The Megalomorphic Phase of Bacteria

Wahlin, Joel G.; Almaden, Philip J.

doi:10.1093/infdis/65.2.147

Cited by 20 publications

(6 citation statements)

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“…Earlier, the development of large homogeneous forms (whose nature has not yet been satisfactorily resolved), when typhus rickettsiae were introduced into certain unusual hosts, was regarded by some (but not other) investigators as evidence for the occurrence of some kind of life cycle (1,4,(15)(16)(17)24). Similar diverse views were expressed about other bacteria in earlier years (19)(20)(21)(22)49). In the present study, no evidence was obtained for a cycle in any way analogous to that of the chlamydiae or for any other unusual growth or reproductive cycle.…”

supporting

confidence: 82%

In Vitro Studies on Rickettsia-Host Cell Interactions: Intracellular Growth Cycle of Virulent and Attenuated Rickettsia prowazeki in Chicken Embryo Cells in Slide Chamber Cultures

Wisseman

Waddell

1975

Infect Immun

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Upon entry into the cytoplasm of irradiated chicken embryo cells in slide chamber cultures infected over a 2-h period, yolk sac-grown virulent (Breinl strain) and attenuated (E strain) Rickettsia prowazeki underwent indistinguishable reproducible intracellular growth cycles. They promptly entered an exponential growth phase, without detectable lag and without microscopic evidence for any unusual early replicative phase. The generation time for both strains was 8.8 to 8.9 h at 34 C. During most of this period, the state of the organisms and growth were very similar from one cell to another. The exponential-growth phase continued for at least 36 to 48 h, when the rickettsiae became too numerous to count by microscopic examination. Between about 36 and 48 h, cells packed with rickettsiae began irregularly to break down and release organisms. These began to initiate new infection cycles in previously uninfected cells over many hours, as demonstrated by the rise in percentage of cells infected, yielding a highly disordered infected culture with different cells containing rickettsiae in diverse stages of growth. The organisms underwent regular minor changes in morphology, similar to those seen in bacterial cultures, in the first infection cycle. As the cells became packed with rickettsiae, the microorganisms regularly diminished in size to become minute coccobacillary to coccoid forms. However, the rickettsiae in the second and subsequent infection cycles in aging cultures often assumed filamentous or swollen bizarre forms. Only the first infection cycle conformed closely to the concept of a one-step growth cycle. A set of terms is proposed and defined for the infection cycle.

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supporting

confidence: 82%

In Vitro Studies on Rickettsia-Host Cell Interactions: Intracellular Growth Cycle of Virulent and Attenuated Rickettsia prowazeki in Chicken Embryo Cells in Slide Chamber Cultures

Wisseman

Waddell

1975

Infect Immun

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“…Filament or long-thread formation by Proteus vulgaris growing in the presence of small amounts of penicillin was reported by Fleming et al (1950). Filament formation by E. coli resembling that found in our pressurized cultures was reported to result from sublethal doses of ultraviolet radiation (Curry and Greenberg, 1962), unfavorable pH (Wahlin andAlmaden, 1939), various antibiotics (Pulvertaft, 1952), magnesium excess (Webb, 1949), folic acid analogues (Nickerson and Webb, 1956), and a number of other chemicals (Loveless, Spoerl, and Weisman 1954). According to Webb and Nickerson (1956), abnormal morphology and filamentous growth resulting from various combinations of chemicals bear a relationship to DNA synthesis.…”

Section: Discussionsupporting

confidence: 61%

GROWTH, REPRODUCTION, AND DEATH RATES OF ESCHERICHIA COLI AT INCREASED HYDROSTATIC PRESSURES

ZoBell

Cobet

1962

J Bacteriol

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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.

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“…This conclusion agrees with the observation that pleomorphism and swelling of bacteria into large bodies occur under various conditions interfering with usual growth. This subject has a large literature which has been reviewed repeatedly (44,79,92). Toxic substances in an otherwise appropriate medium often induce the development of large bodies.…”

Section: Conditions Favoring the Transformation Into L Formsmentioning

confidence: 99%