中文摘要：

【目的】挖掘我国海洋紫色硫细菌物种资源、深入理解紫色硫细菌在红树林生态系统中的作用。【方法】采用琼脂振荡稀释法、显微技术、紫外可见吸收光谱法、TLC、HPLC和MS法。【结果】从福建泉州洛阳桥红树林潮间带泥水样分离获得一株细胞内含多个硫粒的细菌菌株,光合内膜呈囊状、含细菌叶绿素a和螺菌黄质系类胡萝卜素,结合16S rRNA基因序列分析和系统发育分析,表明该菌株属于海洋着色菌属（Marichromatium）。该菌株细胞球杆状;最适pH范围5.7-6.7;最适盐度范围2%-3.5%;温度范围20℃-35℃;能耐受3.6 mmol/L硫化物;主要积累玫红品类胡萝卜素,而不是螺菌黄质;3种细菌叶绿素组分中,一种为BChl aP,另2种未见报道;不需要生长因子;可光同化固定CO2、能很好利用多种有机酸盐、多价态氮化物和硫化物,尤其能利用柠檬酸、葡萄糖、蔗糖、果糖和丙醇;对氯霉素、头孢唑林、苯、对羟基联苯、恩诺沙星、啶虫脒、HgCl2和CdCl2的IC50值分别为70、100、20、20、3、170、5 mg/L和25 mg/L。【结论】该菌株是一株轻度耐酸、高含玫红品类胡萝卜素的紫色硫细菌,被鉴定为Marichromatium gracile新菌株,编号YL28。该菌株具有广泛利用多种碳源、氮源和硫源物质的能力,对抗生素氯霉素和头孢唑啉、农药啶虫脒、重金属汞和镉具有较强耐受性,对抗生素恩诺沙星较敏感。

英文摘要：

[Objective]To exploit resources of purple sulfur bacteria in China and further investigate its response mechanism to ecological environment of mangrove.[Methods] Repeated agar shake dilution method,microscope techniques,UV-Vis absorption spectra,thin layer chromatography,HPLC and MS were used.[Results] We isolated a purple sulfur bacterium,designated as strain YL28,from a intertidal sediment sample collected from inshore mangrove near Luoyang Bridge of Quanzhou city,Fujian Province of China.Cells were ovoid to rod shaped,0.5 μm-1 μm × 2 μm-3 μm.Color of cell suspensions was reddish-brown.It possessed vesicular intracytoplasmic membrane structures,contained rhodopin and phytylated bacteriochlorophyll a as well as the other two novel bacteriochlorophyll a intermediates.The optimum growth was at 2%-3.5% NaCl,pH 5.7-6.7 and 20℃-35℃.Photoautotrophically growth anaerobically in the light with sulphide,sulphur,thiosulfate,sulfite as electron donor.Globules of S0 distributed inside the cells.Photoheterotrophic growth with various organic substrates,especially citrate,glucose,sucrose,fructose and propanol in the presence of sulfide.Nitrogen sources： ammonium salts,N2,urea,glutamate,nitrate and nitrite.Vitamins were not required.Qualitative assessment of IC50 values of chloromycetin,cefazolin,benzene,hydroxy biphenyl,enrofloxacin,acetamiprid,mercuric chloride and cadmium chloride were 70,100,20,20,3,170,5 mg/L and 25 mg/L,respectively.[Conclusion]Based on phenotype characteristics and 16S rRNA gene sequence similarity of 99% to M.gracile,strain YL28 was identified as novel isolate of M.gracile despite its different physiological characteristics with respect to the species of M.gracile.The organism is possessed of slightly acid tolerance,higher amount of carotenoid of rhodopin and tolerance towards certain antibiotics,pesticide as well as heavy metals.