Pseudomonas mendocina LYX: A novel aerobic bacterium with advantage of removing nitrate high effectively by assimilation
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RESEARCH ARTICLE
Pseudomonas mendocina LYX: A novel aerobic bacterium with advantage of removing nitrate high effectively by assimilation and dissimilation simultaneously Yuxin Li1, Jiayin Ling1, Pengcheng Chen1, Jinliang Chen1, Ruizhi Dai2, Jinsong Liao2, Jiejing Yu2, Yanbin Xu (✉)1,3
1 School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China 2 Guangdong Yikangsheng Environmental Protection Science and Technology Company, Yunfu 527300, China 3 Analysis and Test Center, Guangdong University of Technology, Guangzhou 510006, China
HIGHLIGHTS
GRAPHIC ABSTRACT
• Pseudomonas mendocina was first reported for aerobic nitrate removal. – • It removed 90% of NO3 -N in 24 h under aerobic conditions. • This strain converted NO3–-N to bio-nitrogen (37.9%) and gaseous nitrogen (49.7%). • Inoculation of this strain increased sludge denitrification rate by 4.3 times.
ARTICLE INFO Article history:
Received 16 April 2020 Revised 6 July 2020 Accepted 28 September 2020 Available online 10 October 2020 Keywords: Pseudomonas mendocina Aerobic nitrate removal 15 N tracing technique Denitrification assimilatively and disimilatively Aerobic denitrifying genes
ABSTRACT The problem of nitrate accumulation in aerobic tank and total nitrogen excessive discharge in effluent was very common in traditional livestock and poultry farming wastewater treatment systems owing to the lengthy process flow and low process control level. A strain LYX of aerobic bacterium was isolated from the activated sludge of a wastewater treatment system in a pig farm, which could remove nitrate effectively in aerobic tank and was identified Pseudomonas mendocina by 16S rRNA sequencing. Under the condition of nitrate as the sole nitrogen source, this strain removed over 90% of NO3–-N with an initial–concentration of 110 mg/L under aerobic conditions within 48 hours. Among them, 37.9% of NO3 -N was assimilated into Bio-N, about 51.9% was reduced to gaseous nitrogen and less than 0.5% of nitrogen was replaced by NO2–-N and NH4+-N, 9.7% NO3–-N remained in the effluent at the end. At the same time, four key genes (napA, nirK, norB and nosZ) related to nitrate nitrogen removal were expressed during the denitrification process of P. mendocina LYX, in which the transcription level of the indicator genes of this aerobic denitrifying bacterium (napA) was the highest. In addition, it was found with the 15N tracer technique that inoculation of this strain on sludge increased the amount of nitrogen loss from 9.26 nmol N/(g$h) to 23.835 nmol N/(g$h). Therefore, P. medocina LYX is a potential bioagent for advanced nitrogen removal by assimilating and reducing nitrate simultaneously in aerobic tanks. © Higher Education Press 2020
1 ✉ Corresponding author E-mail: [email protected]
Introduction
With the development of economy and the improvement of
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Front. Environ. Sci. Eng. 2021, 15(4): 57
people’s living standards, the demand for livestock and poultry products continues to increase, and the scale of production continues to ex
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