Responses of Acinetobacter guillouiae SFC500-1A to the simultaneous phenol and Cr(VI) contamination: A proteomic approach

ONTAÑON O.M; GONZALEZ P; LANDI; CARLEO A.; GAGLIARDI A,; BINI L.; AGOSTINI E

San Miguel de Tucuman

Simposio; X Simposio Nacional de Biotecnología REDBIO 2015; 2015

REDBIO Argentina

Microbial bioremediation has a great potential torestore contaminated environments. However, the lack of information aboutfactors regulating the microbial growth and metabolism in polluted environmentsoften limits its implementation. This problem worsens when trying to usemicroorganisms for the remediation of mixtures of toxic substances. In thissense, Acinetobacter guillouiae SFC500-1A is a strain able to simultaneously detoxify phenol and Cr(VI). Althoughsome mechanisms implied in such process were previously elucidated by ourresearch group, the use of this strain for remediating co-contaminated sitesrequires a deep understanding of protein components and cellular pathwaysenabling to tolerate and biotransform these pollutants. Proteomics is a promising tool to address somequestions regarding the molecular mechanisms involved in bioremediation. Therefore,the total proteome of A. guillouiaegrowing in the absence and in the presence of phenol and Cr(VI) was evaluatedby 2-D electrophoresis plus MALDI-TOF MS. The results revealed that in the presenceof phenol as well as phenol and Cr(VI), all the enzymes involved in phenoldegradation were up-regulated, under the control of AraC transcriptionalregulator. Some important enzymes catalyzing the transformation of phenoldegradation products into intermediates of glyoxylate and methylisocitratecycles, were also overexpressed, but TCA cycle key enzymes were down-regulated.Probably this behavior tends to stimulate the synthesis of carbon compounds ratherthan energy production, as a cellular regulation mechanism. Furthermore, indicatorsof membrane damage and oxidative stress were detected, mostly when the pollutantswere simultaneously incorporated, whereas cellular defense proteins likechaperones, peroxiredoxin and catalase were up-regulated. The importance ofporins and efflux pumps in the regulation of pollutants content and theirmetabolic products was also demonstrated. When Cr(VI) was added, two differentoxidoreductases were overexpressed, which could be directly implied in Cr(VI)reduction to Cr(III), the main biological mechanism for Cr(VI) detoxification. Therefore,A. guillouiae SFC500-1A would containthe cellular tools to cope with contaminants-induced stress, which could allowtheir detoxification. These findings constitute an initial attempt tounderstand the processes triggered in this microorganism, which could help toimprove its performance in bioremediation.