碳酸酐酶对猪链球菌生长及抗氧化应激的影响.

[Objectives] This article aimed to study the effect of Streptococcus suis carbonic anhydrase ( SCA) on the growth and oxidative stress response of S. suis and to analyse its biological functions. [Methods] The deletion mutant strain Δsca was constructed using S. suis wild-type strain SC070731, and the effect of SCA on the growth of S. suis under different conditions including H2O2 treatment was evaluated; the assay of mouse macrophage cells RAW264.7 phagocytosis and survival, and pig blood survival were performed. [Results]Compared with the wild-type strain, the growth of Δsca strain in the absence of CO2 was significantly inhibited, and its A600 value of 12 h growth was lower than 0.5. Under the condition of 5% CO2, although the lag phase of Δsca strain was longer than that of the wild-type strain, the A600 values of both wild-type strain and Δsca strain were close to 1.6 at stationary period; in the absence of CO2, with the gradient increase of NaHCO3 concentration in the medium, the growth ability of Δsca strain was significantly improved. Compared with Δsca strain, adding unsaturated fatty acid ( UFA) oleic acid or UFA derivatives such as Tween-80 and Tween-20 significantly promoted the growth of Δsca strain. The survival rate of the wild-type strains was 99.48% after H2O2 treatment for 20 min, while the survival rate of Δsca strain significantly reduced to 74.04% ( P<0.01). There was no significant difference in the phagocytosis rates of RAW264.7 on the wild-type strain and Δsca strain; the survival assay showed that after 3 hours of antibiotic treatment, the survival rate of the wild-type strain was 77.98%, while the survival rate of Δsca strain in RAW264.7 significantly reduced to 38.93% ( P<0.01). Pig blood survival assay showed that the survival rate of the wild-type strain was 110.02%, but the survival rate of Δsca strain in pig blood was only 51.39% ( P<0.01). [Conclusions]The SCA, necessary for S. suis to utilize CO2 and HCO-3, is involved in the synthesis of UFA. Thus, it contributes to the growth and oxidative stress response of S. suis; the enzyme promotes the survival of S. suis in pig blood and macrophages, suggesting that it plays a vital role in pathogenesis of S. suis. [ABSTRACT FROM AUTHOR]

[目的] 本文旨在研究碳酸酐酶 ( SCA) 对猪链球菌生长及抗氧化应激的影响,并分析其生物学功能。[方法]以猪链球菌2型野生株 SC070731 为背景,构建 sca 缺失株 Δsca, 通过测定不同条件下的生长曲线和 H2O2 应激、小鼠巨噬细胞 RAW264.7 吞噬与存活、猪全血存活等试验,评价 SCA 对猪链球菌生长及抗氧化应激的影响。[结果] 与野生株相比, Δsca 株在缺乏 CO2 条件下的生长受到显著抑制,生长 12 h A600 值低于 0.5; 在 5% CO2 条件下,虽然 Δsca 株的迟缓期较野生株长,但平台期其恢复到与野生株相同的水平, A600 值均接近 1.6; 在缺乏 CO2 条件下,添加 NaHCO3 可显著刺激Δsca 株生长,且与浓度呈正相关; 添加不饱和脂肪酸 ( UFA) 油酸或 Tween-80、Tween-20 等 UFA 衍生物均可显著促进 Δsca 株生长。经H2O2作用 20 min 后,野生株存活率为 99.48%, 而 Δsca 株存活率为 74.04% ( P<0.01)。吞噬试验表明, RAW264.7 对野生株和 Δsca 株的吞噬率无显著差异; 存活试验表明,经抗生素处理 3 h 后,野生株的存活率为 77.98%, 而Δsca株在 RAW264.7 内的存活率显著降低,仅为 38.93% ( P<0.01)。猪全血存活试验表明,与野生株的存活率 ( 110.02%) 相比,Δsca株在猪全血中的存活率为 51.39% ( P<0.01)。[结论] SCA 促进猪链球菌利用 CO2和HCO-3,并参与 UFA 合成,因而有助于猪链球菌的生长及抗氧化应激; 该酶促进猪链球菌在猪全血和小鼠巨噬细胞中存活, 提示其在猪链球菌致病过程中发挥重要作用。 [ABSTRACT FROM AUTHOR]