Potential of the strain Raoultella sp. KDF8 for removal of analgesics

Abstract

The bacterial strain KDF8 capable of growth in the presence of diclofenac and codeine analgesics was obtained after chemical mutagenesis of nature isolates from polluted soils. The strain KDF8 was identified as Raoultella sp. based on its morphology, biochemical properties, and 16S rRNA gene sequence. It was deposited in the Czech Collection of Microorganisms under the number CCM 8678. A growing culture efficiently removed diclofenac (92% removal) and partially also codeine (about 30% degradation) from culture supernatants within 72 h at 28 °C. The degradation of six analgesics by the whole cell catalyst was investigated in detail. The maximum degradation of diclofenac (91%) by the catalyst was achieved at pH^INI of 7 (1 g/L diclofenac). The specific removal rate at high concentrations of diclofenac and codeine increased up to 16.5 mg/g_CDW per h and 5.1 mg/g_CDW per h, respectively. HPLC analysis identified 4'-hydroxydiclofenac as a major metabolite of diclofenac transformation and 14-hydroxycodeinone as codeine transformation product. The analgesics ibuprofen and ketoprofen were also removed, albeit to a lower extent of 3.2 and 2.0 mg/g_CDW per h, respectively. Naproxen and mefenamic acid were not degraded.

Keywords: Analgesics; Co-metabolism; Microbial degradation; Raoultella sp.; Whole cell catalyst.