ABSTRACT
The authors studied the effect of a number of carbohydrates on the sporogenesis of Clostridium perfringens and Bacillus anthracis (vaccine strain STI) as probable soil factors capable of influencing the duration of survival of these causative agents in the external environment. Differences in the effect of the same sugars on the formation of spores by these microorganisms and clearly expressed sporogenesis-inhibiting effect of glucose (and also of lactose in clostridia) have been demonstrated. The analysis of the peculiarities of sporogenesis under unadjusted and stabilized pH values provides a basis for regarding the "glucose effect" as repression of sporogenesis in the given causative agent, but not as inhibition resulting from considerable acidification of the culture medium. This is essential for the soil conditions characterized by high buffer capacity. The ecological value of substances of carbohydrate nature consists in their important role in the energetics and trophicity of microbial coenoses of the soil which cannot fail reflecting on the fate of pathogenic microorganisms in the soil.
Subject(s)
Bacillus anthracis/drug effects , Carbohydrates/pharmacology , Clostridium perfringens/drug effects , Bacillus anthracis/physiology , Clostridium perfringens/physiology , Hydrogen-Ion Concentration , Soil Microbiology , Spores, Bacterial/drug effects , Spores, Bacterial/growth & developmentABSTRACT
The composition of the fatty acid profiles of Cl. perfringens type A, grown on media with initial pH values from 5.5 to 9.0, was determined by the method of gas-liquid chromatography. The fatty acid profiles are stabilized in 18- to 24-h cultures. Hydrogen ions stimulate the synthesis of cyclopropane carboxylic fatty acids and "desaturase" activity; hydroxyl ions inhibit these processes. The content of saturated fatty acids in the bacteria is regulated by the initial acid-alkaline conditions of the medium. An increase in biomass accumulation under the influence of hydroxyl ions is coupled with a decrease in the energy supply of the bacteria. Possible mechanisms of the development of resistance to hydrogen and hydroxyl ions during the cultivation of Clostridia on a period growth medium are discussed.
Subject(s)
Clostridium perfringens/metabolism , Fatty Acids/metabolism , Anions , Chromatography, Gas , Hydrogen-Ion Concentration , Hydroxides/pharmacology , Hydroxyl Radical , KineticsABSTRACT
Enteric bacteria having a high content of cyclopropane fatty acids steeply increase their synthesis when grown on insufficiently propitious culture media (meat-peptone agar or modified Drobot'ko synthetic medium) as compared with bacteria grown under more favourable conditions (meat-peptone broth). Simultaneously, a decrease in monounsaturated fatty acids and increase in palmitic acid are observed. One of the main factors underlying the change in the proportion of fatty acids in bacteria grown on synthetic medium is an increase in medium pH in the process of their growth. Enteric bacteria containing minute amounts/or not containing cyclopropane fatty acids at all (under the experimental conditions used) change their fatty-acid profile little if the culture medium is changed. When grown under insufficiently favourable conditions, these bacteria mainly display an enhanced content of palmitic acid and a lowered content of octadacenoic acid as compared with bacteria grown under more favourable conditions. Of the culture media used, meat-peptone broth, which affords the most favourable conditions for eneteric bacteria growth, is the most suitable medium for obtaining data of taxonomic value.
