An iterative fractionation approach to identify antimicrobial proteins in snake venom

Antimicrobial resistance (AMR) increasingly poses a significant global health challenge. New antimicrobials are desperately needed, driving the need to explore novel sources of natural products. Snake venom has shown promise due to the complex mixture of proteins and peptides which demonstrate therapeutic utility in other aspects of healthcare. In this study we took an iterative approach to screen 14 snake venoms against the clinically important bacteria Escherichia coli and Klebsiella pneumoniae and identify venom-derived proteins with diverse activity against E. coli. Six venoms exhibited significant antimicrobial activity comparable to ciprofloxacin and four were retained after dialysis, confirming a protein-mediated effect. Fractionation of two active venoms from Naja mossambica and Naja subfulva revealed protein fractions which have either subtle or significant antimicrobial activity. SDS-PAGE and mass spectrometry identified phospholipase A2 isoforms in N. mossambica venom fractions and neurotoxic proteins (long and short neurotoxin) in N. subfulva venom fractions as potential antimicrobials.