Effectiveness of nutrient media for the recovery of lyophilisates of fastidious microorganisms: evidence from Streptococcus spp.

Abstract

To restore the biological and morphological properties of fastidious bacteria during lyophilization, one of which is a type of streptococcus – bacteria of the genus Streptococcus, it is necessary to use expensive specialized nutrient media that are limited in availability for laboratories. In this regard, the purpose of this study was to find the most effective methods of preservation and recovery of fastidious microorganisms using the example of Streptococcus spp. The study was performed by a bacteriological method. The isolates of Streptococcus spp., which had the property of alpha- or beta-haemolysis, were selected for the study. The microorganisms were collected as a result of bacteriological research of pathological and biological materials from 20 animals (10 dogs and 10 cats). Microorganisms were determined and counted using Vitek 2 compact, easySpiral, and Scan 500 systems. As a result, the effectiveness of using various combinations of nutrient media for cryopreservation, freeze-drying, and further revitalization of cultures was proven. It was found that the most effective medium for lyophilization is meat-peptone broth with the addition of 5% bovine blood serum, diluted 1:1 with Faibich’s medium, and for recovery after lyophilization – meat-peptone broth with the addition of 5% blood serum cattle and 5% glucose. With this combination, the concentration of viable cells corresponded to the limits of 1.7×106 -2.4×106 CFU/cm3 . The use of other combinations of nutrient media for the revitalization of Streptococcus bacteria showed lower efficiency, which corresponded to the concentration of viable cells within 1.2×105 -2.1×106 CFU/cm3 . The obtained results increase the efficiency of the method of lyophilization of demanding cultures due to combination of non-selective nutrient media and components available in laboratory practice