Pseudomonas anguilliseptica Strain-A1 Degradation of Polycyclic Aromatic Hydrocarbons in Soil Microcosms: Focus on Detoxification Activity and Free Water-Soluble Protein Extracts Kinetics and Efficiency

Abstract

Pseudomans anguilliseptica-A1 strain, isolated in an urban area, improved the efficiency of a microbial consortium, composed of Bacillaceae, Staphylococcacea, Xantomonadaceae and Enterbacteriaceae, whose ability to degrade five Polycyclic Aromatic Hydrocarbons (PAHs) among the priority pollutants was previously ascertained. Six soil microcosms were prepared with a slurry (60% soil, 40% water) artificially contaminated with anthracene (0.4 mg g-1), phenanthrene (0.2 mg g-1), naphthalene (0.2 mg g-1), pyrene (mg g-1) and benzo(a)pyrene (0.1 mg g-1) and opportunely aerated for two months. PAHs were monthly quantified by inverse phase High Performance Liquid Chromatography (HPLC), coupled with UV-Vis spectrophotometry and spectrofluorimetry. Acute toxicity assays vs Dapnia magna and Lepidium sativum, and chronic essays vs Ceriodaphniadubia were monthly performed. Our results showed a 100% degradation for naphthalene, 99.14% for anthracene, 99.23% for phenanthrene, 86% for pyrene and 72.5% for benzo[a]pyrene after two months of treatment.  A sterile P. anguilliseptica-A1 lysate in Na-K buffer added with each of the chosen PAHs (53%, wtPAHs/volsusp), operated at 30°C the oxidative degradation of naphthalene, pyrene, benzo(a)pyrene and anthracene in a few hours, while the phenanthrene enzyme degradation process took about 15 h. The GC-MS analysis revealed interesting metabolite structures such as 2-hydroxynaphthalene, 9,10-phenanthrenedione, 2,2’ diphenic acid and methyl 4-hydroxybenzoate. The direct utilization of enzymes/microbial extracts from P. anguilliseptica-A1 could present specific advantages such as availability and a fast PAHs degradation time in bioremediation processes.