Identification of a new intestinal spirochete with pathogenicity for chickens

Two intestinal spirochete isolates obtained from chickens with diarrhea were examined by electron microscopy, biochemical tests, rRNA gene restriction pattern analysis, and multilocus enzyme electrophoresis. One isolate (strain 91-1207/C1) was pathogenicity tested in vivo in chickens. The chicken spirochetes were morphologically indistinguishable from Serpulina innocens and Serpulina hyodysenteriae and phenotypically similar to S. innocens. However, the chicken spirochetes could be distinguished from S. innocens, S. hyodysenteriae, and other swine intestinal spirochetes by rRNA gene restriction pattern analysis and multilocus enzyme electrophoresis. In pathogenicity tests in 1-day-old chicks and 14-month-old hens, chicken spirochete 91-1207/C1 produced pale-yellow, watery cecal contents and mild lymphocytic typhlitis. These findings support the conclusion that avian intestinal spirochetes can be pathogenic to commercial poultry and that the microorganisms are different from intestinal spirochetes that infect pigs.     

Hip impact velocities and body configurations for voluntary falls from standing height

OBJECTIVE: To determine prevalence of various pheno- and genotypes of Serpulina sp in young pigs in relation to diarrhea and feed medication in Swedish pig-rearing herds. DESIGN: Isolation of spirochetes. Phenotypical and genotypical classification. SAMPLE POPULATION: Young pigs (n = 358) in 19 pigrearing herds. PROCEDURE: Serpulina isolates were classified according to a biochemical scheme based on hemolysis, indole production, hippurate hydrolysis, and alpha-galactosidase, alpha-glucosidase, and beta-glucosidase activities. The 16S rRNA sequences for 10 of the field strains and 2 type strains of Serpulina spp were aligned and compared. Minimum inhibitory concentrations of olaquindox for 9 of the strains were determined. RESULTS: Weakly beta-hemolytic intestinal spirochetes (WBHIS) were isolated from 17 of the herds and 65% of the samples. More than 1 phenotype of WBHIS was found in 12 of the 19 herds. S hyodysenteriae was not isolated in any of the herds. Hippurate-positive WBHIS were isolated in 6 of 7 herds affected by diarrhea, but in only 1 of 8 herds without diarrhea. Hippurate-positive strains were closely related to the pathogenic strain P43 if judged from sequence comparisons. Strains with the same biochemical profile isolated within a herd had identical sequences, but when isolated from different herds, sequence differences were observed. The prevalence of WBHIS was reduced in herds medicated with olaquindox. Investigated field strains had minimum inhibitory concentration values < or = 1 microgram/ml for olaquindox. CONCLUSION: The presence of WBHIS, with the ability to hydrolyze hippurate, was related to diarrhea in pig herds. CLINICAL RELEVANCE: Potentially pathogenic WBHIS can be distinguished from nonpathogenic strains by the hippurate hydrolysis test.     

Survival during exposure to the electrophilic reagent N-ethylmaleimide in Escherichia coli: role of KefB and KefC potassium channels

On the basis of DNA-DNA hybridization data, nine intestinal spirochete strains were grouped into five genospecies. Three of these genospecies were previously recognized Serpulina species, Serpulina hyodysenteriae (type strain, B78), Serpulina innocens (type strain, B256), and Serpulina pilosicoli (type strain, P43/6/78; previously "Anguillina coli"). The other two genospecies were found to be new Serpulina species, for which we propose the names Serpulina intermedia sp. nov. (with type strain PWS/A) and Serpulina murdochii sp. nov. (with type strain 56-150). S. intermedia and S. murdochii cells had a typical spirochete ultrastructure with 22 to 28 periplasmic flagella per cell. Various soluble sugars were growth substrates for S. intermedia and S. murdochii. During growth in basal heart infusion broth supplemented with fetal calf serum beneath an O2-N2 (1:99) atmosphere, cells of these new species consumed oxygen and glucose and produced H2, CO2, acetate, butyrate, and ethanol. The G + C content of the DNA of S. murdochii 56-150T was 27 mol%, and the G + C content of the DNA of S. intermedia PWS/AT was 25 mol%. In addition, a restriction fragment length polymorphism-PCR assay for the detection of intestinal spirochetes was developed. The assay was based on generation and restriction endonuclease analysis (with HinfI, TaqI, Sau3A, and MboII) of a 558-bp amplicon of ribosomal DNA (rDNA) encoding 16S rRNA. The PCR amplification was specific for Serpulina species and Brachyspira aalborgi. Four restriction digest patterns were found for the five Serpulina species. HinfI restriction differentiated S. murdochii and S. innocens from the other species. Sau3A and TaqI restrictions gave unique fragment patterns for S. murdochii and S. pilosicoli, respectively. S. hyodysenteriae and S. intermedia DNAs gave the same fragment pattern regardless of the enzyme tested. B. aalborgi was differentiated from the Serpulina species by MboII digestion of the 16S rDNA amplicon.     

Expression of arachidonate platelet-type 12-lipoxygenase in human rheumatoid arthritis type B synoviocytes

Pathogenic intestinal spirochetes cause damage to the intestinal mucosa of humans and animals by an unknown mechanism. The purpose of this study was to assess the pathogenic intestinal spirochetes Serpulina hyodysenteriae, Serpulina pilosicoli, and Brachyspira aalborgi and the non-pathogenic commensal intestinal spirochetes Serpulina innocens and Treponema succinifaciens for protease activity. A partially heat stable, subtilisin-like, serine protease was identified in the outer membrane of all spirochetes and thus may be essential for survival in the intestinal environment. The outer membrane protease may indirectly contribute to intestinal damage caused by pathogenic spirochetes during association with the mucosal surface of the host.     

Evaluation of day-old specific pathogen-free chicks as an experimental model for pathogenicity testing of intestinal spirochaete species

Specific pathogen-free chicks aged 1 day were challenged per os with strains of five different species of intestinal spirochaete originally isolated from pigs or human beings. A virulent strain of Serpulina hyodysenteriae (WA 15) colonized chicks, causing retarded growth rate and histological changes, including caecal atrophy, epithelial and goblet cell hyperplasia, and crypt elongation. A further strain of S. hyodysenteriae (SA3), which was apparently avirulent for pigs, and a strain of Serpulina intermedia (889) colonized fewer chicks, caused less severe lesions and did not significantly depress growth rate. Strains of Serpulina murdochii and Brachyspira aalborgi failed to colonize or cause histological changes. Four strains of Serpulina pilosicoli (Kar, Rosie-2299 and GAP 401, isolated from human beings, and 3295, isolated from a pig) colonized chicks, and large numbers showed polar attachment to the caecal epithelium; all strains, apart from Rosie-2299, caused watery diarrhoea and wet litter, but did not significantly retard growth. Variation both in the degree of spirochaetal attachment and the resulting development of lesions was observed between S. pilosicoli strains as well as between individual chicks infected with the same strain. The study indicated that chicks may be useful in studying the pathogenicity of strains of S. hyodysenteriae, S. intermedia and S. pilosicoli.     

Basic fibroblast growth factor prevents cAMP-induced apoptosis in cultured Schwann cells

The periplasmic-flagellum (PF) proteins of Triton X-100-soluble and Triton X-100-insoluble sodium dodecyl sulfate-treated fractions from reference and field strains of Serpulina hyodysenteriae, Serpulina innocens, and Serpulina pilosicoli were characterized by Western blotting with a rabbit polyclonal antibody (PAb) specific for the 44-kDa PF sheath protein of S. hyodysenteriae (Z. Li, F. Dumas, D. Dubreuil, and M. Jacques, J. Bacteriol. 175:8000-8007, 1993) and a murine monoclonal antibody (MAb), designated 7G2, specific for the PF core FlaB proteins of S. hyodysenteriae. The MAb 7G2 reacted with a conserved epitope present in the 37-, 34-, and 32-kDa PF core FlaB proteins of all Serpulina species. This suggested that the core FlaB proteins are conserved among porcine Serpulina species. An immunoreactive band of approximately 44 kDa was present with all S. hyodysenteriae, S. innocens, and S. pilosicoli strains that were reacted with the PAb. The specificities of the PAb and the MAb for the FlaA1 and FlaB proteins of Serpulina species were confirmed by N-terminal amino acid sequencing of 44- and 37-kDa proteins, respectively, of S. hyodysenteriae and S. pilosicoli. Results from this study provide further evidence that the 44-kDa protein FlaA1 and the 37-, 34-, and 32-kDa FlaB proteins are conserved among porcine Serpulina species.     

The effect of the length of a malarial epitope on its antigenicity and immunogenicity in an epitope presentation system using the Pseudomonas aeruginosa outer membrane protein OprF as the carrier

The phenotypic characteristics of three Serpulina pilosicoli strains isolated from humans with diarrhoea (WesB, Kar, Hrm7) and two porcine S. pilosicoli strains isolated from pigs with intestinal spirochaetosis (1648, 3295), were compared with the type strain of the species P43/6/78T (T = type strain) and other intestinal spirochaetes within the genus Serpulina. All S. pilosicoli strains had a characteristic ultrastructural appearance, displayed similar growth rates, hydrolysed hippurate, lacked beta-glucosidase activity, utilised D-ribose as a growth substrate, and had similar sensitivities to rifampicin and spiramycin. The only consistent phenotypic characteristic that differentiated human strains from porcine strains of S. pilosicoli was that the human strains all utilised the pentose sugar D-xylose. These distinguishing phenotypic traits appear useful for identifying S. pilosicoli.     

Bacteriophages induced from weakly beta-haemolytic human intestinal spirochaetes by mitomycin C

A comparative electron microscopic analysis of weakly beta-haemolytic spirochaetes related to human and animal intestinal spirochaetosis was done in order to search for the presence of inducible bacteriophages associated with these spirochaetes. Bacteriophages were detected at the electron microscope after experimental induction with mitomycin C in 4 strains of weakly beta-haemolytic spirochaetes related to human intestinal spirochaetosis, in Serpulina pilosicoli strain P43/6/78, the causative agent of swine intestinal spirochaetosis, in a spirochaetal strain related to avian intestinal spirochaetosis, and in Serpulina hyodysenteriae, strain P18A, the causative agent of swine dysentery, which was comparatively analysed as control. All phage-particles observed in both human and animal intestinal spirochaetes were morphologically similar with an isometric head of 45 nm diameter and a tail 63-70 nm long and 7-12 nm width. The presence of morphologically similar phages in all the haemolytic intestinal spirochaetes of human and animal origin analysed in this study opens some important questions, about the genetic relationship of phages present in pathogenic intestinal spirochaetes, their host range, and the possibility of natural gene transfer among pathogenic haemolytic intestinal spirochaetes of human and animal origin.     

Genetic and phenotypic characterization of intestinal spirochetes colonizing chickens and allocation of known pathogenic isolates to three distinct genetic groups

Infection with intestinal spirochetes has recently been recognized as a cause of lost production in the poultry industry. Little is known about these organisms, so a collection of 56 isolates originating from chickens in commercial flocks in Australia, the United States, The Netherlands, and the United Kingdom was examined. Strength of beta-hemolysis on blood agar, indole production, API ZYM enzyme profiles, and cellular morphology were determined, and multilocus enzyme electrophoresis was used to analyze the extent of genetic diversity among the isolates. The results were compared with those previously obtained for well-characterized porcine intestinal spirochetes. The chicken isolates were genetically heterogeneous. They were divided into 40 electrophoretic types distributed among six diverse genetic groups (groups b to g), with a mean genetic diversity of 0.587. Strains in two groups (groups d and e) may represent new species of Serpulina, and the groups contained only strains isolated from chickens. Three genetic groups contained isolates previously shown to be pathogenic for chickens. These corresponded to the proposed species "Serpulina intermedius," to an unnamed group (group e), and to Serpulina pilosicoli. Two of the chicken isolates (one "S. intermedius" and one S. pilosicoli isolate) were strongly beta-hemolytic, two (both "S. intermedius") had an intermediate level of beta-hemolysis, and the rest were weakly beta-hemolytic. Fourteen isolates of "S. intermedius" produced indole, as did one isolate from group d. Isolates identified as S. pilosicoli resembled porcine isolates of this species, having four to six periplasmic flagella inserted subterminally in a single row at each end of the cell, and had tapered cell ends. All other spirochetes were morphologically similar, having seven or more periplasmic flagella and blunt cell ends. The identification of three genetic groups containing pathogenic isolates provides an opportunity for more detailed epidemiologic studies with these pathogens and for the development of improved diagnostic tests.     

Competing conceptions of diagnostic reasoning--is there a way out?

A polymerase chain reaction (PCR) was optimized to detect Lawsonia intracellularis in faeces from naturally infected pigs. By combining a boiling procedure to extract DNA and a nested PCR procedure, a detection limit at 2 x 10(2) bacterial cells per gram of faeces was achieved. The optimized PCR was used together with conventional culture techniques to detect Serpulina hyodysenteriae, weakly beta-haemolytic intestinal spirochaetes (WBHIS), Salmonella enterica, and haemolytic Escherichia coli, in a case control study to examine selected risk factors for the development of diarrhoea in growing pigs. Herds with diarrhoea were selected as cases and randomly chosen herds without diarrhoea were chosen as controls. Infection with L. intracellularis significantly enhanced the chance of diarrhoea. S. hyodysenteriae, WBHIS group IV (Serpulina pilosicoli), and S. enterica were isolated only from case herds which indicate that these species may influence the development of diarrhoea. In addition, herd-type had a significant impact, that is specific pathogen-free herds showed an odds ratio at 0.2 relative to conventional herds for the development of diarrhoea.     

Dual flaA1 flaB1 mutant of Serpulina hyodysenteriae expressing periplasmic flagella is severely attenuated in a murine model of swine dysentery

The motility imparted by the periplasmic flagella (PF) of Serpulina hyodysenteriae is thought to play a pivotal role in the enteropathogenicity of this spirochete. The complex PF are composed of multiple class A and class B polypeptides. Isogenic strains containing specifically disrupted flaAl or flaB1 alleles remain capable of expressing PF, although such mutants display aberrant motility in vitro. To further examine the role that these proteins play in the maintenance of periplasmic flagellar structural integrity, motility, and fitness for intestinal colonization, we constructed a novel strain of S. hyodysenteriae which is deficient in both FlaA1 and FlaB1. To facilitate construction of this strain, a chloramphenicol gene cassette, with general application as a selectable marker in prokaryotes, was developed. The cloned flaAl and flaB1 genes were disrupted by replacement of internal fragments with chloramphenicol and kanamycin gene cassettes, respectively. The inactivated flagellar genes were introduced into S. hyodysenteriae, and allelic exchange at the targeted chromosomal flaA1 and flaB1 loci was verified by PCR analysis. Immunoblots or cell lysates with antiserum raised against purified FlaA or FlaB confirmed the absence of the corresponding sheath and core proteins in this dual flagellar mutant. These mutations selectively abolished the expression of the targeted genes without affecting the synthesis of other immunologically related FlaB proteins. The resulting flaA1 flaB1 mutant exhibited altered motility in vitro. Surprisingly, it was capable of assembling periplasmic flagella that were morphologically normal as evidenced by electron microscopy. The virulence of this strain was assessed in a murine model of swine dysentery by determining the incidence of cecal lesions and the persistence of S. hyodysenteriae in the gut. Mice challenged with the wild-type strain or a passage control strain showed a dose-related response to the challenge organism. The dual flagellar mutant was severely attenuated in murine challenge experiments, suggesting that the FlaA1 and FlaB1 proteins are dispensable for flagellar assembly but critical for normal flagellar function and colonization of mucosal surfaces of the gastrointestinal tract. This strain represents the first spirochete engineered to contain specifically defined mutations in more than one genetic locus.     

Identification and characterization of genus-specific epitopes of Serpulina species using monoclonal antibodies

Four murine monoclonal antibodies (mAbs) designated as C9E8, A10, G12, and G8 which recognized both Serpulina hyodysenteriae and S. innocens were produced and characterized. The mAbs reacted with whole cell antigens in ELISA, indirect immunofluorescence and immunoblot assays. The mAbs did not show any cross reactivity in rapid dot ELISA or immunoblot assay with Leptospira icterohemorrhagiae, Campylobacter jejuni and Escherichia coli. Treatment of whole cell suspension with proteinase K and sodium periodate indicated that the reacting epitopes of the mAbs were protein in nature. The genus-specific antigens were identified as heat-stable proteins with molecular weight in the range of 26 to 45 kDa. Immunofluorescence and immunogold labelling studies showed that the antibody-binding epitopes were exposed on the outer-surface of the spirochaetal cell wall. The mAbs inhibited growth of reference strains of both S. hyodysenteriae and S. innocens in vitro but failed to cause agglutination. The detection of spirochaetal forms directly in fecal smears or paraffin-embeded tissue sections from experimentally infected pigs indicated that such mAbs were potentially useful for the diagnosis of swine spirochaetosis. This is the first report of mAbs identifying and characterizing common antigens of porcine Serpulina.     

Prophylactic effect of dietary zinc in a laboratory mouse model of swine dysentery

Reduced prevalence of diarrhea and mortality has been reported after dietary supplementation with zinc compounds in swine with naturally acquired colibacillosis and those challenge-exposed with Serpulina hyodysenteriae; however, the usefulness of this approach for control of enteric diseases of swine remains to be determined. To examine the effect of dietary zinc-containing compounds on the colonization and development of cecal lesions associated with S hyodysenteriae infection, a defined diet alone or with added ZnO, ZnSO4, or Zn-methionine complex to a final concentration of approximately 6,000 mg of Zn2+/kg of complete feed was fed ad libitum to 156 female mice (strain C3H/HeN) for 10 days prior to oral inoculation either with S hyodysenteriae or sterile trypticase soy broth. Rations were continued for 42 days, while at weekly intervals, 3 mice/group were necropsied for determination of body weight, cecal weight, liver zinc concentration, presence of S hyodysenteriae in the cecum, and gross and histologic assessments of cecal lesions. From postinoculation day 0 to 42, the liver zinc concentration of mice fed the zinc-supplemented diets was approximately twice that of mice fed the basal diet, irrespective of the source of zinc. From postinoculation day 7 through 42, the overall recovery rate of S hyodysenteriae in infected mice fed the basal diet was 77.8%. In contrast, recovery rates of S hyodysenteriae from S hyodysenteriae-inoculated mice fed the zinc-supplemented diets were 0% for Zn-methionine and ZnO and 16.7% for ZnSO4. Mice fed the basal diet had significantly (P < 0.05) higher weight gain than mice fed the zinc-supplemented diets.(ABSTRACT TRUNCATED AT 250 WORDS)     

Search for bacteriophages spontaneously occurring in cultures of haemolytic intestinal spirochaetes of human and animal origin

An electron microscopic survey of the occurrence of bacteriophages which appear spontaneously in cultures of haemolytic intestinal spirochaetes of human and animal origin was made. Excluding one isometric tailed phage particle which was observed in the form of free particle in proximity to a spirochaete of the w beta HIS strain HRM18, bacteriophages were never observed while examining cells of 21 weakly beta-haemolytic human intestinal spirochaetes (w beta HIS), swine Serpulina pilosicoli strain P43/6/78, and the avian strain 1380, although 50-100 cells of each spirochaetal strain were analysed. Isometric tailed bacteriophages were found associated with only three out of the 100 cells of strongly beta-haemolytic swine Serpulina hyodysenteriae strain P18A comparatively analysed. According to our results and previous published reports, the occurrence of bacteriophages which appear spontaneously in cultures of intestinal spirochaetes is a rare event.     

Changes in bacterial populations in the colon of pigs fed different sources of dietary fibre, and the development of swine dysentery after experimental infection

Swine dysentery (SD) is a disease which can be controlled by feeding a diet low in dietary fibre. The influence of source and inclusion level of dietary fibre both on bacterial populations in the colon, and on subsequent development of SD in pigs experimentally infected with Serpulina hyodysenteriae was evaluated. In Experiment 1, pigs were fed a low-fibre diet based on cooked rice and a animal protein supplement, or the same diet containing added insoluble (iNSP, fed as oaten chaff) or soluble (sNSP, fed as guar gum) non-starch polysaccharides, resistant starch (RS), or a combination of the last two (sNSP/RS). In Experiment 2, different levels of RS were added to the diet. With the base rice diet and with the addition of iNSP, the total number of colonic bacteria was low, the Gram-positive population predominated, S. hyodysenteriae did not colonize and SD did not develop. Synergistic bacteria (Fusobacterium necrophorum and Fus. nucleatum), which have been reported to facilitate colonization by S. hyodysenteriae, were found only among isolates from pigs fed the sNSP/RS diet, and these animals developed SD. Addition of RS to the diet increased total bacterial counts and stimulated growth of Gram-negative bacteria in the colon. In Experiment 1, this permitted colonization by S. hyodysenteriae, but not expression of SD. In contrast, in Experiment 2, this level of inclusion and two others allowed both colonization and development of SD. In conclusion, the addition of sNSP and/or RS to an otherwise protective rice-based diet generated changes in the large intestine microbiota which might have some influence on proliferation of S. hyodysenteriae and the development of SD.     

Acetogenesis from H2 plus CO2 by spirochetes from termite guts

Pure cultures of termite gut spirochetes were obtained and were shown to catalyze the synthesis of acetate from H2 plus CO2. The 16S ribosomal DNA sequences of two strains were 98 percent similar and were affiliated with those of the genus Treponema. However, neither was closely related to any known treponeme. These findings imply an important role for spirochetes in termite nutrition, help to reconcile the dominance of acetogenesis over methanogenesis as an H2 sink in termite hindguts, suggest that the motility of termite gut protozoa by means of attached spirochetes may be based on interspecies H2 transfer, and underscore the importance of termites as a rich reservoir of novel microbial diversity.     

The phylogeny of unicellular, extremely halotolerant cyanobacteria

We examined the morphology, physiology, and 16S rRNA gene sequences of three culture collection strains and of ten novel isolates of unicellular cyanobacteria from hypersaline environments. The strains were morphologically diverse, with average cell widths ranging from 2.8 to 10.3 micron. There were single-celled, colonial, and baeocyte-forming strains. However, morphological traits were markedly variable with culture conditions. In contrast, all strains displayed extreme halotolerance (growing close to optimally at above 12% salinity); all were obligately marine, euryhaline, and moderately thermophilic; and all shared a suite of chemotaxonomic markers including phycobilins, carotenoids, and mycosporine-like amino acids. 16S rRNA gene sequence analysis indicated that the strains were related to each other. Sequence similarity analysis placed the strains in a monophyletic cluster (which we named the Halothece cluster) apart from all cultured or uncultured, not extremely halotolerant cyanobacteria whose 16S rRNA gene sequences are available in public nucleotide sequence databases. This represents the first case in which a phylogenetically coherent group of cyanobacteria can be defined on the basis of physiology. The Halothece cluster contained two subclusters that may be divergent at the generic level, one encompassing 12 strains (spanning 5% 16S rRNA gene sequence divergence and named the Euhalothece subcluster), and a single deep-branching isolate. Phenotypic characterization of the isolates, including morphological, physiological, and chemotaxonomic traits, did not distinguish these subclusters and only weakly suggested the existence of two separate clades, one encompassing strains of small cell size (cell width < 5 m) and another one encompassing strains of larger cell size.     

The use of 16S rRNA-targeted oligonucleotide probes to study competition between ruminal fibrolytic bacteria: development of probes for Ruminococcus species and evidence for bacteriocin production

A total of six oligonucleotide probes, complementary to the 16S rRNA, were evaluated for quantitative and determinative studies of Ruminococcus albus and Ruminococcus flavefaciens. On the basis of specificity studies, probes for R. albus (probe RAL196) and R. flavefaciens (probe RFL196) were selected to quantitate these species in mixed culture. In combination with a Fibrobacter succinogenes S85 subspecies probe (SUB1) and a domain Bacteria (formerly kingdom Eubacteria) probe (EUB338), they were used to quantitate these species competing in mixed cultures for cellobiose as the carbon source. In dicultures containing R. albus 8 and F. succinogenes S85, competition was not observed. However, R. flavefaciens FD-1 eventually outcompeted F. succinogenes S85 when cellobiose was the substrate. When R. albus 8 and R. flavefaciens FD-1 were grown together on cellobiose medium, R. albus 8 outcompeted R. flavefaciens FD-1, resulting in undetectable R. flavefaciens 16S rRNA only 1 to 3 h after inoculation, suggesting production of an antagonistic compound by R. albus 8 during rapid growth on soluble substrates. Further, when R. albus 8, R. flavefaciens FD-1, and F. succinogenes S85 were grown together in a triculture, R. flavefaciens FD-1 16S rRNA was detectable for only 2 h after inoculation, while R. albus 8 and F. succinogenes S85 showed a similar competition pattern to that of the dicultures. The results show that the Ruminococcus probes were effective in the measurement of relative populations of selected R. albus and R. flavefaciens strains during in vitro competition studies with F. succinogenes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Inelastic x-ray scattering from TiC and Ti single crystals

During a study of microbial communities in athalassic bodies of water, three new species within the genus Spirochaeta were described. These are alkaliphilic Spirochaeta alkalica sp. nov. Z-7491 (DSM 8900) and halophilic S. africana sp. nov. Z-7692 (DSM 8902) from the soda-depositing Lake Magadi in Central Africa and haloalkaliphilic S. asiatica sp. nov. Z-7591 (DSM 8901) from Lake Khatyn, Central Asia. These mesophilic spirochetes develop at pHs of > 9 as anaerobic saccharolytic dissipotrophs. The DNA base compositions (moles percent G+C) of the strains were as follows: S. alkalica Z-7491, 57.1; S. africana Z-7692, 56.1; and S. asiatica Z-7591, 49.2. The optimum growth parameters (temperature, pH, and NaCl concentration [percent, wt/vol], respectively) were as follows: for S. alkalica Z-7491, 35 degrees C, 9.2, and 5 to 7%; for S. africana Z-7692, 35 degrees C, 9.3, and 5 to 7%; and for S. asiatica Z-7591, 35 degrees C, 8.9, and 3 to 6%. The products of glucose fermentation were acetate, hydrogen, ethanol, and lactate, in different proportions, for S. alkalica and S. africana; for S. asiatica, they were acetate, ethanol, and lactate. S. asiatica is strictly anaerobic, while S. alkalica and S. africana are rather aerotolerant. All three species group within the radiation of the majority of the species of the genus Spirochaeta. Studies of the genes encoding 16S rRNA indicate a possible fanning out of the phylogenetic tree of spirochetes.