Noha M. Mesbah

Geobacter lovleyi sp. nov. Strain SZ, a Novel Metal-Reducing and Tetrachloroethene-Dechlorinating Bacterium†

ABSTRACT A bacterial isolate, designated strain SZ, was obtained from noncontaminated creek sediment microcosms based on its ability to derive energy from acetate oxidation coupled to tetrachloroethene (PCE)-to-cis-1,2-dichloroethene (cis-DCE) dechlorination (i.e., chlororespiration). Hydrogen and pyruvate served as alternate electron donors for strain SZ, and the range of electron acceptors included (reduced products are given in brackets) PCE and trichloroethene [cis-DCE], nitrate [ammonium], fumarate [succinate], Fe(III) [Fe(II)], malate [succinate], Mn(IV) [Mn(II)], U(VI) [U(IV)], and elemental sulfur [sulfide]. PCE and soluble Fe(III) (as ferric citrate) were reduced at rates of 56.5 and 164 nmol min−1 mg of protein−1, respectively, with acetate as the electron donor. Alternate electron acceptors, such as U(VI) and nitrate, did not inhibit PCE dechlorination and were consumed concomitantly. With PCE, Fe(III) (as ferric citrate), and nitrate as electron acceptors, H2 was consumed to threshold concentrations of 0.08 ± 0.03 nM, 0.16 ± 0.07 nM, and 0.5 ± 0.06 nM, respectively, and acetate was consumed to 3.0 ± 2.1 nM, 1.2 ± 0.5 nM, and 3.6 ± 0.25 nM, respectively. Apparently, electron acceptor-specific acetate consumption threshold concentrations exist, suggesting that similar to the hydrogen threshold model, the measurement of acetate threshold concentrations offers an additional diagnostic tool to delineate terminal electron-accepting processes in anaerobic subsurface environments. Genetic and phenotypic analyses classify strain SZ as the type strain of the new species, Geobacter lovleyi sp. nov., with Geobacter (formerly Trichlorobacter) thiogenes as the closest relative. Furthermore, the analysis of 16S rRNA gene sequences recovered from PCE-dechlorinating consortia and chloroethene-contaminated subsurface environments suggests that Geobacter lovleyi belongs to a distinct, dechlorinating clade within the metal-reducing Geobacter group. Substrate versatility, consumption of electron donors to low threshold concentrations, and simultaneous reduction of electron acceptors suggest that strain SZ-type organisms have desirable characteristics for bioremediation applications.

Life under multiple extreme conditions: diversity and physiology of the halophilic alkalithermophiles.

ABSTRACT Around the world, there are numerous alkaline, hypersaline environments that are heated either geothermally or through intense solar radiation. It was once thought that such harsh environments were inhospitable and incapable of supporting a variety of life. However, numerous culture-dependent and -independent studies revealed the presence of an extensive diversity of aerobic and anaerobic bacteria and archaea that survive and grow under these multiple harsh conditions. This diversity includes the halophilic alkalithermophiles, a novel group of polyextremophiles that require for growth and proliferation the multiple extremes of high salinity, alkaline pH, and elevated temperature. Life under these conditions undoubtedly involves the development of unique physiological characteristics, phenotypic properties, and adaptive mechanisms that enable control of membrane permeability, control of intracellular osmotic balance, and stability of the cell wall, intracellular proteins, and other cellular constituents. This minireview highlights the ecology and growth characteristics of the extremely halophilic alkalithermophiles that have been isolated thus far. Biochemical, metabolic, and physiological properties of the extremely halophilic alkalithermophiles are described, and their roles in resistance to the combined stressors of high salinity, alkaline pH, and high temperature are discussed. The isolation of halophilic alkalithermophiles broadens the physicochemical boundaries for life and extends the boundaries for the combinations of the maximum salinity, pH, and temperature that can support microbial growth.

Determination of the G+C Content of Prokaryotes

Abstract The mol% G+C content of bacteria is a key in the complete description of novel genera and higher taxa, and also influences several physiological properties such as codon usage and DNA stability. Since differences in the G+C content can be used in the differentiation between different bacterial groups, the description of a standardized and uniform procedure for its determination is critical. This chapter provides an overview of many common methods as well as a detailed protocol for determination of the G+C content by reverse-phase high-performance liquid chromatography. Detailed protocols on DNA digestion and chromatographic nucleoside separation are presented, and methods employed for buffer and reagent preparation and storage are described. The method of G+C content calculation is also presented. High-performance liquid chromatography has proved to be one of the most accurate methods for determination of G+C content and will allow more precise comparison of values determined by different researchers and laboratories worldwide.

Halophilic alkali- and thermostable amylase from a novel polyextremophilic Amphibacillus sp. NM-Ra2

Extracellular gluco-amylo-pullulanase from Amphibacillus sp. NM-Ra2 was purified to homogeneity by ethanol precipitation, anion exchange chromatography and gel filtration chromatography. Molecular mass of the enzyme was 50kDa (SDS-PAGE). The enzyme showed maximal activity at 1.9 M NaCl, pH50°C 8.0 and 54°C and was active from 0 to 4.3 M NaCl and 37 to 65°C. The enzyme was inhibited by EDTA and was stable and active in the presence of PMSF, DTT, H2O2, Triton-X-100, Tween 20 and Tween 80. Ca2+ is inessential for activity. The amylase was stimulated with K+ and inhibited with Cu2+ and Mg2+. Hg2+, Zn2+ and Fe2+ had no effect on activity. Amylase was stable and active in the presence of ethanol, methanol and benzene (25%, v/v). The enzyme hydrolyzed linear and branched polysaccharides including pullulan, glycogen and amylopectin, and hydrolyzed raw wheat starch and raw corn starch (14.6% and 13.5% over 2 h). Amylase activity was inhibited by soluble starch concentrations greater than 0.3%. The major products of soluble starch hydrolysis were maltose and maltotriose. The amylase, being halophilic and alkali-thermostable, in addition to being resistant to surfactants, oxidizing agents and organic solvents, can find applications in the starch processing, pharmaceutical, food and paper/pulp industries.

Relaxin-3 is associated with metabolic syndrome and its component traits in women

OBJECTIVES Relaxin-3 was found to play a role in appetite regulation, increasing food intake and body weight. The current study aimed to investigate the relation of relaxin-3 to metabolic syndrome and its component traits in women. DESIGN AND METHODS The study was conducted on 300 female subjects, 150 healthy control and 150 metabolic syndrome patients. The component traits of metabolic syndrome were determined for all participants. RESULTS Serum relaxin-3 level was significantly higher in the metabolic syndrome patients than in the healthy control group. It was also significantly correlated with all the component traits of metabolic syndrome. CONCLUSION The results suggest that metabolic syndrome is associated with increased serum relaxin-3 levels in women. Relaxin-3 might be considered as a potential biomarker of metabolic syndrome.

Association of estrogen receptor alpha gene polymorphisms with metabolic syndrome in Egyptian women

OBJECTIVE Metabolic syndrome is a risk factor for coronary heart diseases as well as diabetes, fatty liver and several cancers. The prevalence of metabolic syndrome in women appears to be increasing, particularly in women of childbearing age. In the present study, we assessed the association of estrogen receptor-alpha gene polymorphisms (XbaI and PvuII) with metabolic syndrome and its related phenotypes. MATERIALS/METHODS One hundred and fifty Egyptian female patients with metabolic syndrome (mean age 35.52±6.86) were compared with one hundred and fifty age matched healthy Egyptian women (controls). The component traits of metabolic syndrome were determined, and the XbaI and PvuII genotypes were assessed with the PCR-RFLP method. RESULTS Our data indicated a significant difference in the allele frequencies of XbaI, but not PvuII, between the metabolic syndrome and control groups (P=0.0003 and P=0.164). Carriers of the minor alleles of XbaI and PvuII gene polymorphisms, in either the homozygous or heterozygous form, were associated with high diastolic blood pressure, high total cholesterol and LDL-c levels, increased HOMA-IR values and decreased QUICKI values compared to carriers of the major allele. However, only the minor G allele of XbaI was associated with measures of adiposity, specifically, BMI and waist circumference. CONCLUSIONS The XbaI polymorphism of the estrogen receptor alpha gene is associated with metabolic syndrome. On the other hand, PvuII gene polymorphism is not associated with the occurrence of the disease in this sample of Egyptian women.

Omentin and apelin concentrations in relation to obesity, diabetes mellitus type two, and cardiovascular diseases in Egyptian population

Dysregulation of omentin, a beneficial adipokine, and apelin, an inflammatory adipokine, is thought to play a role in the development of type 2 diabetes mellitus and cardiovascular disease. The objective of this study was to evaluate the relationship between circulating omentin and apelin concentrations and components of the metabolic syndrome in adults with and without type 2 diabetes mellitus or cardiovascular disease. A total of 240 adults, sex- and age-matched, were included in the current case–control study, including 80 healthy, non-obese controls, 80 obese patients with T2DM without cardiovascular disease, and 80 obese patients with T2DM with cardiovascular disease. A fasting blood sample was collected to determine biochemical indicators and insulin resistance index (HOMA-IR). Omentin, apelin, interleukin-1β (IL-1β), troponin-T, and oxidized LDL (Ox-LDL) plasma level was assessed by ELISA. Associations of adipokines with biochemical parameters of the patients were determined. Serum omentin levels were significantly lower and serum apelin and IL-1β concentrations were significantly higher in obese diabetic groups compared to non-obese controls. In correlation analyses, omentin negatively associated with the HOMA-IR index, apelin, and troponin-T, whereas apelin was positively associated with IL-1β, BMI, and troponin-T. Our study supports the hypothesis that abnormal production of omentin and apelin can contribute to the pathogenesis of obesity-related complications including T2DM and cardiovascular disease.

Halophiles Exposed Concomitantly to Multiple Stressors: Adaptive Mechanisms of Halophilic Alkalithermophiles

The anaerobic halophilic alkalithermophiles are a novel group of “poly-extremophiles.” The recent isolation of novel anaerobic halophilic alkalithermophiles belonging to the genera Natranaerobius and Natronovirga (forming the order Natranaerobiales) has provided a platform for detailed biochemical and bioenergetic experiments, allowing a greater understanding of the novel adaptive mechanisms employed by the poly-extremophiles. This review highlights the adaptive mechanisms employed by the model anaerobic halophilic alkalithermophile, Natranaerobius thermophilus. N. thermophilus grows optimally at 3.3 M Na+, pH55°C 9.5 and 53°C. Biochemical and physiological analyses revealed that N. thermophilus combines two mechanisms for adaptation to high salinity. N. thermophilus also shows an unusual pattern of cytoplasm acidification, and utilizes a dual mechanism for cytoplasm acidification based on an unusually large number of cation/proton antiporters and cytoplasmic buffering, a feature not previously observed in other alkalithermophiles studied. Both Natranaerobius thermophilus and Natronovirga wadinatrunensis showed significant resistance to ultra-violet radiation.

Association of chemerin Rs17173608 and vaspin Rs2236242 gene polymorphisms with metabolic syndrome in Egyptian women

Abstract Aim: The metabolic syndrome is a complex of interrelated risk factors for cardiovascular disease and diabetes. The adipokines, chemerin and vaspin, are known to have metabolic regulatory roles. This study aimed to assess the relation of chemerin rs17173608 and vaspin rs2236242 polymorphisms with metabolic syndrome and its related phenotypes in Egyptian women. Subjects and methods: The study included 100 healthy female subjects and 100 metabolic syndrome patients. The component traits of metabolic syndrome were determined and the genotypes of the polymorphisms were assessed using the tetra amplification refractory mutation system polymerase chain reaction procedure. Results: The minor G allele of the chemerin rs17173608 polymorphism had a significantly higher frequency in metabolic syndrome patients (p = 0.0001). The component traits of metabolic syndrome were significantly increased in the carriers of the GG and TG genotypes. In contrast, the rare A allele of vaspin rs2236242 polymorphism was significantly higher in the control subjects (p = 0.005). The carriers of the TA and AA genotypes showed significant relation with lower values of the phenotypes of metabolic syndrome. Conclusion: Metabolic syndrome in Egyptian females is associated with the minor allele of chemerin rs17173608 polymorphism, whereas the minor allele of vaspin rs2236242 polymorphism plays a protective role against metabolic syndrome.

Associations of Serum Omentin and Apelin Concentrations with Obesity, Diabetes Mellitus Type 2 and Cardiovascular Diseases in Egyptian Population

Background and aim: Dysregulation of omentin, a beneficial adipokine and apelin, an inflammatory adipokine, is thought to play a role in the development of type 2 diabetes mellitus and cardiovascular disease. The objective of this study was to evaluate the relationship between circulating omentin and apelin concentrations and components of the metabolic syndrome in adults with and without type 2 diabetes mellitus or cardiovascular disease. Methods: A total of 240 adults sex and age-matched were included in the current case-control study, including 80 healthy non-obese controls, 80 obese patients with T2DM without cardiovascular disease, and 80 obese patients with T2DM with cardiovascular disease . Fasting blood sample was collected to determine biochemical indicators and insulin resistance index (HOMA-IR). Omentin, apelin, interleukin-1β (IL-1β), troponin-T, and oxidized LDL (Ox-LDL) plasma level was assessed by ELISA. Associations of adipokines with biochemical parameters of the patients were determined. Results: Serum omentin levels were significantly lower and serum apelin and IL-1β concentrations were significantly higher in obese diabetic groups compared to non-obese controls. In correlation analyses, omentin negatively associated with the HOMA-IR index, apelin, and troponin-T, whereas apelin was positively associated with IL-1β, BMI, and troponin. Conclusions: Our study supports the hypothesis that abnormal production of omentin and apelin can contribute to the pathogenesis of obesity-related complications including T2DM and cardiovascular disease.