Morphological changes of Vibrio parahaemolyticus from rods to spheres took place after a culture was subjected to starvation at a wide range of temperatures. Scanning electron micrographs revealed that starved spherical cells gradually developed a rippled cell surface with blebs and an extracellular filamentous substance adhesive to the cell surface. Cells starved at a low temperature for certain intervals were counted by various bacterial enumeration methods, including plate count, direct viable count, and total cell count for both Kanagawa-positive and-negative strains. The results indicated that this species could reach the nonculturable stage in 50 to ϳ80 days during starvation at 3.5؇C. Kanagawa-negative strain 38C6 lost culturability more slowly than Kanagawa-positive strain 38C1 at low temperature. As detected by thiosulfate-citrate-bile salts-sucrose plate count, a high percentage of the surviving cells at 3.5؇C in starvation medium were possibly injured by the low temperature rather than by starvation. Both addition of nalidixic acid to the starved cultures and the most-probable-number method demonstrated that the cells recovered after a temperature upshift probably represented the regrowth of a few surviving cells. These surviving cells were capable of growth and multiplication with limited nutrients at an extraordinary rate when the temperature was upshifted.

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The expression of ompF, the gene encoding a major outer membrane protein of Escherichia coli, is regulated by various environmental factors. The mechanism by which salicylate (SAL) drastically reduces ompF expression was studied here by means of lacZ fusions to ompF, ompC, and micF, by sodium dodecyl sulfate-gel electrophoresis of outer membrane proteins, and by measurements of outer membrane permeability. Growth of E. coli in LB broth containing SAL strongly reduced ompF-specific translation of an ompF-lacZ fusion. The extent of this reduction varied with the SAL concentration from 64% at 0.5 mM to 95% at 2 mM and >99% at 10 mM. ompF-lacZ transcription was not affected by SAL, whereas ompC-lacZ transcription was elevated by 70%. Since the micF transcript is antisense to a portion of the ompF transcript and is capable of decreasing the translation of ompF, the effect of SAL on micF transcription was measured in a micF-lacZ fusion strain. SAL-grown cells contained three-to fourfold more micF transcript during the logarithmic phase of growth than did the control cultures. However, micF was not absolutely required for the response to SAL. In micF-deleted strains, the effects of SAL on ompF translation, on OmpF in the outer membrane, and on outer membrane permeability were diminished but still evident. The effect of SAL on ompF expression was independent of the osmolarity of the medium and was epistatic to certain ompB regulatory mutations: the high levels of ompF expression found in envZ3 and ompR472 strains were greatly reduced by growth in SAL. Unexpectedly, the OmpC-phenotypes of these mutants were suppressed by SAL. Thus, growth in SAL severely decreases the translation of ompF while enhancing the transcription of micF and ompC. In this respect, SAL-grown cells resemble certain marA and toiC mutants that have high levels of micF and ompC transcripts and low levels of OmpF.

Freshly collected cerumen (dry form) suspended at a concentration of 3% in glycerol-sodium bicarbonate buffer showed bactericidal activity against some strains of bacteria tested. This suspension reduced the viability of Haemophilus influenzae, Escherichia coli K-12, and Serratia marcescens by more than 99%, whereas the viability of two Pseudomonas aeruginosa isolates, E. coli K-1, Streptococcus, and two Staphylococcus aureus isolates of human origin was reduced by 30 to 80%. The results support the hypothesis that cerumen functions to kill certain foreign organisms which enter the ear canal.Cerumen, commonly known as earwax, is secreted by both ceruminous and sebaceous glands. Two distinct forms of human cerumen, dry and wet, are associated with race and controlled by two autosomal alleles (10). The dry allele is predominant in Mongoloid populations of Asia and in American Indians, whereas the wet allele is found predominantly in Caucasian and Negro populations (1, 10). Earwax has been found to contain amino acids, fatty acids, neurostearic acid, cerotic acid, cholesterol, triglyceride, hexone bases, lysozyme, immunoglobulin, glycopeptide, copper, and other components, although differences in composition between the cerumen types have been described (6,7,9,15).The function of cerumen in protecting the ear against invasion of microorganisms has long been a subject of controversy. It has been suggested that cerumen is unable to prevent infection and that the rich nutrients of earwax support luxuriant growth of bacteria and fungi (3,8,13,14). On the other hand, it has been suggested that cerumen might have antimicrobial activity, although little evidence has been presented to support this contention (5, 9). Burtenshaw (2) extracted cerumen with either saline or an alcohol-ether solvent and showed that the saline extract promoted the growth of streptococci somewhat, whereas the alcohol-ether extract was inhibitory. However, the concentration of cerumen in the alcohol-ether extract used by this author was not specified. In this communication we will describe a potent antibacterial activity of cerumen suspended in buffer against certain strains of common bacteria which are often encountered in humans.Pooled cerumen was collected with a sterile earwax hook from 12 healthy individuals aged from 5 to 42, including males and females, and kept in a sterile bottle at 4°C. All cerumen belonged to the typical dry form, which appeared flaky or granular and yellowish white. The pooled cerumen was mixed well, weighed, and suspended in buffer (5% NaHCO3, pH 8.2, containing 30% glycerol) at a concentration of 3.5% (wt/vol). The cerumen-buffer mixture was homogenized by repeated passage through a series of needles ranging from 19 to 23 gauge. This procedure broke the cerumen into fine particles distributed evenly in buffer and resulted in a milky suspension. Cerumen suspensions at concentrations over 3.5% were unsatisfactory because all the cerumen remained in big particles even after prolonged homogenization. The cerumen was ster...

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Cell envelopes prepared from an Escherichia coli tolF strain selected as resistant to phage TuIb contained a new major outer membrane protein related to outer membrane proteins la and Ib. The strain that produces this protein is a tolF par double mutant but contains an additional mutation leading to the production of the new major outer membrane protein. Antibiotic sensitivity lost as a result of the tolF mutation is regained in strains that contain the new major outer membrane protein. This indicates that this protein functions to restore the selective permeability of the outer membrane to low-molecular-weight hydrophilic molecules.

Escherichia coli strain JF694 contains a new major outer membrane protein which we have called protein E (J. Foulds, and T. Chai, J. Bacteriol. 133:1478-1483). Two new bacteriophages, TC45 and TC23, were isolated that require the presence of protein E in the outer membrane of host cells for growth. Both of these bacteriophages have a morphology similar to T-even bacteriophages but are distinct in properties such as plaque morphology, buoyant density, and burst size. Although strain JF694, containing protein E, adsorbs bacteriophage TC45 efficiently, cells killed with heat or chloroform are unable to inactivate this bacteriophage. Purified protein E either in the presence or absence of additional probable cofactors such as lipopolysaccharide was also unable to inactivate bacteriophage TC45. Both bacteriophages probably use protein E as at least part of their receptor but require, in addition, other outer membrane components or a specific orientation or organization of this protein in the outer membrane.