Behavioural Influences on Mineralization and Cometabolism of PAHs by Motile Bacteria in Membrane Bioreactors With Restricted Porosities

Abstract

Poster presentado en the SETAC Europe 31st Annual Meeting from 2–6 May 2021 in Seville, Spain.The controlled dispersal of motile bacteria through contaminated soils is currently considered as one of the most promising aspects in bioremediation. The difficulty caused by the heterogeneous distribution of the pollutants and the degrading bacteria can be overcome by the use of different chemoefectors. These compounds provide the control over bacterial tactic motility, what results in an increase in the efficiency of the microorganisms dispersion and subsequently, enhanced biodegradation rates (Environ. Sci. Technol. 42: 1131-1137, 2008; Environ. Sci. Technol. 46: 6790-6797, 2012). The objective of this study was to evaluate the dispersal and biodegradation capacity through Mineralization tests with 14C-labelled naphthalene and cometabolism tests [by synchronous fluorescence spectrophotometry (Appl. Environ. Microbiol. 76 (13): 4430-4437; Sci. Total Environ. 717: 137210)] with pyrene by the chemotactic bacterium Pseudomonas putida G7 (cell dimensions: 1 μm x 3 μm). The experimental design consisted in a bioreactor system with two chambers separated by a membrane with specific pore sizes that restrict bacterial dispersal (Environ. Sci. Technol. 49: 14368-14375, 2015). Different chemoffectors (GABA and artificial root exudates) were used to modulate the motile bacterial behavior throught restricted porosities (5 μm). The initial results were promising. The transport of P. putida G7 through the membrane occurred at higher rates than the control for both chemoeffectors, thus enhancing biodegradation rates. The cometabolism process was evaluated by fluorescence spectrophotometry determinations, measuring the effect of P. putida G7 on the removal of aqueous- dissolved pyrene in the presence of the chemical effectors. Progress in this field will undoubtedly open up new possibilities for bioremediation processes in contaminated soils, improving the existing techniques for the treatment of poorly bioaccessible contaminants.N