Microbial characterization and hydrocarbon biodegradation potential of natural bilge waste microflora

Abstract

Shipping operations produce oily wastes that must be managed properly to avoid environmental pollution. The aim of this study was to characterize microorganisms occurring in ship bilge wastes placed in open lagoons and, particularly, to assess their potential to degrade polycyclic aromatic hydrocarbons (PAHs). A first-order kinetic was suitable for describing hydrocarbon biodegradation after 17 days of treatment. The calculated rate constants were 0.0668 and 0.0513 day(-1) with a corresponding half-life of 10.3 and 13.5 days for the aliphatic and aromatic hydrocarbon fractions, respectively. At day 17, PAH removal percentages were: acenaphtylene 100, fluorene 95.2, phenanthrene 93.6, anthracene 70.3, and pyrene 71.5. Methyl phenanthrene removals were lower than that of their parent compound (3-methyl phenanthrene 83.6, 2-methyl phenanthrene 80.8, 1-methyl phenanthrene 77.3, 9-methyl phenanthrene 75.1, and 2,7-dimethyl phenanthrene 76.6). Neither pure cultures nor the microbial community from these wastes showed extracellular biosurfactant production suggesting that the addition of an exogenously produced biosurfactant may be important in enhancing hydrocarbon bioavailability and biodegradation. DNA analysis of bilge waste samples revealed a ubiquitous distribution of the nahAc genotype in the dump pools. Although almost all of the isolates grew on naphthalene as sole carbon source, only some of them yielded nahAc amplification under the experimental conditions used. The variety of PAHs in bilge wastes could support bacteria with multiple degradation pathways and a diversity of catabolic genes divergent from the classical nah-like type.

Co-variations of bacterial composition and catabolic genes related to PAH degradation in a produced water treatment system consisting of successive anoxic and aerobic units

“…This result was in accordance with our lab scale experimental systems. Results from other research groups also testified to a ubiquitous distribution of the nahAc genotype in bilge waste, petroleum waste sludge, and soil contaminated with creosote and petroleum products (Mavrodi et al, 2003;Olivera et al, 2003;Katsivela et al, 2005). It is possible that oil-polluted environments containing a relatively high PAH concentration favored the nahAc genotype, while [Pi], where Pi is the intensity of a given band divided by the total intensity of bands detected; (S): Ratio of sum of three most dominant bands (intensity) to the total bands intensity; (Cs): Cs = 2j / (a + b), where j is the number of bands common to influent samples, a and b are the number of bands in different samples; 1# from aerobic sludge, 2# from anoxic sludge, and 3# from influent.…”

Relation between Candida maltosa Hydrophobicity and Hydrocarbon Biodegradation

“…Many different microbial species, such as bacteria, yeast and moulds are involved in the biodegradation process. Bacteria are the best described hydrocarbonutilizing microorganisms (Walker & Colwell 1976a, b;Atlas 1981;Kiyohara et al 1982;Wilson & Jones 1993;Olivera et al 2003). Also, yeasts isolated from hydrocarbon-contaminated sites display the ability to utilize oil-related compounds (Margesin & Schinner 1997;Ijah 1998;Horakova & Nemec 2000;Bouchez-Naı¨tali et al 2001;Lahav et al 2002;Spencer et al 2002;Okerentugba & Ezeronye 2003).…”

Cell hydrophobicity of Pseudomonas spp. and Bacillus spp. bacteria and hydrocarbon biodegradation in the presence of Quillaya saponin

“…Bacteria are the best-described hydrocarbon-utilizing microorganisms (Atlas 1981;Kiyohara et al 1982;Wilson and Jones 1993;Olivera et al 2003). This process is of great interest for the preservation of the natural environment by reducing the amount of oil-related contaminants.…”