Isolation and identification of a novel aerobic denitrifying bacterium with quorum quenching activity and the effect of environmental factors on its performance

Abstract

A novel aerobic denitrifying bacterium capable of quorum quenching (QQ), Acinetobacter strain WZL728, was first isolated. WZL728 showed excellent aerobic denitrification performance and QQ activity. Besides, its optimal aerobic denitrification condition was pH 7.1, temperature 32.0 °C, C/N ratio 7.4 and shaking speed 108.0 rpm. However, its optimal QQ condition was pH 7.2, temperature 32.4 °C, C/N ratio 7.1 and shaking speed 96.1 rpm. The QQ activity of WZL728 was more tolerant to environmental changes than its aerobic denitrification performance because of the different response of its denitrification and QQ function genes expression. Moreover, it was revealed that the strain degraded N-acyl-homoserine lactones (AHLs) with long acyl chains by secreting extracellular QQ acylase. Due to the high QQ activity of the aerobic denitrifying bacterium, it may have great potential for controlling membrane biofouling in the field of wastewater treatment. • A novel aerobic denitrifier with QQ activity (WZL728) was isolated and identified. • WZL728 efficiently removed nitrate and degraded AHLs under aerobic conditions. • The QQ of WZL728 was more tolerant to environmental changes than denitrification. • WZL728 hydrolyzed AHLs with long acyl chains by secreting exogenous acylase.