A comparison between different fouling-release elastomer coatings containing surface-active polymers.

Surface-active polymers derived from styrene monomers containing siloxane (S), fluoroalkyl (F) and/or ethoxylated (E) side chains were blended with an elastomer matrix, either poly(dimethyl siloxane) (PDMS) or poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS), and spray-coated on top of PDMS or SEBS preformed films. By contact angle and X-ray photoelectron spectroscopy measurements, it was found that the surface-active polymer preferentially populated the outermost layers of the coating, despite its low content in the blend. However, the self-segregation process and the response to the external environment strongly depended on both the chemistry of the polymer and the type of matrix used for the blend. Additionally, mechanical testing showed that the elastic modulus of SEBS-based coatings was one order of magnitude higher than that of the corresponding PDMS-based coatings. The coatings were subjected to laboratory bioassays with the marine alga Ulva linza. PDMS-based coatings had superior fouling-release properties compared to the SEBS-based coatings.

Identification of the origin of faecal contamination in estuarine oysters using Bacteroidales and F-specific RNA bacteriophage markers.

AIMS: The aim of this study was to identify the origin of faecal pollution impacting the Elorn estuary (Brittany, France) by applying microbial source tracking (MST) markers in both oysters and estuarine waters. METHODS AND RESULTS: The MST markers used were as follows: (i) human-, ruminant- and pig-associated Bacteroidales markers by real-time PCR and (ii) human genogroup II and animal genogroup I of F-specific RNA bacteriophages (FRNAPH) by culture/genotyping and by direct real-time reverse-transcriptase PCR. The higher occurrence of the human genogroup II of F-specific RNA bacteriophages using a culture/genotyping method, and human-associated Bacteroidales marker by real-time PCR, allowed the identification of human faecal contamination as the predominant source of contamination in oysters (total of 18 oyster batches tested) and waters (total of 24 water samples tested). The importance of using the intravalvular liquids instead of digestive tissues, when applying host-associated Bacteroidales markers in oysters, was also revealed. CONCLUSIONS: This study has shown that the application of a MST toolbox of diverse bacterial and viral methods can provide multiple lines of evidence to identify the predominant source of faecal contamination in shellfish from an estuarine environment. SIGNIFICANCE AND IMPACT OF THE STUDY: Application of this MST toolbox is a useful approach to understand the origin of faecal contamination in shellfish harvesting areas in an estuarine setting.

Recent innovation in microbial source tracking using bacterial real-time PCR markers in shellfish.

We assessed the capacity of real-time PCR markers to identify the origin of contamination in shellfish. Oyster, cockles or clams were either contaminated with fecal materials and host-associated markers designed from Bacteroidales or Catellicoccus marimammalium 16S RNA genes were extracted from their intravalvular liquid, digestive tissues or shellfish flesh. Extraction of bacterial DNA from the oyster intravalvular liquid with FastDNA spin kit for soil enabled the selected markers to be quantified in 100% of artificially contaminated samples, and the source of contamination to be identified in 13 out of 38 naturally contaminated batches from European Class B and Class C areas. However, this protocol did not enable the origin of the contamination to be identified in cockle or clam samples. Although results are promising for extracts from intravalvular liquid in oyster, it is unlikely that a single protocol could be the best across all bacterial markers and types of shellfish.

Effect of oxygen and temperature on the dynamic of the dominant bacterial populations of pig manure and on the persistence of pig-associated genetic markers, assessed in river water microcosms.

AIMS: The aim is to evaluate the dynamic of Bacteroides-Prevotella and Bacillus-Streptococcus-Lactobacillus populations originating from pig manure and the persistence of pig-associated markers belonging to these groups according to temperature and oxygen. METHODS AND RESULTS: River water was inoculated with pig manure and incubated under microaerophilic and aerobic conditions, at 4 and 20°C over 43 days. The diversity of bacterial populations was analysed by capillary electrophoresis-single-strand conformation polymorphism. The persistence of the pig-associated markers was measured by real-time PCR and compared with the survival of Escherichia coli and enterococci. Decay was characterized by the estimation of the time needed to produce a 1-log reduction (T90). The greatest changes were observed at 20°C under aerobic conditions, leading to a reduction in the diversity of the bacterial populations and in the concentrations of the Pig-1-Bac, Pig-2-Bac and Lactobacillus amylovorus markers with a T90 of 10·5, 8·1 and 17·2 days, respectively. CONCLUSIONS: Oxygen and temperature were found to have a combined effect on the persistence of the pig-associated markers in river waters. SIGNIFICANCE AND IMPACT OF THE STUDY: The persistence profiles of the Pig-1-Bac, Pig-2-Bac and Lact. amylovorus markers in addition to their high specificity and sensitivity support their use as relevant markers to identify pig faecal contamination in river waters.

Development of microbial and chemical MST tools to identify the origin of the faecal pollution in bathing and shellfish harvesting waters in France.

The microbiological quality of coastal or river waters can be affected by faecal pollution from human or animal sources. An efficient MST (Microbial Source Tracking) toolbox consisting of several host-specific markers would therefore be valuable for identifying the origin of the faecal pollution in the environment and thus for effective resource management and remediation. In this multidisciplinary study, after having tested some MST markers on faecal samples, we compared a selection of 17 parameters corresponding to chemical (steroid ratios, caffeine, and synthetic compounds), bacterial (host-specific Bacteroidales, Lactobacillus amylovorus and Bifidobacterium adolescentis) and viral (genotypes I-IV of F-specific bacteriophages, FRNAPH) markers on environmental water samples (n = 33; wastewater, runoff and river waters) with variable Escherichia coli concentrations. Eleven microbial and chemical parameters were finally chosen for our MST toolbox, based on their specificity for particular pollution sources represented by our samples and their detection in river waters impacted by human or animal pollution; these were: the human-specific chemical compounds caffeine, TCEP (tri(2-chloroethyl)phosphate) and benzophenone; the ratios of sitostanol/coprostanol and coprostanol/(coprostanol+24-ethylcopstanol); real-time PCR (Polymerase Chain Reaction) human-specific (HF183 and B. adolescentis), pig-specific (Pig-2-Bac and L. amylovorus) and ruminant-specific (Rum-2-Bac) markers; and human FRNAPH genogroup II.

Application of library-independent microbial source tracking methods for identifying the sources of faecal contamination in coastal areas.

Faecal contamination sources were identified in coastal areas around the Guerande-Atlantique peninsula using two microbial source tracking (MST) methods: (i) Bacteroidales host-specific 16S rRNA gene markers measured by real-time PCR and (ii) F-specific bacteriophage (FRNAPH) genotyping. Both methods were used on 63 water samples from 7 water courses. HF183 marker and bacteriophage genogroup II (FRNAPH II) were detected in all water samples and in the majority of water samples, respectively, from La Torre stream (W5), Piriac (W2), R2000 (W3) and Mazy (W7) rain water drains, and also detected, less frequently, in Le Nau drain (W4), suggesting contamination by human faecal sources at these sites. These human markers were weakly detected in Pouliguen channel (W6). Furthermore, BacR and bacteriophage genogroup I (FRNAPH I) were also detected, but at lower concentration and frequency. So, site W6 seems to be contaminated by multiple sources, though mainly human. Finally, BacR was detected twice in Pont d'Armes channel (W1), whereas HF183 was not detected. FRNAPH I and II were detected in only 3 out of 12 water samples. Site W1 seems mainly contaminated by animal sources. As a result of our findings, actions were taken to remediate water and shellfish quality.

Phylogenetic analysis of Bacteroidales 16S rRNA gene sequences from human and animal effluents and assessment of ruminant faecal pollution by real-time PCR.

AIMS: The aims of this study were to evaluate the host-specific distribution of Bacteroidales 16S rRNA gene sequences from human- and animal-related effluents and faeces, and to define a ruminant-specific marker. METHODS AND RESULTS: Bacteroidales 16S rRNA gene clone libraries were constructed from samples of effluent (sewage, bovine manure and pig slurry) and faeces (human, bovine, pig and wild bird), using PCR primers targeting order Bacteroidales. The phylogenetic analysis revealed six main distinct human-, bovine-, pig- and wild bird-specific clusters. From the bovine-specific cluster II, we designed a ruminant-specific marker, Rum-2-Bac, and this showed 97% sensitivity (n=30) and 100% specificity (n=40) when tested by TaqMan real-time PCR. Average concentrations of this marker in bovine and sheep faeces and in bovine manure were 8.2+/-0.5, 8.4+/-1.3 and 7+/-0.5 log10 copies per gram, respectively. It was also quantified in samples of runoff water impacted by bovine manure, with average concentrations of 5.1+/-0.3 log10 copies per millilitre water. CONCLUSIONS: Our results confirmed that some members of Bacteroidales isolated from effluents and faeces had host-specific distributions. Identification of a bovine-specific cluster made it possible to design a reliable ruminant-specific marker. SIGNIFICANCE AND IMPACT OF THE STUDY: The host-specific distribution of Bacteroidales sequences from effluents mirrored the host-specific distribution of sequences observed in individual faeces. This efficient new ruminant-specific Bacteroidales 16S rRNA marker represents a useful addition to the microbial source tracking toolbox.