Nitrogen Removal Characteristics of a Newly Isolated Indigenous Aerobic Denitrifier from Oligotrophic Drinking Water Reservoir, Zoogloea sp. N299

Abstract

Nitrogen is considered to be one of the most widespread pollutants leading to eutrophication of freshwater ecosystems, especially in drinking water reservoirs. In this study, an oligotrophic aerobic denitrifier was isolated from drinking water reservoir sediment. Nitrogen removal performance was explored. The strain was identified by 16S rRNA gene sequence analysis as Zoogloea sp. N299. This species exhibits a periplasmic nitrate reductase gene (napA). Its specific growth rate was 0.22 h−1. Obvious denitrification and perfect nitrogen removal performances occurred when cultured in nitrate and nitrite mediums, at rates of 75.53% ± 1.69% and 58.65% ± 0.61%, respectively. The ammonia removal rate reached 44.12% ± 1.61% in ammonia medium. Zoogloea sp. N299 was inoculated into sterilized and unsterilized reservoir source waters with a dissolved oxygen level of 5–9 mg/L, pH 8–9, and C/N 1.14:1. The total nitrogen removal rate reached 46.41% ± 3.17% (sterilized) and 44.88% ± 4.31% (unsterilized). The cell optical density suggested the strain could survive in oligotrophic drinking water reservoir water conditions and perform nitrogen removal. Sodium acetate was the most favorable carbon source for nitrogen removal by strain N299 (p < 0.05). High C/N was beneficial for nitrate reduction (p < 0.05). The nitrate removal efficiencies showed no significant differences among the tested inoculums dosage (p > 0.05). Furthermore, strain N299 could efficiently remove nitrate at neutral and slightly alkaline and low temperature conditions. These results, therefore, demonstrate that Zoogloea sp. N299 has high removal characteristics, and can be used as a nitrogen removal microbial inoculum with simultaneous aerobic nitrification and denitrification in a micro-polluted reservoir water ecosystem.

Oligotrophic Nitrification and Denitrification Bacterial Communities in a Constructed Sewage Treatment Ecosystem and Nitrogen Removal of Delftia tsuruhatensis NF4

“…The nutritional status, like the amounts of carbon (C) and nitrogen (N) in the environments, will regulate the nitrifiers and denitrifiers community in the system (Meyer-Reil et al 2000). Numerous oligotrophic microorganisms have been isolated from oligotrophic environments, such as water reservoirs, deserts, and oceans (Anderson et al 2003;Huang et al 2015a;Montiel-González et al 2017). Oligotrophic nitrifiers and denitrifiers have important theoretical and engineering application values for micro-polluted water treatment (Su et al 2015).…”

“…It has also been reported that NO 2 --N removal can be enhanced by immobilized Bacillus megaterium (Gao et al 2018). Oligotrophic aerobic denitrifiers have been used to study the N removal rate in both sterilized and unsterilized reservoir water (Huang et al 2015a), while the N removal of oligotrophic aerobic denitrifiers in both wastewater and oligotrophic medium had not been studied before. Further studies of different oligotrophic aerobic denitrifiers will help to prompt wastewater treatment in situ.…”

Nitrogen removal characteristics of indigenous aerobic denitrifiers and changes in the microbial community of a reservoir enclosure system via in situ oxygen enhancement using water lifting and aeration technology

“…During the past few decades, WLA (water lifting and aeration) technology has been developed and used effectively to increase dissolved oxygen concentration and improve water quality of micro-polluted drinking water reservoirs (Cong et al 2006, Cong et al 2009, Bryant et al 2011, Gerling et al 2014. Meanwhile, aerobic denitrifying species with nitrogen removal characteristics have also been isolated from reservoirs (Wei et al 2010, Guo et al 2013, Huang et al 2015a, Huang et al 2015b). This suggests that aerobic denitrification is an effective way to decrease endogenous nitrogen pollution in aquatic ecosystems.…”

Molecular phylogeny of heterotrophic nitrifiers and aerobic denitrifiers and their potential role in ammonium removal

“…Similar observation has also been made with >50% removal efficiency of novel Rhizobium sp. from oligotrophic drinking water reservoir . Among all strains obtained in this study, Ochrobactrum sp.…”