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Abstract
Like eukaryotes, bacteria must coordinate division with growth to ensure cells are the appropriate size for a given environmental condition or developmental fate. As single-celled organisms, nutrient availability is one of the strongest influences on bacterial cell size. Classic physiological experiments conducted over four decades ago first demonstrated that cell size is directly correlated with nutrient source and growth rate in the Gram-negative bacterium Salmonella typhimurium. This observation subsequently served as the basis for studies revealing a role for cell size in cell cycle progression in a closely related organism, Escherichia coli. More recently, the development of powerful genetic, molecular, and imaging tools has allowed us to identify and characterize the nutrient-dependent pathway responsible for coordinating cell division and cell size with growth rate in the Gram-positive model organism Bacillus subtilis. Here, we discuss the role of cell size in bacterial growth and development and propose a broadly applicable model for cell size control in this important and highly divergent domain of life.
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Affiliation(s)
- An-Chun Chien
- Department of Biology, Box 1137, Washington University, 1 Brookings Dr., Saint Louis, MO, USA
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2
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Dabrazhynetskaya A, Volokhov D, David S, Ikonomi P, Brewer A, Chang A, Chizhikov V. Preparation of reference strains for validation and comparison of mycoplasma testing methods. J Appl Microbiol 2011; 111:904-14. [DOI: 10.1111/j.1365-2672.2011.05108.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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3
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Davis RE, Whitcomb RF, Chen TA, Granados RR. Current Status of the Aetiology of Corn Stunt Disease. ACTA ACUST UNITED AC 2008. [DOI: 10.1002/9780470719893.ch10] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
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4
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Johnson PA, Larson K, Weibull C. The shape of pleuropneumonia-like organisms (PPLO, Mycoplasma) in liquid media. J Basic Microbiol 2007. [DOI: 10.1002/jobm.19670070309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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5
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Affiliation(s)
- S Razin
- Department of Membrane and Ultrastructure Research, Hebrew University-Hadassah Medical School, Jerusalem, Israel
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Gershfeld NL. The critical unilamellar lipid state: a perspective for membrane bilayer assembly. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 988:335-50. [PMID: 2686756 DOI: 10.1016/0304-4157(89)90009-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- N L Gershfeld
- Laboratory of Physical Biology NIAMS, National Institutes of Health, Bethesda, MD 20892
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Banai M, Kahane I, Feldner J, Razin S. Attachment of killed Mycoplasma gallisepticum cells and membranes to erythrocytes. Infect Immun 1981; 34:422-7. [PMID: 6796518 PMCID: PMC350883 DOI: 10.1128/iai.34.2.422-427.1981] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
To correlate viability with attachment capacity, Mycoplasma gallisepticum cell harvested at different growth phases and treated by various agents were tested for their capacity to attach to human erythrocytes. The results show that viability per se is not essential for M. gallisepticum attachment to erythrocytes, as cells killed by ultraviolet irradiation anmd membranes isolated by lysing M. gallisepticum cells by various means retained attachment capacity. However, treatment of the mycoplasmas by protein-denaturing agents, such as heart, glutaraldehyde, or prolonged exposure to low pH, drastically affected or even abolished attachment, supporting the protein nature of the mycoplasma membrane components responsible for specific binding to the sialoglycoprotein receptors on the erythrocytes.
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Razin S, Banai M, Gamliel H, Polliack A, Bredt W, Kahane I. Scanning electron microscopy of mycoplasmas adhering to erythrocytes. Infect Immun 1980; 30:538-46. [PMID: 6777306 PMCID: PMC551345 DOI: 10.1128/iai.30.2.538-546.1980] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The interaction of Mycoplasma pneumoniae and Mycoplasma gallisepticum with human erythrocytes (RBC) was studied by scanning electron microscopy. The tight nature of the attachment of the microorganisms to the RBC was indicated by the indentation of the RBC surface at the site of attachment of M. gallisepticum cells and by traction and resulting distortion in the shape of the RBC at the point of its attachment to M. pneumoniae filaments growing on glass or plastic. In many cases attachment took place via the tip of the filaments, the membrane of the parasite appearing to be fused with that of the RBC. The morphology of the mycoplasmas growing on cover slips conformed in general with previous descriptions obtained by scanning electron microscopy. Growth of M. pneumoniae on glass or plastic consisted of branching filaments spread on the inert surface and microcolonies made up of intertwining filaments projecting into the medium. The filaments had a bulbous swelling adjacent to a tapered tip end. A few filaments were shown to have a ropelike helical twist. M. gallisepticum grown on the cover slips of Leighton tubes had a peculiar fusiform or teardrop shape with blebs at one or both poles of the cells. Elongated filamentous forms and chains of coccobacillary bodies were observed as well.
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Razin S, Masover GK, Palant M, Hayflick L. Morphology of Ureaplasma urealyticum (T-mycoplasma) organisms and colonies. J Bacteriol 1977; 130:464-71. [PMID: 15986 PMCID: PMC235225 DOI: 10.1128/jb.130.1.464-471.1977] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The morphology of Ureaplasm urealyticum in broth cultures was studied by phase-contrast microscopy. Most organisms appeared singly or in pairs. Long filaments and long chains of cocci, common in classical mycoplasma cultures, were not observed. On solid medium, U. urealyticum produced "fried-egg" colonies which developed according to the scheme suggested by Razin and Oliver (J. Gen. Microbiol., 1961) for the morphogenesis of the classical mycoplasma colonies. The formation of the peripheral zone of the colonies followed that of the central zone only when growth conditions were adequate, Hence, the appearance of peripheral zones, and consequently the larger colony size, can be taken as an indicator of improved growth conditions. Incubation in an atmosphere of 100% CO2 resulted in significantly larger colonies than in an atmosphere of N2, O2, or air. CO2 acts as a buffer, keeping the pH at the optimal range for Ureaplasma growth (pH 6.0 to 6.5) in the presence of the ammonia produced from the urea hydrolyzed by the organisms. The addition to the medium of 0.01 M urea together with 0.01 M putrescine enabled better growth than with urea alone. Small amounts of phosphate improved growth in an atmosphere of CO2, apparently fulfilling a nutritional role. Under nitrogen, higher phosphate concentrations were required for good growth, apparently serving as a buffer as well as a nutrient. Sodium chloride and sucrose which had been added to increase the tonicity of the medium inhibited growth above 0.1 M. An increase in the agar concentration above 2% resulted in decreased colony size. Likewise, prolonged drying of the agar plates caused a marked decrease in colony size, mostly affecting the peripheral zone. The addition of both urea and putrescine to the growth medium and incubation in a humidified CO2 atmosphere are recommended for improved growth and formation of fried-egg colonies of U. ureaplyticum on agar. It must be emphasized that these experiments were carried out with a laboratory-adapted strain.
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Razin S, Hasin M, Ne'eman Z, Rottem S. Isolation, chemical composition, and ultrastructural features of the cell membrane of the mycoplasma-like organism Spiroplasma citri. J Bacteriol 1973; 116:1421-35. [PMID: 4127633 PMCID: PMC246502 DOI: 10.1128/jb.116.3.1421-1435.1973] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Thin sections of Spiroplasma citri, a mycoplasma-like organism isolated from citrus infected with "Stubborn" disease, showed the organisms to be limited by a single trilaminar plasma membrane. An additional outer layer could, however, be frequently seen in freeze-etched preparations of unwashed cells. The organisms were found to be extremely sensitive to lysis by osmotic shock. The cell membrane of S. citri isolated in this way resembled that of mycoplasmas in ultrastructure and gross chemical composition. The isolated membranes showed the characteristic trilaminar shape in section and the typical particle-studded fracture faces in freeze-etched preparations. Protein and lipid formed over 80% of the total dry weight of the membrane, which had a density of ~1.180 g/cm(3). Cholesterol constituted over 20% of the total membrane lipid. Phosphatidyl-glycerol, synthesized by the organisms, was the major phospholipid. Significant amounts of hexosamine (15 to 35 mug/mg of membrane protein) could be found in the membrane preparations. Our results support the thesis that S. citri does not possess a cell wall, either of the gram-positive or the gram-negative type, though it may be coated by some other type of an envelope or by a slime layer, at least temporarily.
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Klainer AS, Pollack JD. SCANNING ELECTRON MICROSCOPY TECHNIQUES IN THE STUDY OF THE SURFACE STRUCTURE OF MYCOPLASMAS. Ann N Y Acad Sci 1973. [DOI: 10.1111/j.1749-6632.1973.tb45652.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Das J, Maniloff J, Bhattacharjee SB. Dark and light repair in ultraviolet-irradiated Acholeplasma laidlawii. BIOCHIMICA ET BIOPHYSICA ACTA 1972; 259:189-97. [PMID: 5060072 DOI: 10.1016/0005-2787(72)90058-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Abstract
Techniques were developed for continuous microscopic observation of mycoplasmata growing in vitro in Rose chambers by using an inverted phase microscope. The methods permitted direct microscopic observation of undisturbed growth of mycoplasmata in liquid medium. Inocula of mycoplasmata were passed through 0.22-mum filters before culture to provide a suspension of discrete particles. The sequential growth of Mycoplasma pneumoniae was followed from points or single straight lines, with development of branching, a net-like confluence of filaments, large bodies occurring in the center of developing colonies, and finally coccoid forms. Other species of Mycoplasma which did not attach as readily to glass could be observed also by inverted phase microscopy. Umbonation of colonies (a "friedegg" appearance) occurred in liquid medium, indicating that this appearance was not due simply to interaction with the agar medium, but may reflect a qualitative difference in growth patterns between center and periphery. For growth on solid medium, direct observation of colonies in uncovered plates of agar medium was made by using inverted phase microscopy. This was found helpful in detecting small colonies and in observing relationships between colonies.
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Abstract
During growth in fluid medium, most strains of Mycoplasma pneumoniae produce free-floating granules which become larger with time. We have called these granules "spherules." This study describes the morphological and ultrastructural features of M. pneumoniae strain AP-164 spherules, both free and in association with HeLa cells in cell culture. In thin section, spherules were composed of lobulated cells, connected together by membranes, and ring-shaped cells. The two-dimensional morphology observed varied according to the plane of section and to the age of the culture. In HeLa cell cultures, mycoplasmata were found attached to plasma membranes of cells; in sections, individual mycoplasmata were often aligned in radial apposition to the membranes. Mycoplasmata were not found intracellularly. The three-dimensional morphology of spherules was examined by the critical point method and by scanning electron microscopy. Both methods revealed lobulated forms, ring-shaped forms, and star-shaped forms. Treatment of the spherules with crude porcine pancreatic lipase effectively released large numbers of free organisms. Phosphotungstic acid preparations of these uncentrifuged forms revealed a morphology in agreement with the other methods used. Lobulated ring forms with "beaded" filaments were prominent. In respect to morphology, M. pneumoniae under our conditions resembles that of the type species M. mycoides.
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Abstract
The morphology and the existence of a growth cycle of Mycoplasma pneumoniae have not been clearly established. There is disagreement as to whether this organism exists as a spherical or filamentous form, and whether it progresses from filamentous to spherical forms as the organism ages. A scanning-beam electron microscope (SEM) was utilized to provide detailed observations of the cycle of morphological changes during growth phases of M. pneumoniae. Cultures of cells grown and fixed in liquid suspension displayed morphological changes from spherical to filamentous and then to larger round forms. After 8 hr to 2 days of growth (phase I), spherical forms and aggregates were revealed. Two- to 6-day-old growth (phase II) was composed of both straight and branching filaments with bulbous elements situated at intervals along their lengths, and microcolonies composed predominantly of intertwined filaments. Six- to 10-day-old growth (phase III) was characterized by flattened, spherical organisms larger than those observed in phase I, occasional membranes or ghosts, and a paucity of aggregates or microcolonies. Thus, stereo-scan electron microscopic studies suggest that M. pneumoniae undergoes an orderly and sequential metamorphosis during its life cycle.
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Abstract
Mycoplasma laidlawii B has been studied by phase-contrast and electron microscopy (thin-section and negative staining). Exponential-phase cells are filaments with the following structures: surface unit membrane, nuclear material, ribosomes, and intracellular granular region. These cells appear to reproduce by binary fission. In stationary phase, the filamentous cells have numerous constrictions, giving them a beaded appearance. Nonviable death-phase cultures contain cellular debris: swollen cells, granular bodies, and other aberrant forms.
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Abstract
The size, ultrastructure, and reproduction of Mycoplasma hominis species H39 were studied by electron microscopy. These are the smallest known cells.
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Chapter X Isolation, Cultivation and Maintenance of Mycoplasmas. METHODS IN MICROBIOLOGY 1969. [DOI: 10.1016/s0580-9517(08)70509-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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Abstract
The uptake of l-histidine by Mycoplasma fermentans and l-methionine by M. hominis was found to be dependent on temperature and pH and to follow saturation kinetics. Several metabolic inhibitors inhibited this uptake. The transport system for l-methionine was highly specific. The l-histidine transport system was less specific, and the uptake was competitively inhibited by l-arginine and l-lysine. l-Histidine accumulated in the intracellular pool of M. fermentans at a concentration about 200 times that found in the medium. Efflux of accumulated l-histidine was demonstrated at 37 C, but not at 0 C. The rate of efflux was greatly accelerated by addition of l-histidine to the medium. The findings indicate that the Mycoplasma cell membrane contains specific transport systems resembling the permease systems of other microorganisms.
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Abstract
Cell membranes of Mycoplasma were isolated either by osmotic lysis or by ultrasonic disruption of the organisms. The membranes were dissolved in phenol-acetic acid-water (2:1:0.5, w/v/v), and membrane proteins were separated electrophoretically in polyacrylamide gels containing 5 m urea and 35% (v/v) acetic acid. The electrophoretic patterns of membrane proteins were highly specific for the different Mycoplasma strains examined. The use of this method to prove the identity or dissimilarity of Mycoplasma strains is suggested.
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Dienes L, Bullivant S. Comparison of the morphology of PPLO and L-forms of bacteria with light and electron microscopy. Ann N Y Acad Sci 1967; 143:719-33. [PMID: 5233801 DOI: 10.1111/j.1749-6632.1967.tb27719.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Spears DM, Provost PJ. A comparison of the osmotic and passive permeability properties of Mycoplasma laidlawii and Mycoplasma hominis. Can J Microbiol 1967; 13:213-25. [PMID: 6035538 DOI: 10.1139/m67-028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Turbidity variations induced by a variety of solutes at known levels of osmolality were determined in suspensions of Mycoplasma laidlawii and Mycoplasma hominis. Turbidity values were corrected for refractive index effects using Ficoll solutions. The two organisms differed in passive permeability properties, cell refractilities, estimated internal osmotic pressures, and cation stabilization effect. More specifically, M. laidlawii gave large turbidity responses, interpreted as caused by osmotic influences on cell volume, to potassium and sodium chlorides, sodium acetate, and sucrose. In addition a non-osmotic enhancement of turbidity was produced by potassium and sodium salts. Glucose, glycerol, and dimethylsulfoxide induced little turbidity variation. Of the above solutes, only glycerol and dimethylsulfoxide failed to induce maximum turbidity responses in M. hominis. M. laidlawii appeared to be more retractile and had higher estimated internal osmotic pressure values than M. hominis. These differences undoubtedly reflect properties of the enclosing cell membranes that are unlike in the two organisms. Their pertinence to saprophytic versus parasitic existence is obscure at the present time.
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Johnson PA, Larson K, Weibull C. The shape of pleuropneumonia-like organisms (PPLO,Mycoplasma) in liquid media. J Basic Microbiol 1967. [DOI: 10.1002/jobm.3630070309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
Kim, Kwang S. (University of North Carolina, Chapel Hill), Wallace A. Clyde, Jr., and Floyd W. Denny. Physical properties of human mycoplasma species. J. Bacteriol. 92:214-219. 1966.-Studies were made of the comparative morphology and stability of five Mycoplasma species of human origin (M. hominis type 1, M. salivarium, M. fermentans, M. pneumoniae, M. pharyngis). Broth-cultivated organisms were examined by electron microscopy to determine their relative appearance after uniform processing, including fixation-drying with formaldehyde vapor. M. pneumoniae was characterized by the occurrence of 250- to 300-mmu spheres in clusters, and M. pharyngis by the appearance of filaments 120 mmu by 1.5 to 8 mu; the remaining species revealed a variety of structures, including spheres, rings, and short filaments. To complement these findings, the effect of physical stresses on viability of the mycoplasmas was measured by exposing the organisms to heat (in saline), osmotic variations (in sucrose), and sonic oscillation and repetitive freeze-thawing (in culture medium). M. pneumoniae was most resistant to heat, vibration, and freeze-thawing; M. pharyngis was most sensitive to heart and vibration, but was least affected by osmotic changes. The remaining organisms assumed intermediate positions. The type-related variations in relative morphology and stability suggest differing physical attributes of the mycoplasmas studied, supporting taxonomic differentiation of the five species based on metabolic and immunological criteria.
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