González J M, Kiene R P, Moran M A
Department of Marine Sciences, University of Georgia, Athens, Georgia 30602, USA.
Appl Environ Microbiol. 1999 Sep;65(9):3810-9. doi: 10.1128/AEM.65.9.3810-3819.1999.
Members of a group of marine bacteria that is numerically important in coastal seawater and sediments were characterized with respect to their ability to transform organic and inorganic sulfur compounds. Fifteen strains representing the Roseobacter group (a phylogenetic cluster of marine bacteria in the alpha-subclass of the class Proteobacteria) were isolated from seawater, primarily from the southeastern United States. Although more than one-half of the isolates were obtained without any selection for sulfur metabolism, all of the isolates were able to degrade the sulfur-containing osmolyte dimethyl sulfoniopropionate (DMSP) with production of dimethyl sulfide (DMS). Five isolates also degraded DMSP with production of methanethiol, indicating that both cleavage and demethylation pathways for DMSP occurred in the same organism, which is unusual. Five isolates were able to reduce dimethyl sulfoxide to DMS, and several isolates also degraded DMS and methanethiol. Sulfite oxygenase activity and methanesulfonic acid oxygenase activity were also present in some of the isolates. The ability to incorporate the reduced sulfur in DMSP and methanethiol into cellular material was studied with one of the isolates. A group-specific 16S rRNA probe indicated that the relative abundance of uncultured bacteria in the Roseobacter group increased in seawater enriched with DMSP or DMS. Because this group typically accounts for >10% of the 16S ribosomal DNA pool in coastal seawater and sediments of the southern United States, clues about its potential biogeochemical role are of particular interest. Studies of culturable representatives suggested that the group could mediate a number of steps in the cycling of both organic and inorganic forms of sulfur in marine environments.
在沿海水域和沉积物中数量众多的一群海洋细菌，就其转化有机和无机硫化合物的能力进行了表征。从海水中分离出了代表玫瑰杆菌属（变形菌纲α亚类中的一个海洋细菌系统发育簇）的15个菌株，主要来自美国东南部。尽管超过一半的分离株是在没有对硫代谢进行任何选择的情况下获得的，但所有分离株都能够降解含硫渗透剂二甲基巯基丙酸内盐（DMSP）并产生二甲基硫醚（DMS）。5个分离株还降解DMSP并产生甲硫醇，这表明DMSP的裂解和去甲基化途径在同一生物体中发生，这是不寻常的。5个分离株能够将二甲基亚砜还原为DMS，并且几个分离株还降解DMS和甲硫醇。一些分离株中还存在亚硫酸盐加氧酶活性和甲磺酸加氧酶活性。用其中一个分离株研究了将DMSP和甲硫醇中的还原态硫纳入细胞物质的能力。一种属特异性16S rRNA探针表明，在富含DMSP或DMS的海水中，玫瑰杆菌属中未培养细菌的相对丰度增加。因为该类群通常占美国南部沿海水域和沉积物中16S核糖体DNA库的10%以上，所以关于其潜在生物地球化学作用的线索特别令人感兴趣。对可培养代表菌株的研究表明，该类群可以介导海洋环境中有机和无机硫形式循环中的多个步骤。
