Mix-cultured Aerobic Denitrifying Bacterial Communities Reduce Nitrate: Novel Insights in Micro-Polluted Water Treatment at Lower Temperature.

Three mix-cultured aerobic denitrifiers were screened from a source water reservoir and named HE1, HE3 and SU4. Approximately 72.9%, 68.6% and 66.2% of nitrate were effectively removed from basal medium, respectively, after 120 h of cultivation at 8 degrees C. The nitrogen balance analysis revealed about one-fifth of the initial nitrogen was converted into gaseous denitrification products. According to the results of Biolog, the three microfloras had high metabolic capacity to carbon sources. The dominant genera were Pseudomonas and Paracoccus in these bacterial communities based on nirS gene sequencing. Response surface methodology elucidated that the denitrification rates of identified bacteria reached the maximum under the following optimal parameters: C/N ratio of 7.51-8.34, pH of 8.03-8.09, temperature of 18.03-20.19 degrees C, and shaking speed of 67.04-120 rpm. All results suggested that screened aerobic denitrifiers could potentially be applied to improve the source water quality at low temperature. (c) 2021 Elsevier B.V. All rights reserved.