[Standardization of cryopreservation process of Saccharomyces boulardii yeasts for usage in collections and banks of industrial microorganism strains].

New implementation principle of freeze-thawing during cryopreservation of microorganisms, initiation of the process of crystal formation at cooling and thawing stage with the controlled rate of heating was experimentally substantiated. This allows increasing the cell viability, guaranteeing their equal number in each preparation, decreasing the contamination risk of the samples at thawing stage.

Probability of lethal damages of cryopreserved biological objects during storage.

This study demonstrated that with a cyclic change of the temperature from -196 degree C up to -130 degree C or -100 degree C part of cryopreserved microorganisms, tumor and human embryo cells died. This should be taken into account when moving and transporting the cryopreserved objects. Storage of samples under the above-mentioned stable temperatures did not result in additional death of cells.

[Preservation of Pseudomonas putida bacteria at low temperatures].

We have found that the mode of cooling, composition of cryopreservation medium, original concentration of cells and storage temperature affect viability of Pseudomonas putida bacteria during low-temperature preservation. We have elaborated the conditions of preservation, providing for a high survival of bacteria, namely: one-stage cooling with the rates of 30, 40 degrees C/min or immersion into liquid nitrogen in the culturing medium with addition of sucrose, glycerol or dimexide in the concentration of 0.5 M; storage temperature is -80 degrees C divided by -196 degrees C.

[Intracellular development of Escherichia coli bacteriophages after culturing the infected bacteria under conditions of anabiosis and hypothermia].

The intracellular growth of bacteriophages T3, T4 and phi X174 was studied in Escherichia coli cells frozen to -196 degrees C and cooled to 0 degree C at various intervals from the instant of phage infection. The processes of biosynthesis were delayed and the latent period was longer in the growth of cells frozen to -196 degrees C. The levels of RNA and protein biosynthesis as well as the yield of phages decreased when cells were frozen at a later stage of the phage growth.

[Intracellular neutralization of bacteriophage T4 by antiphagic serum].

Specific antiserum, introduced into the spheroplasts of Escherichia coli B infected with bacteriophage T4, has been shown to neutralize phage particles formed within the cells.

[Sensitivity of Escherichia coli phages to the action of the physicochemical factors accompanying the process of cryopreservation].

A temperature shock, a change in the pH of the medium for conservation within the range of 4.0 to 10.0, and an increase of NaCl concentration up to 5 M do not inactivate Escherichia coli phages T3, T4 and phi X174.

[Infectiousness of phage T4 frozen to -196 degrees in the presence of cryoprotectors].

Polyethylene oxide with a molecular weight of 400 at a concentration of 5 to 15% and dimethyl sulfoxide at a concentration of 5% produce the protecting action when T4 phage is being frozen. The survival rate of the phage is lower when dimethyl sulfoxide at a concentration of 15% and glycerol and sucrose at a concentration from 5 to 15% are added to samples to be frozen as compared with samples frozen in the absence of the cryoprotectors.

[Effect of freezing modes on the survival of Escherichia coli bacteriophages].

The object of this work was to study the effect of freezing down to--196 degrees C at different cooling and warming rates on the survival of T3, T4 and phiX174 phages. Phage particles survived when T3 phage was frozen at a rate of 20-400 degrees/min and phiX174 phage at a rate of 20-45 degrees/min. The survival rate of T4 phage was highest when it was frozen at a rate of 45 degrees/min.