In this study we determined that Aspergillus tamarii Kita is able to utilize Avena sativa L. (oats) for the production of β-xylosidase under static or shaking conditions in submerged liquid-state (LSF), solid-state (SSF) and slurry-state (SlSF) cultures. The produced enzyme was purified and characterized. Maximum yield occurred under shaking conditions in SSF cultures (33.7 U/ml), with 24.9 and 5.5 U/ml produced in SISF and LSF cultures, respectively. Peptone was found to be the best nitrogen additive and enhanced enzyme production (41.5 U/ml). The produced enzyme was precipitated by ammonium sulfate (60 %) and further purified by gel filtration through a Sephadex G-100 and ion exchange column of diethylaminoethyl cellulose, with a yield of 40.57 % and 35.73-fold purification. Enzyme activity was optimal at pH 5.5 and 55 °C. The purified enzyme retained full activity even at the end of a 1-h incubation at this optimal condition. Midpoint of thermal inactivation (Tm) was recorded at 60 °C after 90 min of exposure. The Michaelis–Menten constant, maximal reaction velocity, turnover number and specificity constant of the purified enzyme were calculated to be 0.075 mg/ml, 71.42 U/mg of protein, 7.14/S and 95.2 mg/ml/s, respectively. The inability of the purified enzyme to hydrolyze celluloses indicated that the enzyme was a free cellulase. The most efficient enzyme activators were Mg2+, followed by Mn2+ and Zn2+ in that order. The molecular mass of the purified enzyme was 91 kDa as determined by SDS-PAGE. The possibility of using the fermentation of ground oat hydrolysate for the production of ethanol and xylitol in the presence of Pichia stipitis Pignal was assessed. The maximum production of ethanol and xylitol were obtained after 72 h of fermentation, resulting in 11.06 and 21.51 g/l respectively. 相似文献
Mammalian myocardial contractility is believed to be related to the amount of calcium contained in a highly labile superficial calcium pool. The purpose of this study was to determine the role of such sites in the positive inotropic effect of isoproterenol. Lanthanum, an ion that is restricted to the extracellular space and that displaces the superficially bound calcium, was selected as a tool for this investigation. In Langendorff preparations of the guinea pig heart, lanthanum decreased the basal contractility index (+dP/dtmax) in a concentration-dependent fashion (0.05-3 microM) and blocked the inotropic response of isoproterenol in a noncompetitive manner (0.25-3 microM). Three-micromolar lanthanum (i) reduced basal contractility and the maximum response to isoproterenol by 97 and 95%, respectively, (ii) had no significant effect (p greater than 0.05) on basal and isoproterenol-induced cyclic AMP levels, and (iii) had no effect on the Kd of [3H]nitrendipine binding, but reduced the Bmax by 31%. While 1 microM lanthanum reduced basal contractility and the maximum response to isoproterenol by 90 and 70%, respectively, it had no effect on [3H]nitrendipine binding. These results suggest that the effects of such low concentrations of lanthanum (less than or equal to 3 microM) are not related to a direct action on the calcium channels and are not mediated by an inhibition of isoproterenol stimulation of the enzyme adenylate cyclase. Therefore, one interpretation of these results suggests that superficially bound calcium is required for the inotropic response of isoproterenol. 相似文献
Globally, water resources contaminated with petroleum hydrocarbons are under much consideration due to their hazardous effects on human beings as well as on plants and animals in the ecosystem. Petroleum hydrocarbons are classified as recalcitrant pollutants in nature. These petroleum products are mostly released in the water resources during the petroleum refining process by oil refineries. The conventional clean-up technologies for hydrocarbons contaminated water have more destructive effects on the aquatic and land ecosystems. Consequently, to develop cost-effective and more environment-friendly techniques that clean up the environment and restore the marine ecosystem to its original forms. Keeping in view, this review article explores the detailed information on fabrication, cost-effectiveness, and an overview of innovation of the floating treatment wetlands (FTWs) using plants and bacterial combined functions to remediate the petroleum hydrocarbons contaminated water. The review also discusses the improvement of microbial efficacy for hydrocarbon degradation using FTWs. The review article shows the various applications of FTWs to remove different organic pollutants in petroleum hydrocarbons contaminated water. The review also describes the prospective benefits of FTWs for their multiple uses for removal of hydrocarbons, chemical oxygen demand (COD), biochemical oxygen demand (BOD), phenol, and solids from hydrocarbons contaminated water. This review widely discusses the role of hydrocarbons in degrading bacteria, and wetland plants and the mechanism involved during the remediation process of hydrocarbons in FTWs. It further demonstrates features disturbing the treatment efficiency of FTWs, and finally, it is concluded by successful applications of FTWs and various suggestions for potential future research prospects.
