Isolation of two Kocuria species capable of growing on various polycyclic aromatic hydrocarbons

Abstract

Different samples collected from crude oil contaminated beach were enriched for isolation of bacterial strains capable of growing on naphthalene, phenanthrene and fluoranthene. Respiratory reduction of
WST-1{4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate} to a colored formazan showed that one isolated strain CMG2028, identified as Kocuria flava by 16s rRNA, grew on
naphthalene and phenanthrene while CMG2042, identified as Kocuria rosea grew on all three polycyclic aromatic hydrocarbons (PAHs). In naphthalene degradation test, 64 and 47% residual naphthalene was extracted after ten days of incubation from culture medium of K. rosea CMG2042 and K. flava CMG2028, respectively, when provided with 0.5 mg ml-1 concentration as sole carbon source. Due to addition of 0.5 mg ml-1 yeast extract as additional carbon source, residual naphthalene extracted was 41 and 55% from K. rosea CMG2042 and K. flava CMG2028, respectively. Both strains exhibited growth on 0.01 mg ml-1 phenanthrene and fluoranthene in yeast extract added or omitted medium but only K. rosea CMG2042
degraded 9% phenanthrene as a sole carbon source. Both strains had growth on minimal agar plates coated with Iranian light crude oil as sole carbon source and on agar medium added with yeast extract.