多次接触高浓度的硒酸盐可显著提高山茶花根瘤菌 WT00C 对硒酸盐的耐受性、红色元素硒（Se）和硒蛋白的生物合成。

Multiple exposures to high concentrations of selenate significantly improve selenate tolerability, red elemental selenium (Se) and selenoprotein biosynthesis in Herbaspirillum camelliae WT00C.

机构信息

State Key Laboratory of Biocatalysis and Enzyme Engineering, The Faculty of Life Science, Hubei University, Wuhan, China.

Obstetrics and Gynecology Department, Fifth Hospital in Wuhan, Wuhan, China.

出版信息

World J Microbiol Biotechnol. 2021 Nov 27;38(1):5. doi: 10.1007/s11274-021-03190-4.

DOI:10.1007/s11274-021-03190-4

PMID:34837115

Abstract

Herbaspirillum camelliae WT00C is a gram-negative endophyte isolated from the tea plant. It has an intact selenate metabolism pathway but poor selenate tolerability. In this study, microbiological properties of the strain WT00C were examined and compared with other three strains CT00C, NCT00C and NT00C, which were obtained respectively from four, six and eight rounds of 24-h exposures to 200 mM selenate. The selenate tolerability and the ability to generate red elemental selenium (Se0) and selenoproteins in H. camelliae WT00C has significantly improved by the forced evolution via 4-6 rounds of multiple exposures a high concentration of selenate. The original strain WT00C grew in 200 mM selenate with the lag phase of 12 h and 400 mM selenate with the lag phase of 60 h, whereas the strains CT00C and NCT00C grew in 800 mM selenate and showed a relatively short lag phase when they grew in 50-400 mM selenate. Besides selenate tolerance, the strains CT00C and NCT00C significantly improved the biosynthesis of red elemental selenium (Se) and selenoproteins. Two strains exhibited more than 30% selenium conversion efficiency and 40% selenoprotein biosynthesis, compared to the original strain WT00C. These characteristics of the strains CT00C and NCT00C make them applicable in pharmaceuticals and feed industries. The strain NT00C obtained from eight rounds of 24-h exposures to 200 mM selenate was unable to grow in ≥ 400 mM selenate. Its selenium conversion efficiency and selenoprotein biosynthesis were similar to the strain WT00C, indicating that too many exposures may cause gene inactivation of some critical enzymes involving selenate metabolism and antioxidative stress. In addition, bacterial cells underwent obviously physiological and morphological changes, including gene activity, cell enlargement and surface-roughness alterations during the process of multiple exposures to high concentrations of selenate.

摘要

从茶树中分离得到的革兰氏阴性内生菌 Herbaspirillum camelliae WT00C 具有完整的硒酸盐代谢途径，但对硒酸盐的耐受性差。在这项研究中，我们对该菌株 WT00C 的微生物特性进行了研究，并与从四轮、六轮和八轮 24 小时暴露于 200 mM 硒酸盐中分别获得的 CT00C、NCT00C 和 NT00C 菌株进行了比较。通过四轮到六轮的多次暴露于高浓度硒酸盐的强制进化，WT00C 菌株的硒酸盐耐受性和生成红色元素硒（Se0）和硒蛋白的能力得到了显著提高。原始菌株 WT00C 在 200 mM 硒酸盐中的生长有 12 小时的迟滞期，在 400 mM 硒酸盐中的生长有 60 小时的迟滞期，而 CT00C 和 NCT00C 菌株在 800 mM 硒酸盐中生长，并且在 50-400 mM 硒酸盐中生长时迟滞期相对较短。除了硒酸盐耐受性外，CT00C 和 NCT00C 菌株还显著提高了红色元素硒（Se）和硒蛋白的生物合成。与原始菌株 WT00C 相比，这两个菌株的硒转化率效率超过 30%，硒蛋白生物合成超过 40%。CT00C 和 NCT00C 菌株的这些特性使它们适用于制药和饲料工业。从八轮 24 小时暴露于 200 mM 硒酸盐中获得的菌株 NT00C 无法在≥400 mM 硒酸盐中生长。其硒转化率效率和硒蛋白生物合成与菌株 WT00C 相似，表明过多的暴露可能导致参与硒酸盐代谢和抗氧化应激的一些关键酶的基因失活。此外，在多次暴露于高浓度硒酸盐的过程中，细菌细胞经历了明显的生理和形态变化，包括基因活性、细胞增大和表面粗糙度的改变。