. Our observations suggest that population heterogeneity in phage induction could be widespread among other bacterial genera and we propose this is a mechanism positively selected to prevent the extinction of the lysogenic population that can be modulated by environmental conditions.


Assuntos
Proteínas de Bactérias/biossíntese , Bacteriófagos/genética , Escherichia coli/virologia , Lisogenia/genética , Fator sigma/biossíntese , Proteínas de Bactérias/genética , Bacteriófagos/metabolismo , Dados de Sequência Molecular , Toxina Shiga/genética , Toxina Shiga II/genética , Fator sigma/genética
20.
New Microbiol ; 37(3): 339-46, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25180848

RESUMO

The aim of this work was to assess the susceptibility of Vibrio spp. strains isolated from fish cultures against some usually applied antibiotics and the occurrence of the SXT mobile genetic element among them. Antimicrobial resistance was assessed by the standard disk diffusion technique while the presence of the SXT mobile genetic element was determined by conventional PCR. High levels of resistance to ampicillin (70%), cefoxitin (44%), streptomycin (31%), aztreonam (25%) and sulfamethoxazole (21%) were detected, and a high inter-and-intraspecies diversity in the resistance profile was observed for the majority of the analysed isolates. The SXT mobile genetic element was detected in only 4 isolates belonging to the species V. diazotrophicus (1), V. mediterranei (2) and V. vulnificus (1), which showed a variable antibiotic resistance profile. Horizontal antibiotic resistance gene transfer from the V. diazotrophicus SXT-positive strain to a laboratory E. coli strain was demonstrated under laboratory conditions. Our results suggest that the Vibrio spp. isolated from aquaculture facilities analysed in this study, although not being pathogenic, they constitute a source of antimicrobial resistance genes that could be mobilized to other bacterial populations through mobile genetic elements. However, the low occurrence of the SXT element in these isolates supports the hypothesis that this element is not involved in the development of resistance in the majority of Vibrio spp. in the examined aquaculture facilities.


Assuntos
Antibacterianos/farmacologia , Elementos de DNA Transponíveis , Farmacorresistência Bacteriana Múltipla , Peixes/microbiologia , Vibrio/efeitos dos fármacos , Vibrio/genética , Animais , Pesqueiros , Transferência Genética Horizontal , Testes de Sensibilidade Microbiana , Vibrio/classificação , Vibrio/isolamento & purificação
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