Oxidative stress prevents colony formation in an Escherichia coli impaired in catechols synthesis

PERALTA, DAIANA; ADLER CONRADO; CORBALAN NATALIA; POMARES FERNANDA; VINCENT, PAULA

Congreso; SAIB; 2012

Under iron-limited conditions, Escherichia coli produces the catecholate siderophore enterobactin. We proposed that enterobactin has a new role as an intracellular protector against oxidative stress. We also showed that an E. coli impaired in enterobactin synthesis (entE) is unable to develop colonies on solid M9 medium. Iron supplementation did not recover colony formation, indicating that this phenotype is not due to iron deficiency. It is known that the viable but non-culturable phenotype is associated to oxidative stress. As we propose that catechols may act as radical scavengers, the absence of colonies in an entE mutant context could be related with an increment in the oxidative stress. Comparing with the wild type strain, the mutant entE showed greater sensitivity to hydrogen peroxide, paraquat and antibiotics which promote reactive oxygen species. The double mutant sodAentE displayed a pronounced colony impairment phenotype. Finally, we observed that a normal growth was achieved when ascorbic acid was added to the medium or when the mentioned strains were grown in anaerobiosis. Results suggest that the incapacity to form colonies could be due to hostile conditions caused by oxidative stress and support our hypothesis implying cathecols siderophores in a oxidative stress protection function.