[Mathematical model of zone formation taking into account the inactivation of polyene antibiotics diffusing into an inoculated gel].

The procedure for investigation of the inhibition growth zone formation on diffusion of polyenic antibiotics into inoculated gel is presented. The model of strong inactivation is applicable when the drug inactivation is significant during the period of the zone formation and not only during the period of the 2-fold increasing of the number of the test microbe cells. The experimental study on the passive inactivation of polyenic antibiotics, such as levorin, amphotericin B, mycoheptin and nystatin showed that during the period of the zone formation the first 2 antibiotics were inactivated to such a level that their passive inactivation could be considered strong. A case of drug active inactivation with the test microbe cells is discussed. An equation for the specific period of the zone formation with respect to this particular case of the drug strong inactivation was developed. The parameters of the active inactivation were estimated. The results for levorin are in good agreement with some of its physico-chemical properties, i. e. poor solubility and mycella formation.