Biotransformation of doxycycline by Brevundimonas naejangsanensis and Sphingobacterium mizutaii strains

Authors

Ting He, China University of Geosciences
Jianguo Bao, China University of GeosciencesFollow
Yifei Leng, Hubei University of Technology
Daniel D. Snow, University of Nebraska-LincolnFollow
Shuqiong Kong, China University of Geosciences
Tong Wang, China University of Geosciences
Xu Li, University of Nebraska-LincolnFollow

ORCID IDs

Xu Li 0000-0002-1006-3027

Document Type

Article

Date of this Version

6-5-2021

Citation

Published in Journal of Hazardous Materials 411 (2021) 125126

doi:10.1016/j.jhazmat.2021.125126

Comments

Copyright © 2021 Elsevier B.V. Used by permission

Abstract

The fate of doxycycline (DC), a second generation tetracycline antibiotic, in the environment has drawn increasing attention in recent years due to its wide usage. Little is known about the biodegradability of DC in the environment. The objective of this study was to characterize the biotransformation of DC by pure bacterial strains with respect to reaction kinetics under different environmental conditions and biotransformation products. Two bacterial strains, Brevundimonas naejangsanensis DD1 and Sphingobacterium mizutaii DD2, were isolated from chicken litter and characterized for their biotransformation capability of DC. Results show both strains rely on cometabolism to biotransform DC with tryptone as primary growth substrate. DD2 had higher biotransformation kinetics than DD1. The two strains prefer similar pHs (7 and 8) and temperature (30 °C), however, they exhibited opposite responses to increasing background tryptone concentration. While hydrolysis converted DC to its isomer or epimer, the two bacterial strains converted DC to various biotransformation products through a series of demethylation, dehydration, decarbonylation and deamination. Findings from the study can be used to better predict the fate of DC in the environment.