Acta Botanica Croatica, Vol. 31 No. 1, 1972.
Izvorni znanstveni članak
Lyophilization in Long Term Preservation of Streptomyces Oxytetracycline Producing Strains
Emin Kapetanović
; Hrvatska
Zlatko Pavletić
; Hrvatska
Sažetak
In the course of several years of use of lyophilization for long term preservation of oxytetracycline producing Streptomyces strains, their morphogenetic stability and the stability of their antibiotic yields were verified.
The described process of lyophilization, as regards the viability and morphogenetic stability of both sporogenous and the asporogenous forms, has been proved very successful, with few exceptions. Data are given in Table II. Viable spore counts of 40—90.8% were satisfactory.
The growth of lyophilized cultures on agar medium (P—1) did not differ much from the growth of non-lyophilized (control) cultures: the populations of the cultures invariably retained all essential »starting« morphological characteristics. Only in a small number of cases alterations in some lyophilized cultures in comparison with the »starting« cultures were observed (e. g. T6—429, T6—483 and BIM—197 in Table II). These differences were manifested by the appearance of small colonies (5%), the disappearance of drops of exudate from the colonies center, or by differences in intensity of soluble pigment in the medium. No reliable explanation has been found for this phenomenon. It can probably be ascribed to microecological conditions (different composition of medium, temperature and the like).
The growth of lyophilizates in a liquid medium (P—2) owing to the almost complete anabiosis, was obviously somewhat slower (it averaged 10—16 hours) in comparison to the control cultures; the lyophilized asporogenous cultures, however, grew faster (4—6 hours) than the lyophilized sporogenous ones (see Table II).
It has been proved that the remaining moisture in the lyophilizates is the limiting factor in attaining anabiosis and that, therefore, it is necessary to maintain the moisture within a narrow range and at a low level.
The quality of cotton plugs considerably influences the process of lyophilization, especially at the stage of drying in the vacuum, so that full attention must be paid to the preparation of these plugs, particularly to their hardness.
With regard to the stability in Oxytetracycline antibiotic yields (Table III), the tested lyophilizates have given different yields in comparison to the control cultures, in spite of the same testing conditions in the course of experiments, especially in the laboratory.
Tests with some lyophilized cultures were repeated, and results obtained showed approximately the same differences (Table III, figures in brackets). The yields were often higher than those of the control.
The obtained Oxytetracycline yields on a production scale were very favourable and uniform, even in the course of prolonged use of lyophilized cultures for the preparation of inoculum.
The following conclusions are the result of many years of work and of data presented here:
1) The described process of lyophilization, as a whole, is suitable for a long term preservation of tested Oxytetracycline producing Streptomyces strains.
2) Both apparatuses used for lyophilization are suitable for the purpose described and produce lyophilizates of uniform quality. The model DELTA I/a is of higher capacity and therefore more suitable for production purposes, and for the maintaining of larger collections of cultures.
3) The optimum freezing temperature of the cultures is — 50 to — 55 °C.
4) The remainder of moisture in the lyophilizates — because it is a determinant factor in attaining anabiosis on which the stability of cultures depends — must be kept at the same, previously verified level.
5) Lyophilized cultures retained constant Oxytetracycline yields in the course of the four-year storage.
6) The porousness and the hardness of the microbiological cotton plugs must be standardized for the sake of more successful lyophilization process.
Ključne riječi
Hrčak ID:
157137
URI
Datum izdavanja:
31.12.1972.
Posjeta: 931 *