Diesel Degradation in Presence of Copper and Microaerobiosis by Pseudomonas extremaustralis

LAURA J. RAIGER IUSTMAN; LETICIA ROSSI; NANCY I. LOPEZ

Boston

Congreso; ASM Microbes 2016; 2016

ASM

Microorganisms adapted to contaminated environments represent an alternative to bioremediation of pollutants. Diesel is a widely distributed one, being its composition a mixture of alkanes that could be degraded by some microorganisms. Cooper is an essential metal for most organisms, but at high concentrations commonly detected in diesel-polluted waters, can be lethal.Previous work show that P. extremaustralis was able to degrade diesel in biofilm growth conditions but not in shaken flasks and tolerate up to 4mM CuSo4 in aerobiosis. Finally, it was described that co-substrate addition could enhance xenobiotic degradation. The aim of this work was to determine if P.extremaustralis was able to degrade diesel in microaerobiosis without biofilm formation and to evaluate the effect of glucose as co-substrate and Cu in diesel degradation.P. extremaustralis 14-3b strain was used for the assays. Cultures of 20 mL were incubated for 7 days at 30 °C in 100 mL capped bottles with E2 minimal medium, supplemented with 20 mM KNO3 and 1% v/v Diesel. To determine the growth variables, different Cu and glucose concentrations were evaluated: CuSO4 (0.1 to 1.5 mM) and glucose (0.5 to 20 g/L). Diesel degradation was evaluated by extracting the remnant hydrocarbon with 10% v/v n-hexane, and analyzing by GC. A residual hydrocarbon percentage was calculated using a control without bacteria as 100%.The growth conditions were finally set at CuSO4 0.1 mM for it was the highest full soluble concentration in this media, and 0.5 g/L glucose.P. extremaustralis was able to degrade 16% of the total diesel when it was added as sole carbon source, and no differences were observed when glucose was added as co-substrate or Cu was present. When the culture media was supplemented with both glucose and Cu, 30% degradation was achieved. Analyzing each alkane in particular, there was a clear degradation in the ones with 14 to 21 Carbon atoms, consistent with the results found in biofilm. This suggests that the addition of a co-substrate and a stress promoter as Cu in a sub lethal concentration could enhance diesel biodegradation in P. extremaustralis.