Jornal de Biorremediação e Biodegradação

Abstrato

Factors Alleviating Cadmium Toxicity in White Rot Fungus

Kuber Chandra Bhainsa, Khajamohiddin Syed and Jagjit S Yadav 

Co-contamination with heavy metals and polycyclic aromatic hydrocarbon (PAHs) poses a challenge for bioremediation of polluted environments. In order to degrade PAH-metal mixtures, the biodegrading organism needs to be in a metabolically active state to degrade the PAH moiety while being able to tolerate the co-contaminant metal(s). Due to this fact, tolerance studies were carried out on the model white rot fungus, Phanerochaete chrysosporium known to have the ability to degrade PAHs. Toxicity to the organism was investigated using cadmium (Cd) and various PAHs separately as well as in combinations and growth inhibition were measured as an index of the xenobiotic toxicity. Treatment with Cd showed inhibition of fungal growth in a dose-dependent manner. PAHs of varying ring size (3-5 ring) showed inhibitory effect in the 10-25 ppm concentration range and the effect varied with the PAH type. The pattern of initial growth inhibition followed the order pyrene>phenanthrene>benzo(a)pyrene. Both the xenobiotics (metaland PAH)at their respective inhibitory concentrations led to morphological changes in the growth pattern of the organism, observed in terms of variable mycelial pellet morphology. Interestingly, co-exposure with a PAH alleviated the Cd toxicity, indicating a protective effect of the PAHs. Taken together, this is the first report on the metal tolerance properties of this organism in a co-contamination scenarioas well as on demonstration of a protective effect of PAHs in Cd toxicity.