The Morphology and Motility of Proteus vulgaris and Other Organisms Cultured in the Presence of Penicillin

Abstract

SUMMARY:Mimobes were grown on microscope slides so that the growth could readily be observed by phase-contrast microscopy.ProtGUs &garis, grown on agar containing peNcillin, undergoes extraordinary morphological changes which vary with the temperature of incubation, the concentration of the penicillin, the concentxation of the agar and the presence of small amounts of fluid between the agar and the cover-slip. The bacilli may divide noxznally once or twice into elements that grow without dividing and which may develop into fantastically shaped thread or swollen forms. In high concentrations of penicillin the fantastic shapes are obtained by enlargement without division. At first the nuclei divide as in nomud organisms. The thread forms have condensed nuclei arranged in alternating pattern along the side of the cells. In the swellings there may be either nuclear material Wing the cells, a condensed central mass or a reticulum. When vacuoles are present these displace the nuclear material.When the misshapen organisms are transferred to a medium free from penicillin and containing penicillinase they divide, forming normal bacilli. Many of the swollen elements burst and disappear.The motility of the greatly enlarged organisms is sluggish, and flagellar movement can clearly be observed by phase contrast. The movement of the flagella of the organisms responds readily to radiant heat, and a careful study of these movements makes it impossible to accept Pijper's contention that bacterial motility is due entirely to undulatory movements of the body and that the flagella are merely mucoid strands cast off as the result of motility."he flagella were demonstrated in the large forms by fixing the culture through the s g a~ for several days, detaching the agar and stainingthe cover-slip, which carries the fixed colony, with a saturated watery solution of night blue. The nuclei were shown by treating films with hot nitric acid, washing and staining first with cresyl blue then Leishman's stain.

The Site of Action of Penicillin: some Changes in Staphylococcus aureus during the First Two Hours Growth in Penicillin Media

“…Absence of Mg decreases the rate of RNA synthesis to onetenth in Escherichia coli (Abelson & Aldous, 1950), but it is not known at present what role if any metallic elements play in nucleic acid structure. It is interesting that the giant forms induced by deficiency of Mg (Webb, 1951) are similar to those formed in sub-lethal penicillin concentrations (Fleming, Voureka, Kramer & Hughes, 1950), although it is true that other substances besides penicillin can induce giant forms.…”

“…l), and therefore differs from the formation of 'giant forms' in sub-inhibitory titres (e.g. Fleming, Voureka, Kramer & Hughes, 1950) where increase in cell mass occurs but division is inhibited. Fig.…”

Anomalous cellular morphology and growth characteristics of Neisseria meningitidis in subminimal inhibitory concentrations of penicillin G

“…Such low concentrations, often referred to as subminimal inhibitory concentrations (sub-MIC's), have been known to affect the morphology of bacteria since the early report on penicillin by Gardner in 1940 (10). After Gardner's work, the production of abnormal bacterial morphology by ,B-lactam compounds has been reported for a variety of gram-negative organisms (6,9,13,15,(18)(19)(20)(21) and gram-positive organisms (6,(17)(18)(19). In addition to the phenotypic changes associated with such low levels of antibiotics, changes in growth rates and diminution in the total bacterial population have also been shown in a number of instances (7, 11-13, 16, 24).…”

A Simple Method for Producing Microcultures in Hanging Drops with special reference to Organisms Utilizing Oils

“…The drops formed under these conditions tend to spread out into flat irregular shapes where they hit the coverslip surface. The only way I have been able to fix and stain cells with this method in their original position is to dry in air the untreated coverslips after spraying, and coat them with molten agar media according to the methods of Fleming, Voureka, Kramer & Hughes (1950). With this method, the initial cells of the resulting microculture are more evenly dispersed than when the suspension is, in the ordinary way, spread over the coverslip.…”