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This study aimed to evaluate the effect of different forms of artificially salinized on the zootechnical performance, bacterial counts in shrimp gut, and proximate composition of Penaeus vannamei in the grow-out phase in a synbiotic system. Four treatments in triplicate using a completely randomized design were established: SD — seawater diluted, LCSM — low-cost salt mixture, CS — commercial salt mixture, and SW — seawater were evaluated during 60 days in experimental tanks with 416 shrimp m−3. The values of calcium, magnesium, and total hardness remained above 35, 90, and 400 mg L−1, respectively. The main ions tended to increase along the culture, especially potassium, which caused a reduction in the Na:K ratio, providing values below 10:1, adding to total alkalinity values below 100 mg CaCO3 L−1 that may have reduced survival in low salinity treatments. The different forms of artificially salinized did not influence the final weight and specific growth rate; however, yield, FCR and survival were lower in low-salinity as compared to seawater. There was no influence of the different forms of artificially salinized on TCBS and MYP bacterial count values, shrimp proximate composition, and microbial floc. Based on the results obtained, it can be concluded that to improve survival and FCR, it is necessary to adjust the Na:K ratio, as well as increase total alkalinity levels throughout the culture time to rear P. vannamei in higher stocking densities in artificially salinized low-salinity water. [ABSTRACT FROM AUTHOR]

Coastal water quality assessment is important to maintain a healthy environment for various uses including fisheries and recreation. Microbial populations are used as biological indicators of contamination to monitor water quality and are considered by the government to be one of the critical features for issuing safety guidelines. Different bacterial groups (pathogenic, vibrio and faecal) from five major recreational beaches of Chennai, India, were monitored for the assessment of coastal water quality. Faecal coliforms (FC) were high at all the beaches, with up to 4.2 × 105 CFU/mL and exceeding the normal standard limits of 100 CFU/100 mL set by the Central Pollution Control Board (CPCB) of India. Rainfall was found to have a role in the variability and distribution of indicator and pathogenic bacteria. The seasonal dry period witnessed elevated FC, while dilution in the wet period reduced Escherichia coli–like organisms (ECLO). High microbial counts were detected near the beach situated close to the river mouth, mainly due to discharges of untreated domestic sewage and industrial wastes. Similarly, the biological oxygen demand (BOD) was also high, 0.32 to 10.32 mg/L. Dissolved inorganic nitrogen (DIN) ranged from 2.21 to 134.53 μmol/L and inorganic phosphate (IP) ranged from 0 to 57.53 μmol/L. These values indicated the presence of significant untreated sewage in the coastal water. This study revealed that Chennai coastal waters carry high levels of faecal and pathogenic bacteria, detrimental for recreational and other contact activities. The quantitative and qualitative analyses will be useful for modelling and prediction of coastal water quality and management of other recreational beaches in India. [ABSTRACT FROM AUTHOR]

Marine Streptomyces sp. isolate S073 was shown to have strong antagonistic activity towards the pathogenic Vibrio parahaemolyticus using the agar diffusion method. The antagonistic substance(s) secreted into the supernatant was thermostable and non-proteinaceous in nature. S073 was found to produce carboxylate-type siderophores during most of its life cycle using a chrome azurol S assay. The antagonistic activity of S073 was mostly attributed to its higher ability to compete for iron compared with that of V. parahaemolyticus, as deduced from siderophore quantification. Iron supplementation studies indicated that additional mechanisms besides iron competition were simultaneously involved in governing the observed inhibition. Co-culture analysis indicated that S073, although disadvantaged in growth rate, was still competitive in inhibiting vibrios. The promising potential of S073 development as a biocontrol agent in aquaculture was discussed. [ABSTRACT FROM AUTHOR]

Rapid growth of shrimp farming industry is affected by the recurrence of diverse diseases, among which vibriosis is predominant. Eco-friendly disease management strategy by the application of antagonistic probiotics is widely accepted. In the present study, culture conditions of antagonistic probiotics, Pseudomonas MCCB 102 and 103, were optimized to enhance their biomass production and antagonistic activity against the shrimp pathogen V. harveyi MCCB 111. Primarily, one-dimensional screening was carried out to fix the optimum range of sodium chloride concentration, pH and temperature. The second step optimization was done using a full-factorial central composite design of response surface methodology. As per the model, 12.9 g/L sodium chloride and pH 6.5 for Pseudomonas MCCB 102, and 5 g/L sodium chloride and pH 7 for Pseudomonas MCCB 103 were found to be ideal to maximize antagonistic activity. However, optimum temperature was the same (25 °C) for both isolates. Finally, the models were experimentally validated for enhanced biomass production and antagonistic activity. The optima for biomass and antagonistic activity were more or less the same, suggesting the possible influence of biomass on antagonistic activity. [ABSTRACT FROM AUTHOR]

Microorganisms play an indispensable role in the ecological functioning of marine environment. Some species are sensitive while others are insensitive for a specific pollutant. The aim of this work is a preliminary study of the quantitative and qualitative distribution of cultivable vibrios in sediments and water samples characterized by different toxicity levels. For 1 year, in three suitably selected sampling stations of Mar Piccolo in Taranto (Ionian Sea, Italy), we have evaluated the toxicity level by Microtox® system, vibrios, total, and fecal coliform densities. The results of the Microtox® tests showed sediments characterized by an elevated level of toxicity, while the interstitial water of the same sites always showed biostimulatory phenomenon. The quantitative results show that vibrios and coliforms are more abundant in water than in sediment samples. The most often isolated strains were: Vibrio alginolyticus, Vibrio mediterranei, Vibrio metschinkovii, and Vibrio splendidus II. This work is the first example of study on the distribution of Vibrio species related to toxicity evaluation conducted by the Microtox® bioassay. The results show the different distribution of Vibrionaceae in two environmental matrices analyzed and characterized by different levels of toxicity. [ABSTRACT FROM AUTHOR]

Analysis of conditions of formation of microplanktonic microbial communities (MC) was carried out for the Pechora Sea using the data of winter 2002-2005. The patterns of distribution of different MC groups in different water types are discussed. Regular variations of the indices of abundance in a gradient of physicochemical variables were revealed. The estimated average bacterial numbers for under-ice conditions were 234 × 10 cells/mL, with the average cell volume of 0.58 μm and total cell area ∼550 mm/L. The estimated total microbial biomass in the 0-25 m water horizon of the Pechora Sea is 187 × 10 g wet biomass. [ABSTRACT FROM AUTHOR]

Some bacteria produce a satellite RNA-DNA complex termed msDNA, multicopy single-stranded DNA. In this report, msDNA from Vibrio parahaemolyticus, a cause of acute gastroenteritis, was identified and named msDNA-Vp96. The retron element containing the ret gene, encoding the reverse transcriptase (RT) that is responsible for msDNA production, was cloned and characterized. Comparison of msDNA-Vp96 and msDNA-Vc95, from Vibrio cholerae, showed a high level of sequence similarity. We exchanged the two ret genes to examine whether msDNA was produced by the RT from different sources. We found that RT-Vp96 of V. parahaemolyticus was able to synthesize msDNA-Vc95 of V. cholerae and vice versa. To the best of our knowledge, this is the first report that RT from different bacterial species can synthesize msDNA. [ABSTRACT FROM AUTHOR]

Vibrios are highly motile, facultatively anaerobic bacteria that are ubiquitous in aquatic environments and part of the normal intestinal microflora of healthy fish, but some species can cause vibriosis. The adherence of vibrios to host fish intestines is a significant event not only for their survival and growth, but also in terms of pathogenicity. However, the molecular mechanism underlying the adhesion of vibrios to the intestinal tract of fish is not fully understood. We report here the identification of intestinal glycosphingolipid (GSL) receptors to which pathogenic vibrios attach in typical mariculture fish. Thin-layer chromatography overlay assays using five species of S-labeled vibrios and intestinal glycosphingolipids of seven species of mariculture fish revealed that all of the fish tested possessed GM3 (NeuAcα2-3Galβ1-4Glcβ1-1′Cer) and/or GM4 (NeuAcα2-3Galβ1-1′Cer) as major acidic intestinal GSLs and that all of the vibrios tested specifically adhered to GM3 and/or GM4. Our results demonstrate that these GSLs were able to function as a receptor for the various vibrios tested. Analysis of the relationship between sugar structure and receptor activity for vibrios revealed that 'NeuAcα2-3Galβ1-' is required at the non-reducing end of glycosphingolipids for the bacteria to attach. [ABSTRACT FROM AUTHOR]

Wetland dynamics are probably linked to cholera endemicity in South Asia. We focus on links between Vibrio cholerae abundance, chitin content and suspended particle load in size fractions of suspended particulate matter (SPM) along the salinity gradient of Sunderban mangrove waters. SPM decreased downstream, while salinity increased from 0.2 to 4. Particulate organic carbon (90 ± 25 μM) and nitrogen (9.1 ± 3.3 μM) highly correlated with SPM and turbidity, suggesting a significant contribution of fine particles to organic matter. Total chitin ranged 1-2 mg/l and decreased downstream. The distribution among size fractions of SPM, chitin and V. cholerae O1 (the bacterial serogroup mainly associated with cholera epidemics) was similar, with ~98% of the total in the fraction <20 μm. In comparison, the number of V. cholerae O1 attached to zooplankton and microplankton size classes >20 μm was almost negligible, in contrast to usual assumptions. Thus, microdetritus, nanoplankton and fungal cells in size classes <20 μm represent a chitinaceous substrate on which V. cholerae can grow and survive. Total bacteria, cultivable vibrios and V. cholera O1 increased 5-10 times downstream, together with salinity and nitrite concentration. Overall, nitrate and silicate concentrations were relatively constant (>22 μM N and 100 μM Si). However, nitrite increased ~9 times in the outer sector, reaching ~1.2 μM N, probably as a result of increased abundance of nitrate-reducing vibrios. A characterization of Vibrio habitats that takes account of the presence of nitrate-reducing bacteria could improve the understanding of both mangrove nitrogen cycling and cholera seasonality. [ABSTRACT FROM AUTHOR]

The enzymatic hydrolysis of chitin has been studied for almost a century, and early work established that at least two enzymes are required, a chitinase that mainly yields the disaccharide N,N'-diacetylchitobiose, or (GlcNAc), and a 'chitobiase', or β-N-acetylglucosaminidase, which gives the final product GlcNAc. This pathway has not been completely identified but has remained the central concept for the chitin catabolism through the 20 century including in marine bacteria. However, the chitin catabolic cascade is quite complex, as described in this review. This report describes three biologically functional genes involved in the chitin catabolic cascade of Vibrios in an attempt to better understand the metabolic pathway of chitin. [ABSTRACT FROM AUTHOR]

The marine bacterium Vibrio fluvialis NCTC11328 responded to nutrient depletion by a reduction in cell volume, and this was prevented by conditions that eliminated respiration as a source of energy. Addition of the protonophore, CCCP, removal of oxygen and introduction of mutations leading to defects of the respiratory chain prevented size reduction during periods of nutrient limitation. Further, survival of the wild-type strain during starvation was reduced under anaerobic conditions and survival of respiratory mutants under aerobic conditions was reduced compared with that of the parent strain. Removal by mutation of the respiratory Na pump from Vibrio alginolyticus did not inhibit size reduction or lead to reduced viability in starved cultures. [ABSTRACT FROM AUTHOR]