Search of optimal media for highly active bacterial phosphotriesterases

JULIA SANTILLAN; ANDRES MUZLERA; ELIZABETH LEWKOWICZ; ADOLFO IRIBARREN

Viena

Simposio; X Simposio Internacional de Biocatalisis y Biotransformaciones (BIOTRANS 2015); 2015

Universidad Tecnológica de Viena

Phosphotriesterases (PTEs; E.C. 3.1.8.1) catalyse the stereoselective hydrolysis of organophosphorous compounds (OPs) through a mechanism that involves the nuclephilic attack of a water molecule and subsequent elimination of a leaving group to afford a phosphodiester as product. PTEs have been found from bacteria to mammalian except insects, being the best characterized ones those from Brevundimonas diminuta and Flavobacterium sp., and human serum and rabbit paraoxonases. OPs are widely used as pesticides in agriculture, in gardens and in veterinary practices and also are the basis of chemical weapons due to their activity as acetylcholinesterase inhibitors. Therefore, PTE is a promising candidate for in vivo and in vitro detoxification of organophosphate pesticides and nerve agents, providing a possible catalytic antidote for therapeutical use.In our lab we had previously developed a fluorometric screening to search hydrolytic activity using methyl paraoxon as substrate, which allowed the selection of 6 strains that belong to Arthrobacter, Nocardia and Streptomyces genera. In this work, we evaluate the performance of these strains under different conditions of pH and temperature, determining optimal conditions for each of them.At particular conditions, all the tested microorganisms showed higher PTE activity than Brevundimonas diminuta. It is noteworthy, that the hydrolytic activity at 50° C of two of the selected strains, whose PTE activity has not been previously reported, is 50 and 20 time higher than B. diminuta.