Laboratório de Bioquímica e Microbiologia Aplicada, Universidade Federal do Rio Grande do Sul, 91501-970, Porto Alegre, Brazil.
Biol Trace Elem Res. 2013 Dec;155(3):447-54. doi: 10.1007/s12011-013-9818-1. Epub 2013 Sep 14.
Selenium (Se) is an essential micronutrient for several organisms, and there is an increased interest about adequate sources for dietary selenium supplementation. The aim of this study was to evaluate the selenium bioaccumulation capacity of an Enterococcus strain. The isolate LAB18s was identified as Enterococcus durans by the VITEK® 2 system and analysis of both 16S rDNA gene sequence (JX503528) and the 16S-23S rDNA intergenic spacer (ITS). After 24-h incubation, E. durans LAB18s bioaccumulated elevated Se(IV) concentrations, reaching 2.60 and 176.97 mg/g in media containing initial amounts of 15 and 240 mg/l sodium selenite, respectively. The isolate grew optimally and had high selenium bioaccumulation at initial pH of 7.0 and 30 °C. Time course studies showed that E. durans LAB18s displayed the highest bioaccumulation of Se(IV) after 6 h of incubation. Analyses from scanning electron microscopy (SEM) demonstrated the presence of filaments connecting the cells of E. durans LAB18s cultivated in the presence of sodium selenite. It was demonstrated that a considerable amount of Se(IV) was absorbed by E. durans LAB18s. Therefore, this strain may represent an alternative source of organic dietary selenium.
硒（Se）是几种生物体必需的微量元素，人们对饮食中硒补充剂的合适来源越来越感兴趣。本研究的目的是评估一株肠球菌菌株的硒生物累积能力。通过 VITEK® 2 系统和 16S rDNA 基因序列（JX503528）和 16S-23S rDNA 基因间隔区（ITS）分析，分离株 LAB18s 被鉴定为耐久肠球菌。在 24 小时孵育后，E. durans LAB18s 生物累积了高浓度的 Se(IV)，在含有初始浓度为 15 和 240mg/l 亚硒酸钠的培养基中分别达到 2.60 和 176.97mg/g。该分离株在初始 pH 值为 7.0 和 30°C 时最佳生长并具有高硒生物累积能力。时程研究表明，E. durans LAB18s 在孵育 6 小时后显示出最高的 Se(IV)生物累积量。扫描电子显微镜（SEM）分析表明，在存在亚硒酸钠的情况下培养的 E. durans LAB18s 细胞之间存在丝状结构。结果表明，相当数量的 Se(IV)被 E. durans LAB18s 吸收。因此，该菌株可能是有机饮食硒的替代来源。
