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    Biosorption of 2,4-d, 2,4-DP, and 2,4-DB from aqueous solution by using thermophilic anoxybacillus flavithermus and analysis by high-performance thin layer chromatography: Equilibrium and kinetic studies
    (Wiley, 2012) Ozdemir, Sadin; Bekler, Fatma Matpan; Okumus, Veysi; Dundar, Abdurrahman; Kilinc, Ersin
    In this study, the potential biosorption characteristics of the thermophilic Anoxybacillus flavithermus (A. flavithermus) was investigated for the removal of the chlorophenoxy acid derivates, namely, 2,4-dichlorophenoxy acetic acid (2,4-D), 2,4-dichlorophenoxy propanoic acid (2,4-DP or dichlorprop), and 2,4-dichlorophenoxy butyric acid (2,4-DB). The experiments were performed for the simultaneous biosorption of the studied pesticides. Optimum biosorption conditions were determined as a function of contact time, pH of the solution, amount of biomass, and initial pesticides concentrations. The concentrations of the pesticides in the remaining solutions were simultaneously analyzed by high performance thin layer chromatography. The optimum parameters were found as pH: 4.0 for biosorption medium, 60 min of contact time, 50 mg of bacteria, and 50 mg L-1 of initial pesticides concentrations. Langmuir and Freundlich models were applied to describe the biosorption isotherm of the pesticides by A. flavithermus as biomass. Biosorption of pesticides on to A. flavithermus showed pseudo first-order rate kinetics at different initial concentration of pesticides and different temperatures. The experimental adsorption data were fitted both the Langmuir and Freundlich adsorption models. Fourier-transform Infrared spectroscopy was used to understand the bonding mechanism of pesticides to biosorbent and surface functionality of the biosorbent The highest pesticide uptake was calculated from Langmuir isotherm and found to be 24.15 mg g-1 for 2,4-D. Among the studied pesticides, 2,4-DP showed difference adsorption behavior. According to in your comments the reason of this that 2,4-DP contain an asymmetric carbon atom, which provide a molecular chirality. (C) 2011 American Institute of Chemical Engineers Environ Prog, 2011
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    Characterization of a Thermally Stable ?-galactosidase Produced by Thermophilic Anoxybacillus sp. AH1
    (2021) Acer, Ömer Acer; Bekler, Fatma Matpan
    Thermostable ?-galactosidases from thermophilic bacteria have attracted increasing interest to have various advantages in industrial and biotechnological applications. In this study, a highly thermally stable ?-galactosidase produced by Anoxybacillus sp. AH1was purified and characterized. The highest enzyme production was achieved after the bacterium was incubated for 24 hours. The enzyme was purified by precipitation with ammonium sulphate dialysis, gel filtration chromatography using Sephadex G-75. After the purification steps, ?-galactosidase was found to be purified 10.2-fold and a yield of 13.9%. The molecular mass of the galactosidase was estimated to be 75 kDa by SDS-PAGE. The purified enzyme was highly stable and retained at 71% of the original activity at 60 °C and 53% at 70 oC within 120 minutes. The Km and Vmax values of purified ?-galactosidase were calculated as 1.249 mM and 0.5 ?mol minutes-1, respectively. Ca2+, Zn2+, and Mg2+ significantly activated ?-galactosidase activity, whereas enzyme activity was inhibited significantly by Cu+2 as well as by the metal ion chelators1,10-phenanthroline (phen) and ethylenediaminetetraacetic acid (EDTA). The Purified ?-galactosidase activity was increased by PMSF (phenylmethylsulfonyl fluoride), PCMB (p-chloromercuribenzoic acid), DTT (dithiothreitol), and ?-ME (?-mercaptoethanol) at 2 mM, but inhibited completely by NEM (N-ethylmaleimide) at 1 mM.