Uptake of Re(VII) from aqueous solutions by Bacillus sp. GT-83-23

Thirty-eight water samples were collected from various areas of Anzali lagoon, Iran. Initial screening of a total of 100 bacterial isolates, resulted in the selection of one isolate with maximum adsorption capacity. It was tentatively identified as Bacillus sp. and named strain GT-83-23. The optimum pH of the medium was found to be 2.0 for Re(VII) adsorption. Uptakes of Re(VII) increased with increasing Re(VII) concentration and decreased sharply by the presence of increasing concentrations of NaCl. The kinetic of Re(VII) sorption by Bacillus sp. GT-83-23 was fast, reaching more than 62% of the total sorption capacity within 5 min. As the cell concentration increased, the amount of Re(VII) adsorbed by each cell (specific uptake) decreased, whereas the total amount of Re(VII) adsorbed enhanced. Cells immobilized in calcium alginate gel took up 77% of the Re(VII). The binding of Re(VII) on the Bacillus sp. GT-83-23 was studied with micro-PIXE.     

Growth and nitrogen removal characteristics of Halomonas sp. B01 under high salinity

At present, the nitrogen (N) removal efficiency of the microbial treatment in the high-salinity nitrogenous wastewaters is relatively low. Study on the N removal behavior and properties of moderately halophilic bacteria Halomonas under high salinity is of great significance for the microbial treatment of high-salinity nitrogenous wastewater. The response mechanism of Halomonas sp. B01 to high osmotic pressure stress was investigated by measuring the compatible solute ectoine concentration and superoxide dismutase (SOD) activity. The salt tolerance during growth and N removal of the strain was evaluated by measuring the activities of growth-related and N removal–related enzymes and the mRNA expression abundance of ammonia monooxygenase-encoding gene (amoA). The process of simultaneous heterotrophic nitrification and aerobic denitrification (SND) under high salinity was described by measuring the concentration of inorganic N. Halomonas sp. B01 synthesized ectoine under NaCl stress, and the intracellular ectoine concentration increased with increased NaCl concentration in the growth medium. When the NaCl concentration of the medium reached 120 g L−1, the malondialdehyde concentration and SOD activity were significantly increased to 576.1 μg mg−1 and 1.7 U mg−1, respectively. The growth-related and N removal–related enzymes of the strain were active or most active in medium with 30–60 g L−1 NaCl. The amoA of the strain cultured in medium with 60 g L−1 NaCl had the highest mRNA expression abundance. In the N removal medium containing 60 g L−1 NaCl and 2121 mg L−1 NH4+-N, SND by Halomonas sp. B01 was performed over 96 h and the N removal rate reached 98.8%. In addition to the protective mechanism of synthetic compatible solutes, Halomonas sp. B01 had the repair mechanism of SOD for lipid peroxidation. The growth-related and N removal–related enzymes of the strain were most active at a certain salt concentration; amoA also had the highest mRNA expression abundance under high salinity. Halomonas sp. B01 could efficiently perform N removal by SND under high salinity.     

Effect of salinity and pH on cobalt biosorption by the estuarine microalgaChlorella saliva

Summary Accumulation of cobalt (⁶⁰Co) by the estuarine microalgaChlorella salina has been characterized. At cobalt concentrations ranging over 3.125–100 M, a significant amount of cobalt was bound within 1 min. This was metabolism-independent and unaffected by incubation in light or dark conditions. This initial rapid phase of biosorption was followed by a slower phase of uptake which was apparently active and inhibited by incubation in the dark, or by the uncoupler dinitrophenol and the respiratory and photosynthetic inhibitor potassium cyanide in the light. For cells suspended in 10 mM Taps pH 8, cobalt biosorption followed a Freundlich adsorption isotherm. However, in the presence of 0.5 M NaCl, biosorption deviated from the Freundlich model because of competition by Na⁺. Cobalt biosorption was decreased by increasing concentrations of Na⁺, decreasing pH and the presence of Cs⁺, Li⁺, Rb⁺, Zn²⁺. Mn²⁺ and Sr²⁺ (added as chlorides). This was a result of competition between Co²⁺ and the other cations, including H⁺, for available binding sites on the cell wall and was confirmed by increased desorption of cobalt by solutions of low pH or high salinity. Increasing cell density resulted in increased removal of cobalt from solution but decreased the specific amount of cobalt taken up by the cells.     

Azo dyes decolorization under high alkalinity and salinity conditions by Halomonas sp. in batch and packed bed reactor

Biodecolorization and biodegradation of azo dyes are a challenge due to their recalcitrance and the characteristics of textile effluents. This study presents the use of Halomonas sp. in the decolorization of azo dyes Reactive Black 5 (RB5), Remazol Brilliant Violet 5R (RV5), and Reactive Orange 16 (RO16) under high alkalinity and salinity conditions. Firstly, the effect of air supply, pH, salinity and dye concentration was evaluated. Halomonas sp. was able to remove above 84% of all dyes in a wide range of pH (6–11) and salt concentrations (2–10%). The decolorization efficiency of RB5, RV5, and RO16 was found to be ≥ 90% after 24, 13 and 3 h, respectively, at 50 mg L⁻¹ of dyes. The process was monitored by HPLC-DAD, finding a reduction of dyes along the time. Further, Halomonas sp. was immobilized in volcanic rocks and used in a packed bed reactor for 72 days, achieving a removal rate of 3.48, 5.73, and 8.52 mg L⁻¹ h⁻¹, for RB5, RV5 and RO16, respectively, at 11.8 h. The study has confirmed the potential of Halomonas sp. to decolorize azo dyes under high salinity and alkalinity conditions and opened a scope for future research in the treatment of textile effluents.

     

Lanthanum biosorption by a Pseudomonas sp.: equilibrium studies and chemical characterization

Lanthanum biosorption by a Pseudomonas sp. was characterized in terms of equilibrium metal loading, model fitting, kinetics, effect of solution pH, lanthanum–bacteria interaction mechanism and recovery of sorbed metal. Lanthanum sorption by the bacterium was rapid and optimum at pH 5.0 with equilibrium metal loading as high as 950 mg g⁻¹ biomass dry wt. Scatchard model and potentiometric titration suggested the presence of at least two types of metal-binding sites, corresponding to a strong and a weak binding affinity. The chemical nature of metal–microbe interaction has been elucidated employing FTIR spectroscopy, energy dispersive X-ray analysis (EDX) and X-ray diffraction analysis (XRD). FTIR spectroscopy and XRD analysis revealed strong involvement of cellular carboxyl and phosphate groups in lanthanum binding by the bacterial biomass. EDX and the elemental analysis of the sorption solution ascertained the binding of lanthanum with the bacterial biomass via displacement of cellular potassium and calcium. Transmission electron microscopy exhibited La accumulation throughout the bacterial cell with some granular deposits in cell periphery and in cytoplasm. XRD confirmed the presence of LaPO₄ crystals onto the bacterial biomass after La accumulation for a long period. A combined ion-exchange–complexation–microprecipitation mechanism could be involved in lanthanum accumulation by the biomass. Almost 98% of biomass-bound La could be recovered using CaCO₃ as the desorbing agent.     

Utilization of arylaliphatic nitriles by haloalkaliphilic Halomonas nitrilicus sp. nov. isolated from soda soils

An enrichment culture from saline soda soils, using acetate as carbon and energy source and 2-phenylpropionitrile as nitrogen source (PPN) at pH 10, resulted in the isolation of strain ANL-αCH3. The strain was identified as a representative of the genus Halomonas in the Gammaproteobacteria. The bacterium was capable of PPN utilization as a nitrogen source only, while phenylacetonitrile (PAN) served both as carbon, energy and nitrogen source. This capacity was not described previously for any other haloalkaliphilic bacteria. Apart from the nitriles mentioned above, resting cells of ANL-αCH3 also hydrolyzed mandelonitrile, benzonitrile, acrylonitrile, and phenylglycinonitrile, presumably using nitrilase pathway. Neither nitrile hydratase nor amidase activity was detected. The isolate showed a capacity to grow with benzoate and salicylate as carbon and energy source and demonstrated the ability to completely mineralize PAN. These clearly indicated a potential to catabolize aromatic compounds. On the basis of unique phenotype and distinct phylogeny, strain ANL-αCH3 is proposed as a novel species of the genus Halomonas—Halomonas nitrilicus sp. nov. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Effect of salinity on the lipid and fatty acid composition of the halophyteNavicula sp.: potential in mariculture

Navicula sp. (cf.N. tenelloides) was isolated from a salt marsh in Kuwait. The alga grew best with 0.5M NaCl, but abundant growth still occurred up to 2.5M NaCl. The total lipid content and the carotene to chlorophyll ratio of the cells increased with increasing salinity of the medium from 0.5 to 1.7M NaCl, but declined with 2.5M NaCl. Irrespective of the medium salinity, the major lipid class was that of triacylglycerols. The predominant fatty acids in the total lipids of cells grown at different NaCl concentrations were palmitic (16:0) and palmitoleic (16:1) acids; eicosapentaenoic acid (20:5) made up 8–9% of the total fatty acids. The fatty acid composition of the individual lipid classes of cells grown at different salinities is described. The highest concentration of 20:5 occurred in monogalactosyldiacylglycerols and digalactosyldiacylglycerols. In view of the rather small size of this diatom, its halotolerance and its fair content of 20:5, it is suggested as a potential food source for the mariculture industry.     

Effect of pH on nickel biosorption by aerobic granular sludge

The Ni2+ biosorption by aerobic granular sludge was studied at various initial pH values of 2-7. Results showed that the initial pH would play an important role in the Ni2+ removal by aerobic granules and affected the zeta potential of aerobic granules. A thermodynamic equilibrium isotherm previously developed can fit the experimental data very well at all studied pH values. The close relationship between the zeta potential and Ni2+ biosorption capacity of aerobic granules showed the electrostatic attraction between the aerobic granules and Ni2+ ions. It was also found that some light metals, such as K+, Mg2+ and Ca2+ would be released into the bulk solution during the Ni2+ uptake onto the aerobic granules, which in turn indicated that ion-exchange was one of the Ni2+ biosorption mechanisms.     

曲霉产角质蛋白酶发酵条件的初步研究

曲酶F_(23)是一株角质蛋白酶分泌型菌株。我们研究了各种发酵条件如碳源、氮源等对产酶能力的影响,确定了适宜的发酵条件。摇瓶发酵培养基以1％的玉米浆为氮源,1％的玉米粉为碳源,0.3％的羽毛粉为诱导物及各种无机盐和维生素等。最适发酵pH范围为6.5～7.5,最适发酵温度为28℃～32℃,转速为180rpm,发酵102h左右酶活性达238ku/ml。     

Effect of vanadate on water transport by the toad bladder

Vanadate increases renal Na and water excretion. The mechanism whereby vanadate impairs water transport was examined in the toad bladder. Vanadate did not alter baseline water transport but caused a significant inhibition of water transport elicited by high doses of AVP. The inhibition of AVP stimulated water flow by vanadate was dose dependent with inhibition present with concentration as low as 10(-7) and maximal inhibition occurring at 10(-5) M. Vanadate also inhibited water transport stimulated by cyclic AMP or by phosphodiesterase inhibition indicating that vanadate has an effect beyond cyclic AMP step, in addition to whatever effect it might have on adenylate cyclase. The inhibitory effect of vanadate on AVP stimulated water flow was not altered by prior Na-K-ATPase or prostaglandin inhibition. Since vanadate has been shown to stimulate adenylate cyclase in other tissues we examined whether addition of vanadate 10 minutes after addition of AVP would enhance water transport. Vanadate caused a transient enhancement of AVP stimulated water flow. These data demonstrate that vanadate can inhibit or stimulate water flow in the toad bladder.     

Effect of vanadate on cardiac contraction and adenylate cyclase.

Vanadate produces a positive inotropic effect on ventricular muscle from rat, rabbit, guinea pig and cat; a positive inotropic effect on the atria of rat and rabbit, but a negative inotropic effect on the atria of guinea pig and cat. The effects of vanadate are completely reversible and occur in a concentration range of 10^?5M to 10^?3M. In this same concentration range, vanadate also causes a marked activation of cardiac adenylate cyclase suggesting that the positive inotropic action might be due in part to an elevation of cyclic AMP levels. The effects of vanadate are not influenced by alprenolol, cimetidine, or mepyramine, indicating a lack of involvement of β-adrenergic or histamine H₂ and H₁ receptors.     

Biodegradation of pyrene by Candida sp. S1 under high salinity conditions

Polycyclic aromatic hydrocarbon is a toxic recalcitrant environmental pollutant and its removal from the environment is very essential. In this study, a novel S1 strain isolated from the tropical rain forest was identified as Candida species based on 18S rRNA. The pyrene biodegradation was performed by Candida sp. S1. Pyrene was 35% degraded in 15 days. The percentage of pyrene biodegradation increased up to 75% with 24 g L⁻¹ of sodium chloride and decreased along with increasing salinity. Under the acidic condition, the biodegradation was increased up to 60% at pH 5. It was also found that the increasing glucose concentration of more than 10 g L⁻¹ had no significant effect on pyrene biodegradation, while agitation proved to have greater influence. There was a positive relationship between biomass growth and biodegradation rate of pyrene. One pyrene metabolite was identified from the extract solution and analyzed by a thin-layer chromatography, UV–visible absorption and gas chromatography–mass spectrometry. The metabolite found in the pyrene degradation was benzoic acid. Suitable conditions must be found to promote a successful microbial augmentation in liquid culture.

     

Improved composting of Undaria pinnatifida seaweed by inoculation with Halomonas and Gracilibacillus sp. isolated from marine environments

Composting of the Undaria pinnatifida (wakame) seaweed was conducted after inoculation with 6×10(8) CFU g(-1)Halomonas sp. AW4 and the alginate-degrading bacterium Gracilibacillus sp. A7. Inoculation with strains A7 and AW4 resulted in 27.8% and 24.7% degradation of U. pinnatifida dry mass after 168 h, whereas only 17.5% degradation occurred in the uninoculated control. The C/N ratio decreased in the A7 and AW4 inoculated compost by 7.0% and 9.2% after 72 h, but increased by 11.5% in the control. Inoculation with A7 resulted in 2.8 times faster degradation of alginate and 1.2 and 1.6 times higher levels of reducing sugars and unsaturated sugars than inoculation with AW4. The compost produced from the inoculation with A7 had low plant toxicity as measured by germination experiment. The results suggest that inoculation of wakame with alginate-degrading bacteria not only shortened the length of composting but also created seaweed compost with good fertilizer qualities.     

Development of an enhanced chromosomal expression system based on porin synthesis operon for halophile Halomonas sp.

Since halophile Halomonas spp. can grow contamination free in seawater under unsterile and continuous conditions, it holds great promise for industrial biotechnology to produce low-cost chemicals in an economic way. Yet, metabolic engineering methods are urgently needed for Halomonas spp. It is commonly known that chromosomal expression is more stable yet weaker than plasmid one is. To overcome this challenge, a novel chromosomal expression method was developed for halophile Halomonas TD01 and its derivatives based on a strongly expressed porin gene as a site for external gene integration. The gene of interest was inserted downstream the porin gene, forming an artificial operon porin-inserted gene. This chromosome expression system was proven functional by some examples: First, chromosomal expression of heterologous polyhydroxybutyrate (PHB) synthase gene phaC _Re from Ralstonia eutropha completely restored the PHB accumulation level in endogenous phaC knockout mutant of Halomonas TD01. The integrated phaC _Re was expressed at the highest level when inserted at the locus of porin compared with insertions in other chromosome locations. Second, an inducible expression system was constructed in phaC-deleted Halomonas TD01 by integrating the lac repressor gene (lacI) into the porin site in the host chromosome. The native porin promoter was inserted with the key 21 bp DNA of lac operator (lacO) sequence to become an inducible promoter encoded in a plasmid. This inducible system allowed on-off switch of gene expression in Halomonas TD strains. Thus, the stable and strong chromosomal expression method in Halomonas TD spp. was established.     

Effect of vanadate on tryptophan metabolism in streptozotocin diabetic rats.

Administration of sodium orthovanadate (0.3 mg/ml) through drinking water for 20 days to streptozotocin-induced diabetic rats resulted in reversal of markedly elevated activities of some of the key enzymes of tryptophan-niacin pathway, viz. hepatic and renal aminocarboxymuconate semialdehyde decarboxylase and hepatic tryptophan oxygenase, to normal levels without restoring the elevated blood sugar level to normal state. However vanadate administration to normal rats did not cause any significant change.     

Effect of temperature and salinity on in vitro zoosporulation of Perkinsus sp. in Manila clams Ruditapes philippinarum

The effects of temperature and salinity on in vitro development of Perkinsus sp. prezoosporangia isolated from cultured Manila clams in Korea were investigated, and the difference in resistance to low temperature between prezoosporangia collected in winter and those collected in summer was compared. Temperature and salinity had significant effects on the development of prezoosporangia, and the developmental rates increased with increasing temperature and salinity. Prezoosporangia isolated in winter sporulated and released motile zoospores at 10 degrees C, although the rates were significantly lower than those at 20 and 30 degrees C. However, no prezoosporangia collected in summer sporulated at 10 degrees C. Low salinities (< or = 10/1000) had a significant negative effect on the development of prezoosporangia. A small number of prezoosporangia sampled in summer did sporulate at 5/1000, but further developments including formation and release of zoospores were not observed. However, prezoosporangia sampled in winter and incubated at 5/1000 released motile zoospores, although the rates were significantly lower than those at higher salinities.     

Effect of salinity on nodule formation by soybean

A split-root growth system was employed to evaluate the effect of NaCl on nodule formation by soybean (Glycine max L. Merr. cv Davis). By applying the salinity stress and rhizobial inoculum to only one-half the root system, the effects of salinity on shoot growth were eliminated in the nodulation process. Rhizobium colonization of inoculated root surfaces was not affected by the salt treatments (0.0, 26.6, 53.2, and 79.9 millimolar NaCl). While shoot dry weight remained unaffected by the treatments, total shoot N declined from 1.26 grams N per pot at 0.0 millimolar NaCl to 0.44 grams N per pot at 79.9 millimolar NaCl. The concentration of N in the shoot decreased from 3.75% N (0.0 millimolar NaCl) to 1.26% N at 79.9 millimolar NaCl. The decrease in shoot N was attributed to a sharp reduction in nodule number and dry weight. Nodule number and weight were reduced by approximately 50% at 26.6 millimolar NaCl, and by more than 90% at 53.2 and 79.9 millimolar NaCl. Nodule development, as evidenced by the average weight of a nodule, was not as greatly affected by salt as was nodule number. Total nitrogenase activity (C₂H₂ reduction) decreased proportionally in relation to nodule number and dry weight. Specific nitrogenase activity, however, was less affected by salinity and was not depressed significantly until 79.9 millimolar NaCl. In a second experiment, isolates of Rhizobium japonicum from nodules formed at 79.9 millimolar NaCl did not increase nodulation of roots under salt stress compared to nodule isolates from normal media (0.0 millimolar NaCl). Salt was applied (53.2 millimolar NaCl) to half root systems at 0, 4, 12, and 96 hours from inoculation in a third experiment. By delaying the application of salt for 12 hours, an increase in nodule number, nodule weight, and shoot N was observed. Nodule formation in the 12- and 96-hour treatments was, however, lower than the control. The early steps in nodule initiation are, therefore, extremely sensitive to even low concentrations of NaCl. The sensitivity is not related to rhizobial survival and is probably due to the salt sensitivity of root infection sites.     

Complete genome sequence of the halophilic PHA-producing bacterium Halomonas sp. SF2003: insights into its biotechnological potential

World Journal of Microbiology and Biotechnology - The present study investigated biodegradation and removal of Reactive Red 198 (RR198) dye from aqueous environments using a new bacterial...