ISSN:
1432-072X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary When milk cultures of Streptococcus lactis are held near 00, the number of living cells decreases rather slowly for about one month. Even after 3 months, viable cells are still present, though reduced to a few thousands. The death is partly due to accumulation of acid, but mainly to oxygen. Neutralization and replacement of the free oxygen by nitrogen in the culture prolong the viability. The early cessation of fermentation when large numbers of cells are kept in milk at 00 (or at any temperature below the growth minimum) is due to some damaging effect of oxygen which the inactivated growth mechanism can not prevent or repair. The enzyme content of the cells, measured by their fermenting capacity (mg lactic acid per cell per hour) slowly decreases at temperatures below the growth minimum. After restoration of higher temperatures, the cells recover their enzyme content very slowly, and require several generations for complete recovery. The damage caused by oxygen is not the cause, but the result of the minimal temperature of growth.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00407241
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