Submitted to: Current Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/1999
Publication Date: N/A
Citation: Interpretive Summary: Pasteurella multocida (Pm) is one of the bacteria which causes shipping fever in market stressed calves and costs the feeder/stocker industry $750,000,000 per year. The pathogenic mechanism of how Pm causes its damage to the lung tissue of calves is not entirely known. Little is known about this bacteria's virulence factors. The lipase enzyme is a known virulence factor in a few other types of bacteria. Therefore, the discovery of the lipase enzyme in many strains of Pm, except for Pm serotype 2, is an important discovery that may reveal one of the virulence mechanisms of how this bacteria causes disease. The present impact is on science; however, it may lead to better treatment of shipping fever in calves.
Technical Abstract: Thirteen clinical isolates of Pasteurella multocida, from a variety of different animals and humans, were examined for their ability to produce lipase. Lipase substrates used included Tween 20, Tween 40, Tween 80, and Tween 85. Lipase activity was detected in the filtrates of organisms grown to the exponential phase in RPMI-1640, but activity increased in the filtrates if the cultures were allowed to proceed to the stationary phase. All strains examined (except for serotype 2) produced a lipase against at least one of the Tweens. Tween 40 was the best substrate to demonstrate lipase activity. Pasteurella multocida serotype 8 produced the most active lipase against Tween 40 (3,561.7 units of activity/micro g of protein). Its production continued to increase after Pasteurella multocida entered a stationary growth phase. Pasteurella multocida lipase activity was optimal at pH 8.0. Lipase activity of Pasteurella multocida serotype 8 was eluted from a Sepharose 2B column at several points indicating that several lipases may be produced in vitro by this organism.