ZO)BELL, (CLA-UDE E. (University of California, La Jolla), AND ANDRE B. COBET. Filament formIa-tioIn by Escherichia coli at increased hydrostatic pressures. J. Bacteriol. 87:710-719. 1964.-The repiroduction ais well as the growth of Escher-ichia coli is retarded by hydrostatic pressures ranging froii 200 to 500 atm. Reproduction was indicated by an increase in the nunmber of cells deternmined by plating on EMIB Agar as well as by direct microscopic counts. (Growth, whiCh is not necessarily synonymnouls with reproduction, was indicated by increase in dry weight, and protein content of the bacterial bioimass. At incretased pressures, cells of thiree different strains of E. coli tended to form long filaiments. Whereas Imlost normal cells of E. coli that developed at 1 atim were only about 2 A long, the imiean length of those that, dleveloped at 475 atml was 2.93 u for strain R4 3.99 , for strain 5, and 5.82 , for strain B cells. Nearly 90e/, of the bac
Both biologically active and autoclaved sediments convert trimethyltin hydroxide to the volatile tetramethyltin. Larger amounts of tetramethyltin were formed in the bioactive sediments than in the sterile sediments. No volatile tin compounds were detected in the absence of trimethyltin hydroxide or from trimethyltin hydroxide in seawater or in seawater containing bentonite. The formation of tetramethyltin is slow, taking over 80 days at 16 degrees C to reach a maximum. The extent of conversion, although significant, is not extensive. The formation of tetramethyltin occurs in estuarine sediments by both abiotic and biologically enhanced pathways. A redistribution mechanism accounts for at least the abiotic pathway and possibly both formation pathways.
ZoBell, Claude
E. (University of California, La Jolla)
and Andre B. Cobet
. Growth, reproduction, and death rates of
Escherichia coli
at increased hydrostatic pressures. J. Bacteriol.
84:
1228–1236. 1962.—Pressures ranging from 100 to 500 atm were found to retard the growth and reproduction of
Escherichia coli
in nutrient medium. Reproduction (as manifested by cell division or an increase in the number of viable cells) was retarded more than was growth (as manifested by increase in cell size or the formation of biomass). When incubated near the threshold of pressure tolerance (about 475 atm at 30 C), some cells of
E. coli
grew into long slender filaments showing little evidence of fission or cell division. Compression prolonged the lag phase of
E. coli
in nutrient medium, particularly at pressures higher than 400 atm. The inhibiting effects of pressure on reproduction and growth were found to be less at 30 than at 20 or 40 C. Pressures of 400 to 1,000 atm accelerated the death rate of
E. coli
cultures in nutrient medium. The lethal effects of pressure were greater at 40 than at 30 C and greater at 30 than at 20 C.
Bacterial colonies were isolated from Caribbean and Atlantic Ocean seawaters by the membrane filter technique and enrichment cultures in which thiosulfate was the only added source of energy. Although colonies were never abundant (0–275 per 100 ml), they have been recovered from the open ocean. The colonies were translucent to pale yellow on thiosulfate marine agar. The cells were Gram-negative motile rods (1–3 μ in length) requiring seawater for growth. The pH of the culture flasks dropped to 2.1 – 2.3 in some cases, and to 5.6 in others. On the basis of these observations, the colonies have been classified as marine thiobacilli.In seawater samples examined, the total reduced sulfur compounds ranged from 0 to 0.101 milliequivalents per liter.
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