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1.
J Appl Microbiol ; 111(1): 209-15, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21477066

RESUMO

AIM: To assess the persistence and diversity of faecal bacterial populations (faecal coliforms and enterococci) that have recently been included in microbial source tracking (MST) predictive models. METHODS AND RESULTS: The analysed bacterial populations included members of the enterococci group (ENT) [Enterococcus faecium (FM), Enterococcus faecalis (FS) and Enterococcus hirae (HIR)] and the faecal coliform group (FC) [diverse Escherichia coli phenotypes (ECP) and cellobiose-negative faecal coliforms (CNFC)]. The inactivation of these distinct groups was monitored over time on-site in river by biochemical fingerprinting, and diversity indices were calculated. Among the different analysed species belonging to the ENT group, HIR persisted longer and was able to replicate in the environment at a higher rate. On the other hand, ECP and NCFC showed a similar persistence throughout the different seasons. The diversity index (Di) for FC increased substantially in the summer after 96 h to a maximum value of 0·96. On the other hand, the Di for ENT diminished over the same period to a value of 0·86, suggesting a different persistence for the different species integrating this group. CONCLUSIONS: The persistence of ECP, CNFC, FM and FS in the aquatic environment is high, particularly for the members of the FC and in the summer season. On the contrary, HIR is able to replicate in the environment at a high rate even in winter, and therefore, its inclusion in MST predictive models is discouraged. SIGNIFICANCE AND IMPACT OF THE STUDY: ECP, CNFC, FMFS and HIR have been proposed as additional variables in MST predictive models. However, the different persistence of HIR compared with the other variables should be taken into account for the development of such models.


Assuntos
Enterococcus/crescimento & desenvolvimento , Fezes/microbiologia , Rios/microbiologia , Poluição da Água , Contagem de Colônia Microbiana , Monitoramento Ambiental/métodos , Esgotos/microbiologia , Espanha
2.
J Appl Microbiol ; 107(4): 1178-85, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19486397

RESUMO

AIMS: To determine relative to faecal coliforms (FC) and sulfite-reducing clostridia (SRC), the environmental persistence of natural populations of Bifidobacterium spp. enumerated by culturing and quantitative polymerase chain reaction (q-PCR). METHODS AND RESULTS: Dialysis tubing containing river supplemented with overnight cultures of Bifidobacterium adolescentis (BA) and Bifidobacterium dentium (BD) or urban wastewater were suspended in a river for up to 10 days. At intervals, the contents of each dialysis tube were assayed using q-PCR assays for BA and BD, and selective culture media for FC, SRC, total bifidobacteria (TB), sorbitol-fermenting bifidobacteria (SFB) and cultivable BA. Mean summer T(90) values were 251 h for SRC, 92 h for FC, 48 h for BA and BD by q-PCR, and 9 h for TB. CONCLUSIONS: Bifidobacterium spp. was the population with the lowest persistence, showing seasonal differences in T(90) when measured by culture techniques or by q-PCR. This difference in relative persistence is because of a longer persistence of molecular targets than cultivable cells. SIGNIFICANCE AND IMPACT OF THE STUDY: The persistence of a viable bifidobacteria cells is shorter, but the longest persistence of molecular targets. This factor could be used for origin the faecal pollution in water for the development of microbial source tracking (MST).


Assuntos
Bifidobacterium/isolamento & purificação , Rios/microbiologia , Microbiologia da Água , Técnicas Bacteriológicas , Bifidobacterium/genética , Bifidobacterium/crescimento & desenvolvimento , Contagem de Colônia Microbiana , Primers do DNA/genética , Reação em Cadeia da Polimerase/métodos , Estações do Ano , Sensibilidade e Especificidade , Fatores de Tempo
3.
Microb Ecol ; 57(3): 478-83, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18773234

RESUMO

The composition of the most abundant facultative anaerobic bacteria populations [faecal coliforms (FC) and enterococci (ENT)] in sludge can be modified after different treatments. These involve the disposal or reuse of sludge and include: anaerobic digesters, incineration, composting, pasteurization and lime treatments. In this study, three treatment types (mesophilic anaerobic digestion, composting and pasteurization) were compared in terms of their ability to reduce both bacterial populations. The diversity and any changes in composition of main phenotypic groups for both populations were also analyzed. Mesophilic anaerobic digestion (MAD) was carried out at 35 degrees C for 20 days. Digested sludge was then dehydrated by centrifugation at 2,500 rpm. Composting (COM) was performed at 55 degrees C with windrow phases. Pasteurization was assayed at 60 degrees C for 90 min (P60), at 80 degrees C for 60 min (P80). A 1-1.5 log unit reduction was observed for FC, and 1 log unit reduction was noted for ENT by MAD treatment. In composting, this reduction proved higher for FC than for ENT (6 log and 3-4 log units, respectively). Optimal pasteurization was obtained at 80 degrees C for 60 min, resulting in a 5 log unit reduction for FC and a 2 log unit reduction for ENT. High diversity indices (Di) for both bacterial populations were detected both before and after implementation of the different treatments. Analyses of the population's similarity provided that FC were diverse both before and after COM, P60 and P80 treatments. However, no differences were observed on the composition of ENT populations after the different treatments assayed.


Assuntos
Enterobacteriaceae/fisiologia , Enterococcus/fisiologia , Esgotos/microbiologia , Eliminação de Resíduos Líquidos/métodos , Anaerobiose , Reatores Biológicos , Análise por Conglomerados , Contagem de Colônia Microbiana , Enterobacteriaceae/crescimento & desenvolvimento , Enterococcus/crescimento & desenvolvimento , Fezes/microbiologia , Temperatura Alta
4.
J Appl Microbiol ; 98(3): 589-97, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15715861

RESUMO

AIMS: The detection of Escherichia coli O157:H7 in environmental samples is a human concern. The high persistence of this serotype in the environment suggests that contaminated animal wastewater could act as a potential reservoir. Nevertheless, the high levels of background microflora and cell damage because of environmental stress hamper the isolation of this pathogen without using enrichment methods. This study develops a method for the detection of E. coli and investigates its prevalence in animal and human wastewaters. METHODS AND RESULTS: Incubation of the sample for 1 h 30 min at 37 degrees C in peptone water supplemented with vancomycin and cefsulodin, enhanced the recovery of bacteria whilst ensuring that no growth occurred. Subsequently, a combination of immunomagnetic separation, cefixime-tellurite-sorbitol MacConkey (CT-SMAC) plating and immunoblotting with specific O157 antibodies allowed the detection, enumeration and isolation of E. coli O157 strains in human, swine and cattle wastewaters, which presented values of 0.2, 0.4, and 1.0 log10 ml(-1) units, respectively. Some of the isolates carried genes coding for Shiga toxins, intimin and enterohemolysin. CONCLUSIONS: Escherichia coli O157 is commonly present in animal and human wastewaters. The developed method reduced the high rate of false positives reported for other technical approaches. SIGNIFICANCE AND IMPACT OF THE STUDY: The confirmation of serotype by specific immunomethods is necessary to prevent false-positive detection and incorrect enumeration.


Assuntos
Escherichia coli O157/isolamento & purificação , Esgotos , Microbiologia da Água , Poluição da Água , Criação de Animais Domésticos , Animais , Antígenos de Bactérias/análise , Bovinos , Análise por Conglomerados , Impressões Digitais de DNA , Monitoramento Ambiental/métodos , Escherichia coli O157/genética , Genes Bacterianos , Humanos , Immunoblotting/métodos , Separação Imunomagnética , Lipopolissacarídeos , Suínos , Virulência
5.
Appl Environ Microbiol ; 70(5): 3171-5, 2004 May.
Artigo em Inglês | MEDLINE | ID: mdl-15128586

RESUMO

Bifidobacteria are one of the most common bacterial types found in the intestines of humans and other animals and may be used as indicators of human fecal pollution. The presence of nine human-related Bifidobacterium species was analyzed in human and animal wastewater samples of different origins by using species-specific primers based on 16S rRNA sequences. Only B. adolescentis and B. dentium were found exclusively in human sewage. A multiplex PCR approach with strain-specific primers was developed. The method showed a sensitivity threshold of 10 cells/ml. This new molecular method could provide useful information for the characterization of fecal pollution sources.


Assuntos
Bifidobacterium/classificação , Primers do DNA , Fezes/microbiologia , Reação em Cadeia da Polimerase/métodos , RNA Ribossômico 16S/genética , Poluição da Água , Animais , Bifidobacterium/genética , DNA Ribossômico/análise , Genes de RNAr , Humanos , Esgotos/microbiologia , Especificidade da Espécie , Microbiologia da Água , Purificação da Água
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