Inactivation of a wild isolated Klebsiella pneumoniae by photo-chemical processes: UV-C, UV-C/H2O2 and UV-C/H2O2/Fe3+

Abstract

Shrimp (Litopenaeus vannamei) farming is an important economic activity in several countries. Pathogens in shrimp farms and its effluents pose a potential hazard for both humans and shrimps. Wild strains of bacteria were characterized in a shrimp farm, and Klebsiella pneumoniae was chosen as a good indicator due to its presence in the pond and the effluent and its resistance to antibiotics. Different photochemical processes (UV/H2O2, UV/H2O2/Fe3+) were tested for inactivation of wild isolated K. pneumoniae and compared to UV-C radiation. By kinetic modelling, a kmax equal to 0.43 s?1 was obtained for UV-C treatment. After optimizing the cited processes, ranging [H2O2]: 1030 mgl?1; an optimal [H2O2] of 10 mgl?1 was found, increasing kmax on 13.63% compared to UV-C. This optimal concentration was tested for UV/H2O2/Fe3+ process; ranging [Fe3+]: 220 mgl?1. The highest yield was obtained by a [H2O2]:[Fe3+] = 10:2, which leads to 4-Log reduction in 12.88 s of treatment. Moreover, resistance of K. pneumoniae was compared to Escherichia coli. The latter proved to be more sensitive despite its similar cellular structure. Results suggested that the photochemical processes could enhance disinfection efficiency, especially for photo-assisted Fenton-like process in most resistant bacteria. 2017 Elsevier B.V.