Isolation and characterization of phenol-degrading yeasts from an oil refinery wastewater in Brazil.
This study investigated the aerobic degradation of phenol by yeast strains isolated from an oil refinery wastewater from the Northeast of Brazil. The samples displayed low fungal diversity, as only yeast colonies were detected on Sabouraud dextrose agar containing chloramphenicol 0.05% (w/v). Among the isolates, three yeast strains were selected to be evaluated for their potential for degrading high phenol concentrations. These species were identified through morphological and biochemical characteristics as Candida tropicalis, C. rugosa, and Pichia membranaefaciens. Although the strains were able to degrade the phenol concentration present in the wastewater, which was 7 mg l(-1), only C. tropicalis was capable of growing at high concentrations of phenol such as 500 mg l(-1 )and 1,000 mg l(-1) in a mineral medium containing this pollutant as the only carbon source. C. rugosa and P. membranaefaciens were inhibited in the presence of 500 mg l(-1) of phenol. However, a longer incubation time was needed for C. tropicalis strain to degrade 1,000 mg l(-1) of phenol compared to the time required to degrade 500 mg l(-1). Moreover, the strain released a significant amount of polysaccharide biosurfactant in the medium probably to minimize the toxic effect of the high phenol concentration. When challenged with 1,500 and 2,000 mg l(-1 )of phenol, C. tropicalis was unable to grow at the tested conditions. The results indicate that this strain of C. tropicalis can be considered both a good phenol-degrader and biosurfactant-producer. Application of this strain might be useful in bioremediation activities or treatment of phenol-polluted wastewater.
Laboratory of Microbiology and Immunology, Department of Biology, Sciences Center, Federal University of Ceará, Campus do Pici, Bloco 909, Fortaleza, CE, CEP, Brazil.
Lidianne Leal
LL
Rocha
Rossana
R
de Aguiar Cordeiro
Rivelino Martins
RM
Cavalcante
Ronaldo Ferreira
RF
do Nascimento
Suzana Cláudia Silveira
SC
Martins
Sandra Tédde
ST
Santaella
Vânia Maria Maciel
VM
Melo
D001673:Biodegradation, Environmental; D001938:Brazil; D009821:Oils; D019800:Phenol / Q000378:metabolism*; D014865:Waste Disposal, Fluid; D014871:Water Microbiology; D015003:Yeasts / Q000302:isolation & purification* / Q000378:metabolism*
D009821:Oils; D019800:Phenol