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Chapter: Heavy Metal Effects on Extremophiles and on Enzyme Biosynthesis in a New Bacillus Strain from Mount Rittmann, Antarctica
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ABSTRACT: Several extremophiles, in particular thermophilic microorganisms, coming from different and various environmental sites, were studied for their heavy metal resistance. These strains were exposed to heavy metals up to 60 ppm in the growth media. We focused our attention on a new acidothermophilic Bacillus, designated strain MR3CT, isolated from geothermal soil samples collected from Mount Rittmann in Antarctica. MR3CT synthesized an extracellular constitutive amylolytic activity. This activity was inhibited by exposure of cells, during the exponential or early stationary growth phases, with various concentrations of heavy metals (Ni2+, Cu2+, Zn2+, Hg2+). It was shown that MR3CT a-amylase activity was very sensitive to nature and quantity of heavy metals used. Hg2+ was by far the strongest inhibitor of α-amylase activity among the heavy metals tested. This study suggests the potential role of MR3CT strain as toxicological indicator of heavy metals and it evaluates the use of a microbial assay to detect heavy metals trace in industrial wastes.02/2008: pages 83 - 88; , ISBN: 9783527611904 -
Article: Polysaccharides from extremophilic microorganisms.
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ABSTRACT: Several marine thermophilic strains were analyzed for exopolysaccharide production. The screening process revealed that a significant number of thermophilic microorganisms were able to produce biopolymers, and some of them also revealed interesting chemical compositions. We have identified four new polysaccharides from thermophilic marine bacteria, with complex primary structures and with different repetitive units: a galacto-mannane type from strain number 4004 and mannane type for the other strains. The thermophilic Bacillus thermantarcticus produces two exocellular polysaccharides (EPS 1, EPS 2) that give the colonies a typical mucous character. The exopolysaccharide fraction was produced with all substrates assayed, although a higher yield 400 mg liter(-1) was obtained with mannose as carbon and energy source. NMR spectra confirmed that EPS 1 was a heteropolysaccharide of which the repeating unit was constituted by four different alpha-D-mannoses and three different beta-D-glucoses. It seems to be close to some xantan polymers. EPS 2 was a mannan. Four different alpha-D-mannoses were found as the repeating unit. Production and chemical studies of biopolymers produced by halophilic archaea, Haloarcula species were also reported.Origins of Life and Evolution of Biospheres 03/2004; 34(1-2):159-69. · 2.66 Impact Factor -
Article: Production of exopolysaccharides from a thermophilic microorganism isolated from a marine hot spring in flegrean areas.
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ABSTRACT: A thermophilic strain isolated from sea sand at Maronti, near Sant' Angelo (Ischia), is described. The organism grows well at an optimal temperature of 60 degrees C at pH 7.0. The thermophilic bacterium, named strain 4004, produces an exocellular polysaccharide (EPS) in yields of 90 mg/l. The EPS fraction was produced with all substrates tested, although a higher yield was obtained with sucrose or trehalose as sole carbon source. During growth, the EPS content was proportional to the biomass. Three fractions (EPS1, EPS2, EPS3) were obtained after purification. Quantitative monosaccharide analysis of the EPSs revealed the presence of mannose:glucose:galactose in a relative ratio of 0.5:1.0:0.3 in EPS1, mannose:glucose:galactose in a relative ratio of 1.0:0.3:trace in EPS2, and galactose:mannose:glucosamine:arabinose in a relative ratio of 1.0:0.8:0.4:0.2 in EPS3. The average molecular mass of EPS3 was determined to be 1x10(6) Da. From comparison of the chemical shift values in (1)H and (13)C spectra, we conclude that EPS3 presents a pentasaccharide repeating unit.Journal of Industrial Microbiology and Biotechnology 03/2003; 30(2):95-101. · 2.73 Impact Factor -
Article: Accumulation of osmoprotectants and lipid pattern modulation in response to growth conditions by Halomonas pantelleriense.
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ABSTRACT: The effects of salinity, growth temperature, pH and composition of the medium on the accumulation of intracellular organic solutes, by nuclear magnetic resonance spectroscopy (NMR) in Halomonas pantelleriense were examined. The modulation of lipid pattern in different growth conditions was also reported. H. pantelleriense accumulated glycine betaine, ectoine, hydroxyectoine and glutamate. The type of osmoprotectant and the relative proportion depended on growth conditions. The main lipids identified by NMR studies were 1,2 diacylglycero-3-phosphorylethanolamine (PEA), 1,2 diacylglycero-3-phosphoryl-glycerol (PG) and cardiolipin, (DPG). The predominant fatty acids were C16:0 and C18:1, minor fatty acids were C16:1 and C18:0. The relative percentage of polar lipids and fatty acids were affected by growth conditions.Systematic and Applied Microbiology 12/2001; 24(3):342-52. · 3.37 Impact Factor -
Article: Purification and characterization of thermostable xylose(glucose) isomerase from Bacillus thermoantarcticus.
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ABSTRACT: Xylose isomerase produced by Bacillus thermoantarcticus was purified 73-fold to homogeneity and its biochemical properties were determined. It was a homotetramer with a native molecular mass of 200 kDa and a subunit molecular mass of 47 kDa, with an isoelectric point at 4.8. The enzyme had a K(m) of 33 mM for xylose and also accepted D-glucose as substrate. Arrhenius plots of the enzyme activity of xylose isomerase were linear up to a temperature of 85 degrees C. Its optimum pH was around 7.0, and it had 80% of its maximum activity at pH 6.0. This enzyme required divalent cations for its activity and thermal stability. Mn(2+), Co(2+) or Mg(2+) were of comparable efficiency for xylose isomerase reaction, while Mg(2+) was necessary for glucose isomerase reaction.Journal of Industrial Microbiology and Biotechnology 11/2001; 27(4):234-40. · 2.73 Impact Factor
