Identification and denitrification characterization of a novel hypothermia and aerobic nitrite-denitrifying bacterium, Arthrobacter arilaitensis strain Y-10

Abstract

Based on morphology, phospholipid fatty acid and 16S rRNA gene sequence analyses, a novel hypothermia and aerobic nitrite-denitrifying bacterium, named to be Y-10, has been identified as Arthrobacter arilaitensis, which was further tested for its efficiency in disposing of wastewater in alkaline or/and low-temperature circumstances. This is the first report showing that A. arilaitensis can act as hypothermia and aerobic nitrite-denitrifying bacteria. Then, various factors that potentially affect the aerobic denitrification of strain Y-10 are comprehensively investigated in this study. The optimal temperature for denitrification is 15°C, where the nitrite and total nitrogen removal efficiencies reach up to 100 and 52.8%, respectively. In addition, it has been found that the nitrogen removal efficiency decreases sharply when temperatures are below 10°C or beyond 30°C. Alkaline conditions are beneficial for the aerobic denitrification of strain Y-10, and the highest removal efficiencies correspond to pH 9.0 (15°C) with nitrite and total nitrogen removal efficiencies of 100 and 84.0%, respectively. The optimal conditions of other factors such as shaking speed, incubation quantity, carbon source, and nitrite nitrogen content on the aerobic denitrification have also been determined; e.g. for sodium acetate (one of the carbon sources presently considered), 150 r/min and 1.5 × 106 CFU/mL are the most favorable. In addition, strain Y-10 can perform denitrification over a wide range of nitrite loadings, implying the great potential to treat high concentrated nitrite nitrogen.