a Department of Polymer Science and Technology , University of Calcutta , Calcutta , India.
b Calcutta Institute of Technology , Howrah , West Bengal , India.
J Environ Sci Health A Tox Hazard Subst Environ Eng. 2019;54(1):65-78. doi: 10.1080/10934529.2018.1516070. Epub 2019 Mar 1.
This report presents the substrate inhibitory effect of xanthine (XN) on microbial growth and optimisation of effective parameters to achieve high enzyme activity of xanthine oxidoreductase (XOR) through statistical design. Three efficient isolated strains (Pseudomonas aeruginosa CEBP1 and CEBP2, Pseudomonas sp. CEB1G) were screened for growth kinetic studies. Substrate inhibitory models (eg. Aiba, Edward) could explain the growth kinetics of CEBP1, CEBP2 and CEB1G very well with various initial [XN] (S), e.g., 0.1-35 g L. Highest XOR activity was obtained at stationary phase when biomass yield was high. Highest catalytic efficiency (k/K) of XOR was obtained by CEBP1 at optimum specific growth rate of 0.082 h and biomass yield of 0.196 g g at S = 5 g L. The effects of S, pH and temperature were studied by Box-Behnken experimental design to evaluate the interactive effects of the significant variables influencing XOR production by CEBP1. ANOVA with high correlation coefficient (R > 0.99) and lower 'Prob > F'value (< 0.05) validated the second order polynomial model for the enzyme production. The highest XOR activity of 31.2 KU minmg was achieved by CEBP1 under optimised conditions (35 °C; S=5 g L; pH = 7.0) as compared to any report in literature. A sevenfold substrate affinity of the enzyme was observed after purification.
本报告介绍了黄嘌呤（XN）对微生物生长的基质抑制作用，并通过统计设计优化了有效参数，以实现黄嘌呤氧化还原酶（XOR）的高酶活。筛选了三种高效分离株（铜绿假单胞菌 CEBP1 和 CEBP2、假单胞菌 CEB1G）进行生长动力学研究。基质抑制模型（如 Aiba、Edward）可以很好地解释 CEBP1、CEBP2 和 CEB1G 的生长动力学，初始 [XN]（S）范围很广，例如 0.1-35 g/L。当生物量产量较高时，在静止期获得最高的 XOR 活性。在 S = 5 g/L 时，CEBP1 的最佳比生长速率为 0.082 h 和生物量产率为 0.196 g/g 时，获得了最高的 XOR 催化效率（k/K）。通过 Box-Behnken 实验设计研究了 S、pH 和温度的影响，以评估影响 CEBP1 产生 XOR 的显著变量之间的相互作用。具有高相关系数（R > 0.99）和较低“Prob > F”值（<0.05）的 ANOVA 验证了用于酶生产的二次多项式模型。CEBP1 在优化条件（35°C；S=5 g/L；pH = 7.0）下实现了 31.2 KU minmg 的最高 XOR 活性，与文献中的任何报道相比都有所提高。酶的底物亲和力提高了七倍。
