Biodegradation Potential of Phenol-Resistant Bacteria Localized in Different Stream Habitats

ABSTRACT

The process of biotransformation and elimination of toxic xenobiotics in natural river ecosystems is a matter of intensive research regarding its applicability in biomonitoring and bioremediation procedures. The main objectives of this study were (1) to assess and compare the phenol-biodegradation potential among the basic river habitats using isolated mixed microbial cultures from sites, with different level of pollution, located in Iskar River; (2) to examine relationships between main parameters of the degradation process and functional structure of local microbial community using multivariate approaches.

The results showed that all investigated microbial cultures were able to eliminate almost entirely (95-98%) the introduced quantities of phenol (150 mg/ml) as a sole source of carbon and energy for a period of 72 hours and that phenol was mainly degraded through the ortho ring cleavage pathways. However the extensive research revealed a significant excellence of biodegradation potential in microbial communities located in the sediment water. On the other hand the most distinct rates of phenol-degradation between sites were observed with regard to the mixed cultures, adsorbed to river sediments.

Conducted principal component (PCA) and co-inertia (CIA) analyses underlined some habitat specifics in the relationships between biodegradation and microbial community characteristics. We concluded that the anthropogenic pollution leads to decrease and serious transformation of relationships mentioned above in surface water and sediments.

Keywords:

• Iskar River
• stream habitats
• phenol-biodegradation
• multiscale relationships