Submitted to: Meeting Abstract
Publication Type: Experiment Station
Publication Acceptance Date: 1/31/2005
Publication Date: 3/15/2005
Citation: Dimitrijevic, M., Anderson, R.C., Callaway, T.R., Nisbet, D.J. 2005. Inhibitory effect of select nitroalkanes on growth rate of Listeria monocytogenes in vitro [abstract]. International Conference on Environmental, Industrial and Applied Microbiology. p. 488. Interpretive Summary:
Technical Abstract: Listeria monocytogenes has been associated with a number of food-borne outbreaks and recalls. Listeriosis is an important foodborne disease that causes considerable high rates off morbidity and mortality. It is estimated that L. monocytogenes infections cause approximately 2,500 causes of serious illness and as many as 500 deaths per year in the USA. Listeria monocytogenes is widespread throughout nature, having been isolated from the environment and animals, and is not fastidious, capable of growing in minimal media under refrigeration temperatures from 1 deg C up to 44 deg C and at pH values of between 4.6 and 9.6. Therefore, it is important to consider processes and substances that can inhibit the growth and if possible, eliminate L. monocytogenes from animals and the environment. 2-Nitropropanol (2NPOH), an alternative electron acceptor used by Denitrobacterium detoxifican, has been shown to inhibit Salmonella Typhimurium, Escherihia coli 0157:H7 and Enteroccocus faecalis in vitro and has recently been shown to reduce gut concentrations of Salmonella in broilers. The aim of this study was to examine the effect of 2NPOH, and two related compounds, 2-nitroethanol (2NEOH) and nitroethane (NE) on specific growth rates, as determined by increases in optical density at 600 nm, of L. monocytogenes during aerobic culture (37 deg C) in Brain Heart Infusion broth. When cultured with 5, 10 or 15 mM added 2NPOH, specific growth rates were reduced (P < 0.05) 55, 76 and 88% from rates of control cultures grown without added 2NPOH (0.42 +/- 0.02 h**-1). When cultured with 5, 10 or 15 mM added 2NEOH, specific growth rates were reduced (P < 0.05) 37, 60 and 62% from rates of control cultures grown without added 2NEOH (0.52 +/- 0.05 h**-1). When cultured with 10 or 15 mM added NE, specific growth rates (h**-1) were reduced 30 and 35% from the rate of the controls (0.37 +/- 0.07); however, the specific growth rate during culture in medium containing 5 mM NE (0.37 +/1 0.07) was not significantly reduced from the controls. The inhibitory effect of 2NPOH was approximately 20% greater during growth at pH 7.0 than at pH 5.6 or 8.0. These results demonstrate the differential inhibitory activity of 2NPOH, 2NEOH and NE against L. monocytogenes in vitro.