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A cell regulatory sialoglycopeptide, CeReS-18, purified from intact bovine cerebral cortex cells, has exhibited the capability of reversibly inhibiting cellular DNA synthesis and the proliferation of a wide array of mammalian cells. In the present study, the effect of CeReS-18 on the proliferation of bacterial ( Bacillus cereus and Escherichia coli) and yeast ( Saccharomyces cerevisiae and Schizosaccharomyces pombe) cells was investigated. The results showed that replication and viability of the bacterial cells were not affected by CeReS-18 at any concentration tested, including 15-fold higher than that used for inhibiting mouse 3T3 cell proliferation. In contrast to bacterial cells, CeReS-18 was able to inhibit the replication of yeast cells, in a concentration-dependent, reversible manner, and the addition of calcium to the culture medium could abrogate the inhibitory effect of CeReS-18. A cytotoxic effect of CeReS-18 on both yeast cell species was observed when it was applied at higher concentrations.

A protocol has been developed for storing Gram (-) bacterial cells at 0 degrees C, which allows greater than 90% of stored cells to retain colony-forming ability for up to 60 days. The protocol, which yields essentially identical results when used with Escherichia coli or Pseudomonas aeruginosa, does not enhance survivability of Bacillus cereus. The greatest and longest survival is enjoyed when exponentially growing cells in minimal-glucose medium are deprived of carbon for about 9 h, supplemented with 750 microg/ml chloramphenicol, and immediately placed at 0 degrees C. By decreasing the period of carbon starvation from 9 to 5 h, or increasing the period of carbon starvation from 9 to 12 h, both the ultimate survival rate and kinetics of loss of culturability are affected. Survival enhancement induced by chloramphenicol is not similarly induced by kanamycin.

Escherichia coli 15T- was grown with glucose, succinic acid, aspartic acid, oleic acid, and oleic plus aspartic acids as carbon sources, and a fatty acid auxotroph derived from 15T- was grown on oleic acid and oleic plus aspartic acids. The doubling time, phospholipid composition, phosphorus content, and the fatty acid composition of the phospholipids of cells in each of the media were determined. In all cases, phosphatidylethanolamine was the major phospholipid present; but with 15T- its concentration was inversely proportional to the doubling time in unsupplemented media. With the auxotroph the phosphatidylethanolamine concentration was essentially unchanged with growth. Total lipid phosphorus was inversely proportional to doubling time, an effect particularly evident with the auxotroph. Without oleic acid supplementation, the major effects of carbon source on fatty acid composition are decreases in the content of palmitoleic acid and increases in the content of cis-9, 10-methylene hexadecanoic acid as growth rate decreases. Oleic acid supplementation elevated 18:1 fatty acid content in both 15T- and the auxotroph.

DNA synthesis was measured via 3H-thymidine pulses, and patterns of incorporation were compared to cell number increases during synchronous division of Escherichia coli 15T- (555-7) in M9.01% aspartate. The timing of chromosome initiation, duration of chromosome synthesis, and the D period were found to vary over the three cycles of division analysed. In addition, the D period measured by comparing 3H-thymidine incorporation and concomitant division, differed from D period measurements made by timing division cessation in DNA synthesis inhibitors.

When Escherichia coli 15T- cells growing exponentially at 70- to 80-min doubling times are subjected to a nutritional shift-up via glucose addition, cell division continues at the preshift rate for about 70 min (rate maintenance). The same cells growing at doubling times of 120 min or longer, however, begin to divide at a new faster rate immediately upon glucose addition. In both the rate maintenance and immediate division situations, cell mass, as measured by optical density (OD), begins to increase immediately upon shift-up. Consequently, the OD/cell pattern differs in the two growth-rate transitions. During rate maintenance, the OD/cell ratio increases dramatically for 60 to 70 min, and then slows appreciably and approaches the OD/cell characteristic of the new medium. During immediate division situations, the OD/cell increases only slightly for the first 180 +/- min; then the rate of increase accelerates but does not stop at the OD/cell characteristic of the new medium. Immediate division upon nutritional shift-up apparently depends upon initial doubling times in excess of 115 to 120 min and provision of a readily metabolized carbon source supporting doubling times of about 40 min. Similar immediate division occurs in E. coli B/r and K-12.

The saturated/unsaturated fatty acid ratio of Escherichia coli 15T- decreases almost threefold as growth temperature decreases from 43 to 27 degrees C, wheras the ratio of a fast-growing mutant derived from 15T- changes only half as much. Strain 15T- experiences a 2.4-fold change in doubling time across this temperature range, but doubling time in the mutant changes 3.3-fold.