寡养单胞菌对S2-氧化特性及主要代谢途径

以无机硫（S²）^-为目标污染物，从北京东沙河黑臭水体筛选出一株能够高效氧化S^2-的土著硫氧化菌，并对其进行16S rRNA测序及生理生化特性鉴定，结果表明，该菌株属于寡养单胞菌属（Stenotrophomonas），命名为Stenotrophomonas sp.sp3.菌株sp3在温度25℃，初始pH值7.0，初始葡萄糖浓度0.25%，初始菌浓度1.00g/L时，菌株sp3对S^2-的氧化率最高.在此适宜条件下，反应60h后，菌株sp3对S^2-的最高氧化率达到86.6%.S^2-的浓度在整个氧化过程中持续下降后保持稳定，在此过程中产生了S⁰，S₂O₃^2-，SO₃^2-以及SO₄^2-这4种其它存在形态的硫.随着S^2-被氧化，SO₄^2-的浓度呈缓慢上升的趋势.利用高通量测序技术推测菌株sp3主要是通过副球菌硫氧化途径（PSO）将非稳定态的S^2-逐步转化为稳定态的SO₄^2-.在此代谢途径中，一部分S^2-被氧化为S⁰，另一部分S^2-则直接氧化为SO₃^2-；S⁰与SO₃^2-可自发反应生成S₂O₃^2-，而S₂O₃^2-发生歧化反应再释放出SO₃^2-和S⁰；反应生成的部分SO₃^2-继续直接氧化为SO₄^2-.菌株sp3在黑臭水体的水质净化过程中有一定的应用前景.

S2--oxidizing characteristics and main bio-oxidation metabolic pathway of Stenotrophomonas sp.sp3

Inorganic sulfur (S^2-) was used as the target pollutant, and a single strain capable of S^2--oxidizing was obtained from Dongsha river (a black-stinking river) located in Beijing. Through both of the physiological-biochemical characteristics and the 16S rRNA sequencing experiment, this single strain was identified as Stenotrophomonas, and named as Stenotrophomonas sp.sp3. The experiment on the growth and S^2--oxidizing characteristics of this strain sp3 was then carried out. The best conditions of S^2--oxidizing were as follows:initial pH of 7.0, 25℃, initial glucose concentration of 0.25% along with initial cell concentration of 1.00g/L. Under the above bio-oxidation conditions, the highest S^2--oxidizing ratio was arrived at 86.6% by this strain sp3 after the bio-reaction of 60h. The concentration of S^2-decreased continually and then kept in a stable status in the whole bio-reaction process, and other sulphur chemical forms including S⁰, S₂O₃^2-, SO₃^2- and SO₄^2- were produced in this period. With the bio-oxidation of S^2-, the concentration of SO₄^2- increased slowly. High-throughput sequencing technologies were used to investigate the main metabolic pathway of S^2-bio-oxidation by this strain sp3. The paracoccus sulfur oxidation process was the possibly main metabolic pathway of S^2-(unstable valence state) to SO₄^2- (stable valence state). It was initially concluded that a portion of S^2-was oxidized to S⁰, while other part of S^2-was directly oxidized to SO₃²; and then S⁰ reacted with SO₃^2- spontaneously to form S₂O₃^2-, while the latter was released SO₃^2- and S⁰ by the disproportionate reaction again. The SO₃^2- accumulated gradually in the system was further directly oxidized to SO₄^2-. This study indicated that this strain sp3 has potential application in water purification of the black-stinking wate bodies.