Showing papers on "Halomonas published in 2003"
TL;DR: Although most culture collection strains are not able to produce hydrolases, it has been shown that environmental isolates can produce these potentially biotechnological important enzymes.
Abstract: C. S ANCHEZ-PORRO, S. M ARTIN , E. M E L L A D O A N D A. V E N T O S A. 2003. Aims: The aim of this study was to determine the diversity of moderately halophilic bacteria with hydrolase activities. Methods and Results: Screening bacteria from different hypersaline environments in South Spain led to the isolation of a total of 122 moderately halophilic bacteria able to produce different hydrolases (amylases, DNases, lipases, proteases and pullulanases). These bacteria are able to grow optimally in media with 5-15% salts and in most cases up to 20-25% salts. In contrast to strains belonging to previously described species, that showed very little hydrolase activities, environmental isolates produced a great variety of hydrolases. These strains were identified as members of the genera: Salinivibrio (55 strains), Halomonas (25 strains), Chromohalobacter (two strains), Bacillus-Salibacillus (29 strains), Salinicoccus (two strains) and Marinococcus (one strain), as well as eight non- identified isolates. Conclusions: Moderately halophilic bacteria are a source of hydrolytic enzymes such as amylases, DNases, lipases, proteases and pullulanases. Significance and Impact of the Study: Although most culture collection strains are not able to produce hydrolases, it has been shown that environmental isolates can produce these potentially biotechnological important enzymes.
267 citations
TL;DR: Mauran is an anionic, sulfated heteropolysaccharide with a high uronic-acid content, synthesized by strain S-30 of the halophilic bacterium Halomonas maura, capable of producing up to 3.8 g of mauran per liter of medium under optimum environmental and nutritional conditions.
Abstract: Mauran is an anionic, sulfated heteropolysaccharide with a high uronic-acid content, synthesized by strain S-30 of the halophilic bacterium Halomonas maura Under optimum environmental and nutritional conditions, it is capable of producing up to 38 g of mauran per liter of medium Aqueous solutions of mauran are highly viscous and display pseudoplastic, viscoelastic and thixotropic behavior Its viscosity is stable over a wide pH range (3–11), after freezing-thawing processes, and in the presence of sucrose, salts, surfactants and α-hydroxyl acids It has a high capacity for binding lead and other cations Its molecular mass when collected from an MY medium supplemented with 25% w/v salt during the stationary growth phase is 47×106 Da
183 citations
TL;DR: Overall, the spatial association between spores and bacteria appears to be independent of the overall quantitative influence of bacterial cells on spore settlement.
Abstract: Summary Previous studies have shown that the rate of settle- ment of zoospores of the green alga Enteromorpha is stimulated by mixed microbial biofilms and that the number of zoospores settling is positively correlated with the number of bacteria in the biofilm In the present study the specificity of this relationship has been investigated Ninety-nine strains of marine bac- teria were isolated from natural biofilms on rocks and the surface of Enteromorpha plants Isolates were screened by denaturing gradient gel electrophoresis (DGGE) to eliminate replicates and 16S rDNA sequencing identified a total of 37 unique strains Phylogenetic analysis revealed that the isolated bac- terial strains belonged to three groups g - Proteobacte- ria (28 strains), Cytophaga-Flavobacteria-Bacteroid (CFB) group (six strains) and a - Proteobacteria (one strain) Two strains were unassigned, showing < < < 93% sequence similarity with the CFB group The main genera of g - Proteobacteria were Pseudoalteromonas (14 strains), Vibrio (five strains), Shewanella (five strains), Halomonas (three strains) and Pseudomo- nas (one strain) Spore settlement experiments were conducted on single-species biofilms, developed for different times on glass slides The effect of correct- ing spore settlement values for biofilm density was evaluated Results showed that the effect of bacterial strains on spore settlement was strain- but not taxon- specific and activity varied with the age of the biofilm However, most of the strains belonging to genera Vibrio and Shewanella showed stimulation Pseudoalteromonas strains showed a range of effects including settlement-inhibiting, paralysing and lysing activities Spatial analysis of bacterial density in the presence and absence of spores revealed a range of different types of association between spores and bacteria Overall, the spatial association between spores and bacteria appears to be independent of the overall quantitative influence of bacterial cells on spore settlement
167 citations
TL;DR: It was observed that DD 39 formed a robust cluster with H. variabilis, and it is proposed thatDD 39 should be placed in the genus Halomonas as a new species that isHalomonas glaciei.
Abstract: Eleven psychrophilic bacteria were isolated from a solid layer of fast ice in the middle of Pointe-Geologie Archipelago, Adelie Land, Antarctica. The 11 isolates based on the phenotypic characteristics, chemotaxonomic and phylogenetic analysis have been identified as members of the genus Halomonas. All the isolates at the 16S rDNA sequence level were identical, possessed the 15 conserved nucleotides of the family Halomonadaceae and four nucleotides of the genus Halomonas. Therefore, the 16S rDNA sequence of DD 39 was used for calculating the evolutionary distances and for phylogenetic analysis. It was observed that DD 39 formed a robust cluster with H. variabilis, from which it differed by 0.7%. Further DNA–DNA hybridization studies indicated low DNA–DNA homology (15%) between H. variabilis and DD 39. Between the 11 Antarctic isolates the homology was >85%. In addition it was observed that DD 39 was different from H. variabilis in that it was psychrophilic, could tolerate only up to 15% sodium chloride, could not hydrolyse esculin, could not reduce nitrate, was urease negative, could not utilize glycerol as a carbon source, and was resistant to ampicillin and erythromycin and sensitive to nalidixic acid. In addition, it also exhibited distinct differences with respect to high content of C16:1 and low levels of cyclo-C17:0 and cyclo-C19:0. DD 39 also differed from all the other reported species of Halomonas with respect to many phenotypic characteristics. It is proposed therefore that DD 39 should be placed in the genus Halomonas as a new species that is Halomonas glaciei. The type strain of H. glaciei is DD 39T (MTCC 4321; JCM 11692).
55 citations
TL;DR: A very high requirement for chloride was demonstrated in two groups of Bacteria that accumulate inorganic salts intracellularly rather than using organic osmotic solutes: the anaerobic Halanaerobiales and the aerobic extremely halophilic Salinibacter ruber.
Abstract: While much understanding has been achieved on the intracellular sodium and potassium concentrations of halophilic and halotolerant microorganisms and on their regulation, we know little on the metabolism of anions. Archaea of the family Halobacteriaceae contain molar concentrations of chloride, which is pumped into the cells by cotransport with sodium ions and/or using the light-driven primary chloride pump halorhodopsin. Most halophilic and halotolerant representatives of the bacterial domain contain low intracellular ion concentrations, with organic osmotic solutes providing osmotic balance. However, some species show a specific requirement for chloride. In Halobacillus halophilus certain functions, such as growth, endospore germination, motility and flagellar synthesis, and glycine betaine transport are chloride dependent. In this organism the expression of a large number of proteins is chloride regulated. Other moderately halophilic Bacteria such as Halomonas elongata do not show a specific demand for chloride. A very high requirement for chloride was demonstrated in two groups of Bacteria that accumulate inorganic salts intracellularly rather than using organic osmotic solutes: the anaerobic Halanaerobiales and the aerobic extremely halophilic Salinibacter ruber. It is thus becoming increasingly clear that chloride has specific functions in haloadaptation in different groups of halophilic microorganisms.
48 citations
TL;DR: This study demonstrates that aerobic heterotrophs, which are phy- logenetically affiliated to genera such as Rhodobacter, Roseobacteria, Marinobacter and Halomonas, are important in hypersaline microbial mats, and that their specific in situ role in the carbon cycle needs to be further investigated.
Abstract: Aerobic heterotrophic bacteria inhabiting microbial mats play an important role in carbon-cycling, yet information about their identity is scarce. We used the most probable number technique combined with denaturing gradient gel electrophoresis (DGGE) to identify apparent numerically important populations of aerobic heterotrophic bacteria in a hypersaline microbial mat. At high dilutions, populations related to the genera Rhodobacter and Roseobacter and to the genera Marinobacter and Halomonas dominated glycolate and yeast extract-amended enrichment cultures respectively. Three selected isolates of aerobic heterotrophic bacteria were obtained from glycolate- amended enrichments and found to relate phylogenetically to species of the genus Roseobacter. These strains were found to grow, in addition to glycolate, on several other photosynthetic compounds known to be produced by cyanobacteria suggesting that they specialize in mineralizing photosynthetic excretion products. Our study demonstrates that aerobic heterotrophs, which are phy- logenetically affiliated to genera such as Rhodobacter, Roseobacter, Marinobacter and Halomonas, are important in hypersaline microbial mats, and that their specific in situ role in the carbon cycle needs to be further investigated.
42 citations
TL;DR: Morphological, physiological and genotypic differences from these previously described genera support the description of a novel genus and species, Saccharospirillum impatiens gen. nov, in the gamma-Proteobacteria.
Abstract: Five Gram-negative, motile, aerobic to microaerophilic spirilla were isolated from various depths of the hypersaline, heliothermal and meromictic Ekho Lake (East Antarctica). The strains are oxidase- and catalase-positive, metabolize a variety of sugars and carboxylic acids and have an absolute requirement for sodium ions. The predominant fatty acids of the organisms are C16 : 1v7c ,C 16 : 0 and C18 : 1v7c, with C10 : 1 3-OH, C10 : 0 3-OH, C12 : 0 3-OH, C14 : 1 3-OH, C14 : 0 3-OH and C19 : 1 present in smaller amounts. The main polar lipids are diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylmonomethylamine. The DNA base composition of the strains is 54–55 mol% G+C. 16S rRNA gene sequence comparisons show that the isolates are related to the genera Oceanospirillum, Pseudospirillum, Marinospirillum, Halomonas and Chromohalobacter in the c-Proteobacteria. Morphological, physiological and genotypic differences from these previously described genera support the description of a novel genus and species, Saccharospirillum impatiens gen. nov., sp. nov. The type strain is EL-105 T (=DSM 12546 T =CECT 5721 T ).
32 citations
TL;DR: It is discovered that many Halomonas species harbour large extrachromosomal DNA elements and the common presence of these megaplasmids may well be related to the survival strategies of the bacteria in their special surroundings.
Abstract: We have discovered that many Halomonas species harbour large extrachromosomal DNA elements. Using currently available protocols it is technically very difficult to identify large plasmids in bacteria, and even more so when they are coated in mucous polysaccharide. We used culture conditions suitable for both halophilic and halophilic exopolysaccharide-producing bacteria and applied a modified gel electrophoresis method to locate and visualise the megaplasmids. Almost all the species of Halomonas studied harbour two plasmids of about 70 kb and 600 kb and some species carry other smaller extrachromosomal DNA elements. The common presence of these megaplasmids may well be related to the survival strategies of the bacteria in their special surroundings.
22 citations
TL;DR: The cloning and characterization of the carAB genes, which encode carbamoylphosphate synthetase in Halomonas eurihalina, are described and discussed, and this enzyme's possible role in the pathways for the synthesis of exopolysaccharides in strain F2–7 is discussed.
Abstract: Halomonas eurihalina is a moderately halophilic bacterium which produces exopolysaccharides potentially of great use in many fields of industry and ecology. Strain F2–7 of H. eurihalina synthesizes an anionic exopolysaccharide known as polymer V2–7, which not only has emulsifying activity but also becomes viscous under acidic conditions, and therefore we consider it worthwhile making a detailed study of the genetics of this strain. By insertional mutagenesis using the mini-Tn5 Km2 transposon we isolated and characterized a mutant strain, S36 K, which requires both arginine and uracil for growth and does not excrete EPS. S36 K carries a mutation within the carB gene that encodes the synthesis of the large subunit of the carbamoylphosphate synthetase enzyme, which in turn catalyzes the synthesis of carbamoylphosphate, an important precursor of arginine and pyrimidines. We describe here the cloning and characterization of the carAB genes, which encode carbamoylphosphate synthetase in Halomonas eurihalina, and discuss this enzyme's possible role in the pathways for the synthesis of exopolysaccharides in strain F2–7.
17 citations
TL;DR: Cloning of the ndk gene of nucleoside diphosphate kinase from a moderately halophilic eubacterium and overexpression of the protein in E. coli as an N-terminal hexa-His fusion to facilitate its purification on Ni-NTA affinity resin demonstrate evidence that the protein is properly folded and exhibits the same specific activity and stability as the native protein from Halomonas cells.
7 citations
Journal Article•
TL;DR: Results showed that the two strains isolated from the salt of some sea products from Qingdao possessed the features of the genus Halomonas, but some of them were not identical to those of the classical species of this genus, suggesting that they may be new species ofThis genus.
Abstract: Physiological and biochemical analysis of two Halomonas species CM1 and CM4,which were isolated from the salt of some sea products from Qingdao,was carried out and the results showed that the two strains possessed the features of the genus Halomonas, but some of them were not identical to those of the classical species of this genus,suggesting that they may be new species of this genus.Further comparison of the two strains showed that the two strains may use different evolution stability strategy(ESS) to adapt to their specially high NaCl concentration environment.That is to say,CM1 used K strategy while CM4 used r strategy and ESS was expanded to the asexual bacteria.