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Morphological, cultural and biochemical characteristics of 12 cultures of myxobacteria isolated mainly from eels with ‘branchionephritis’ and cyprinids with ‘ulcer disease’ were studied.These organisms were gram-negative, slender rods which exhibited gliding motility on agar medium. All cultures were able to grow at 5°, 10°, 20° and 27°, and tolerated a sodium chloride concentration of 1% for growth. They were uniform in their biochemical properties, though diverse in the production of cytochrome oxidase and in the reduction of nitrate. Some distinguishing features of the organisms were as follows: Degradation of starch, esculin and chitin; utilization of glucose, galactose and citrate; decomposition of tyrosine; nonproduction of hydrogen sulfide; negative reaction to Congo red. They are physiologically similar to the myxobacteria isolated from the Amerian hatchery-raised salmonids with gill disease, tail rot or other myxobacterial infections.The histopathological features of experimentally infected eels resembled those of salmonids with ‘hemorrhagic type of gill disease’ described by WOOD and YASUTAKE.

The occurrence of agarolytic microorganisms in a variety of natural environments was investigated using enrichment culture techniques. From samples taken from the IJsselmeer, and adjacent areas in the central part of The Netherlands a new agarolytic flexibacterium was isolated. Enrichments inoculated with samples from other sources were unsuccessful. The yellow-pigmented organism exhibits gliding motility, but spreading was only occasionally detected. Since neither fruiting bodies nor microcysts were observed, the organism was placed into the genus Cytophaga and designated as Cytophaga flevensis sp. nov. The occurrence of this species is probably restricted to the IJsselmeer, a fresh-water lake that was in open contact with the North Sea until 1932, and some other lakes which are in direct contact with the IJsselmeer. The organism utilizes only carbohydrates as a carbon and energy source for growth and is strictly aerobic. When the organism is grown on agar, on its components or on melibiose, an extracellular agarase is produced. This enzyme is highly specific for polysaccharides containing neoagarobiose units and hydrolyzes neoagaro-oligosaccharides with a degree of polymerization of more than four.

1. Gliding motility ofMyxococcus xanthus FBt is reversibly inhibited by treatment with proteolytic enzymes and with 10-3 M ethylenediaminetetraacetic acid and by osmotic shock. Chloramphenicol inhibits regeneration of the ability to glide. Shearing and ultrasound treatments do not affect movement. 2. At least 18 periplasmic proteins are released by osmotic shock, as determined by SDS-polyacrylamide gel electrophoresis. These proteins are indistinguishable from those of the non-motile strain NM. Pronase treatment of FBt degrades most of the higher molecular weight periplasmic proteins. 3. Antisera prepared against periplasmic antigens of FBt and NM do not demonstrate strain-specific antigenic differences by immunodiffusion. NM does not agglutinate as well as FBt with either antiserum. Osmotic shocked FBt cells do not agglutinate. Both strains FBt and NM demonstrate a predominance of pole-to-pole agglutination. 4. These antisera inhibit gliding motility. Serum against FBt periplasmic antigens, adsorbed with FBt, does not inhibit gliding; adsorption with NM or osmotically shocked FBt only partially inhibits gliding. 5. Surface property differences among strains FBt, NM and SM (semi-motile) are indicated.

Cells of Chondrococcus columnaris were sectioned and examined in the electron microscope after fixation by two different methods. After fixation with osmium tetroxide alone, the surface layers of the cells consisted of a plasma membrane, a dense layer (mucopeptide layer), and an outer unit membrane. The outer membrane appeared distorted and was widely separated from the rest of the cell. The intracytoplasmic membranes (mesosomes) appeared as convoluted tubules packaged up within the cytoplasm by a unit membrane. The unit membrane surrounding the tubules was continuous with the plasma membrane. When the cells were fixed with glutaraldehyde prior to fixation with osmium tetroxide, the outer membrane was not distorted and separated from the rest of the cell, structural elements (peripheral fibrils) were seen situated between the outer membrane and dense layer, and the mesosomes appeared as highly organized structures produced by the invagination and proliferation of the plasma membrane. The mesosomes were made up of a series of compound membranes bounded by unit membranes. The compound membranes were formed by the union of two unit membranes along their cytoplasmic surfaces.

A plate technique for detecting gliding motility is described in which glass beads placed between agar surfaces and coverslips produced surrounding areas of liquid, thus allowing cells to move freely. Some relatively short non-spreading flexibacteria glided obviously. The movements are described and also those of myxobacteria and a fimbriate twitching bacterium. Flavobacterium aquatile F36 glided and its taxonomic status is discussed.

1. A number of motility mutants derived from the gliding bacterium Cytophaga columnaris were obtained by allowing motile cells to spread from an inoculated area on an agar plate and then removing cells from the center of the inoculated area. This procedure was repeated ten times. Suspensions of cells resulting from this selection procedure were spread on agar plates, and colonies which lacked the spreading edges typical of wild-type cells were picked for further study. 2. Mutants were examined in slide cultures, on agar plates under various conditions of incubation, and by electron microscopy. 3. Two classes of motility mutants were isolated. Cells of one class are only nonmotile under certain conditions of incubation, whereas cells of the second class are nonmotile under all conditions tested. One mutant of this second class lacks a system of fibrils which is present in surface layers of cells of the parent strain.

Two gliding motility mutants of Myxococcus xanthus are described. The semimotile mutant (SM) originated by high-frequency segregation from the motile FB t strain. Segregation was enhanced by acridine dye treatment. SM cells glide only when apposed to other cells in a swarm. The nonmotile strain (NM) originated by mutation from SM. NM cells neither glide individually nor cooperatively. FB t , SM, and NM are indistinguishable with respect to fine structure, vegetative growth rate, glycerol-induced microcyst formation, spheroplasting, bacteriophage sensitivity, and responses to light. The motility mutants are more resistant to penicillin and more sensitive to actinomycin D than is the gliding wild type. The NM mutant is also a morphogenetic mutant; it is unable to form fruiting bodies.

Characteristics of 10 strains of Cytophaga psychrophila isolated during a number of epizootics of bacterial cold-water disease were compared. Morphological, cultural, biochemical, and serological data showed that the organisms were very closely related. The isolates exhibited gliding motility, formed neither fruiting bodies nor microcysts, were actively proteolytic, and grew only at low temperatures. Data presented extend the description of C. psychrophila .

SUMMARY Gliding is an active movement displayed by a microorganism in contact with a solid substrate where there is no evidence of a motility organelle or of a conformational change in the organism. Gliding may be accompanied by rotations, reversals, flectional activity, and mucilage sheath production, as well as linear translation. Previous explanations of the mechanism responsible did not consider all these aspects of behavior. The gliding behavior and ultrastructure of the blue-green alga Oscillatoria princeps Vaucher were examined. O. princeps has a maximum observed gliding rate of 11.1 μm/sec. The trichomes can glide in either longitudinal direction following rapid and occasionally frequent reversals. Right-handed trichome rotation was always observed, which means that any surface point on these trichomes traces a 60-deg right-handed helix. A mucilage sheath envelopes the moving trichomes. The rate of gliding was reduced by viscous substrates, extreme pH, lysozyme, DNP, and cyanide, while sustained darkness had no inhibitory effect. Ultrastructurally, the cell wall is composed of an L-1 layer which is 10 nm thick and often ill-defined. The L-2 layer which is outside this is 200 nm thick and participates in septum formation. The L-3 layer is outside the L-2 and is continuous over the trichome surface. The L-4 “membrane” lies outside the L-3 layer. Grazing surface sections and freeze-etch replicas show a parallel and tight array of 6–9 nm wide continuous fibrils in the cell wall on the surface of the distinctive L-2 layer. Isolated wall fragments were tightly coiled inside out with the fibrils on the inside. The angle of orientation for the fibrils was to the right in a helix with a pitch of 60 deg. O. animalis, a blue-green alga with a movement tracing a left-handed helix, showed a similar array of fibrils oriented in a left-handed helix with a pitch of 60 deg. It is proposed that gliding is produced by unidirectional waves of bending in the fibrils which, act against the sheath or substrate, tints displacing the trichome.

Studies on cells harvested from the natural habitat showed thatA. oxaliferum is gram-negative and catalase-negative. Electron micrographs of carefully fixed cells revealed the presence of peritrichously arranged appendages with a minimum thickness of 90 A as well as capsular slime. The hypothesis is advanced that the gliding motility ofAchromatium is caused by peritrichous bacterial flagella beating in a slime layer that surrounds the cell.

The effect of the antibiotic cytochalasin B on gliding motility of Oscillatoria and Navicula was studied using time lapse microcinematography. Contrary to its effects on many other non-muscle motile systems, cytochalasin B did not significantly inhibit motility.

SummaryProgressive gliding motility, lashing around a fixed pole, and flexion were found in five strains of Fusobacterium girans when examined in fluid suspensions by dark-field microscopy. Electron, phase contrast, and polarized light microscopy failed to reveal flagella on these organisms. The presence of a slime layer was indicated by electron microscopy, and by the use of India ink preparations. Motility apparently was not affected by the addition to the medium of either “Tween 80” or alkylated aryl sulphonate. Motility was inhibited in the presence of specific antiserum. No explanation is offered for the mechanism of motility in Fusobacterium girans.

SUMMARY The energy required to overcome viscous drag in a gliding trichome of a blue-green alga advancing and rotating through a medium of known viscosity (67 poise at 25 C) has been calculated to be about 0.05% of the energy available from oxidative phosphorylation (based on respiration measurements), whereas 0.2–5% are possible figures for the amount actually expended. These values represent a low energy demand for a function of probable high survival value, but are comparable to estimates for motility in flagellated cells.

GLIDING motility has been studied for many years with limited success1–3. The gliding movements displayed by several species of blue–green algae and bacteria have not as yet been satisfactorily explained. Earlier observations of gross behaviour and morphology have suggested several mechanisms, but we believe that none of the previous explanations encompass all of the motility characteristics observed in the blue–green alga, Oscillatoria princeps Vaucher (Fig. 1).

This paper is a report on the microbial flora of the waters and sediments of five lakes from the Canadian Subarctic, with special emphasis on the genus Cytophaga. The cytophagas are long, thin rods which are capable of flexing in liquids and of gliding motility on solid surfaces. They are important in the degradation and recycling of many relatively resistant, macromolecular polysaccharides and proteins such as cellulose, chitin, agar and keratin which occur as structural or storage residues of "higher" plants and animals in the natural environment. ... The samples were collected aseptically during the summer of 1971, flown to Edmonton and stored at 4 °C until processed, within two days of sampling time. ... Tests, which were carried out at the isolation temperature of each organism (10° or 25 °C), were as follows: C.C.A. [Cook's cytophaga agar] - growth, spreading, colour, length, width, shape and motility were described at 3-4 days (25 °C) or 5-6 days (10 °C); S.M.A. [skim milk acetate] - proteolysis (clearing) and silkiness of the liquid culture were noted at 2, 3 and 6 days and length, width, shape, flexing and motility observations were made at 10-14 hrs. and 2 days (25 °C) or 24-42 hrs. and 5 days (10 °C); S.M.A.-growth at 5° and 30 °C, and proteolysis were noted at 6 days. Gram stains and Munsell colour determinations were made at 4 days. ... The small number of samples used does not permit large-scale generalization; nevertheless some useful observations can be made. The three media and two temperatures used for isolation should screen the samples exhaustively for cytophagas (with the exception of any as yet unknown psychrophiles), as well as support the growth of various other micro-organisms. Very likely, other organisms could be found if a greater selection of media and conditions were used. The uniqueness of the microbial community of each site is noteworthy. The number and variety of bacterial types present varied widely. It is reasonable to conclude that those sites possessing a greater range of morphological types are likely to have a greater range of biochemical capacity in the degradation of organic molecules too. Of the total isolates 65% grew better at 30° than at 5 °C, 13% showed similar growth at both temperatures, and 16% showed no growth at 5 °C, whilst only 1% showed no growth at 30 °C, and 5% better growth at 5 °C than at 30 °C. The results for the Cytophaga cultures followed this trend, giving 61%, 13%, 15%, 4% and 6% respectively. This scarcity of psychrophiles should not be interpreted as necessarily reflecting the situation in the lakes, since the transit temperature and the temperatures of culture isolation were all higher than those in situ. The results do show a good potential for mesophilic growth if these areas were ever heated (by an oil pipeline for example), and turnover of materials could be expected to be fairly rapid. The genus Cytophaga, members of which spread by gliding motility on nutritionally weak media, were well represented in these lakes. ... Members of the genus Cytophaga, with their potential for waste polymer degradation, were recovered from all five lakes examined, and very large numbers were present in samples 4796 water and mud and 4810 water. ... The Cytophaga found in these subarctic lakes seem to differ very little from those present in more temperature regions of Canada.

SUMMARY: The cultural, biochemical and morphological characteristics of six cultures of Simonsiella and four cultures of Alysiella are described. The multicellular filaments of both Simonsiella and Alysiella, originally termed “disk-bacteria”, are ribbon-like, non-sporing, non-branching, aerobic and Gram-negative. They are greater than 2 μ wide, exhibit gliding motility on solid media and ferment carbohydrates. The family Simonsiellaceae fam.nov. is proposed to include the genus Simonsiella Schmid and the genus Alysiella Langeron. Amended descriptions of the species Simonsiella crassa Schmid and of Alysiella filifornis (Schmid) Langeron are given.

Summary 1. Procaryotic motility mechanisms are more difficult to investigate than those of the generally larger, hence more easily observable, eucaryotic forms. Furthermore, although the function—namely translational locomotion—is the same, the biomechanisms by which this end is accomplished may be, in fact, quite distinct in the two forms. 2. Observational techniques for studying procaryotic motility are relatively crude and qualitative. Progress toward a greater understanding of motility phenomena will be made correlative with advances derived from devising specific techniques involving approaches adapted from electrical engineering, biophysics and cybernetics. 3. There is a great amount of information at hand concerning the qualitative and quantitative chemical composition of procaryotic flagella, but there is no assurance that preparatory techniques include either the entire organelle on the one hand, or do not introduce subtle errors on the other hand. Similarly, the structural features of flagella as derived from electron-microscope studies of fixed preparations may be themselves influenced by the techniques employed to reveal them. 4. Chemotactic responses of bacteria have been noted almost since the beginning of bacteriology as a formal scientific endeavour, yet the study of transduction of environmental stimuli, using motile bacteria as experimental subjects, is a relatively recent development. We have proposed that the cytoplasmic membrane may act as a non-specific receptor-transmitter of such signals in motile bacteria. If this is found to be the case, perhaps a sensory code may be more amenable to discovery here than with more complex forms of organisms. 5. Knowledge of the physical aspects in procaryotic flagellar movement is extremely fragmentary. There is some information on the movements of living functional flagellar fascicles, but this form of movement of an individual flagellum is purely speculative. We have proposed that the procaryotic flagellum is a rigid or semi-rigid helix, which does not transmit helical waves of contraction, and that its movements are governed by a specialized area of the cytoplasmic membrane. The flagellum may rotate or wobble within the flagellar basal bulb to produce the motion necessary for propulsion. This view ‘explains’ many of the known properties of procaryotic flagella. 6. The basis of gliding motility remains unknown even after a great deal of experimental work. In our view, the secretion of slime is necessary for adhesion to a solid surface, and movement is believed to be mediated by a mechanism involving contractile waves. 7. Studies on procaryotic motility may yield valuable information on certain areas of general biological interest. Among these are: (a) the transduction of environmental stimuli and the sensory code; (b) the development of reproducible observational techniques for quantitative data on the hydrodynamic and biophysical parameters of cell motion in procaryotic forms; (c) the phenomenon of unicellular ‘behaviour’ and the survival value and evolutionary significance of motility; and (d) the elucidation of the mechanism of gliding with perhaps an assessment of its utility in a wide variety of micro-organisms. All of these areas are ripe for imaginative and innovative experimentation; let us hope it will be forthcoming!

Two strains of Vitreoscilla were studied. Their trichomes showed gliding motility on surfaces and they were immobile in fluid suspension. Motility is the property of the individual cells which make up the trichome, but floating, living cells rebounded when they touched a surface. A copious slime layer has been demonstrated and its possible roles in gliding motility is discussed. An association of the unique, scalloped, outer layer of the cell walls of these organisms with their curious motility suggested a new hypothesis: a vibratile, actively undulating surface. Specific antiserum caused rapid cessation of gliding motility; pasteurization and fixation prevented the rebound phenomenon. Stained preparations and electron micrographs of thin sections have provided a general description of structure. This shows, at least, that the classification of Vitreoscilla among the bacteria is reasonably founded. Similarities to certain bacteria are seen in the mode of cell division. On the other hand differentiation of central and peripheral cytoplasmic organization is reminiscent of the Myxophyceae, while the diffuse chromatin distribution has precedent in both groups.

SUMMARY: Two facultatively anaerobic agar-decomposing myxobacteria were isolated from marine mud and described as Cytophaga fermentans Bachmann var. agarovorans var. nov. and C. salmonicolor var. agarovorans var. nov. A third organism which does not attack agar was isolated from the same source; it has been included in the present study for comparative purposes. The specific name Cytophaga salmonicolor has been given to this organism. All organisms are characterized by exhibiting flexing and gliding motility and by absence of microcysts and fruiting bodies. The organisms can be grown in a mineral glucose medium, although growth is accelerated and more abundant when a vitamin mixture is included in the medium. CO2 is an absolute requirement for growth. Growth of C. fermentans var. agarovorans and C. salmonicolor var. agarovorans on aerobic plate cultures is markedly inhibited by 0.1 % glucose or galactose. Acetic, propionic and succinic acids are major end products of sugar fermentation of all three types. C. salmonicolor and C. salmonicolor var. agarovorans form in addition CO2 and H2, and small amounts of lactic and formic acids and ethanol.