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  • Characterization of cefalexin degradation capabilities of two Pseudomonas strains isolated from activated sludge.

Characterization of cefalexin degradation capabilities of two Pseudomonas strains isolated from activated sludge.

Journal of hazardous materials (2014-07-30)
Bokun Lin, Jinling Lyu, Xian-jin Lyu, Han-qing Yu, Zhong Hu, James C W Lam, Paul K S Lam
ABSTRACT

Pharmaceuticals have recently been regarded as contaminants of emerging concern. To date, there is limited knowledge about antibiotic-degrading microorganisms in conventional activated sludge treatment systems and their characteristics toward antibiotic degradation especially in the presence of a pharmaceutical mixture. As such, antibiotic-degrading microorganisms were investigated and isolated from the activated sludge, and their degradation capabilities were evaluated. Two strains of cefalexin-degrading bacteria CE21 and CE22 were isolated and identified as Pseudomonas sp. in the collected activated sludge. Strain CE22 was able to degrade over 90% of cefalexin, while CE21 was able to remove 46.7% of cefalexin after incubation for 24h. The removal efficiency of cefalexin by CE22, different from that of CE21, was not significantly affected by an increase in cefalexin concentration, even up to 10ppm, however the presence of 1ppm of other pharmaceuticals had a significant effect on the degradation of cefalexin by CE22, but no significant effect on CE21. The degradation product of cefalexin by the two strains was identified to be 2-hydroxy-3-phenyl pyrazine. Our results also indicated that CE21 and CE22 were able to degrade caffeine, salicylic acid and chloramphenicol. Moreover, CE21 was found to be capable of eliminating sulfamethoxazole and naproxen.

MATERIALS
Product Number
Brand
Product Description

Supelco
Caffeine, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
Naproxen, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
Caffeine Melting Point Standard, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
Sulfamethoxazole, certified reference material, TraceCERT®, Manufactured by: Sigma-Aldrich Production GmbH, Switzerland
Supelco
Chloramphenicol, VETRANAL®, analytical standard
Supelco
Sulfamethoxazole, VETRANAL®, analytical standard
Supelco
Ciprofloxacin, VETRANAL®, analytical standard
Supelco
Ciprofloxacin, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
Sulfamethoxazole, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
Caffeine, certified reference material, TraceCERT®, Manufactured by: Sigma-Aldrich Production GmbH, Switzerland
Sigma-Aldrich
(S)-(+)-6-Methoxy-α-methyl-2-naphthaleneacetic acid, 98%
Sigma-Aldrich
Caffeine, anhydrous, 99%, FCC, FG
Supelco
Naproxen, VETRANAL®, analytical standard
Supelco
Mettler-Toledo Calibration substance ME 18872, Caffeine, traceable to primary standards (LGC)
Sigma-Aldrich
Ciprofloxacin, ≥98% (HPLC)
Sigma-Aldrich
Caffeine, meets USP testing specifications, anhydrous
Sigma-Aldrich
Caffeine, powder, ReagentPlus®
Sigma-Aldrich
Caffeine, BioXtra
Sigma-Aldrich
Caffeine, Sigma Reference Standard, vial of 250 mg
Supelco
Sulfamethoxazole
Sigma-Aldrich
Chloramphenicol, BioReagent, suitable for plant cell culture
Sigma-Aldrich
Chloramphenicol, ≥98% (HPLC)
Sigma-Aldrich
Chloramphenicol, meets USP testing specifications
Sigma-Aldrich
Ofloxacin, fluoroquinolone antibiotic
Sigma-Aldrich
Naproxen, meets USP testing specifications
Supelco
Ofloxacin, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
Cefalexin, VETRANAL®, analytical standard
USP
Sulfamethoxazole, United States Pharmacopeia (USP) Reference Standard
Supelco
Ofloxacin, VETRANAL®, analytical standard
USP
Caffeine, United States Pharmacopeia (USP) Reference Standard