含奥氏酮嗜盐紫色硫细菌的分离鉴定及系统发育分析

Identification and phylogenetic analysis of an okenone-containing halophilic purple sulfur bacterium

摘要:

【目的】为挖掘我国紫色硫细菌物种和光合蛋白基因资源。【方法】采用Pfennig紫色硫细菌无机选择性培养基和琼脂稀释法。【结果】从青岛东风盐场分离获得一株含奥氏酮、耐高浓度硫化物、嗜盐耐碱紫色硫细菌菌株283-1。该菌株能氧化硫化物产生硫粒储存在细胞内、嗜盐、细胞含有奥氏酮类胡萝卜素、细菌叶绿素a强吸收峰位于830 nm处、运动、不产生气囊，表明属于Marichromatium属，16S rDNA序列同源性比较和系统发育分析也表明这一点。但该菌株能在1%~15% NaCl、7.5 mmol/L高浓度硫化物、45℃、5000lux、pH9.0条件下生长良好，能很好的光同化C3和C4有机酸和葡萄糖酸钠等特性，与Marichromatium属4个种有明显不同。 【结论】菌株283-1是Marichromatium属一个新分离物，编号 Marichromatium sp. 283-1。

关键词:紫色硫细菌;奥氏酮;耐硫化物;嗜盐;系统发育

Abstract:

[Objective] To exploit resources of purple sulfur bacteria and their photosynthetic genes. [Methods] A purple sulfur bacterium strain 283-1 of okenone-containing, halophilic, high sulfide tolerance was isolated by agar dilution method in Pfennig medium from photolithoautotrophic enrichments of Dongfeng saltern, Qingdao, China. [Results] Cells of strain 283-1 were Gram–negative, halophile, straight or slightly curved rods, motile by monopolar single flagella, no gas vacuoles, carotenoid of okenone series and bacteriochlorophylla as photosynthetic pigment, purple red. It could photolithoautotrophically grow under anoxic condition in the light with sulfide as electron donor, sulfur globules accu-mulate as intermediate oxidation product and stored in the form of highly refractile globules inside the cells. The strain 283-1 belonged to Gammaproteobacteria, Chromatiales, Chroamtiaceae, genus of Marichromatium. Phylogenetic analysis based on 16S rRNA gene sequence also confirmed that strain 283-1 belonged to Marichromatium genus. However, the physiological characteristics of strain 283-1 were significantly different from four species of the genus Marichromatium. NaCl requirement range from 1% to 15%, good growth was observed at 7.5mmol· L-1NaS·9H2O, 45℃, 5000lux and pH9.0, a number of organic substances of C3 and C4 of TCA cycles and gluconate could be photoassililated in the presence of sulfide, no growth factors were required. [Conclusion] On the basis of 16S rRNA gene sequence analysis and its mor-phological and physiological characteristics, strain 283-1 is a new isolate of Marichromatium genus, named as Marichromatium sp. 283-1.

Key words:purple sulfur bacterium; okenone; halophile; sulfide tolerance; phylogenetic analysis