Factors Affecting Microbial Degradation of Polycyclic Aromatic Hydrocarbon Phenanthrene in the Caribbean Coastal Water

Abstract

Studies were conducted to assess factors that may influence the rate and extent of biodegradation of polyaromatic hydrocarbons (PAHs) in waters of Guayanilla Bay (latitude, 18°N; longitude, 66.45°W) Puerto Rico. Phenanthrene was used as a model PAHs compound. Both the rate and extent of phenanthrene degradation by natural microbial flora present in seawater samples from Guayanilla Bay were quite slow. Addition of KNO 3 as a source of inorganic nitrogen (N) resulted in a 10-fold increase in the rate of phenanthrene degradation within a 125 h period, whereas, addition of K 2HPO 4 as a source of inorganic nutrient phosphorus (P) had no effect. Phenanthrene degradation was strongly inhibited when seawater pH was adjusted to 10.0. Phenanthrene in seawater samples degraded rapidly when first pretreated with hydrogen peroxide (H 2O 2) and then inoculated with a known indigenous phenanthrene degrading bacterium, Alteromonas sp. Pretreatment of phenanthrene with Triton- x-100 had little or no effect on its degradation by the same bacteria, whereas, degradation in samples preheated at 60°C was somewhat inhibited.