Submitted to: Letters in Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/21/2001
Publication Date: 11/1/2001
Citation: JARVIS, G.N., FIELDS, M.W., ADAMOVICH, D.A., ARTHURS, C.E., RUSSELL, J.B. THE MECHANISM OF CARBONATE KILLING IN ESCHERICHIA COLI. LETTERS IN APPLIED MICROBIOLOGY. 2001. Interpretive Summary: Escherichia coli inhabits the GI intestinal tract of warm blooded mammals, and it can survive for long periods of time in manure. Most E. coli are harmless, but some strains (e.g. E. coli O157:H7) are highly pathogenic. Recent work indicated that E. coli counts decreased rapidly if sodium carbonate and alkali were added to dairy cattle manure, but the mechanism of this antimicrobial activity was not defined. Carbonate anion is a reactive molecule that forms insoluble divalent metal ion complexes at alkaline pH. A variety of bacterial enzymes are activated by magnesium and other divalent cations, and magnesium cross-bridges are needed to stabilize the outer membrane of gram-negative bacteria like E. coli. Results were consistent with the idea that carbonate was forming insoluble divalent cation complexes, but further work will be needed to confirm this hypothesis. The use of carbonate to kill E. coli in cattle manure is an inexpensive method that could decrease contaminated water and food supplies.
Technical Abstract: Sodium carbonate and ethylenediaminetetraacetic acid (EDTA) both killed E. coli K-12 when the pH was 8.5, but ammonium chloride was ineffective. EDTA was a 5-fold more potent agent than carbonate, but some of this difference could be explained by ionization. At pH 8.5, only 1.6% of the carbonate is CO-2, but nearly 100% of the EDTA is EDTA-2. Because carbonate and EDTA had similar effects on viability, cellular morphology, protein release and enzymatic activities, the antibacterial activity of carbonate may be mediated by divalent metal binding.