EFFECT OF GROWTH CONDITIONS ON THIOCYANATE DEGRADATION AND EMISSION OF CARBONYL SULFIDE BY THIOBACILLUS THIOPARUS THI115
EFFECT OF GROWTH CONDITIONS ON THIOCYANATE DEGRADATION AND EMISSION OF CARBONYL SULFIDE BY THIOBACILLUS THIOPARUS THI115
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DOI：
10.1016/s0043-1354(00)00046-4
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发表时间：
2000-08
期刊：
影响因子：
12.8
通讯作者：
Se-jeong Kim;Y. Katayama
中科院分区：
文献类型：
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作者：
Se-jeong Kim;Y. Katayama
排硫硫杆菌THI115利用硫氰酸盐作为其生长的唯一能量来源。羰基硫（COS）被发现作为一个中间体在密封烧瓶的顶部空间中的硫氰酸盐降解过程中，和氨和硫酸盐作为最终产物产生的介质pH值略有下降。在一个pH控制TC培养基中，最高的硫氰酸盐降解活性在pH 6.2和活性被抑制在pH 6.0。当通过强制通风将液体培养基和顶空中的全部气体从培养容器中去除时，T. thioparus THI115对硫氰酸盐的降解作用也不明显。另一方面，硫氰酸盐降解后，约150小时的滞后期时，只有在顶部空间的气体被删除。这些结果表明，产生的整个COS容易扩散到细胞外，并且进化的COS被重新掺入以被细胞代谢。尽管COS对生物体具有毒性，但T.当向培养物中加入总共500 μmol COS时，thioparus THI115是耐受的，该COS约为大鼠90 min致死剂量50的17倍。T.当提供足够的氧气并保持培养基pH超过6.2时，thioparus THI115在130 h内降解高达60 mM的硫氰酸盐。
Thiobacillus thioparus THI115 utilizes thiocyanate as its sole source of energy for growth. Carbonyl sulfide (COS) was found as an intermediate in the headspace of a sealed flask during the degradation of thiocyanate, and ammonia and sulfate were produced as the final products which slightly decreased the medium pH. In a pH-controlled TC medium, the highest degradation activity for thiocyanate was obtained at pH 6.2 and the activity was inhibited at pH 6.0. When whole gases in both liquid medium and headspace were removed from the culture vessel by forced aeration, neither growth of T. thioparus THI115 nor the degradation of thiocyanate could be observed. On the other hand, thiocyanate was degraded after a lag period of about 150 h when only the gases in the headspace were removed. These results suggest that the entire COS produced was easy to diffuse outside the cells and that the evolved COS was re-incorporated to be metabolized by cells. Despite the fact that COS is toxic to organisms, thiocyanate degradation by T. thioparus THI115 was tolerated when a total of 500 μmol of COS, which is about 17 times higher than the lethal dose of 50 for 90 min in rats, was added to the culture. T. thioparus THI115 degraded up to 60 mM thiocyanate in 130 h when supplied with sufficient oxygen and keeping the medium pH over 6.2.