Evaluation of Sulfadiazine Degradation in Three Newly Isolated Pure Bacterial Cultures.

Sikandar I Mulla,Syed Ali Musstjab Akber Shah Eqani,Qian Sun,Anyi Hu,Yuwen Wang,Chang-Ping Yu,Muhammad Ashfaq,Zhi Zhou

doi:10.1371/journal.pone.0165013

Abstract

This study is aimed to assess the biodegradation of sulfadiazine (SDZ) and characterization of heavy metal resistance in three pure bacterial cultures and also their chemotactic response towards 2-aminopyrimidine. The bacterial cultures were isolated from pig manure, activated sludge and sediment samples, by enrichment technique on SDZ (6 mg L-1). Based on the 16S rRNA gene sequence analysis, the microorganisms were identified within the genera of Paracoccus, Methylobacterium and Kribbella, which were further designated as SDZ-PM2-BSH30, SDZ-W2-SJ40 and SDZ-3S-SCL47. The three identified pure bacterial strains degraded up to 50.0, 55.2 and 60.0% of SDZ (5 mg L-1), respectively within 290 h. On the basis of quadrupole time-of-flight mass spectrometry and high performance liquid chromatography, 2-aminopyrimidine and 4-hydroxy-2-aminopyrimidine were identified as the main intermediates of SDZ biodegradation. These bacteria were also able to degrade the metabolite, 2-aminopyrimidine, of the SDZ. Furthermore, SDZ-PM2-BSH30, SDZ-W2-SJ40 and SDZ-3S-SCL47 also showed resistance to various heavy metals like copper, cadmium, chromium, cobalt, lead, nickel and zinc. Additionally, all three bacteria exhibited positive chemotaxis towards 2-aminopyrimidine based on the drop plate method and capillary assay. The results of this study advanced our understanding about the microbial degradation of SDZ, which would be useful towards the future SDZ removal in the environment.

Highlights

Sulfadiazine [4-amino-N-(2-pyrimidinyl)benzene sulfonamide, SDZ] is one of the most common sulfonamide antibiotics, utilized widely in animal husbandry to treat and inhibit bacterial diseases [1]
We report the isolation and characterization of three different bacteria capable of degrading SDZ as well as 2-aminopyrimidine, and their resistance capabilities towards various heavy metals
SDZ (6 mg L-1) degrading microorganisms were isolated from PM2, W2 and 3S samples by enrichment culture technique

Summary

Introduction

Sulfadiazine [4-amino-N-(2-pyrimidinyl)benzene sulfonamide, SDZ] is one of the most common sulfonamide antibiotics, utilized widely in animal husbandry to treat and inhibit bacterial diseases [1]. Treated animals have been reported to excrete unbroken SDZ with its metabolite(s) into the ecosystem through their excretory system [2]. SDZ has been detected in the range of 0.3–198 mg kg-1 (dry matter of pig manure), depending on medication, dilution and age of the manure [3, 4] and in slurry at high concentrations, almost. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

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