|
Isolation and molecular
genetic characterization of a yeast strain able to degrade
petroleum polycyclic aromatic hydrocarbons
Abd El-Latif Hesham1,*
Saad A. Alamri2, Sardar Khan3, Motamed
E. Mahmoud4 and Hashem M. Mahmoud5
1Genetics
Department, Faculty of Agriculture, Assiut University,
Assiut, Egypt.
2Biological
Science Department, Faculty of Science, King Khalid
University, Saudi Arabia
3Department
of Environmental Sciences, University of Peshawar, Peshawar,
Pakistan.
4Department
of Animal Hygiene, Animal behavior, Faculty of Veterinary
Medicine, Assiut University, Egypt.
5Soils
and Water Department, Faculty of Agriculture, Assiut
University, Assiut, Egypt
*Correspondence author. E-mail:
hesham_egypt5@yahoo.com. Fax: +2088-2331384.
Accepted
16 February, 2009 |
|
Polycyclic aromatic hydrocarbons (PAHs) belong to a class of
toxic environmental pollutants and PAH exposure causes
public health risks and raises environmental concerns.
Identification of the key microorganisms that play a role in
pollutant degradation processes is relevant to the
development of optimal in situ bioremediation
strategies. In the current study, three yeast strains were
isolated from oil-contaminated soil by enrichment technique
in mineral basal salts (MBS) medium supplemented with
phenanthrene as a sole carbon source. Out of these, strain
AH70 was selected for PAHs degradation, because of its fast
growth on agar plate coated by PAHs as sole source of carbon
and energy. The yeast was identified by molecular genetics
technique based on sequence analysis of the variable D1/D2
domain of the large subunit (26S) ribosomal DNA. Subsequent
26S rRNA gene sequencing showed 100% base sequence homology
and it was identified as Candida viswanathii. The
degradation of PAHs by this yeast was confirmed by GC-MS
analyses. The yeast was capable of degrading a mixture of
low and high molecular weight PAHs and degradation
efficiency was found as 89.76% for naphthalene, 77.21% for
phenanthrene, 60.77% for pyrene and 55.53% for
benzo(a)pyrene at the end of 10 days.
Key
words:
Yeast, PAHs pollutant, 26S rRNA gene. |
