AUTHOR=Zhou Jia , Chen Tian , Cui Jing , Chen Yan , Zhao Shuai , Qu Jian-Hang , Wang Zitong , Pan Jingshi , Fan Lixin 

TITLE=Responses of the microbial community and the production of extracellular polymeric substances to sulfamethazine shocks in a novel two-stage biological contact oxidation system

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1240435

DOI=10.3389/fmicb.2023.1240435

ISSN=1664-302X

ABSTRACT=<sec><title>Introduction</title><p>The biological contact oxidation reactor is an effective technology for the treatment of antibiotic wastewater, but there has been little research investigating its performance on the sulfamethazine wastewater treatment.</p></sec><sec><title>Methods</title><p>In this study, a novel two-stage biological contact oxidation reactor was used for the first time to explore the impact of sulfamethazine (SMZ) on the performance, microbial community, extracellular polymeric substances (EPS), and antibiotic-resistant genes (ARGs).</p></sec><sec><title>Results</title><p>The chemical oxygen demand (COD) and ammonia nitrogen (<inline-formula><mml:math id="M1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mrow><mml:mtext>NH</mml:mtext></mml:mrow><mml:mn>4</mml:mn><mml:mo>+</mml:mo></mml:msubsup></mml:mrow></mml:math></inline-formula>-N) removal efficiencies kept stable at 86.93% and 83.97% with 0.1–1 mg/L SMZ addition and were inhibited at 3 mg/L SMZ. The presence of SMZ could affect the production and chemical composition of EPS in the biofilm, especially for the pronounced increase in TB-PN yield in response against the threat of SMZ. Metagenomics sequencing demonstrated that SMZ could impact on the microbial community, a high abundance of <italic>Candidatus_Promineofilum, unclassified_c__Anaerolineae</italic>, and <italic>unclassified_c__Betaproteobacteria</italic> were positively correlated to SMZ, especially for <italic>Candidatus_Promineofilum</italic>.</p></sec><sec><title>Discussion</title><p><italic>Candidatus_Promineofilum</italic> not only had the ability of EPS secretion, but also was significantly associated with the primary SMZ resistance genes of <italic>sul</italic>1 and <italic>sul</italic>2, which developed resistance against SMZ pressure through the mechanism of targeted gene changes, further provided a useful and easy-implement technology for sulfamethazine wastewater treatment.</p></sec>