Insights into Mechanisms and Proteomic Characterisation of <i>Pseudomonas aeruginosa</i> Adaptation to a Novel Antimicrobial Substance

<div><p>Antibiotic resistance has been reported since the introduction of synthetic antibiotics. Bacteria, such as one of the most common nosocomial pathogens <i>P. aeruginosa</i>, adapt quickly to changing environmental conditions, due to their short generation time. Thus microevolutional changes can be monitored <i>in situ</i>. In this study, the microevolutional process of <i>Pseudomonas aeruginosa</i> PAO1 resistance against a recently developed novel antibacterial zinc Schiff-base (ZSB) was investigated at the proteome level. After extended exposure to ZSB the passaged strain differed in tolerance against ZSB, with the adapted <i>P. aeruginosa</i> PAO1 exhibiting 1.6 times higher minimal inhibitory concentration. Using Two-dimensional Difference Gel Electrophoresis, the changes in the proteome of ZSB adapted <i>P. aeruginosa</i> PAO1 were examined by comparison with the non-adapted <i>P. aeruginosa</i> PAO1. The proteome of the adapted <i>P. aeruginosa</i> PAO1 strain differed significantly from the non-adapted in the abundance of two proteins when both strains were grown under stressing conditions. One protein could be identified as the outer membrane protein D that plays a role in uptake of basic amino acids as well as in carbapeneme resistance. The second protein has been identified as alkyl peroxide reductase subunit F. Our data indicated a slight increase in abundance of alkyl peroxide reductase F (AhpF) in the case of ZSB passaged <i>P. aeruginosa</i> PAO1. Higher abundance of Ahp has been discussed in the literature as a promoter of accelerated detoxification of benzene derivatives. The observed up-regulated AhpF thus appears to be connected to an increased tolerance against ZSB. Changes in the abundance of proteins connected to oxidative stress were also found after short-time exposure of <i>P. aeruginosa</i> PAO1 to the ZSB. Furthermore, adapted <i>P. aeruginosa</i> PAO1 showed increased tolerance against hydrogen peroxide and, in addition, showed accelerated degradation of ZSB, as determined by HPLC measurements.</p>