群体感应系统对紫色杆菌CV31532积累PHA的影响

紫色杆菌CV31532中群体感应系统产生的信号分子C6-HSL是由cviI基因编码合成的。在限氮条件下,以D-葡萄糖酸钠、果糖、葡萄糖为唯一碳源时,紫色杆菌CV31532均产生聚-3-羟基丁酸,且以D-葡萄糖酸钠为唯一碳源时积累量最高。利用气相色谱分析发现,紫色杆菌CV31532培养48 h的PHA积累量显著高于其群体感应合成酶突变株CV026 PHA的积累量;通过薄层层析分析发现紫色杆菌CV31532合成信号分子的量在48 h显著提高;外源添加C6-HSL信号分子可显著提高突变体CV026 PHA的积累量。由此推测,紫色杆菌群体感应系统参与调控胞内PHA的合成。

Involvement of quorum-sensing in biosynthesis of polyhydroxyalkanoates in Chromobacterium violaceum 31532

In Chromobacterium violaceum 31532,cviI encodes an enzyme that synthesize N-hexanoyl-homoserine lactone（ C 6-HSL） as the main quorum sensing（ QS） signal. Under limitation of nitrogen CV31532 can accumulate polyhydroxyalkanoate（ PHA） intracellularly when grown on sodium D-glucose,fructose and glucose as the sole carbon source respectively. The highest yield of PHA was obtain with D-glucose as carbon source. GC analysis revealed that mutation of cviI significantly affected the ability of accumulating PHA since the PHA content in cviI mutant CV026 was much lower than that of wild type strain CV31532. The concentration of C 6-HSL was found to reach the maximum after 48h cultivation using TLC analysis. Addition of exogenous C 6-HSL significantly increased the PHA content in CV026,indication that C 6-HSL addition partially restored the defect in CV026 in terms of PHA accumulation. Our date suggested that bacterium QS might be involved in the regulation of PHA biosynthesis in CV31532.