Coccoid Microorganisms Research Articles

Desertic siliciclastic stromatolites in the Upper Jurassic Guará Formation from southwestern Gondwana: Trapping and binding in a non-marine setting

Abstract Siliciclastic stromatolites are rare in the geologic record, and their occurrence recorded in the literature is restricted to marine and coastal environments. The Upper Jurassic Guará Formation, from the Paraná Basin in southern Brazil, hosts unique non-marine siliciclastic stromatolites, providing a rare opportunity to study trapping and binding mechanisms by microbial mats in a continental setting. These microbialites occur interbedded with eolian and fluvial facies. The structural layering of the stromatolite domes is formed by the intercalation of sandy layers, resulting from trapping and binding of siliciclastic grains by microbial mats and in situ precipitation of amorphous to cryptocrystalline silica, which directly replaced the microbial colonies. The silica layers contain partially preserved spherical to ovoid bodies interpreted as colonies of coccoid microorganisms. These siliciclastic stromatolites were formed due to a specific balance of environmental factors, namely water chemistry and sediment supply, which enhanced the processes of trapping and binding and in situ precipitation. They record the presence of microbial life in a non-marine, silica-rich, fluvial-eolian environment in which there were no previous published occurrences of agglutinated stromatolites. These specimens record macroscopically identifiable evidence of microbial life in a continental environment that must be accounted for in the search for ancient life on Earth and Mars.

FRESHWATER STROMATOLITES FROM AN EARLY PERMIAN WETLAND (MANEBACH, THURINGIAN-FOREST BASIN, GERMANY): STRUCTURE, DEVELOPMENT, AND PALEOENVIRONMENTAL CONTEXT

Abstract Fossil stromatolites enclosing structurally preserved land plant remains have rarely been documented and studied in detail. Permineralized woody Tylodendron sp. conifer axes (slender stems, branches) from a lacustrine sedimentary sequence in the lower Permian fossil Lagerstätte of Manebach (Thuringian-Forest Basin, central Germany) are frequently surrounded by stromatolites that consist of successive, usually asymmetrical microbial layers. The stromatolites show various growth forms ranging from laminar to palisadic. They developed in stagnant water from microbial overgrowth dominated by slender, unbranched sessile cyanobacterial filaments aligned vertically into tufts or turf-like stands. Interspersed among the filaments were other filamentous and coccoid microorganisms. Preservation of the Tylodendron axes can be exquisite and sometimes even includes extraxylary tissues containing remains of fungi, suggesting that stromatolite formation began soon after the axes had entered the water and were perhaps even conducive to their preservation. Structurally similar fossil microbialitic structures from elsewhere likewise demonstrate that they were effective in preserving plant morphology. The Manebach stromatolites and the plant remains they contain contribute to a more accurate understanding of the complex biological processes in late Paleozoic lake ecosystems.

Opportunities for using biologically active substances Rhodiola rosea L. in the production of functional food with consideration for antimicrobial activity

Biologically active substances extricated by extraction of water and 40% ethyl alcohol from rootstalks of Rhodiola rosea L.: gallic acid, forms of rosovin and salidroside have been studied. Thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) were used during the research. Determination of antimicrobial activity was performed by agar diffusion method (OFC.1.2.4.0010.15) [8]. The method is based on the evaluation of inhibition of the growth zone of testing cultures of microorganisms by certain concentrations of biologically active substances (BAS). String formed bacteria (8 strains), cocci bacteria (3) and fungal (4) microorganisms, bifidobacterium (10 strains) were used as testing cultures. Various responses of microorganisms to exposure by biologically active substances have been determined. Gallic acid and salidroside in the aqueous phase have the maximum inhibitory property to rod bacteria and coccoid microorganisms. Post-antibiotic effect is shown in rozovin. Salidroside in the butanol phase is more neutral to most microorganisms, with the exclusion of: Acinetobacter baumannii, Pseudomonas aeruginosa, Bacillus cereus and Staphylococcus aureus. The lack of a clearly expressed reaction of BAS to bifidobacterium, most probably, gives the possibility of their use in the development of functional products of a new generation. However, first of all, it is required to organize a special experiment on the structure of the introduction of the studied components into the lactoserum. Next, determine the content of BAS in the derived product, the reaction of bifidobacterium admitted for use in biotechnology, and a standard set of microbiological strains. Gallic acid is suggested to be introduced in applied studies to explore as a target immunomodulator of resistance to the listed microflora and to develop an effective form of a new product.

ЕТІОЛОГІЧНА СТРУКТУРА ГОСТРИХ ШЛУНКОВО–КИШКОВИХ ЗАХВОРЮВАНЬ ТЕЛЯТ

The results of tests of samples of biological material from the calves with acute gastrointestinal diseases presents in the article. It was found that the occurrence and development of acute gastrointestinal diseases the leading role played by opportunistic bacteria association: S. aureus, S. saprophiticus, S. agalactiae, S. faecalis, S. pyogenes, E. coli, E. cloacae, C. jejuni, P. vulgaris, P. mirabilis, P. aeruginosa and K. Pneumoniae. Of the 632 examinations we studied 2,786 samples of biological material. Analysis of the results on our diagnostic work shows that acute gastrointestinal disease in calves caused by microbial associations. At acute gastrointestinal disease isolated pathogen E. coli – 21.0%. Coccoid microorganisms group also had significant representation. Thus, a biomaterial of 15.5% was allocated S. faecalis, at 11.6% was allocated pathogen S. aureus. Although to a lesser extent, but large office in the species spectrum of microorganisms by acute gastrointestinal diseases of calves occupied S. agalactiae – 4.8%, S. saprophiticus – 4.6%, S. pyogenes – 3.7%. Among the important place occupied microorganisms culture P. vulgaris – 8.5% of the total allocation of the samples. The average discharge frequency was characteristic for Campylobacter jejuni – 6.5% of cases.In analyzing the sensitivity of microorganisms isolated from calves with acute gastro–intestinal diseases to different groups of antibiotic drugs found that E. coli has a low sensitivity to antibiotics almost all studied groups. The largest number of selected crops susceptible to cephalosporins – 74.8%. Most of the isolated cultures weaklysensitive or insensitive to antibiotics studied by us. These data are an indication of the spread of antibiotic–resistant strains of microorganisms among newborn calves in the farms of Sumy and Chernihiv regions, which explains the low efficiency of antibiotic therapy. Highly active towards crop S. aureus, S. saprophiticus, S. agalactiae, S. faecalis, S. pyogenes, E. coli, E. cloacae, C. jejuni, P. vulgaris, P. mirabilis, P. aeruginosa, and K. pneumoniae were drug «Ceftioklin» and combined antibacterial agents.

Methanomassiliicoccus luminyensis gen. nov., sp. nov., a methanogenic archaeon isolated from human faeces

During attempts to obtain novel, human-associated species of the domain Archaea, a coccoid micro-organism, designated strain B10(T), was isolated in pure culture from a sample of human faeces collected in Marseille, France. On the basis of its phenotypic characteristics and 16S rRNA and mcrA gene sequences, the novel strain was classified as a methanogenic archaeon. Cells of the strain were non-motile, Gram-staining-positive cocci that were approximately 850 nm in diameter and showed autofluorescence at 420 nm. Cells were lysed by 0.1% (w/v) SDS. With hydrogen as the electron donor, strain B10(T) produced methane by reducing methanol. The novel strain was unable to produce methane when hydrogen or methanol was the sole energy source. In an atmosphere containing CO(2), strain B10(T) could not produce methane from formate, acetate, trimethylamine, 2-butanol, 2-propanol, cyclopentanol, 2-pentanol, ethanol, 1-propanol or 2,3-butanediol. Strain B10(T) grew optimally with 0.5-1.0% (w/v) NaCl, at pH 7.6 and at 37 °C. It required tungstate-selenite for growth. The complete genome of the novel strain was sequenced; the size of the genome was estimated to be 2.05 Mb and the genomic DNA G+C content was 59.93 mol%. In phylogenetic analyses based on 16S rRNA gene sequences, the highest sequence similarities (98.0-98.7%) were seen between strain B10(T) and several uncultured, methanogenic Archaea that had been collected from the digestive tracts of a cockroach, a chicken and mammals. In the same analysis, the non-methanogenic 'Candidatus Aciduliprofundum boonei' DSM 19572 was identified as the cultured micro-organism that was most closely related to strain B10(T) (83.0% 16S rRNA gene sequence similarity). Each of the three treeing algorithms used in the analysis of 16S rRNA gene sequences indicated that strain B10(T) belongs to a novel order that is distinct from the Thermoplasmatales. The novel strain also appeared to be distinct from Methanosphaera stadtmanae DSM 3091(T) (72.9% 16S rRNA gene sequence similarity), another methanogenic archaeon that was isolated from human faeces and can use methanol in the presence of hydrogen. Based on the genetic and phenotypic evidence, strain B10(T) represents a novel species of a new genus for which the name Methanomassiliicoccus luminyensis gen. nov., sp. nov. is proposed. The type strain of the type species is B10(T) ( = DSM 24529(T) = CSUR P135(T)).

Streptococcus agalactiae, an Emerging Pathogen for Cultured Ya-Fish, Schizothorax prenanti, in China

Streptococcus agalactiae (Group B streptococcus) has emerged as an important pathogen that affects humans and animals, including aquatic species. S. agalactiae infections are becoming an increasing problem in aquaculture and have been reported worldwide in a variety of fish species, especially those living in warm water. Recently, a very serious infectious disease of unknown aetiology broke out in ya-fish (Schizothorax prenanti) farms in Sichuan Province. A Gram-positive, chain-forming coccus was isolated from moribund cultured ya-fish. The goals of this study were to identify the bacterial strains isolated from diseased fish between 2009 and 2011 in Sichuan Province, China, to evaluate the pathogenicity of the pathogen in ya-fish, crucian carp (Carassius carassius) and the Nile tilapia (Oreochromis niloticus); and to determine the susceptibility of the pathogen strains to many currently available anti-microbial agents. The virulence tests were conducted by intraperitoneal injection of bacterial suspensions. In this study, four strains of a Gram-positive, chain-forming coccus were isolated from moribund cultured ya-fish (S. prenanti). The coccoid microorganism was identified as S. agalactiae using a commercial streptococcal grouping kit and 16S rDNA sequencing analysis. Susceptibility of the isolates to 22 antibiotics was tested using the disc diffusion method. All isolates showed a similar antibiotic susceptibility, which were sensitive to amoxicillin, ciprofloxacin, lomefloxacin, chloramphenicol, rifampin, vancomycin, azithromycin, florfenicol, cefalexin, cefradine and deoxycycline and resistant to gentamicin, sinomin (SMZ/TMP), penicillin, tenemycin, fradiomycin and streptomycin. Furthermore, the virulence tests were conducted by intraperitoneal injection of the isolated strain GY101 in ya-fish, crucian carp and the Nile tilapia. This coccus was lethal to ya-fish, Nile tilapia and crucian carp. The mortality rates of infected ya-fish were 100%, 100%, 60% and 20% at doses of 1.0 × 10⁷, 1.0 × 10⁶, 1.0 × 10⁵ and 1.0 × 10⁴ CFU/fish, respectively. The values were 100%, 80%, 60% and 30% for Nile tilapia and 100%, 60%, 10% and 0% for crucian carp. To our knowledge, this is the first report of S. agalactiae as a pathogen of ya-fish.

Isolation and characterization of Streptococcus dysgalactiae from diseased Acipenser schrenckii

Streptococcosis became an increasingly significant health problem in intensive aquaculture in China. Fifteen strains of Gram-positive, chain-forming coccus were isolated from moribund Amur sturgeon, Acipenser schrenckii, farmed with high density in central China. The coccoid microorganism was identified as Streptococcus dysgalactiae by means of physiological, biochemical properties and molecular analysis; furthermore, this coccus was confirmed as pathogen of sturgeon by challenge experiments and its infection potential on the cyprinid was also evaluated. To our knowledge, this was the first report of S. dysgalactiae linked to diseased A.schrenckii.

Ultrastructure and Transovarial Transmission of Endosymbiotic Microorganisms in Palaeococcus fuscipennis (Burmeister) (Insecta, Hemiptera, Coccinea: Monophlebidae)

Ovaries ofPalaeococcus fuscipennis (Burmeister) are accompanied by large organs termed bacteriomes which are composed of large cells termed bacteriocytes. Each bacteriocyte is surrounded with small epithelial cells. The bacteriocyte cytoplasm is tightly packed with pleomorphic bacteria, whereas in epithelial cells small coccoid microorganisms are present. The number of coccoid bacteria is significantly lower than pleomorphic bacteria. The ovarioles containing choriogenic oocytes are invaded both by pleomorphic as well by coccoid bacteria. Microorganisms traverse the follicular epithelium and enter the perivitelline space. During advanced choriogenesis, endosymbionts are accumulated in the deep depression of the oocyte. Bacteria do not enter the ooplasm until the end of oocyte growth.

Morphological and immunological characteristics of nanobacteria from human renal stones of a north Indian population.

The aim of this study was to detect, isolate and characterize the nanobacteria from human renal stones from a north Indian population, and to determine their role in biomineralization. Renal stones retrieved from the kidneys of 65 patients were processed and subjected to mammalian cell culture conditions. The isolated bacteria were examined using scanning (SEM) and transmission electron microscopy (TEM). They were characterized for the presence of DNA, proteins and antigenicity. The role of these bacteria in biomineralization was studied by using the (14)C-oxalate based calcium oxalate monohydrate (COM) crystallization assay. We observed the presence of apatite forming, ultrafilterable gram negative, coccoid microorganisms in 62% of the renal stones. SEM studies revealed 60-200 nm sized organisms with a distinct cell wall and a capsule. TEM images showed needle like apatite structures both within and surrounding them. They were heat sensitive, showed antibiotic resistance and accelerated COM crystallization. A potent signal corresponding to the presence of DNA was observed in demineralized nanobacterial cells by flow cytometry. The protein profile showed the presence of several peptide bands of which those of 18 kDa and 39kDa were prominent. Apatite forming nanosized bacteria are present in human renal stones and may play a role in the pathophysiology of renal stone formation by facilitating crystallization and biomineralization. However, further studies are required to establish the exact mechanism by which nanobacteria are involved in the causation of renal stones.

Ultrastructure, distribution, and transmission of endosymbionts in the whitefly Aleurochiton aceris Modeer (Insecta, Hemiptera, Aleyrodinea).

The body of the whitefly Aleurochiton aceris contains specialized cells, termed mycetocytes, that enclose endosymbiotic microorganisms. The endosymbionts are transmitted from one generation to the next transovarially. In contrast to other insects, in whiteflies whole intact mycetocytes migrate into the ovaries, traverse the follicular epithelium, and reach the oocyte surface (i.e., perivitellin space). The migration of mycetocytes begins in the last instar, called puparium, from which imagines emerge. During this stage the cytoplasm of mycetocytes is tightly packed with pleomorphic bacteria and less numerous coccoid microorganisms. In adult females the mycetocytes gather extracellularly in the depression of the vitellarial oocyte. Till the end of oogenesis neither pleomorphic nor coccoid microorganisms are released from mycetocytes into the oocyte.

Magnetite from magnetotactic bacteria; size distributions and twinning

Other| December 01, 1998 Magnetite from magnetotactic bacteria; size distributions and twinning Bertrand Devouard; Bertrand Devouard Arizona State University, Departments of Geology and Chemistry/Biochemistry, Tempe, AZ, United States Search for other works by this author on: GSW Google Scholar Mihaly Posfai; Mihaly Posfai Search for other works by this author on: GSW Google Scholar Xin Hua; Xin Hua Search for other works by this author on: GSW Google Scholar Dennis A. Bazylinski; Dennis A. Bazylinski Search for other works by this author on: GSW Google Scholar Richard B. Frankel; Richard B. Frankel Search for other works by this author on: GSW Google Scholar Peter R. Buseck Peter R. Buseck Search for other works by this author on: GSW Google Scholar Author and Article Information Bertrand Devouard Arizona State University, Departments of Geology and Chemistry/Biochemistry, Tempe, AZ, United States Mihaly Posfai Xin Hua Dennis A. Bazylinski Richard B. Frankel Peter R. Buseck Publisher: Mineralogical Society of America First Online: 02 Mar 2017 Online ISSN: 1945-3027 Print ISSN: 0003-004X GeoRef, Copyright 2004, American Geological Institute. American Mineralogist (1998) 83 (11-12_Part_2): 1387–1398. https://doi.org/10.2138/am-1998-11-1228 Article history First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Bertrand Devouard, Mihaly Posfai, Xin Hua, Dennis A. Bazylinski, Richard B. Frankel, Peter R. Buseck; Magnetite from magnetotactic bacteria; size distributions and twinning. American Mineralogist 1998;; 83 (11-12_Part_2): 1387–1398. doi: https://doi.org/10.2138/am-1998-11-1228 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyAmerican Mineralogist Search Advanced Search Abstract We studied intracellular magnetite particles produced by several morphological types of magnetotactic bacteria including the spirillar (helical) freshwater species, Magnetospirillum magnetotacticum, and four incompletely characterized marine strains: MV-1, a curved rod-shaped bacterium; MC-1 and MC-2, two coccoid (spherical) microorganisms; and MV-4, a spirillum. Particle morphologies, size distributions, and structural features were examined using conventional and high-resolution transmission electron microscopy. The various strains produce crystals with characteristic shapes. All habits can be derived from various combinations of the isometric {111}, {110}, and {100} forms. We compared the size and shape distributions of crystals from magnetotactic bacteria with those of synthetic magnetite grains of similar size and found the biogenic and synthetic distributions to be statistically distinguishable. In particular, the size distributions of the bacterial magnetite crystals are narrower and have a distribution asymmetry that is the opposite of the nonbiogenic sample. The only deviation from ideal structure in the bacterial magnetite seems to be the occurrence of spinel-law twins. Sparse multiple twins were also observed. Because the synthetic magnetite crystals contain twins similar to those in bacteria, in the absence of characteristic chains of crystals, only the size and shape distributions seem to be useful for distinguishing bacterial from nonbiogenic magnetite. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

The Influence of Surface‐Free Energy on Supra‐ and Subgingival Plaque Microbiology. An In Vivo Study on Implants

The influence of surface free energy on supra- and subgingival plaque microbiology was examined in 9 patients with functional fixed prostheses supported by endosseous titanium implants. Two abutments (trans-mucosal part of the 2 stage implant) were replaced by either a new titanium abutment or a fluor-ethylene-propylene (FEP) coated abutment per subject. After 3 months of habitual oral hygiene, plaque samples were taken. Supragingival plaque was examined by means of differential phase-contrast microscopy, whereas for the subgingivial plaque additional analyses (DNA probes analysis, culturing) were performed. The subgingival samples were taken by paper-points and by scraping of the subgingival abutment surface. Differential phase-contrast microscopy showed a significant difference in plaque composition, especially when supragingival plaque was considered (P = 0.05). FEP coated abutments frequently harbored more coccoid microorganisms, whereas spirochetes or motile organisms were only detected around titanium abutments. Subgingivally, the number of colony forming units (CFU) in paper-points was comparable for both types of abutments. If the to-the-abutment-adhering plaque was considered, the number of CFU was 5 times higher on the titanium abutments than on the FEP coated abutments. However, this difference did not reach a statistical level of significance (P = 0.38). The DNA probe analysis of the subgingival plaque collected with paper-points showed a slightly higher frequency and concentration of perio-pathogens around the titanium abutments. However, the inter-substratum differences were smaller than the inter-subject differences. The latter seemed to be related to patient's dental status.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrastructure of the endosymbionts of the whitefly,Bemisia tabaci andTrialeurodes vaporariorum

The ultrastructure of the mycetocytes and mycetome micro-organisms of the sweetpotato whitefly,Bemisia tabaci Genn. andTrialeurodes vaporariorum West are described. InB. tabaci, two morphologically distinct types of micro-organisms were observed in mycetocytes. The predominant type lacked a distinct cell wall, was pleomorphic in shape with a surrounding vacuole. The second type was a coccoid organism, with inner and outer cell membranes. The coccoid organism was often found in groups of varying number within vacuoles, and in many cases appeared to be undergoing degradation. InT. vaporariorum mycetocytes, pleomorphic and coccoid organisms were found, although the coccoid micro-organism inT. vaporariorum, had a thicker cell wall than the coccoid micro-organism inB. tabaci.

An in vivo Study of the Influence of the Surface Roughness of Implants on the Microbiology of Supra- and Subgingival Plaque

In nine patients with fixed prostheses supported by endosseous titanium implants, 2 titanium abutments (transmucosal part of the implant) were replaced by either an unused standard abutment or a roughened titanium abutment. After 3 months of habitual oral hygiene, plaque samples were taken for differential phase-contrast microscopy, DNA probe analysis, and culturing. Supragingivally, rough abutments harbored significantly fewer coccoid micro-organisms (64 vs. 81%), which is indicative of a more mature plaque. Subgingivally, the observations depended on the sampling procedure. For plaque collected with paper points, only minor qualitative and quantitative differences between both substrata could be registered. However, when the microbiota adhering to the abutment were considered, rough surfaces harbored 25 times more bacteria, with a slightly lower density of coccoid organisms. The presence and density of periodontal pathogens subgingivally were, however, more related to the patient's dental status than to the surface characteristics of the abutments. These results justify the search for optimal surface smoothness for all intra-oral and intra-sulcular hard surfaces for reduction of bacterial colonization and of periodontal pathogens.

Iron and graphite associated with fossil bacteria in chert

The mineralization associated with fossilized bacteria in 2.0-Ga stromatolitic grey chert from the Gunflint Iron Formation has been examined using electron microprobe techniques and transmission electron microscopy (TEM). X-ray diffraction showed that the chert consisted mainly of quartz with small amounts of calcite, lepidocrocite, hematite and graphite. In petrographic thin sections, fossilized remains of both filamentous and coccoid microorganisms were detected by optical microscopy. Electron microprobe analyses of these fossilized bacteria revealed high concentration of Si and O, as expected for the quartz matrix of the chert. Trace amounts of Al, S, C, Fe and Cl were also present. Fragments of microfossils were observed by TEM examinations of finely ground chert. Selected areas of this cellular debris generated graphitic electron diffraction patterns with spacings at d = 3.38, 2.04 and 1.23 å. Individual cell fragments were also found in successive stages of mineralization from amorphous to microcrystalline iron oxides.

Effect of critical surface tension on retention of oral microorganisms.

The effect of critical surface tension on the initial retention of microorganisms from unstimulated human saliva was tested in a flow cell system. Prior to each experiment the total numbers and the morphotypes of microorganisms present in saliva were recorded. The test surfaces were prepared to display known increasing critical surface tensions, as verified and standardized by contact angle measurements. Surfaces of initially low (20-22 mN/m), medium (35-38 mN/m) and high (greater than 50 mN/m) critical surface tension were exposed to saliva at a flow rate of 1 ml/min. Microbiota and biofilm material associated with the test surface after 15 min of salivary exposure, were then subjected to standard detachment forces, by introducing a cell-free rinsing fluid at two different shear rates. Both the attachment and the detachment phases were executed at room temperature or 37 degrees C. The retained population was counted in three different zones of the test surfaces with a light microscope and statistically tested for correlation to the main variables (critical surface tension, flow rate and temperature) and interactions. Retention success was significantly dependent on the initial critical surface tension and the flow rate. Surfaces of medium critical surface tension, representative of human tooth surfaces and most restorative dental materials, retained the highest numbers of microorganisms in comparison with the other surfaces tested, with no statistically verified selectivity in proportions of retained coccoid and rodshaped microorganisms for any surface. A 30-fold increase of the flow rate resulted in a 70-80% reduction of the retention success, with a higher relative number of cocci present on all the test surfaces. These results demonstrate that initial retention of microorganisms to surfaces is non-specific with regard to morphotypes, but is strongly related both to the mechanical removal forces and the surface energetic state of the solid surface exposed. Retention of microbial populations at interfaces might, therefore, be controllable by advance selection of the critical surface tensions and predicted if shear forces at given sites are known.

Methanohalophilus mahii gen. nov., sp. nov., a Methylotrophic Halophilic Methanogen

A new genus of methanogenic bacteria (Methanohalophilus) comprising a single species, Methanohalophilus mahii sp. nov., is described. The microorganisms of this genus require sodium chloride concentrations in the moderately halophilic range of 1.0 to 2.5 M for optimal growth and methanogenesis. Methanol and methylamines are the substrates that are utilized for growth. M. mahii is a methanogenic coccoid microorganism isolated from the sediments of the Great Salt Lake. The optimum temperature and salinity for growth and methanogenesis were 37°C and 2.0 M NaCI, respectively. The description is based on a single strain, strain SLP (= ATCC 35705), which is thus the type strain.

Wear of the toothbrush bristles under Bass technique with special reference to the toothbrushing force (author's transl)

The present study was made in vivo and weekly observed to the wear of toothbrush bristles under Bass technique reference to the toothbrushing force, and also to the pollution of the toothbrush bristles.The results obtained were as follows:1. Toothbrushing force in Bass technique was 218g on average.2. Discrepancy in the individual tooth brushing patterns which were evident from the brushing force curve was due to the individual variation in relation to grasp of the toothbrush.3. At one week after brushing, the wear of the toothbrush bristles were a little regardless of the toothbrushing forces. At four weeks after brushing, the tip of bristles was observed to overspread above average of the brushing force.4. At one week after brushing, coccoid microorganisms were observed at the round cut off tip of the bristles. Thereafter, coccoid and rod-like microorganisms were observed around the tip of the bristles.

Bacterial penetration in the apical pocket wall of advanced human periodontitis.

The presence of bacteria in the apical wall of periodontal pockets has been observed in 8 cases of advanced human chronic periodontitis out of a total of 14 patients studied. The apical junctional epithelium and the underlying connective tissue were removed under general anesthesia. Filaments, rodshaped and coccoid microorganisms with predominant Gram‐negative cell walls were observed in the enlarged epithelial intercellular spaces. In the connective tissue, these microorganisms were found among badly damaged cellular fragments and collagen fibrils. Between the apical sub‐gingival plaque and the junctional epithelium of the pocket wall, several layers of polymorphonuclear leukocytes were observed with numerous phagosomes showing engulfed bacteria. Bacterial invasion of the apical wall of the pockets is possible in the final stages of human chronic periodontitis.

Microbial fossils from the lower Yudoma Suite, earliest Phanerozoic, eastern Siberia

Well-preserved nannofossils are here described from black chert lenses in dolomitic and carbonaceous limestones of the lower Yudoma Suite from the Khanda (or Belaya) and Aldan Rivers in eastern Siberia. In this area, Yudoma rocks conformably underlie Lower Cambrian and unconformably overlie Upper Proterozoic strata. Radiometric ages based mainly on glauconite from weakly metamorphosed strata date the Yudoma as 675 ± 25 Ma to 570 ± 10 Ma ago. A K-Ar date for one of the localities here studied is 650 Ma. The Yudoma nannofossils are preserved in the chert as light amber to dark organic residues. The mode of preservation is similar to microbial assemblages in cherts from the older and now classic Gunflint and Bitter Springs formations. Sixteen categories of nannofossils are identified, including 12 species and 4 morphogroups of filamentous and coccoid microorganisms assigned to 11 genera. Of these, three genera and eight species are new. Six of 16 categories are identical to or closely comparable with forms in the roughly 850 Ma old Bitter Springs microbiota. Seven of the 16 categories are identical to or closely comparable with forms in the roughly, 1,900 Ma old Belcher Islands microbiota. Most of the elements of this well-preserved microbiota appear to be cyanophytic, with coccoid forms dominant over filamentous. One form, Micrhystridium, may be planktonic; the others are probably benthic. Age, stratigraphic relations, and microflora all are most consistent with an Ediacarian and Early Phanerozoic age (i.e., pre-Cambrian or sub-Cambrian, but not Precambrian in the sense of conventional usage).