Naphthalene‐anthracene‐utilizing microorganisms

Abstract

Oil-polluted freshwater samples collected from Assiut oil company, Egypt, were screened for hydrocarbon-utilizing microorganisms (bacteria and fungi). Two hydrocarbons (naphthalene and anthracene) were used as a sole source of carbon.Most Probable Number (MPN) technique was used to determine naphthalene and anthraceneutilizing bacteria. Micrococcus, Corynebacteriurn, Nocardia and Pseudonionas were recovered on basal medium supplemented with the hydrocarbons. Numbers of bacteria decreased as the pollution in water increased. Eleven species and 1 variety belonging to 8 terrestrial fungal genera were collected from oil polluted water on naphthalene or anthracene modified CZAPEK agar medium. Aspergillus (A..flauus var. columnaris) and Scopulariopsis ( S . brurnptii) were the most prevalent genera. 75.4 and 24.6% of total bacterial isolates utilized naphthalene and anthracene with different ranges of turbidity, respectively.Presence of polycyclic aromatic hydrocarbons in the natural environment has drawn a great attention since many of these compounds displayed toxic and carcinogenic properties. Microorganisms including bacteria, fungi, yeasts and algae have proved to degrade and/or utilize aromatic hydrocarbons (GIBSON and YEH 1973, JEFFREY et al. A number of bacteria, particularly Pseudonionas, Flauohacter and Vibrio species. have the ability to metabolize naphthalene, anthracene, phenanthrene, biphenyl and other aromatics as a sole source of carbon and energy (MULKINS-PHILIPS and STEWART 1974). Several studies have shown that a wide taxonomic and phylogenetic spectrum of fungi can metabolize naphthalene and anthracene (e.g. CERNIGLIA et al. 1978al. , CERNIGLIA 1981. In polluted freshwater ecosystems, bacteria, yeasts and filamentous fungi all appear to be important hydrocarbon degraders (COONEY and SUMMERS 1976).In Egypt, HEMIDA (1991) studied the fungal flora of oil-polluted soils. But no records concerning the utilization of naphthalene and anthracene by microorganisms are available. Hence this work represents an attempt to identify the microorganisms (bacteria and fungi) of oil-polluted freshwater and to evaluate their ability to degrade naphthalene and anthracene. Materials and methodsFreshwater samples were collected during the purification of oil polluted water in Assiut oil company from different stages as follows: stage I [Oil mixed with water], stage I1 [water after first step of skimming oil by skimmers], stage I11 [water treated with chemicals e.g. coagulants (ferric chloride, ferric sulphate); flocculants (polyelctrolytes); alkalinity adjustment (sodium carbonate or sodium bicarbonate); disinfectant (sodium hypochlorite)], stage IV [water treated with trickling filter] and stage V [water of final step] in addition to lagoon lake [reservoir containing oil mixed with water] and 300 M. M. K. BAGY et 01.artificial lake (control). Three water samples were taken from each stage and from lagoon ( V I ) and artificial (VII) lakes.Water samples were analysed for the determination of temperature, pH. total dissol...