Aims:  The aim of the study was to evaluate the in vitro antibacterial activity of glucosinolates and their enzymatic hydrolysis product against bacteria isolated from the human intestinal tract. Methods and results:  Using a disc diffusion bioassay, different doses of intact glucosinolates and their corresponding hydrolysis products were tested. There were clear structure–activity and concentration differences with respect to the in vitro growth inhibition effects as well as differences in the sensitivities of the individual bacteria. The most effective glucosinolate hydrolysis products were the isothiocyanates; sulforaphane and benzyl isothiocyanate were the best inhibitors of growth. Indole‐3‐carbinol had some inhibitory effects against the Gram‐positive bacteria but had no effect, even at the highest dose, against the Gram‐negative bacteria. Indole‐3‐acetonitrile had some inhibitory activity against the Gram‐negative bacteria. Glucosinolates, nitriles and amines were ineffective at all the doses used. Conclusions:  Glucosinolate hydrolysis products and specifically the isothiocyanates SFN and BITC have significant antimicrobial activity against Gram‐positive and Gram‐negative bacteria, and might be useful in controlling human pathogens through the diet. Significance and Impact of the Study:  This the first major in vitro study demonstrating the potential of these natural dietary chemicals as an alternative to, or in combination with, current antibiotic‐based therapies for treating infectious diseases.

During a survey to determine the prevalence of Aeromonas strains in water and skin of imported ornamental fish, 48 strains presumptively identified as Aeromonas were isolated but they could not be identified as members of any previously described Aeromonas species. These strains were subjected to a polyphasic approach including phylogenetic analysis derived from gyrB, rpoD and 16S rRNA gene sequencing, DNA-DNA hybridization, MALDI-TOF MS analysis, genotyping by RAPD and extensive biochemical and antibiotic susceptibility tests in order to determine their taxonomic position. Based on the results of the phylogenetic analyses and DNA-DNA hybridization data, we describe a novel species of the genus Aeromonas, for which the name Aeromonas aquariorum sp. nov. is proposed, with strain MDC47 T (5DSM 18362 T 5CECT 7289 T ) as the type strain. This is the first Aeromonas species description based on isolations from ornamental fish.Species of Aeromonas are common inhabitants of aquatic environments and have been described in connection with fish and human diseases (Altwegg, 1999;Austin & Adams, 1996;Saavedra et al., 2004;Figueras, 2005). Apart from the psychrophilic suspected fish pathogen Aeromonas salmonicida, many other mesophilic aeromonads are considered to be opportunistic pathogens, capable of producing infections in weakened fish or as secondary invaders in fish populations suffering from other diseases (Camus et al., 1998). Given the large numbers of ornamental fish imported from areas of the world where sanitation is often inadequate and where numerous diseases of man are endemic, it is surprising that little consideration has been given to the role of these aquarium species as vectors of potential pathogens for man. When the occurrence of bacterial pathogens in ornamental fish has been investigated, Aeromonas strains were found in more than 50 % of fish disease cases examined by Kuo & Chung (1994) and were involved in 18 of 23 bacterial disease outbreaks investigated by Hettiarachchi & Cheong (1994). Moreover, noticeable antibiotic resistance has been detected in Aeromonas strains isolated from ornamental fish (Dixon & Issvoran, 1992).The genus Aeromonas belongs to the family Aeromonadaceae (Colwell et al., 1986;Martínez-Murcia et al., 1992a; Yáñez et al., 2003). According to the last edition of Bergey's Manual of Systematic Bacteriology (Martin-Carnahan & Joseph, 2005), the genus comprises the species Aeromonas hydrophila, A. bestiarum, A. salmonicida, A. caviae, A. media, A. eucrenophila, A. sobria, A. veronii (biovars Sobria and Veronii), A. jandaei, A. schubertii, A. trota, A. allosaccharophila, A. encheleia and A. popoffii and two DNA homology groups, Aeromonas sp. HG11 and Aeromonas sp. HG13 (formerly enteric group 501), which remain without a species name. Furthermore, Aeromonas ichthiosmia (Schubert et al., 1990b) and Aeromonas enteropelogenes (Schubert et al., 1990a) are now considered synonyms of A. veronii and A. trota, respectively (Carnahan, 1993;Collins et al., 1993;Huys et al., 2001Huys et al., ,...

Aims:  The aim of the study was to evaluate the in vitro antibacterial effects of glucosinolate hydrolysis products (GHP) against plant pathogenic micro‐organisms namely Agrobacterium tumefaciens, Erwinia chrysanthemi, Pseudomonas cichorii, Pseudomonas tomato, Xanthomonas campestris and Xanthomonas juglandis. Methods and Results:  Using a disc diffusion assay, seven different doses of 10 GHP were tested against each bacteria. The results showed that the isothiocyanates were potent antibacterials, whilst the other GHP were much less efficient. Moreover, the antibacterial effects were dose‐dependent, increasing with the dose applied; 2‐phenylethylisothiocyanate and sulforaphane showed the strongest inhibitory effects. The overall results show a great potential for using the isothiocyanates as an alternative tool to control undesired bacterial growth in plants. Conclusions:  Glucosinolate hydrolysis products and more specifically the isothiocyanates: benzylisothiocyanate, 2‐phenylethylisothiocyanate, the isothiocyanate Mix and sulforaphane, were effective phytochemicals against the in vitro growth of the phytopathogenic bacteria. The antibacterial activity exhibited by these phytochemicals reinforces their potential as alternatives to the traditional chemical control of phytopathogenic bacteria. Significance and Impact of the Study:  This current in vitro study is the first providing comparative data on GHP as potential control agents for plant pathogenic bacteria. However, more studies are needed to determine their possible allelopathic impacts e.g. inhibition of plant growth and negative effects on beneficial soil bacteria and fungi (mycorrhizae).

The potential risk of occurrence of new diseases associated with the trade of live animals is well known. However, little importance is still given to the problematic of the dissemination of resistance genes that pass along with the animal trade. In this study we aimed to isolate Aeromonas spp. strains from water and skin of ornamental fish and test their resistance to antibiotics. The samples were collected from a national ornamental fish importer, with the intent of obtaining a collection of Aeromonas strains. The identification of the strains was made by gyrB and rpoD gene sequencing. A total of 288 strains grouped in seven different species -Aeromonas veronii, Aeromonas media, Aeromonas jandaei, Aeromonas hydrophila, Aeromonas caviae, Aeromonas culicicola, Aeromonas aquariorum, were isolated. The susceptibility profile was determined for 28 antibiotics commonly used. All the strains presented multi-resistance to the tested antibiotics. The antibiotic susceptibility profile to tetracycline, ticarcillin, carbenicillin, ampicillin and erythromycin revealed resistance levels of more than 80%. Few strains resistant to aztreonam and imipenem were identified. On the other hand, all were sensitive to cefotaxime and cefepime. The results show that these Aeromonas spp. strains are potentially reservoirs of antibiotic resistance genes.