Unite de Microbiologie et de Biologie Moleculaire

Sidi el Hani, Tunisia

Unite de Microbiologie et de Biologie Moleculaire

Sidi el Hani, Tunisia

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Jebri S.,Unite de Microbiologie et de Biologie Moleculaire | Jofre J.,University of Barcelona | Barkallah I.,Unite de Microbiologie et de Biologie Moleculaire | Saidi M.,Unite de Microbiologie et de Biologie Moleculaire | And 2 more authors.
Environmental Science and Pollution Research | Year: 2012

Purpose: The role of water in the transmission of infectious diseases is well defined; it may act as a reservoir of different types of pathogens. Enteric viruses can survive and persist for a long time in water, maintaining infectivity in many instances. This suggests the need to include virus detection in the evaluation of the microbiological quality of waters. Methods: In this study, enteric viruses (enteroviruses and hepatitis A virus (HAV)) were investigated by RT-PCR and coliphages (known as indicators of viral contamination) were enumerated with the double-layer technique agar in effluents and sewage sludge from three Tunisian wastewater treatment plants. Results and discussion: The molecular detection of enteric viruses revealed 7. 7% of positive activated sludge samples for enteroviruses. None of the samples was positive for HAV. Molecular virus detection threshold was estimated to be 103 PFU/100 ml. All samples contained high concentrations of coliphages except those of dry sludge. Reductions in the concentrations of bacteriophages attained by the wastewater treatment plants are of the order of magnitude as reductions described elsewhere. Peak concentrations in raw wastewater were associated with winter rains and suspended materials rate in analysed samples. Our data which is the first in North Africa showed that similar trends of coliphages distribution to other studies in other countries. Conclusion: No clear correlation between studied enteric viruses and coliphages concentration was proved. Coliphages abundance in collected samples should raise concerns about human enteric viruses transmission as these residues are reused in agricultural fields. © 2012 Springer-Verlag.


Jebri S.,Unite de Microbiologie et de Biologie Moleculaire | Hmaied F.,Unite de Microbiologie et de Biologie Moleculaire | Yahya M.,Unite de Microbiologie et de Biologie Moleculaire | Ammar A.B.,University of Monastir | Hamdi M.,Tunis Carthage University
Water Science and Technology | Year: 2016

This study was conducted to isolate phages in treated sewage collected from wastewater treatment plant, and explore their morphological diversity by transmission electron microscopy (TEM). Fates of total bacteriophages and their reduction by biological treatment were also assayed. Phages were isolated using the plaque assay then negatively stained and observed by electron microscope. Electron micrographs showed different types of phages with different shapes and sizes. The majority of viruses found in treated sewage ranged from 30 to 100 nm in capsid diameter. Many of them were tailed, belonging to Siphoviridae, Myoviridae and Podoviridae families. Non-tailed phage particles were also found at a low rate, presumably belonging to Leviviridae or Microviridae families. This study shows the diversity and the abundance of bacteriophages in wastewater after biological treatment. Their persistence in wastewater reused in agriculture should raise concerns about their potential role in controlling bacterial populations in the environment. They should be also included in water treatment quality controlling guidelines as fecal and viral indicators. © 2016 IWA Publishing.


PubMed | Unite de Microbiologie et de Biologie Moleculaire, University of Carthage and University of Barcelona
Type: Journal Article | Journal: Current microbiology | Year: 2016

Human enteric viruses are a major causative agent of emerging waterborne diseases and constitute a serious public health concern. Environmental contamination occurs through discharge of waste materials from infected persons. Methods for viral detection should be developed to detect low infective dose of enteric viruses in environment. In this study, we aimed at comparing two concentration methods for the detection of naturally occurring enteroviruses in raw and treated sewage. In the first method, polyethylene glycol is used to concentrate viral particles from the collected samples. The second method is based on ultracentrifugation of viral particles at high speed (110,000g). Genomes of enteroviruses were quantified by the quantitative real-time PCR method in raw and treated sewage samples. PEG-based method yielded higher genomic copies of enteric viruses (with an average of 5.9 log10 genomic copies/100 mL) when applied to raw sewage samples. While the ultracentrifugation assay in the second method decreases genomic copies number (with an average of 5.4 log10 genomic copies/100 mL). The recovery differences between the two methods were not significant when applied to clean samples (treated sewage). This could be explained by the presence of inhibitors, which interfere with qRT-PCR, in less quantity comparatively to raw sewage. PEG-based method would be more accurate for samples with high-organic matter load. This report emphasizes the importance of matrices nature on the recovery of enteroviruses from sewage samples. This should be taken into consideration for establishing standardized virological assays to ensure the virological quality control of discharged water in environment.


PubMed | Tunis Carthage University, Unite de Microbiologie et de Biologie Moleculaire and University of Monastir
Type: Journal Article | Journal: Water science and technology : a journal of the International Association on Water Pollution Research | Year: 2016

This study was conducted to isolate phages in treated sewage collected from wastewater treatment plant, and explore their morphological diversity by transmission electron microscopy (TEM). Fates of total bacteriophages and their reduction by biological treatment were also assayed. Phages were isolated using the plaque assay then negatively stained and observed by electron microscope. Electron micrographs showed different types of phages with different shapes and sizes. The majority of viruses found in treated sewage ranged from 30 to 100 nm in capsid diameter. Many of them were tailed, belonging to Siphoviridae, Myoviridae and Podoviridae families. Non-tailed phage particles were also found at a low rate, presumably belonging to Leviviridae or Microviridae families. This study shows the diversity and the abundance of bacteriophages in wastewater after biological treatment. Their persistence in wastewater reused in agriculture should raise concerns about their potential role in controlling bacterial populations in the environment. They should be also included in water treatment quality controlling guidelines as fecal and viral indicators.


Colomer-Lluch M.,University of Barcelona | Calero-Caceres W.,University of Barcelona | Jebri S.,Unite de Microbiologie et de Biologie Moleculaire | Hmaied F.,Unite de Microbiologie et de Biologie Moleculaire | And 2 more authors.
Environment International | Year: 2014

The emergence and increased prevalence of antibiotic resistance genes (ARGs) in the environment may pose a serious global health concern. This study evaluates the abundance of several ARGs in bacterial and bacteriophage DNA via real-time qPCR in samples from five different sampling points in Tunisia; three wastewater treatment plants (WWTP 1, 2 and 3) and wastewater from two abattoirs slaughtering different animals. Results are compared with those obtained in the Barcelona area, in northeast Spain.Eight ARGs were quantified by qPCR from total and phage DNA fraction from the samples. Three β-lactamases (blaTEM, blaCTX-M cluster 1 and blaCTX-M cluster 9), two quinolone resistance genes (qnrA and qnrS), the mecA gene that confers resistance to methicillin in Staphylococcus aureus, the emerging armA gene, conferring resistance to aminoglycosides and sul1, the most extended gene conferring resistance to sulfonamides, were evaluated.Sul1 and blaTEM were the most prevalent ARGs detected at all five Tunisian sampling points, similarly with the observations in Barcelona. blaCTX-M-9 was more prevalent than blaCTX-M-1 both in bacterial and DNA within phage particles in all samples analysed. mecA and armA were almost absent in Tunisian waters from human or animal origin in contrast with Barcelona that showed a medium prevalence. qnrA was more prevalent than qnrS in bacterial and phage DNA from all sampling points.In conclusion, our study shows that ARGs are found in the bacterial and is reflected in the phage DNA fraction of human and animal wastewaters. The densities of each ARGs vary depending on the ARGs shed by each population and is determined by the characteristics of each area. Thus, the evaluation of ARGs in wastewaters seems to be suitable as marker reflecting the antibiotic resistance patterns of a population. © 2014 Elsevier Ltd.


PubMed | Unite de Microbiologie et de Biologie Moleculaire and University of Barcelona
Type: | Journal: Environment international | Year: 2014

The emergence and increased prevalence of antibiotic resistance genes (ARGs) in the environment may pose a serious global health concern. This study evaluates the abundance of several ARGs in bacterial and bacteriophage DNA via real-time qPCR in samples from five different sampling points in Tunisia; three wastewater treatment plants (WWTP 1, 2 and 3) and wastewater from two abattoirs slaughtering different animals. Results are compared with those obtained in the Barcelona area, in northeast Spain. Eight ARGs were quantified by qPCR from total and phage DNA fraction from the samples. Three -lactamases (bla(TEM), bla(CTX-M) cluster 1 and bla(CTX-M) cluster 9), two quinolone resistance genes (qnrA and qnrS), the mecA gene that confers resistance to methicillin in Staphylococcus aureus, the emerging armA gene, conferring resistance to aminoglycosides and sul1, the most extended gene conferring resistance to sulfonamides, were evaluated. Sul1 and bla(TEM) were the most prevalent ARGs detected at all five Tunisian sampling points, similarly with the observations in Barcelona. bla(CTX-M-9) was more prevalent than bla(CTX-M-1) both in bacterial and DNA within phage particles in all samples analysed. mecA and armA were almost absent in Tunisian waters from human or animal origin in contrast with Barcelona that showed a medium prevalence. qnrA was more prevalent than qnrS in bacterial and phage DNA from all sampling points. In conclusion, our study shows that ARGs are found in the bacterial and is reflected in the phage DNA fraction of human and animal wastewaters. The densities of each ARGs vary depending on the ARGs shed by each population and is determined by the characteristics of each area. Thus, the evaluation of ARGs in wastewaters seems to be suitable as marker reflecting the antibiotic resistance patterns of a population.

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