Search results for "Water microbiology"
showing 10 items of 94 documents
An indirect immunofluorescent antibody technique for detection and enumeration of Vibrio vulnificus serovar E (biotype 2): delevopment and applicatio…
2000
The applications of an indirect fluorescent antibody technique (IFAT), developed to detect and enumerate the pathogenic bacterium Vibrio vulnificus serovar E from water and clinical samples, are described. This technique proved accurate for detecting V. vulnificus, even under starvation conditions and in the non-culturable state, and could differentiate this species from other bacteria which share the same habitats. The IFAT was successfully used to diagnose vibriosis from naturally- and artificially-infected eels. The overall data suggest that applying this technique properly in environmental and epidemiological/epizootiological studies could significantly increase our knowledge of this ba…
Protocol for Specific Isolation of Virulent Strains of Vibrio vulnificus Serovar E (Biotype 2) from Environmental Samples
2004
ABSTRACT The eel pathogen Vibrio vulnificus biotype 2 comprises at least three serovars, with serovar E being the only one involved in both epizootics of eel vibriosis and sporadic cases of human infections. The virulent strains of this serovar (VSE) have only been recovered from clinical (mainly eel tissue) sources. The main objective of this work was to design and validate a new protocol for VSE-specific isolation from environmental samples. The key element of the new protocol is the broth used for the first step (saline eel serum broth [SEB]), which contains eel serum as a nutritive and selective component. This approach takes advantage of the ability of VSE cells to grow in eel serum an…
Assessment of the ecological status of transitional waters in Sicily (Italy): first characterisation and classification according to a multiparametri…
2010
A 1-year cycle of observations was performed in four Sicilian transitional water systems (Oliveri-Tindari, Cape Peloro, Vendicari and Marsala) to characterise their ecological status. A panel of variables among which trophic and microbial (enzyme activities, abundance of hetetrophic bacteria and of bacterial pollution indicators) parameters, were selected. Particulate organic carbon (POC) and nitrogen (PON) and chlorophyll-. a (Chl-. a) contents defined the trophic state, while microbial hydrolysis rates and abundance gave insights on microbial community efficiency in organic matter transformation and on allochthonous inputs. To classify the trophic state of examined waters, the synthetic t…
Heterotrophic bacteria community and pollution indicators of mussel--farm impact in the Gulf of Gaeta (Tyrrhenian Sea).
2001
Field studies were carried out to determine and compare the impact of organic loads due to the biodeposition of a mussel farm on the water quality and sediment in a coastal area of the Tyrrhenian Sea (Western Mediterranean). A total of five environmental and five microbial parameters were examined from March, 1997 to February, 1998 on a monthly basis at three stations: the first was located under the mussel farm, the second located at about 40 m away from the mussel farm, while the third designed as a control was at about 1-km. No clear changes in the physical characteristics of the water masses were observed, comparing the three sampling sites and the water column generally showed homogene…
A combined molecular typing approach does not discriminate Legionella pneumophila serogroup 1 strains of a predominant sequence-based type in Palermo…
2009
Summary: The sequence-based type 1,4,3,1,1,1 of Legionella pneumophila sg.1 is predominant in the Palermo city environment since several years. In this study, extended sequence-based typing and pulsed field gel electrophoresis were used in a combined approach in the aim to enhance discriminatory power of the molecular typing procedures. However, probably due to a common environmental reservoir and genetic stability, most of the strains circulating in the geographic area under study belong to the same clone and are, consequently, indistinguishable by molecular typing. Investigations of clinical cases and tracing to their environmental source require caution and support from sound epidemiolog…
High affinity iron-uptake systems in Vibrio damsela: role in the acquisition of iron from transferrin
1997
In this work, the high affinity iron-acquisition systems displayed by virulent and avirulent strains of Vibrio damsela have been investigated. This species is an autochthonous member of marine ecosystems that can behave as an opportunistic pathogen for fish and mammals. All strains tested (i) were able to grow under the restricted conditions imposed by the iron chelators transferrin (Tf) and EDDHA, (ii) secreted siderophores of hydroxamic type, other than aerobactin and desferal, that were able to stimulate the growth of the auxotroph mutant Arthrobacter flavescens JG9, and (iii) expressed common iron-regulated outer membrane proteins (IROMPs). No change in LPS patterns was observed in resp…
Siderophores and related outer membrane proteins produced by pseudomonads isolated from eels and freshwater.
1992
A total of 46 environmental pseudomonads, together with six type strains, were examined for their siderophore-producing activity. All strains were able to grow under iron-limiting conditions, gave orange halos in the CAS agar assay, and produced hydroxamates, and some of them also produced phenolate-type compounds. Bioassays showed that all strains, except Pseudomonas aeruginosa, promoted growth of mutant strain Arthrobacter flavescens JG-9, deficient in hydroxamate production, and some of them promoted growth of Salmonella typhimurium enb-1, which requires enterobactin for growth. The presence of iron-regulated outer membrane proteins was observed, the molecular size of the main induced pr…
Siderophore-mediated iron acquisition mechanisms in Vibrio vulnificus biotype 2
1996
Vibrio vulnificus biotype 2 is a primary pathogen for eels and, as has recently been suggested, an opportunistic pathogen for humans. In this study we have investigated the ability of V. vulnificus biotype 2 to obtain iron by siderophore-mediated mechanisms and evaluated the importance of free iron in vibriosis. The virulence degree for eels was dependent on iron availability from host fluids, as was revealed by a reduction in the 50% lethal dose for iron-overloaded eels. This biotype produced both phenolate- and hydroxamate-type siderophores of an unknown nature and two new outer membrane proteins of around 84 and 72 kDa in response to iron starvation. No alterations in lipopolysaccharide …
Iron-binding compounds and related outer membrane proteins in Vibrio cholerae non-O1 strains from aquatic environments
1990
A total of 156 strains of Vibrio cholerae non-O1 from aquatic origins were examined for the presence of iron uptake mechanisms and compared with O1 strains and other Vibrio species. All non-O1 strains were able to grow in iron-limiting conditions, with MICs of ethylenediaminedi (O-hydroxyphenylacetic acid) ranging from 20 microM to 2 mM. The production of siderophores was demonstrated by growth in chrome azurol S agar and cross-feeding assays. All strains produced phenolate-type compounds, as assessed by the chemical tests and by bioassays with Salmonella typhimurium enb-7. Some of the strains also promoted the growth of S. typhimurium enb-1 (which can use only enterobactin as a siderophore…
Cellular, physiological, and molecular adaptive responses of Erwinia amylovora to starvation.
2013
Erwinia amylovora causes fire blight, a destructive disease of rosaceous plants distributed worldwide. This bacterium is a nonobligate pathogen able to survive outside the host under starvation conditions, allowing its spread by various means such as rainwater. We studied E. amylovora responses to starvation using water microcosms to mimic natural oligotrophy. Initially, survivability under optimal (28 °C) and suboptimal (20 °C) growth temperatures was compared. Starvation induced a loss of culturability much more pronounced at 28 °C than at 20 °C. Natural water microcosms at 20 °C were then used to characterize cellular, physiological, and molecular starvation responses of E. amylovora. Ch…