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    Acinetobacter mesopotamicussp. nov., Petroleum-degrading Bacterium, Isolated from Petroleum-Contaminated Soil in Diyarbakir, in the Southeast of Turkey
    (Springer, 2020) Acer, Omer; Guven, Kemal; Poli, Annarita; Di Donato, Paola; Leone, Luigi; Buono, Lorena; Guven, Reyhan Gul
    A new petroleum-degrading bacterium, designated strain GC2(T), was isolated from Bozkus 1 petroleum station in Diyarbakir, located in the southeast of Turkey. Cells were Gram-negative staining, aerobic, coccoid-rods, non-motile, non-spore-forming. The bacterium was found to degrade 100% ofn-alkanes ranging from C11 to C34 presented in the 1% crude oil after incubation of 7 days. The membrane phospholipids were 1,2 diacylglycero-3-phosphorylethanolamine (PEA), phosphatidylglycerol (PG), dipalmitoyl-sn-glycerol 1- phosphocholine (PC1), 1,2 dipalmitoyl-sn-glycero-3-phosphocholine monohydrate (PC3), cardiolipin also called diphosphatidylglycerol (CL) and l-alpha- phosphatidic acid, dipalmitoyl (AP); predominant respiratory ubiquinone was Q-8 and C16:0, C18:1 omega 9c and C16:1 were the major cellular fatty acids. The 16S rRNA sequence analysis revealed that the strain GC2(T)was a member of genusAcinetobacterand was most closely related toAcinetobacter lwoffiiDSM 2403( T)(99.79%),Acinetobacter pseudolwoffiiANC 5318( T)(98.83%) andAcinetobacter harbinensisHITLi 7( T)(98.14%). TherpoBandgyrBgene sequence analysis confirmed that the strain GC2(T)was a member of genusAcinetobacterand that the closest relative wasAcinetobacter lwoffiiDSM 2403( T)(99.08% and 100% similarity, respectively). DNA-DNA hybridization values between GC2(T)and its closest relatives ranged from 65.6% (withA. lwoffii) to 5.1% (withA. venetianus). The whole genome sequence of strain GC2(T)was obtained. The DNA G + C content of this strain was determined to be 42.9 mol %. ANI indexes, in silico estimations of DDH values and wet lab DDH values demonstrated that strain GC2(T)represents an independent genomospecies. On the basis of phenotypic characteristics, chemotaxonomic, phylogenetic data and DNA-DNA hybridization and whole genome analysis, we propose to assign strain GC2(T)as a new species of the genusAcinetobacter, for which the nameAcinetobacter mesopotamicussp. nov. is proposed. The type strain of this species is GC2(T)(DSM 26953 T = JCM 31073 T). The whole genome of strain GC2(T)has been deposited at DDBJ/ENA/GenBank under the accession JAALFF010000000.
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    Anoxybacillus kamchatkensis subsp asaccharedens subsp nov., a thermophilic bacterium isolated from a hot spring in Batman
    (Microbiol Res Foundation, 2008) Gul-Guven, Reyhan; Guven, Kemal; Poli, Annarita; Nicolaus, Barbara
    A new thermophilic spore-forming strain KG8(T) Was isolated from the mud of Taslidere hot spring in Batman. Strain KG8(T) was aerobe, Gram-positive, rod-shaped, motile, occurring in pairs or filamentous. Growth was observed from 35-65 degrees C (optimum 55 degrees C) and at pH 5.5-9.5 (optimum pH 7.5). It was capable of utilizing starch, growth was observed until 3% NaCl (w/v) and it was positive for nitrate reduction. On the basis of 16S rRNA gene sequence similarity, strain KG8(T) was shown to be related most closely to Anoxybacillus species. Chemotaxonomic data (major isoprenoid quinone-menaquinone-7; major fatty acid-iso-C15:0 and iso-C17:0) supported the affiliation of strain KG8(T) to the genus Anoxybacillus. The results of DNA-DNA hybridization, physiological and biochemical tests allowed genotypic and phenotypic differentiation of strain KG8(T). Based on these results we propose assigning a novel subspecies of Anoxybacillus kamchatkensis, to be named Anoxybacillus kamchatkensis subsp. asaccharedens subsp. nov. with the type strain KG8(T) (DSM 18475(T)=CIP 109280(T)).
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    Anoxybacillus sp AH1, an ?-amylase-producing thermophilic bacterium isolated from Dargecit hot spring
    (Springer, 2015) Acer, Omer; Pirinccioglu, Hemse; Bekler, Fatma Matpan; Gul-Guven, Reyhan; Guven, Kemal
    The present study was conducted to isolate alpha-amylase-producing thermophilic bacteria from Dargecit hot springs in Turkey. The morphological, biochemical and physiological characterisation, as well as genetic analysis by 16S rRNA sequences indicated that the isolated strain AH1 was a member of Anoxybacillus genus. The strain was aerobe, Gram-positive and spore-forming rod, exhibiting optimum growth temperature and pH of 60 degrees C and 7.0-7.5, respectively. Optimization of growth medium and enzyme assay conditions for extracellular a-amylase production by the novel thermophilic Anoxybacillus sp. AH1 were carried out in many different media containing a variety of carbon and nitrogen sources. Among various carbon and nitrogen sources, peptone (2054.1 U/mL) at 1% and maltose (1862.9 U/mL) at 0.5% increased a-amylase activity, compared to controls. Moreover, a high enzyme production was observed with potato starch at 0.5% and 1% (2668.4 U/mL and 3627 U/mL, respectively), as well as with 1% soluble starch (2051.9 U/mL). The enzyme activity was found to be rather high in the presence of CaCl2 up to 100 mM.
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    Barrier height enhancement of metal/semiconductor contact by an enzyme biofilm interlayer
    (Taylor & Francis Ltd, 2013) Ocak, Yusuf Selim; Guven, Reyhan Gul; Tombak, Ahmet; Kilicoglu, Tahsin; Guven, Kemal; Dogru, Mehmet
    A metal/interlayer/semiconductor (Al/enzyme/p-Si) MIS device was fabricated using -amylase enzyme as a thin biofilm interlayer. It was observed that the device showed an excellent rectifying behavior and the barrier height value of 0.78eV for Al/-amylase/p-Si was meaningfully larger than the one of 0.58eV for conventional Al/p-Si metal/semiconductor (MS) contact. Enhancement of the interfacial potential barrier of Al/p-Si MS diode was realized using enzyme interlayer by influencing the space charge region of Si semiconductor. The electrical properties of the structure were executed by the help of current-voltage and capacitance-voltage measurements. The photovoltaic properties of the structure were executed under a solar simulator with AM1.5 global filter between 40 and 100mW/cm(2) illumination conditions. It was also reported that the -amylase enzyme produced from Bacillus licheniformis had a 3.65eV band gap value obtained from optical method.
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    Biosorption of Cd+2, Cu+2, and Ni+2 Ions by a Thermophilic Haloalkalitolerant Bacterial Strain (KG9) Immobilized on Amberlite XAD-4
    (Hard, 2015) Alkan, Huseyin; Gul-Guven, Reyhan; Guven, Kemal; Erdogan, Salt; Dogru, Mehmet
    A newly isolated thermophilic haloalkalitolerant bacterial strain (KG9) as immobilized cells on a solid support was presented as a new biosorbent for the enrichment of Cd(II), Cu(II), and Ni(II) prior to flame atomic absorption spectrometric analysis. The KG9 strain was identified as a close member of Bacillus licheniformis following complete sequencing of 16S rRNA. The optimum conditions such as pH, amount of adsorbent, eluent type and volume, flow rate of sample solution, volume of sample solution, and matrix interference effect on the retention of the metal ions were evaluated for the quantitative recovery of the analytes. The analyte ions were quantitatively recovered and desorbed at pH range of 6.0-7.0 and 5 mL of 0.5 mol.L-1 HCl. The loading capacities of adsorbents for Cd(II), Cu(II), and Nip were found to be 22.7, 61.1, and 33.4 mu mol.g(-1) respectively. The analytical detection limits for cadmium(II), copper(II), and nickel(II) were 0.42 mu g.L-1, 0.54 mu g.L-1, and 1.24 mu g.L-1. The proposed procedure was applied for the determination of metal ions in river water, drinking water, and mushrooms. The accuracy of the developed procedure was tested by analyzing NRCC-SLRS4 riverine water and SRM1570a spinach leaves as the certified reference materials.
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    Biosorption of Cd, Cu, Ni, Mn and Zn from aqueous solutions by thermophilic bacteria, Geobacillus toebii sub.sp decanicus and Geobacillus thermoleovorans sub.sp stromboliensis: Equilibrium, kinetic and thermodynamic studies
    (Elsevier Science Sa, 2009) Ozdemir, Sadin; Kilinc, Ersin; Poli, Annarita; Nicolaus, Barbara; Guven, Kemal
    Biosorption of each of the ions Cd2+, Cu2+, Ni2+, Zn2+ and Mn2+ on Geobacillus toebii sub.sp. decanicus (G1) and Geobacillus thermoleovorans sub.sp. stromboliensis (G2) in a batch stirred system was investigated. The equilibrium adsorptive quantity was determined to be a function of the solution pH, contact time, biomass concentration, initial metal concentrations and temperature. The results obtained from biosorption experiments are used to understand the driving forces that govern the interaction between metal ions and a biosorbent. The experimental results were fitted well to the Scatchard plot, Langmuir, Freundlich, Dubinin-Radushkevich (D-R) isotherms. According to the parameters of the Langmuir isotherms, the maximum biosorption capacities of Cd2+, Cu2+, Ni2+, Zn2+ and Mn2+ for G2 were 38.8, 41.5, 42, 29 and 23.2 mg/g, respectively, while 29.2, 48.5, 21, 21.1 and 13.9 mg/g for G1, respectively. The mean free energy values evaluated from the D-R model indicated that the biosorptions of studied heavy metal ions onto bacteria were taken place by physical interaction. The biosorption mechanisms of studied metal ions on to the biosorbents were analysed by FT-IR spectra of G1 and G2 with and without metal ions. The first order and second order coefficients were obtained at 298, 308, 318 and 343 K. The experimental results were used to calculate the thermodynamic parameters. (C) 2009 Elsevier B.V. All rights reserved.
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    Cd, Cu, Ni, Mn and Zn resistance and bioaccumulation by thermophilic bacteria, Geobacillus toebii subsp decanicus and Geobacillus thermoleovorans subsp stromboliensis
    (Springer, 2012) Ozdemir, Sadin; Kilinc, Ersin; Poli, Annarita; Nicolaus, Barbara; Guven, Kemal
    Bioaccumulation and heavy metal resistance of Cd2+, Cu2+, Ni2+, Zn2+ and Mn2+ ions by thermophilic Geobacillus toebii subsp. decanicus and Geobacillus thermoleovorans subsp. stromboliensis were investigated. The metal resistance from the most resistant to the most sensitive was found as Mn > Ni > Cu > Zn > Cd for both Geobacillus thermoleovorans subsp. stromboliensis and Geobacillus toebii subsp. decanicus. It was determined that the highest metal bioaccumulation was performed by Geobacillus toebii subsp. decanicus for Zn (36,496 mu g/g dry weight cell), and the lowest metal bioaccumulation was performed by Geobacillus toebii subsp. decanicus for Ni (660.3 mu g/g dry weight cell). Moreover, the dead cells were found to biosorbe more metal in their membranes compared to the live cells. In the presence of 7.32 mg/l Cd concentration, the levels of Cd absorbed in live and dead cell membranes were found as 17.44 and 46.2 mg/g membrane, respectively.
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    Characterisation of a partially purified protease from Bacillus cereus KG5 isolated from a hot spring
    (Elsevier Sci Ltd, 2011) Ahmetoglu, Nazenin; Bekler, Fatma Matpan; Guven, Reyhan Gul; Acer, Omer; Guven, Kemal
    [Abstract Not Available]
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    Effects of endosulfan, thiamethoxam, and indoxacarb in combination with atrazine on multi-biomarkers in Gammarus kischineffensis
    (Academic Press Inc Elsevier Science, 2018) Demirci, Ozlem; Guven, Kemal; Asma, Dilek; Ogut, Serdal; Ugurlu, Pelin
    Studies addressing the toxicity of pesticides towards non-target organisms focus on the median lethal concentration and biochemical response of individual pesticides. However, when determining environmental risks, it is important to test the combined effects of pesticides, such as insecticides and herbicides, which are frequently used together in agricultural areas. Here we aimed to investigate the toxic effects of the combined use of the herbicide atrazine and the insecticides, endosulfan, indoxacarb, and thiamethoxam on Gammarus kischineffensis. To do this, we tested the activities of oxidative stress, detoxification, and neurotoxicity biomarkers. Compared to atrazine alone, we detected higher glutathione-S-transferase, catalase and superoxide dismutase activities (oxidative stress biomarkers) when atrazine was combined with either endosulfan or indoxacarb. However, higher IBR values were determined in organisms where pesticide mixtures were used according to individual use. Based on these results, mixtures of atrazine and other pesticides may cause synergistic effects and may be evidence of increased toxicity and oxidative stress.
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    Effects of radio-frequency fields on bacterial cell membranes and nematode temperature-sensitive mutants
    (Elsevier Science Inc, 2006) Gul Guven, Reyhan; Guven, Kemal; Dawe, Adam; Worthington, John; Harvell, Christopher; Popple, Amy; Smith, Tim
    Membrane-related bioeffects have been reported in response to both radio-frequency (RF) and extremely low-frequency (ELF) electromagnetic fields (EMFs), particularly in neural cells. We have tested whether RF fields might cause inner membrane leakage in ML35 E. coli cells, which express beta-galactosidase (lacZ) constitutively, but lack the lacY permease required for substrate entry. The activity of lacZ (indicating substrate leakage through the inner cell membrane) was increased only slightly by RF exposure (1 GHz, 0.5 W) over 45 min. Since lacZ activity showed no further increase with a longer exposure time of 90 min, this suggests that membrane permeability per se is not significantly affected by RF fields, and that slight heating (<= 0.2 degrees C) could account for this small difference. Temperature-sensitive (ts) mutants of the nematode, Caenorhabditis elegans, are wild-type at 15 degrees C but develop the mutant phenotype at 25 degrees C; an intermediate temperature of 21 degrees C results in a reproducible mixture of both phenotypes. For two ts mutants affecting transmembrane receptors (TRA-2 and GLP-1), RF exposure for 24 h during the thermocritical phase strongly shifts the phenotype mix at 21 degrees C towards the mutant end of the spectrum. For ts mutants affecting nuclear proteins, such phenotype shifts appear smaller (PHA-1) or non-significant (LIN-39), apparently confirming suggestions that RF power is dissipated mainly in the plasma membrane of cells. However, these phenotype shifts are no longer seen when microwave treatment is applied at 21 degrees C in a modified exposure apparatus that minimises the temperature difference between sham and exposed conditions. Like other biological effects attributed to microwaves in the C. elegans system, phenotype shifts in ts mutants appear to be an artefact caused by very slight heating. (c) 2006 Elsevier Inc. All rights reserved.
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    The Effects of Silver Nanoparticles (AgNPs) on Thermophilic Bacteria: Antibacterial, Morphological, Physiological and Biochemical Investigations
    (Mdpi, 2024) Jahan, Israt; Bekler, Fatma Matpan; Tunc, Ahmed; Guven, Kemal
    Since thermophilic microorganisms are valuable sources of thermostable enzymes, it is essential to recognize the potential toxicity of silver nanoparticles used in diverse industrial sectors. Thermophilic bacteria Geobacillus vulcani 2Cx, Bacillus licheniformis 3CA, Paenibacillus macerans 3CA1, Anoxybacillus ayderensis FMB1, and Bacillus paralicheniformis FMB2-1 were selected, and their MIC and MBC values were assessed by treatment with AgNPs in a range of 62.5-1500 mu g mL(-1). The growth inhibition curves showed that the G. vulcani 2Cx, and B. paralicheniformis FMB2-1 strains were more sensitive to AgNPs, demonstrating a reduction in population by 71.1% and 31.7% at 62.5 mu g mL(-1) and by 82.9% and 72.8% at 250 mu g mL(-1), respectively. TEM and FT-IR analysis revealed that AgNPs caused structural damage, cytoplasmic leakage, and disruption of cellular integrity. Furthermore, cell viability showed a significant decrease alongside an increase in superoxide radical (SOR; O-2(-)) production. beta-galactosidase biosynthesis decreased to 28.8% level at 500 mu g mL(-1) AgNPs for G. vulcani 2Cx, 32.2% at 250 mu g mL(-1) for A. ayderensis FMB1, and 38.8% only at 62.5 mu g mL(-1), but it was completely inhibited at 500 mu g mL(-1) for B. licheniformis 3CA. Moreover, B. paralicheniformis FMB2-1 showed a significant decrease to 11.2% at 125 mu g mL(-1). This study is the first to reveal the toxic effects of AgNPs on thermophilic bacteria.
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    Effects of Various Inhibitors on ?-galactosidase Purified from the Thermoacidophilic Alicyclobacillus acidocaldarius Subsp Rittmannii Isolated from Antarctica
    (Korean Soc Biotechnology & Bioengineering, 2011) Guven, Reyhan Gul; Kaplan, Alevcan; Guven, Kemal; Matpan, Fatma; Dogru, Mehmet
    beta-Galactosidase purified from the thermoacidophilic Alicyclobacillus acidocaldarius subsp. rittmannii isolated from Antarctica is a member of the GH42 family. The enzyme was not effected by various concentrations of its reaction product glucose, but was greatly inhibited by the other reaction product galactose using both substrates, ONPG and lactose. Linewever-Burk plot analysis derived from both ONPG and lactose hydrolysis results showed that galactose is a mixed-type inhibitor of the purified beta-galactosidase. The enzyme was slightly activated by Mg(2+) (13% at 20 mM), while inhibited at higher concentrations of Ca(+2) (33% at 10 mM), Zn(+2) (86% at 8 mM) and Cu(+2) (87% at 4 mM). The enzyme activity was not significantly altered by the metal ion chelators EDTA and 1,10-phenanthroline up to 20 mM, indicating that this enzyme is not a metalloenzyme. 2-Mercaptoethanol and DTT were found to enhance beta-galactosidase activity, while p-chloromercuribenzoic acid (PCMB) completely inhibited enzymatic activity (97% at 1 mM; 99.7% at 2 mM), indicating at least one essential Cys residue modified by the reagents in the active site of beta-galactosidase. Iodoacetamide and N-ethylmaleimide had little effect on the beta-galactosidase. Phenylmethylsulfonyl fluoride (PMSF) inhibited the enzyme strongly (19.8% at 1 mM; 71.9% at 10 mM), also showing the participation of serine for enzyme activity.
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    Evaluation of antibacterial effects of some traditional plants against pathogen microorganisms
    (Banats Univ Agricultural Sciences & Veterinary Medicine Timisoara, 2020) Guven, Kemal; Matpan Bekler, Fatma; Yalaz, Secil; Gul Guven, Reyhan; Demirtas Aksu, Merve; Ipekci, Mert; Tusar, Firdevs Rozan
    Antimicrobial resistance has been an increasing problem in public health around the world. Natural plants can be utilised as an important source for antimicrobial agents to be used in place of synthetic drugs due to their costs and side effects. Thus, it is essential to find out new, effective, safer natural antimicrobial products. In the present study, in vitro antibacterial activities of different traditional plants against pathogen microorganisms were tested. The extracts of all plants were prepared in four different solvents (ethanolic, methanolic, hexane and aqueous) and then used for disc-diffusion method. Each assay was repeated in triplicate. The analysis was carried out using two-way analysis of variance (ANOVA). The highest antimicrobial activities were obtained by methanolic extracts of Sorbus domestica against E. coli, while Methanolic Extracts of Epilobium angustifolium were effective against Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa. In addition, Hexanic Extract of Tragacanth gum and S. domestica had high antibacterial activity against K. pneumoniae and P. aeruginosa, respectively.
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    Extremely low-frequency magnetic field induces manganese accumulation in brain, kidney and liver of rats
    (Sage Publications Inc, 2015) Celik, Mustafa Salih; Guven, Kemal; Akpolat, Veysi; Akdag, Mehmet Zulkuf; Naziroglu, Mustafa; Gul-Guven, Reyhan; Celik, M. Yusuf
    The aim of the present study was to determine the effects of extremely low-frequency magnetic field (ELF-MF) on accumulation of manganese (Mn) in the kidney, liver and brain of rats. A total of 40 rats were randomly divided into eight groups. Four control groups received 0, 3.75, 15 and 60 mg Mn per kg body weight orally every 2 days for 45 days, respectively. The remaining four groups received same concentrations of Mn and were also exposed to ELF-MF (1.5 mT; 50 Hz) for 4 h for 5 days a week during 45 days. Following the last exposure, kidney, liver and brain were taken from all rats and they were analyzed for Mn accumulation levels using an inductively coupled plasma-optical emission spectrometer. In result of the current study, we observed that Mn levels in brain, kidney and liver were higher in Mn groups than in control groups. Mn levels in brain, kidney and liver were also higher in Mn plus ELF-MF groups than in Mn groups. In conclusion, result of the current study showed that the ELF-MF induced manganese accumulation in kidney, liver and brain of rats.
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    Geobacillus subterraneus subsp aromaticivorans subsp nov., a novel thermophilic and alkaliphilic bacterium isolated from a hot spring in Sirnak, Turkey
    (Microbiol Res Foundation, 2012) Poli, Annarita; Guven, Kemal; Romano, Ida; Pirinccioglu, Hamsi; Guven, Reyhan Gul; Euzeby, Jean Paul Marie; Matpan, Fatma
    A new thermophilic spore-forming strain Ge1(T) was isolated from the Guclukonak hot spring in Sirnak, Turkey. The strain was identified by using a polyphasic taxonomic approach. Strain Ge1(T) was Gram-positive, spore-forming, alkaliphilic rod-shaped, motile, occurring in pairs or filamentous. Growth was observed between 30 and 65 degrees C (optimum 60 degrees C) and at pH 5.5-10.0 (optimum pH 9.0). It was capable of utilizing starch, growth was observed at 0-3% NaCl (w/v) and was positive for catalase and urease. The major cellular fatty acids were iso-C-15:0 and iso-C-17:0, and the predominant lipoquinone found was menaquinone MK7 type. The DNA G+C content of the genomic DNA of strain Ge1(T) was 52.0%. Comparative 16S rRNA gene sequence studies showed that the isolate belonged to the genus Geobacillus. The DNA-DNA hybridization mean values between the representative strain Ge1(T) and the closely related species G. subterraneus, G. thermodenitrificans, G. thermocatenulatus, G. vulcani and G. thermoleovorans were 69.3%, 57%, 37%, 27% and 26%, respectively. The results of DNA-DNA hybridization, physiological and biochemical tests allowed genotypic and phenotypic differentiation of strain Ge1(T). Based on these results, we propose assigning a novel subspecies of Geobacillus subterraneus, to be named as Geobacillus subterraneus subsp. aromaticivorans subsp. nov. with the type strain Ge1(T) (DSM 23066 (T)= CIP 110341(T)).
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    Isolation and characterization of long-chain alkane-degrading Acinetobacter sp BT1A from oil-contaminated soil in Diyarbakir, in the Southeast of Turkey
    (Taylor & Francis Inc, 2016) Acer, Omer; Guven, Kemal; Bekler, Fatma Matpan; Gul-Guven, Reyhan
    A strain of long-chain alkane-degrading bacteria, BT1A, was isolated from oil-contaminated soil in Diyarbakr, in the southeast of Turkey. Morphological, biochemical, and physiological characterization and 16S rRNA gene sequence analysis showed that the strain BT1A was a member of Acinetobacter genus, and it was found to be closely related to Acinetobacter baumannii. The strain BT1A was able to utilize crude petroleum as carbon and energy sources in order to grow. Among the aliphatic hydrocarbons, growth was observed only in the medium containing long-chain alkanes (tridecane, pentadecane, and hexadecane) and squalene. Hexadecane was the most preferred hydrocarbon among the long-chain alkanes. Gas chromatography-mass spectrometry (GC-MS) analysis showed that BT1A degraded 83% of n-alkanes of 1% crude oil in 7days. The present study indicates that the isolated strain can well be used for biodegradation of hydrocarbons in oil-contaminated sites.
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    Isolation and characterization of long-chain alkane-degrading Acinetobacter sp. BT1A from oil-contaminated soil in Diyarbakir, in the Southeast of Turkey (vol 20, pg 80, 2016)
    (Taylor & Francis Inc, 2017) Acer, Omer; Guven, Kemal; Bekler, Fatma Matpan; Gul-Guven, Reyhan
    [Abstract Not Available]
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    Isolation and cloning of extracellular thermostable ?-galactosidases from a newly isolated Thermophilic Bacillus licheniformis KG9
    (Elsevier Sci Ltd, 2011) Bekler, Fatma Matpan; Stougaard, Peter; Guven, Reyhan Gul; Guven, Kemal
    [Abstract Not Available]
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    Isolation and identification of petroleum degrading bacteria
    (Elsevier Sci Ltd, 2011) Guven, Reyhan Gul; Bekler, Fatma Matpan; Kaya, Hasan; Acer, Omer; Guven, Kemal; Temel, Hamdi
    [Abstract Not Available]
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    Isolation and production of thermostable ?-amylase from thermophilic Anoxybacillus sp KP1 from Diyadin hot spring in Agri, Turkey
    (Springer, 2014) Bekler, Fatma Matpan; Guven, Kemal
    A novel amylolytic enzyme producing thermophilic bacterial strain KP1 from the Diyadin hot spring water in Agri, Turkey, was isolated in the present study. Phylogenetic analysis based on the partial 16S rRNA gene, biochemical and physiological tests revealed that the strain KP1 belongs to the genus Anoxybacillus. The pH and temperature optima for the alpha-amylase production by Anoxybacillus sp. KP1 were 8.0 and 50A degrees C, respectively, where the maximum growth was obtained at the 28(th) hour of incubation and the highest alpha-amylase activity was obtained at the 40(th) hour of incubation (8979.6 U/mL). The optimum pH and temperature for the enzyme activity were 8.0 and 60A degrees C, respectively. The maximum alpha-amylase production was secreted in the presence of 2% (w/v) soluble starch (10837.7 U/mL). Among the various organic and inorganic nitrogen sources tested, while keeping the beef extract concentration constant, casamino acid (14310.6 U/mL), urea (14126 U/mL), and tryptone (13217.2 U/mL) at a concentration of 2% gave the maximum alpha-amylase production. The enzyme activity was enhanced in the presence of 1.5 mM Mn2+ (123%), whereas it was strongly inhibited 1.5 mM by Hg2+. Inhibition by 89% was obtained also with sodium dodecyl sulphate (1%). The enzyme was found to be relatively stable at a range of pH and temperature.