A. del Moral

Halomonas maura sp. nov., a novel moderately halophilic, exopolysaccharide-producing bacterium

Four moderately halophilic, exopolysaccharide-producing bacterial strains isolated from soil samples collected from a saltern at Asilah (Morocco) are reported. These four strains were initially considered to belong to the genus Halomonas. Their DNA G+C contents varied between 62.2 and 64.1 mol %. DNA-DNA hybridization revealed a considerable degree of DNA-DNA similarity amongst all four strains (75.5-80.8%). Nevertheless, similarity with the reference strains of phylogenetically close relatives was lower than 40%. 16S rRNA gene sequences were compared with those of other species of Halomonas and other gram-negative bacteria and they were sufficiently distinct phylogenetically from other recognized Halomonas species to warrant their designation as a novel species. The name Halomonas maura sp. nov. is therefore proposed, with strain S-31T (= CECT 5298T= DSM 13445T) as the type strain. The fatty acid composition of strain S-31T revealed the presence of 18:1omega7c, 16:1omega7c/2-OH i15:0 and 16:0 as the major components. Growth rate analysis showed that strain S-31T had specific cationic requirements for Na+ and Mg2+.

Precipitation of carbonates by Bacillus sp. isolated from saline soils

We studied carbonate precipitation by 26 moderately halophilic strains of Bacillus isolated from a saline soil, haplic Solonchac. They were cultured in both solid and liquid media with salt concentrations varying between 2.5% and 20% (w/v). Bacillus sp. formed mineral crystals in all the media tested, although the mineral precipitation diminished as salinity increased. The minerals that were precipitated included magnesium calcite, aragonite, monohydrocalcite, and dolomite, in varying proportions depending upon the growth medium used. We studied the morphology of the bioliths by means of scanning electron microscopy. We compared our results with those obtained using other taxonomic groups of moderately halophilic bacteria. We discuss possible mechanisms for formation of these biominerals and the probability of their formation in natural habitats.

Formation of calcium carbonate crystals by moderately halophilic bacteria

Abstract Production of calcium carbonate by moderately halophilic bacteria was investigated. The crystalline structures were identified by x‐ray diffraction analysis. The results showed that the CaCO3 formation was a general phenomenon for moderately halophilic bacteria and the different salt concentrations in the growth medium were an important factor in the characteristics of crystals formed.

Distribution and types of bacteria isolated from an inland saltern

The physico-chemical characteristics and bacterial populations of an inland saltern were studied. The well water leading into the ponds of the saltern differed from sea water in its total salinity (18% (w/v)) and had lower Mg2+ and SO4(2-) contents and much higher contents of Cl-, Ca2+- and K+. A high proportion of halotolerant microorganisms were isolated, although marine bacteria were not found. Most of the halophilic strains isolated appeared to be typical moderate halophiles, and included six groups: Vibrio (39%), Deleya-Pseudomonas (28%), Acinetobacter (6.5%), Flavobacterium (6.5%), Paracoccus (1.5%), Planococcus (1.5%) and non-classified (17%). All extreme halophiles could be assigned to Halobacterium (31%) and Halococcus (68%).

Numerical taxonomy of moderately halophilic Gram-negative rods isolated from the salar de Atacama, Chile

Summary A total of 161 moderately halophilic Gram-negative rods isolated from The Salar de Atacama, Northern Chile, were examined for 119 phenotypic characters including morphological, physiological, biochemical, nutritional and antimicrobial susceptibility tests. The results together with those from reference strains, were subjected to numerical analysis, using both, the Simple Matching (S SM ) and Jaccard (S J ) coefficients and clustered by the unweighted pair group method of association (UPGMA). Using the S SM coefficient and UPGMA clustering, five phenons were obtained at a 70% similarity level. Representative strains from each phenon were chosen to determine DNA base composition and cellular morphology by electron microscopy. Strains in phenon A were assigned to the genus Vibrio . Strains in the other four phenons could not be assigned to any recognised taxon but their similarities to the genera Acinetobacter (phenon B), Marinomonas (phenon C) and Alteromonas (phenons D and E) are discussed.

Numerical Taxonomy of Moderately Halophilic Gram-negative Rods from an Inland Saltern

SUMMARY: A total of 174 moderately halophilic bacteria was isolated from an inland saltern with athalassohaline characteristics, located in La Mala, Granada, Spain. The results of 118 phenotypic tests were submitted to a numerical analysis with ten reference strains using simple matching (SSM ) and Jaccard (SJ ) coefficients. Clustering was done by the unweighted pair-group method of association (UPGMA), single linkage and complete linkage analysis. Five phenons were found at the 67% similarity level (SSM ). Phenon A included 74 strains assigned to Vibrio; 22 bacteria belonging to phenon B were assigned to the genus Alteromonas; strains of phenon C were assigned to Deleya (43 strains) and Acinetobacter (7 strains); phenon D resembled Pseudomonas (13 strains); phenon E could be related to Flavobacterium oceanosedimentum (9 strains).

Comparative methods for isolation of Volcaniella eurihalina exopolysaccharide

The best isolation procedure to obtain the EPS of Volcaniella eurihalina was centrifugation at 36,000 x g for 60 min and precipitation with cold ethanol after tangential filtration with 100,000 D ultrafilters. Ion chromatography showed that this EPS contained glucose, rhamnose and mannose in a molar ratio of 3.2: 1.1:1, respectively.

Growth rate and some physiological features of Deleya halophila CCM 3662 at different salt concentrations

The growth rate of the type strain of the new, moderately halophilic species Deleya halophila (Deleya halophila CCM 3662) at different salt concentrations was determined and its optimal marine salt concentration for growth was established. Oxygen uptake and some cellular chemical composition characteristics of cells grown at their optimal salt concentration (7.5% w/v) and at a higher concentration (15% w/v) were compared, showing that both protein and carbohydrate intracellular contents decreased when the external medium salt concentration was increased, with the carbohydrate content reaching 50% of the value presented by cells cultured at optimal salinity conditions. Oxygen uptake and poly-beta-hydroxybutyric acid content were not significantly affected by changes in external salinity.

Taxonomic Study of Moderately Halophilic Gram-positive Endospore-forming Rods

Summary A taxonomic study has been carried out with 24 strains of moderately halophilic endospore-forming rods and 12 related Bacillus species. Phenotypic characteristics were analyzed by numerical taxonomy. Using Ssm and unweighted pair group method of association (UPGMA), two phenons were obtained at 67.6% of similarity level. Guanine plus cytosine (G + C) content ranged from 38.9 to 45.0 (mol%) in phenon A and from 35.0 to 47.0 (mol%) in phenon B. The results of DNA-DNA hybridization among the isolates of phenon A show them to be quite heterogeneous. Members belonging to phenon B are genetically more homogeneous. On the other hand, strains are genetically and phenotypically unrelated with Bacillus species with similar G+C contents. These results suggest that both groups could constitute new taxa of the genus Bacillus.

Ability of O-anisate degrading microorganisms to come tabolize dicamba and other related herbicides

Abstract O-anisate degrading microorganisms were isolated from soil samples and identified. 80, 24, 64 and 64% of the isolates showed cometabolism to the herbicides dicamba, 2, 3, 6-TBA, 2, 4-D and MCPA, respectively.