Biodegradación de ácido tereftálico es sistemas modelos aerobios

Abstract

Terephthalic acid is one of the top 50 most produced industrial organic compounds worldwide because it is a precursor of polyethylene terephthalate (PET), explaining its abundant presence in air, water and soil environments as a contaminant. This fact has led to several concerns about the environmental impact and health risk related to terephthalic acid pollution. Several research projects have originated lines of study on terephthalic acid degradation, most of which are chemical processes of advanced oxidation, but also there exist the biological processes, dealing with the microorganisms able to metabolize this xenobiotic compound. The biological degradation can be accomplished by both anaerobic and aerobic pathways, depending on the metabolism of the degrading microorganisms. This research is focused on the aerobic biodegradation of terephthalic acid as the unique carbon and energy source in cultures with two microorganisms able to biodegrade this xenobiotic compound. These microorganisms were identified by molecular characterization of the 16s rDNA gen and electronic microscopic scanning, resulting in Arthrobacter s.p and Rhodococcus sp. both strains are phthalic isomer degraders (terephthalic acid, phthalic acid and isophthalic acid). The initial concentration of substrate to degrade was of 5 g/L and it was proved that just Rhodococcus sp. can biodegrade efficiently this concentration, so cell kinetics growth and terephthalic acid biodegradation at different substrate concentrations were carried out (3, 4, 5.035, 7.1, 9.7 and 14.5) g/L in order to determine the maximum concentration that Rhodococcus sp. could degrade and characterize this microorganism. Rhodococcus sp. biodegraded AT in all the substrate concentrations proved, being the most efficient 5 g/L according to the specific speed of cell growth and the TA biodegradation, the parameters of maximum speed (μmax), saturation constant (Ks) and inhibition constant (KI) were calculated according to the Andrews equation of substratum inhibition, the model was fitted to the biodegradation kinetics and cell growth using the parameters obtained from μmax, Ks, Ki with Model Marker software version 4.