Inactivation of mycoplasmas by long-chain alcohols

Abstract

In this report, we describe the inhibitory activity of long-chain alcohols on the growth of Mycoplasma gallisepticum and Mycoplasma pneumoniae. Peak inhibition was recorded with saturated primary alcohols (64 ,uM) varying in chain length from 16 to 19 carbon atoms. The unsaturated alcohols (oleyl, linoleyl, and linolenyl) and the secondary alcohol (pentadecan-2-ol), when employed in the same test conditions, were considerably less effective growth inhibitors than the primary saturated alcohols. Stearic and palmitic acids were also ineffective as growth inhibitors of M. pneumoniae and M. gallisepticum at a 128 ,uM concentration. Because these antimycoplasma agents are fatty alcohols and cholesterol is known to be required for the growth of some mycoplasmas, additional cholesterol was added in an attempt to reverse the inhibition observed with these agents. Cholesterol at a 128 ,uM concentration did not significantly relieve the growth inhibition observed with stearyl alcohol at a 48 ,uM concentration. Mammalian cell cultures were found to be significantly more resistant to the effects of these inhibitory alcohols than were the mycoplasmas. Electron micrographs showed that inclusion of stearyl alcohol in the culture medium produced changes in the cellular morphology of the treated mycoplasmas.In previous studies, it has been shown that inhibition of the biosynthesis of primary longchain alcohols in mammalian and some bacterial cells is associated with a decrease in growth rate (4,5,11). In regard to the long-chain alcohols, it was reported by Snipes et al. (16) that saturated primary alcohols, 10 and 11 carbon atoms in chain length, inhibit the growth of lipid-containing viruses. Subsequently, Sands et al. (15) demonstrated even greater viricidal activity with long-chain unsaturated monoglycerides and primary alcohols. These reports stimulated our interest in the effect of long-chain alcohols on the growth of mycoplasmas. The results presented in this manuscript demonstrate that inclusion of small concentrations (64 ,uM) of certain saturated long-chain primary alcohols in the culture medium inhibits the growth of Mycoplasma pneumoniae and Mycoplasma gallisepticum. MATERIALS AND METHODSThe mycoplasmas for this study were obtained as follows-M. pnesmoniae (15293) from the American Type Culture Colleetion and M. gallisepticum (K781-4) from S. H. lieven. These microorganisms were grown in mycoplasma broth (Difco Laboratories) with supplements (2).Purity of long-chain alcohols was assessed by thinlayer and gas-liquid chromatographies (10). In each instance, these alcohols were only one compound on thin-layer chromatography and were greater than 95% one moiety as judged by gas-liquid chromatography.Because the long-chain alcohols are insoluble in water, they were dissolved in 95% ethanol and added in microliter portions to the supplemented mycoplasma medium. The final concentration of ethanol in the cultures was less than 1% (vol/vol), and this percentage of ethanol was not toxic for the species of Mycoplasma studied....

Decontamination efficacy against Mycoplasma

“…Alcohols mainly act by forming hydrogen bonds with proteins, leading to loss of structure and function and molecule coagulation (McDonnell 2007). It has already been demonstrated that various alcohols inhibit growth and trigger rapid lysis of mycoplasma (Razin and Argaman 1963; Fletcher et al. 1981); this was confirmed in our study with complete inactivation of each mycoplasma species after 5‐min exposures to 70% ethanol.…”