Catabolismo de furfurales y compuestos aromáticos en "Pseudomonas pseudoalcaligenes" CECT 5344Aislamiento de nuevas cepas asimiladoras de cianuro y sus complejos metálicos

Resumo

�Pseudomonas pseudoalcaligenes� CECT 5344 is a bacterium able to assimilate free cyanide, although it is not effective at degrading metal-cyanide complexes. Other bacteria able to assimilate these complexes efficiently have been isolated, and the study has been focused on �Achromobacter sp.� and �Microbacterium kitamiense� that, apart from using metal-cyanide complexes as nitrogen sources, they also use jewelry residues efficiently in mixed cultures together with the CECT 5344 strain. In as much as �P. Pseudoalcaligenes� CECT 5344 only assimilates cyanide as a nitrogen source, carbon sources that can quickly assimilate cyanide have been studied, with the octanoate and the DL-malate being the most efficient ones. The �P. Pseudoalcaligenes� CECT 5344 genome sequencing allowed the operons involved in the assimilation of aromatic complexes to be identified, amongst others furfurals: inhibitor compounds present in lignocellulosic hydrolysates that later ferment to obtain bioethanol. The edd gene mutation prevented the bacterium assimilating glucose, leaving the furfural catabolism intact. Consequently, it could be useful for lignocellulosic hydrolysates pretreatment. The transcriptional profile (RNA-seq) of �P. Pseudoalcaligenes� CECT 5344 growing with furfuryl alcohol allowed to identify the expression of a lot of genes. This includes the �hmf� operon which is homologous to the one described in �Cupriavidus basilensis� HMF14 but that includes a new gene, �benE1�, in which a new mutant was generated. A mutation in this gene negatively affected the growth of the bacterium with furan compounds. Furthermore, another mutant was created in another overexpressed operon (�liu�), and its involvement in the metabolism of furoate was demonstrated.