Abstract：
Steroid hormones exhibit potent endocrine disrupting activity and have been shown to disrupt the equilibrium of aquatic ecosystems and pose a threat to public health through their persistent and carcinogenic effects. Pontibacillus chungwhensis HN14, a moderately halophilic bacterium with the capacity to effectively degrade various polycyclic aromatic hydrocarbons and other organic pollutants, was previously isolated. Additionally, the strain HN14 showed strong environmental adaptability under various environmental stress conditions. In this study, the steroid degradation by strain HN14 was studied for the first time. We demonstrated that strain HN14 could degrade estradiol (E2) to maintain the growth of the strain and could convert E2 to estrone. Additionally, the efficient substrate degradation efficiency of P. chungwhensis HN14 under high salinity and high substrate concentration conditions was demonstrated. Furthermore, a 17β-hydroxysteroid dehydrogenase, 17β-HSD(HN14), was identified in strain HN14. Comparative analysis reveals that 17β-HSD(HN14) shares approximately 38% sequence identity with 17β-HSDx from Rhodococcus sp. P14. In addition, 100 µg of purified 17β-HSD(HN14) could effectively convert about 40% of 0.25 mM of E2 within 1 h period, with an enzyme activity of 17.5 U/mg, and catalyze the dehydrogenation of E2 and testosterone at the C-17 position. The characterization of purified enzyme properties reveals that 17β-HSD(HN14) exhibits exceptional structural robustness and enzymatic efficacy even under high salinity conditions of up to 20%. Overall, this study enhances our comprehension of steroid biodegradation in strain HN14 and contributes novel ideas and theoretical underpinnings for advancing bioremediation technologies targeting steroid pollution in high-saline environments.
摘要：
类固醇激素表现出强大的内分泌干扰活性，并已被证明会破坏水生生态系统的平衡，并通过其持续和致癌作用对公众健康构成威胁。中华芽孢杆菌HN14是一种中度嗜盐细菌，能够有效降解各种多环芳烃和其他有机污染物，以前是孤立的。此外,菌株HN14在各种环境胁迫条件下表现出较强的环境适应性。在这项研究中,首次研究了菌株HN14对类固醇的降解。我们证明了菌株HN14可以降解雌二醇（E2）以维持菌株的生长，并可以将E2转化为雌酮。此外,证明了在高盐度和高底物浓度条件下，中华黄连HN14的高效底物降解效率。此外，一种17β-羟基类固醇脱氢酶，17β-HSD(HN14),在菌株HN14中鉴定。比较分析表明，17β-HSD（HN14）与来自红球菌属的17β-HSDx具有约38％的序列同一性。P14.此外,100µg纯化的17β-HSD（HN14）可以在1小时内有效转化约40％的0.25mME2，酶活性为17.5U/mg，并在C-17位催化E2和睾酮的脱氢。纯化的酶特性的表征表明，即使在高达20％的高盐度条件下，17β-HSD（HN14）也表现出出色的结构稳健性和酶促效力。总的来说,这项研究增强了我们对菌株HN14中类固醇生物降解的理解，并为推进针对高盐环境中类固醇污染的生物修复技术提供了新的思路和理论基础。
