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

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 C6-, C8-, and C10-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℃, C6- and C8-HSL showed a continuous decreasing trend due to the decrease of cell concentration, while the concentration of C10-HSL increased first and then decreased, reaching a maximum value of 10.89nmol/L at 20℃, indicating that C10-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 C10-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%. C10-HSL enhanced the ability of quorum sensing of strains by increasing the receptor protein activity regulated by luxR. Adding C10-HSL at low temperature could promote extracellular protein secretion, reduce polysaccharide content, improve biofilm activity, and strengthen its adaptability to harsh low-temperature environments. © 2024 Chinese Society for Environmental Sciences. All rights reserved.