Submitted to: Anaerobe
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2009
Publication Date: 4/14/2010
Citation: Oliver, C.E., Beier, R.C., Hume, M.E., Horrocks, S.M., Casey, T., Caton, J.S., Nisbet, D.J., Smith, D.J., Krueger, N.A., Anderson, R.C. 2010. Effect of chlorate, molybdate, and shikimic acid on Salmonella enterica serovar Typhimurium in aerobic and anaerobic cultures. Anaerobe. 16:106-113.
Interpretive Summary: Salmonella is the second most common bacterial cause of food-borne illness in the United States, causing an estimated 1.4 million cases of food-poisoning each year at a cost of approximately 0.5 to 2.3 billion dollars annually. Our laboratory has developed a potential feed additive that targets an important biochemical pathway used by Salmonella, but not beneficial bacteria, in the gut of food producing animals such as pigs and chickens and research has shown that this feed additive effectively helps farmers grow animals with reduced levels of Salmonella. The aims of the present study were to examine the effects of the feed additive on Salmonella when under conditions like that in dry feed exposed to air and like that when in the animal gut where oxygen is lacking. We found that pure cultures of Salmonella could be made to be insensitive to the feed additive but that this insensitivity could be overcome by adding the chemicals molybdate or shikimate when grown in an atmosphere containing oxygen but not when oxygen was lacking. Molybdate and shikimate are components of the biochemical pathway targeted by the feed additive and the results that were obtained by measuring the effects of these chemicals help us better understand how the feed additive works.This understanding is essential to help scientists make sure that the feed additive is safe and effective under a variety of conditions. Ultimately, these results will help farmers and ranchers by providing them with another tool to produce safe and wholesome meat products for the American consumer.
Technical Abstract: Chlorate is a bactericide that has potential as a pre-slaughter feed additive to improve food safety of meat products. The aims of the present study were to examine the effects of chlorate (5mM), molybdate (1 mM), and shikimate (0.34 mM) on the growth and chlorate-resistance of Salmonella enterica serovar Typhimurium under aerobic or anaerobic conditions. Treatments of chlorate, atmosphere (aerobic or anaerobic) and molybdate or shikimate were arranged in 2 x 2 factorials. Cultures without chlorate grew more rapidly than those with chlorate. Neither molybdate nor shikimate significantly affected growth rate of Salmonella. Pure cultures of Salmonella grown either aerobically or anaerobically without chlorate remain sensitive to chlorate, but develop resistance when grown in the presence of chlorate. Molybdate and shikimate when added individually, but not in combination, protected against development of chlorate resistance in aerobic, but not anaerobic, cultures. These results suggest that co-supplementation of molybdate or shikimate with chlorate will likely have little effect on chlorate resistance of Salmonella in the animal gut as these were not effective under anaerobic conditions.