Antibacterial effects of different snake venoms: purification and characterization of antibacterial proteins from Pseudechis australis (Australian king brown or mulga snake) venom.

Venoms from 30 different snake species were tested in a disc diffusion assay for antibacterial effects against gram-positive and gram-negative bacteria. A number of venoms gave a zone of inhibition against both groups of bacteria, including Aeromonas hydrophila, an important pathogen of reptiles and amphibians. Two antibacterial components from the venom of an Australian elapid, Pseudechis australis (Australian king brown or mulga snake) were purified to homogeneity. The proteins, designated LAO1 and LAO2, had potent antibacterial properties associated with L-amino acid oxidase activity. Both had native and subunit mol. wts of 142,000 and 56,000, respectively. Antibacterial activity correlated with enzymatic activity and was eliminated with catalase. LAO1 and LAO2 had 244 and 113 units of L-amino acid oxidase activity/mg protein, respectively. Compared to tetracycline, a drug of choice for Aeromonas infections in humans, reptiles and amphibians, the in vitro antibacterial effects of LAO1 and LAO2 were respectively 70 and 17.5 times more effective (on a molar basis).