低温对异养硝化菌Acinetobacter sp.生长代谢及群体感应影响研究

Effects of low temperature on the growth,metabolism,and quorum sensing of heterotrophic nitrifying bacteria Acinetobacter sp

为进一步探究低温条件下HN-AD菌氮素转化机理及其群体感应系统对低温响应机制,采用GC-MS测定HN-AD过程中释放的信号分子,结果表明菌株JQ1004至少分泌包括C_(6)-,C_(8)-,和C_(10)-HSL在内3种高丝氨酸内酯(AHLs),其浓度变化均随细菌浓度增加不断累积,呈现显著密度依赖性.当温度由30℃降低至10℃时,C_(6)-和C_(8)-HSL呈不断下降趋势,而C_(10)-HSL变化为先上升后下降,并在20℃达到最大值10.89nmol/L,表明C_(10)-HSL在菌株适应低温环境中发挥重要作用.低温添加10nmol/L C_(10)-HSL可显著缩短细菌迟滞期,提高脱氮速率.20℃和10℃时添加C_(10)-HSL使amoA表达量分别提高了35%和22%,napA表达量分别增加了14%和9.4%.C_(10)-HSL通过提高luxR调控的受体蛋白活性来提高菌株群感能力.低温添加C_(10)-HSL可促进胞外蛋白分泌,降低多糖含量,提高生物膜活性,进而强化其对低温恶劣环境适应能力.

To further explore the mechanism of nitrogen transformation and quorum sensing system of HN-AD bacteria under low temperature,there were at least three AHLs signaling molecules,including C_(6)-,C_(8)-,and C_(10)-HSL produced by the HN-AD bacterium JQ1004 based on the analysis of GC-MS.The concentration of AHLs showed a significant density dependence and continuously accumulated with the increase of biomass.When the temperature decreased from the optimal 30℃ to 10℃ C_(6)-and C_(8)-HSL showed a continuous decreasing trend due to the decrease of cell concentration,while the concentration of C_(10)-HSL increased first and then decreased,reaching a maximum value of 10.89nmol/L at 20℃,indicating that C_(10)-HSL played a crucial role in the bacterial adaptation to low-temperature environments.Further study found that adding 10nmol/L C10-HSL at low temperature could significantly shorten the bacterial lag period and improved the nitrogen removal rate.The addition of C_(10)-HSL at 20 and℃10 increased the expression of amoA by 35%and 22%,respectively,while the expression of napA increased by 14%and 9.4%.C_(10)-HSL enhanced the ability of quorum sensing of strains by increasing the receptor protein activity regulated by luxR.Adding C_(10)-HSL at low temperature could promote extracellular protein secretion,reduce polysaccharide content,improve biofilm activity,and strengthen its adaptability to harsh low-temperature environments.