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Vibrio anguillarum is the causative agent of vibriosis, a deadly haemorrhagic septicaemic disease affecting various marine and fresh/brackish water fish, bivalves and crustaceans. However, the diversity and virulence mechanisms of this pathogen are still insufficiently known. In this study, we aimed to increase our understanding of V. anguillarum diversity and virulence through comparative genome analysis of 15 V. anguillarum strains, obtained from different hosts or non-host niches and geographical regions, among which 10 and 5 strains were found to be virulent and avirulent, respectively, against sea bass larvae. First, the 15 draft genomes were annotated and screened for putative virulence factors, including genes encoding iron uptake systems, transport systems and non-ribosomal peptide synthetases. Second, comparative genome analysis was performed, focusing on single nucleotide polymorphisms ( SNPs) and small insertions and deletions (InDels). Five V. anguillarum strains showed a remarkably high nucleotide identity. However, these strains comprise both virulent and avirulent strains towards sea bass larvae, suggesting that differences in virulence may be caused by subtle nucleotide variations. Clearly, the draft genome sequence of these 15 strains represents a starting point for further genetic research of this economically important fish pathogen. [ABSTRACT FROM AUTHOR]

Fish diseases can be caused by a variety of diverse organisms, including bacteria, fungi, viruses and protozoa, and pose a universal threat to the ornamental fish industry and aquaculture. The lack of rapid, accurate and reliable means by which fish pathogens can be detected and identified has been one of the main limitations in fish pathogen diagnosis and fish disease management and has consequently stimulated the search for alternative diagnostic techniques. Here, we describe a method based on multiplex and broad-range PCR amplification combined with DNA array hybridization for the simultaneous detection and identification of all cyprinid herpesviruses (CyHV-1, CyHV-2 and CyHV-3) and some of the most important fish pathogenic Flavobacterium species, including F. branchiophilum, F. columnare and F. psychrophilum. For virus identification, the DNA polymerase and helicase genes were targeted. For bacterial identification, the ribosomal RNA gene was used. The developed methodology permitted 100% specificity for the identification of the target species. Detection sensitivity was equivalent to 10 viral genomes or less than a picogram of bacterial DNA. The utility and power of the array for sensitive pathogen detection and identification in complex samples such as infected tissue is demonstrated in this study. [ABSTRACT FROM AUTHOR]

The main objective of this study is to explore possible synergistic or additive effects of combinations of chemical disinfectants (sodium hypochlorite, peracetic acid, hydrogen peroxide, chlorine dioxide) and UV in their efficacy in inactivating free-living bacteria and removing biofilms. In contrast to most studies, this study examines disinfection of municipal water in a pilot-scale system using a mixed bacterial suspension, which enables a better simulation of the conditions encountered in actual industrial environments. It was shown that the combination of either hypochlorite, hydrogen peroxide, peracetic acid, or chlorine dioxide with UV yielded additive effects on the inactivation of free-living bacteria. Actual synergy was observed for the combination of UV and 5 ppm hydrogen peroxide. Regarding biofilm treatment, additive effects were observed using the combination of hydrogen peroxide and UV. The promising results obtained in this study indicate that the combination of UV and chemical disinfectants can considerably reduce the amount of chemicals required for the effective disinfection and treatment of biofilms. [ABSTRACT FROM AUTHOR]

Vibrio anguillarum, also known as Listonella anguillarum, is the causative agent of vibriosis, a deadly haemorrhagic septicaemic disease affecting various marine and fresh/brackish water fish, bivalves and crustaceans. In both aquaculture and larviculture, this disease is responsible for severe economic losses worldwide. Because of its high morbidity and mortality rates, substantial research has been carried out to elucidate the virulence mechanisms of this pathogen and to develop rapid detection techniques and effective disease-prevention strategies. This review summarizes the current state of knowledge pertaining to V. anguillarum, focusing on pathogenesis, known virulence factors, diagnosis, prevention and treatment. [ABSTRACT FROM AUTHOR]

Aims: This study assessed the value of a commercial alkaline solution of hop β-acids (HBA) for prevention of microbial degradation of thick juice, a concentrated intermediate product in the production of beet sugar. Methods and Results: The antimicrobial effect of different concentrations of HBA against microbial degradation of thick juice was tested in a pilot-scale storage experiment. Chemical, biochemical and microbial parameters were monitored during thick juice storage. Thick juice degradation, indicated as a decrease in pH, was generally accompanied by an increase in the count of fastidious bacteria (FB) on Columbia Agar with Sheep Blood (CAwSB), which were mainly identified as Tetragenococcus halophilus. Addition of HBA delayed juice acidification and the development of FB in a concentration-dependent manner. The susceptibility of FB to HBA was determined by plating degraded thick juice (FB > 105 CFU ml−1) on CAwSB plates with different concentrations of HBA (0–160 ppm). None of the HBA concentrations tested reduced the number of FB colonies formed, but increasing HBA concentrations extended the lag time of colony formation. Conclusions: HBA produce no measurable bactericidal effect, but retard the development of FB in thick juice. Moreover, HBA do not prevent the thick juice from deteriorating, but significantly delay its degradation. Significance and Impact of the Study: These results indicate that adding a commercially available HBA formulation can prolong the storage life of thick juice in the sugar industry, although degradation cannot be eliminated. Future research will focus on the detailed characterization of FB consistently isolated from degraded thick juice and on determining their role in thick juice degradation. [ABSTRACT FROM AUTHOR]

Twenty-five Aeromonas hydrophila strains, isolated from freshwater fish and from freshwater samples were identified, using API 20NE and CH50. They were screened for the presence of plasmids. A group of 10 strains was found without plasmids, 11 strains harbored one plasmid (20kb), and a third group (four strains) contained two or three plasmids. A 20kb plasmid was common to all plasmid-positive strains. Although their plasmid profile differs, all groups arc very similar with regard to their biochemical and physiological characterization. However, the differences observed using clustering can be explained by characteristics, some of which have been reported as virulence associated. No relationship between these factors and the presence of plasmids is found. The possibility of differentiating A. hydrophila strains on the basis of biochemical characteristics using a cluster analysis is considered. [ABSTRACT FROM AUTHOR]

Abstract: Characterization of the microflora during malting is an essential step towards process management and optimization. Up till now, however, microbial characterization in the malting process has mostly been done using culture-dependent methods, probably leading to biased estimates of microbial diversity. The aim of this study was to characterize the bacterial communities using two culture-independent methods, including Terminal Restriction Fragment Length Polymorphism (T-RFLP) and 454 pyrosequencing, targeting the 16S rRNA gene. Studied samples originated from two harvest years and two malting houses malting the same batch of barley. Besides targeting the entire bacterial community (T-RFLP), emphasis was put on lactic acid bacteria (LAB) (T-RFLP and 454 pyrosequencing). The overall bacterial community richness was limited, but the community structure changed during the process. Zooming in on the LAB community using 454 pyrosequencing revealed a total of 47 species-level operational taxonomic units (OTUs). LAB diversity appeared relatively limited since 88% of the sequences were covered by the same five OTUs (representing members of Weissella, Lactobacillus and Leuconostoc) present in all samples investigated. Fluctuations in the relative abundances of the dominant LAB were observed with the process conditions. In addition, both the year of harvest and malting house influenced the LAB community structure. [Copyright &y& Elsevier]