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PubMed2003

Antimicrobial resistance of Campylobacter jejuni and Campylobacter coli isolates from broiler chickens isolated at an Irish poultry processing plant.

AIMS: The antibiotic susceptibility of Campylobacter jejuni and Campylobacter coli isolates from broiler chickens were determined in order to evaluate the level of antibiotic resistance of Campylobacter species in the Irish poultry industry. METHODS AND RESULTS: Seventy-eight Camp. jejuni and 22 Camp. coli strains were examined for susceptibility to eight antibiotics using the disc diffusion assay. The highest level of resistance of the Camp. jejuni isolates was recorded to ampicillin (35.9%), followed by 20.5% to tetracycline, 20.5% to naladixic acid, 17.9% to ciprofloxacin, 10.2% to erythromycin, 2.5% to streptomycin and 1.2% to kanamycin. Multidrug resistance to two or more antibiotics was seen for 30.7% of Camp. jejuni strains. Resistance of the Camp. coli isolates was shown to ampicillin (9%) and tetracycline (18.2%). CONCLUSIONS: The majority of Camp. jejuni strains were susceptible to antibiotics commonly used for human therapy. Camp. coli strains showed very low resistance levels and were susceptible to six of the eight antimicrobial agents studied. SIGNIFICANCE AND IMPACT OF THE STUDY: Levels of Camp. jejuni and Camp. coli antimicrobial resistance in Irish poultry production was assessed to determine the current situation in Ireland. The prevalence of antibiotic resistance of Campylobacter strains isolated from broiler chickens was low.

Animals↗
PubMed1995

Mouse monoclonal antibodies to human immunodeficiency virus glycoprotein 120 generated by repeated immunization with glycoprotein 120 from a single isolate, or by sequential immunization with glycoprotein 120 from three isolates.

Mouse hybridomas were isolated that produce monoclonal antibodies (MAbs) to several regions of the HIV envelope, gp120, which may be used to map immunogenic regions in animal and human immunity. One series of MAbs was generated by repeated immunization with recombinant gp120 (rgp120) from a single isolate, and a second series by sequential immunization with rgp120 from three isolates. All MAbs bound to rgp120IIIB, but only one bound well to cell surface-expressed gp160. Synthetic peptides spanning much of the length of gp120 were used to map MAb reactivity. Two MAbs were mapped to the C1 region, one to the C2 region, and three to the C5 region by this approach. Six distinct epitopes were detected by competitive binding analysis. One MAb binding the C1 region blocks binding of CD4 to rgp120IIIB, binds by ELISA to rgp120MN (an isolate not used during immunization), and binds to cell surface-expressed gp160. These hybridomas will be made available to the scientific community through a hybridoma culture facility.

AIDS Vaccines↗
PubMed2003

Isolation, excystation and axenization of Giardia lamblia isolates: in vitro susceptibility to metronidazole and albendazole.

From 53 samples of human faeces containing Giardia lamblia cysts, 18 isolates were successfully excysted in vitro, and cultivated axenically in TYI-S-33 modified medium. The in vitro effects of metronidazole and albendazole on these isolates were evaluated by the trophozoite adherence inhibition method. The IC50 was between 2.4 and 11.5 micro M for metronidazole and 0.027 and 0.192 micro M for albendazole. These IC50 values were similar to those found for the ATCC 30888 and 30957 reference isolates. All isolates were susceptible to the antiparasitic drugs tested. These results suggest that resistance of G. lamblia to metronidazole and albendazole does not seem to be a significant problem in our population.

Albendazole↗
PubMed1996

Isolated acute occlusion of a large right ventricular branch of the right coronary artery following coronary balloon angioplasty. The only true 'model' to study ECG changes in acute, isolated right ventricular infarction.

An isolated right ventricular infarction occurs rarely and data on its electrocardiographic appearance and underlying angiographically proven cause are scarce. The electrocardiographic response of acute right ventricular ischaemia is often obscured by the coexisting forces of the ischaemic mass of the inferior wall of the left ventricle when the right coronary artery itself becomes occluded. Percutaneous transluminal coronary angioplasty of the right coronary artery may cause an isolated occlusion of a right ventricular branch. We encountered this phenomenon in nine patients. In all, it led to acute isolated right ventricular ischaemia with ST elevations in the right precordial leads (V1-V3, V3R and V4R) on the electrocardiogram. We conclude that the ECG pattern of pure right ventricular ischaemia can be seen when an isolated occlusion of a large right ventricular branch occurs, for example as a complication of percutaneous transluminal coronary angioplasty.

Aged↗
PubMed1999

Myocardial kinetics of 99m technetium-Q agents: studies in isolated cardiac myocyte, isolated perfused rat heart, and canine regional myocardial ischemia models.

OBJECTIVE: Based on reports of high cellular uptake and low plasma binding of nonreducible mixed ligand Tc(III) cations (Q complexes) and high linear uptake versus blood flow of 99mTc-Q3 in canine hearts, the authors hypothesized that the two Q complexes, 99mTc-Q63 and 99mTc-Q64, would have high cell uptake and better differentiation between ischemic and nonischemic myocardium compared with other 99mTc-based compounds. METHODS: Uptake and retention kinetics of 99mTc-Q63 and 99mTc-Q64 were measured in isolated rat cardiac myocytes, isolated perfused rat hearts, and intact canines and compared with previously reported Q-based compounds, a clinically available 99mTc perfusion agent (sestamibi), and 201Tl. RESULTS: Uptake of Q63, Q64, and sestamibi by isolated cardiac myocytes was similar. Maximum extraction (Emax) of Q64 by isolated perfused rat hearts was greatest among the 99mTc agents (P < 0.02), but net extraction (Enet) of Q64 was not different from Q63 or sestamibi 3 minutes after tracer injection. By 15 minutes, 201Tl Enet was lower than Q63, Q64, and sestamibi (P < 0.05). Among 99mTc agents, the uptake versus flow of Q3, Q63, and Q64 by canine heart was superior to Q12 and sestamibi (P < 0.05). CONCLUSIONS: The activity of Q63 and Q64 in the myocardium is related to actual myocardial blood flow over a broad, clinically relevant range of flows. The ischemic-to-normal zone activity distributions of Q63 and Q64 approximate actual flow in a manner more like that of 201Tl than sestamibi or Q12. These results provide a rational foundation in support of further evaluation of Q63 and Q64 in humans.

Acute Disease↗
PubMed1991

Nucleotide sequence of the genomic RNA of hepatitis C virus isolated from a human carrier: comparison with reported isolates for conserved and divergent regions.

The complete nucleotide sequence of a hepatitis C virus derived from plasma of a human carrier in Japan was determined. The cDNA of the isolate (HC-J6) contained 9481 nucleotides and an additional T stretch of 30 to 108 nucleotides at the 3' end, and had one large open reading frame coding for a polyprotein of 3033 amino acids. It differed by 31.8 to 32.1% in the nucleotide sequence and by 27.4 to 27.7% in the amino acid sequence from an American isolate and two Japanese isolates previously reported. Among these four isolates, the 5' non-coding region of 329 to 341 nucleotides was well conserved (greater than 93% identity), whereas the 3' non-coding region of 39 to 45 nucleotides (T stretches not included) was more variable (greater than 30% identity). An excellent degree of conservation of the 5' non-coding region would reflect its pivotal role in replication, and primers deduced from this region could be applied for the sensitive and specific detection of viral RNA by polymerase chain reaction. Due to a high degree of similarity in the amino acid sequence of the putative core protein (greater than 90%), antigen probes deduced from it would be suitable for the serological diagnosis of HCV infection. Low sequence similarity in the putative envelope protein (greater than 53% identity), however, would have to be taken into account in considering the immunoprophylaxis of HCV infection.

Amino Acid Sequence↗
PubMed1992

A North American hypovirulent isolate of the chestnut blight fungus with European isolate-related dsRNA.

We have synthesized and mapped a cDNA library representing the one major dsRNA element associated with hypovirulence in strain NB58 of the chestnut blight fungus, Cryphonectira (=Endothia) parasitica, which was isolated from recovering chestnut trees in New Jersey, U.S.A. The linear dsRNA has a size of approximately 12.5 kbp and is polyadenylated at the 3' terminus of one strand. Molecular hybridization experiments indicate that there is sequence similarity between the NB58 dsRNA and dsRNAs from European isolates of C. parasitica, but not among dsRNAs of NB58 and those associated with other North American isolates. Hybridization experiments with mapped cDNA clones representing different regions of the 12.5 kbp dsRNA indicate that the termini and the 3'-proximal two-thirds (relative to the plus strand) are more conserved among NB58 and the European isolates than the rest of the 5'-proximal one-third. Nucleotide sequence analysis of the termini of NB58 dsRNA suggests common organizational features between it and the dsRNA from French-derived strain EP713.

Ascomycota↗
PubMed1996

Environmental gasoline-utilizing isolates and clinical isolates of Pseudomonas aeruginosa are taxonomically indistinguishable by chemotaxonomic and molecular techniques.

A total of 42 Pseudomonas aeruginosa strains was isolated previously from clinical sources (27 strains) and from a gasoline-contaminated aquifer (15 strains). Selected strains were subjected to taxonomic tests involving chemical and molecular biological techniques, including membrane fatty acid analysis, phage-sensitivity, growth temperature range, presence of plasmids, and PCR-amplification and sequencing of a species-specific 16S-23S rDNA internal transcribed spacer region. The clinical and environmental isolates formed a coherent taxonomic group with few distinguishing characteristics. Of the phenotypes observed, a consistent difference was the ability of the aquifer strains to utilize gasoline supplied in the gas phase as sole carbon source and, conversely, the inability of the clinical strains to do so. Fourteen of the 15 environmental strains possessed similar-sized cryptic plasmids. The clinical isolates either lacked detectable plasmids or contained plasmids of a different size. The observation that the clinical and environmental isolates of P. aeruginosa were taxonomically indistinguishable is discussed in terms of its relevance to environmental-regulatory guidelines because P. aeruginosa, a known opportunistic pathogen, is a prime candidate for use in bioremediation processes involving deliberate release of this organism to the environment.

Bacteriophages↗
PubMed1995

Ribosomal internal transcribed spacer sequences are identical among Mycobacterium avium-intracellulare complex isolates from AIDS patients, but vary among isolates from elderly pulmonary disease patients.

Sequencing 280 bp of the internal transcribed spacer (ITS) between the 16S and 23S rRNA genes in a collection of 46 clinical isolates of the Mycobacterium avium-intracellulare complex (MAI complex) identified nine different sequences, grouping these isolates in nine 'ITS sequevars'. This analysis extends the subdivision within the MAI complex to 18 ITS sequevars and also improves discrimination from other mycobacterial species. Evaluation of the sequevar grouping among different clinical sources revealed strong association of the M. avium sequevar Mav-B with AIDS and with lymphadenitis in children (18 out of 20 and 3 out of 3 respectively). Isolates from elderly patients with pulmonary disease and not suspected of being HIV infected belonged predominantly to M. intracellulare ITS sequevars and sequevars not assigned to either M. avium or M. intracellulare. On the other hand, animal isolates were of both the Mav-A and Mav-B sequevars. We conclude that ITS sequevar typing is an accurate way of identifying distinct MAI complex strains. The observed differences between clinical sources suggest that ITS sequevars reflect possibly important, biologically and clinically relevant polymorphisms between MAI complex organisms.

Acquired Immunodeficiency Syndrome↗
PubMed2004

Nocardia shimofusensis sp. nov., isolated from soil, and Nocardia higoensis sp. nov., isolated from a patient with lung nocardiosis in Japan.

Three actinomycete strains isolated from soils and one strain isolated from a patient with lung nocardiosis in 1999 and 2001 in Japan have been provisionally assigned to the genus Nocardia on the basis of morphological criteria. These isolates were further investigated to determine their specific taxonomic status. Detailed chemotaxonomic characterization and 16S rRNA gene sequence analysis of these isolates confirmed that they belong to the genus Nocardia. The 16S rRNA gene sequences of the four strains were most similar to that of Nocardia farcinica. However, the sequence similarity values between these four strains and N. farcinica were <98.9 %. These four strains were susceptible to 5-fluorouracil, and they have the ability to decompose urea, which is a very characteristic trait. Furthermore, DNA-DNA relatedness data revealed that IFM 10311(T), IFM 10312 and IFM 10313 comprise a single novel species of Nocardia, that IFM 10084(T) represents another novel species of Nocardia and that these two novel species could be distinguished from N. farcinica. The names Nocardia shimofusensis sp. nov. and Nocardia higoensis sp. nov. are proposed, with IFM 10311(T) (=NBRC 100134(T)=JCM 12122(T)=DSM 44733(T)) and IFM 10084(T) (=NBRC 100133(T)=JCM 12121(T)=DSM 44732(T)) as the respective type strains.

Aged↗
PubMed2004

Analysis of gyrA mutations in quinolone-resistant and -susceptible Campylobacter jejuni isolates from retail poultry and human clinical isolates by non-radioactive single-strand conformation polymorphism analysis and DNA sequencing.

AIMS: The aims of this study were to characterize the molecular variations in the quinolone resistance-determining region (QRDR) of gyrA among quinolone-resistant and -susceptible Campylobacter jejuni isolates originating from foods of animal origin and human infections and to evaluate the suitability of the single-strand conformation polymorphism (SSCP) method as a screening method for molecular characterization of fluoroquinolone resistance. METHODS AND RESULTS: Alterations in QRDR of gyrA from 182 C. jejuni isolates were determined by nonradioisotopic SSCP analysis and direct sequencing. A total of 13 types of nucleic acid sequence combinations within the QRDR of the gyrA gene resulted in 11 different SSCP patterns. All nalidixic acid resistant strains possessed nucleotide substitution at either codon Thr-86 or Asp-90. Silent mutations were detected additionally. Thr-86 to Ile mutation was detected in all 139 ciprofloxacin resistant strains, which showed cross-resistance to nalidixic acid. CONCLUSIONS: The SSCP method is suitable for a molecular screening of quinolone resistant C. jejuni isolates and in combination with DNA sequencing suitable to detect genetic variations of the QRDR of gyrA. SIGNIFICANCE AND IMPACT OF STUDY: This study provides data of the genetic variations of the QRDR of gyrA from C. jejuni isolates of foods and human beings.

Animals↗
PubMed1991

A one-step procedure for isolation of poly(A)+ mRNA from isolated brain capillaries and endothelial cells in culture.

The study of the regulation of low-abundance blood-brain barrier (BBB) transcripts either in isolated brain microvessels or in endothelial cells in tissue culture (ECL cells) requires isolation of poly(A)+ mRNA. Therefore, we describe here a single-step method for isolation of poly(A)+ mRNA from brain capillaries or ECL cells using proteinase K/sodium dodecyl sulfate cell lysis and oligo-deoxythymidine cellulose affinity chromatography. The yield of poly(A)+ mRNA was approximately 15-19 micrograms/g of brain or choroid plexus, 14-17 micrograms per batch of isolated capillaries in a single bovine forebrain (190 g), and 6-12 micrograms/10(7) ECL cells. Northern blot analysis showed characteristic and undegraded 2.1- and 1.7-kb actin transcripts in brain capillaries and a 2.1-kb actin mRNA in brain and ECL cells. Northern analysis was also used to quantify the glucose transporter type I transcript, which is very rare in basal ECL cells, and this mRNA was shown to be up-regulated by glucose deprivation. This method represents a significant improvement in the mRNA yield for brain capillaries or cultured endothelial cells compared with the conventional two-step method.

Animals↗
PubMed1986

Effects of Bay K 8644 on contraction of the human isolated bronchus and guinea-pig isolated trachea.

The effects of Bay K 8644, a dihydropyridine which increases calcium flux through the potential-operated channels were studied on the contractions induced by histamine, acetylcholine, KCl and Ca2+ on human isolated bronchial strips and the results were compared to those obtained on guinea-pig isolated tracheal spirals. Subsequently the contractant effects of Bay K 8644 in K+-enriched medium and in the presence of Ca2+ 0.03 mM were investigated. In Krebs normal calcium medium, Bay K 8644 did not significantly modify the EC50 of acetylcholine or histamine on the human bronchus, but in concentrations of 10(-7)-10(-6)M it potentiated the effects of KCl on that preparation. It did not modify the EC50 of acetylcholine, histamine or KCl on the guinea-pig trachea. In Ca2+-free Krebs medium with additional K+ (30 mM), Ca2+ concentration-response curves were displaced to the left by Bay K 8644 in the two preparations. Shifts were 0.52 +/- 0.11 and 0.72 +/- 0.16 log units respectively with Bay K 8644 10(-8) and 10(-7) M on human bronchus (n = 4) and 0.67 +/- 0.16 and 1.06 +/- 0.19 log units respectively with Bay K 8644 10(-7) and 10(-6) M on the guinea-pig trachea (n = 5). In Krebs medium with Ca2+ 0.03 mM and K+ 30 mM, Bay K 8644 (10(-8) to 10(-6) M) contracted both the human bronchus and the guinea-pig isolated trachea. This effect was competitively antagonized by nicardipine. 5 These results demonstrate the presence of dihydropyridine sites of action on human bronchus and confirm the minor role played by Ca2+ influx through potential-operated channels in the contractile effects of acetylcholine or histamine. They also demonstrate the similar reactivity of human bronchus and guinea-pig isolated trachea to Bay K 8644.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1993

Effect of molsidomine and linsidomine on the human isolated bronchus and the guinea-pig isolated trachea.

The effects of molsidomine and its metabolite linsidomine were studied on the guinea-pig isolated trachea and on the human isolated bronchus. These effects were compared with those of nitrate derivatives (sodium nitroprusside, isosorbide dinitrate), theophylline, zardaverine and isoprenaline. Linsidomine exerted a relaxant effect similar to that of sodium nitroprusside on the two types of preparations precontracted with acetylcholine, histamine or potassium chloride. Molsidomine was about one-hundredth as potent as linsidomine, and less efficacious. The effects of the two substances were not modified by removal of the human bronchial epithelium. The concentration-response curves of linsidomine and sodium nitroprusside were significantly shifted to the right by methylene blue (3 x 10(-5) M) but the effects of isoprenaline were unmodified. The effects of linsidomine and sodium nitroprusside were potentiated specifically by zaprinast (10(-6)-10(-5) M), an inhibitor of type Ia or V phosphodiesterases, whereas the effects of isoprenaline were potentiated by zardaverine (10(-9)-10(-8) M), an inhibitor of class III and IV phosphodiesterases. The effects of all three substances (linsidomine, isoprenaline and sodium nitroprusside) were potentiated equally by theophylline (10(-5)-10(-4) M), a nonspecific inhibitor of phosphodiesterases. It is concluded that linsidomine is a potent relaxant of the smooth muscle of the guinea-pig isolated trachea and human isolated bronchus. In terms of potency and efficacy, its effect is much superior to that of the parent compound molsidomine. It is suggested that linsidomine acts, like nitrate derivatives, through the guanylate cyclase-cGMP system.

Animals↗
PubMed2006

[Isolation rate and antifungal drug susceptibility of yeast like fungi isolated from blood or vascular catheter].

Increased resistance of strains to antifungal drugs has gained increasing attention. We studied the status of fungal isolation from blood and vascular catheters at Juntendo University Hospital from 1994 to 2002. The major fungi isolated were Candida albicans, Candida parapsilosis, Candida glabrata and Candida trophicalis, or 86% yeast-like fungi. Isolation of these fungi from vascular catheters is increasing. The effectiveness of 6 anti-fungal agents against 116 yeast-like fungi was measured by microdilution. In antifungal activity of micafungin (MCFG), MIC90, was < or = 0.03 g/mL for C. albicans, C. glabrata and C. tropicalis. MCFG showed the strongest antifungal activity among the drugs tested for above Candida spp.. Five of 37 strains of C. albicans were resistant to fluconazole (FLCZ) showing MIC > or =64 g/mL. These strains were also resistant to itraconazole (ITCZ) but MICs of MGFG, flurocytosine (5-FC) and amphotericin B (AMPH-B). Two of 38 strains of C. parapsilosis are resistant to flurocytosine (5-FC) showing MIC > or =64 g/mL. There is no resistant strain of fungi (yeast-like organisms) tested against AMPH-B. Six patients from whom resistant fungi were isolated from blood and vascular catheters have severe diseases and/or are have just undergone a major surgical operation. These results indicate that it is vital for deep mycosis to start early treatment with appropriate drugs selected based on rapid detection and identification of organisms and the drug susceptibility of organisms.

Antifungal Agents↗
PubMed2006

Comparison of four different culture media for isolation and growth of type II and type I/III Mycobacterium avium subsp. paratuberculosis strains isolated from cattle and goats.

Culture is considered the definitive technique for Johne's disease diagnosis, and it is essential for later applications of certain molecular typing techniques. In this study, we have tested four solid media (Herrold's egg yolk medium [HEYM] with sodium pyruvate and mycobactin [HEYMm-SP], HEYM with mycobactin and without sodium pyruvate [HEYMm], Middlebrook 7H11 with mycobactin [Mm], and Löwenstein-Jensen with mycobactin [LJm]) for isolation of Mycobacterium avium subsp. paratuberculosis strains in 319 tissue samples from cattle herds and goat flocks. We have shown that each of the two main groups of M. avium subsp. paratuberculosis (type II and type I/III) has different requirements for growth in the culture media studied. The recommended solid media for isolation of type I/III strains are LJm and Mm, since the combination of both media allowed the recovery of all these strains. The most widespread culture medium, HEYM, is not suitable for the isolation of this group of M. avium subsp. paratuberculosis strains. Regarding the type II strains, HEYMm-SP was the medium where more strains were isolated, but the other three media are also needed in order to recover all type II strains. The incubation period is also related to the strain type. In conclusion, because the type of strain cannot be known in advance of culture, coupled with the fact that cattle and goats can be infected with both groups of strains, we recommend the use of the four solid media and the prolongation of the incubation period to more than 6 months to detect paratuberculous herds/flocks and to determine the true prevalence of the infection.

Animals↗
PubMed2006

Longitudinal study of Finnish Campylobacter jejuni and C. coli isolates from humans, using multilocus sequence typing, including comparison with epidemiological data and isolates from poultry and cattle.

We describe a study on the application of multilocus sequence typing for the analysis of Campylobacter jejuni and C. coli isolates from human domestically acquired infections in the Helsinki-Uusimaa area of Finland in 1996, 2002, and 2003. In addition, isolates from poultry meat and fecal samples of cattle from the seasonal peak (July to September) in 2003 were included in the study. In total, 361 Finnish C. jejuni and C. coli strains were typed. Sequence type 45 (ST-45) (45%), ST-21 (21%), and ST-677 (11%) clonal complexes were the most prevalent. The ST-45 and ST-677 complexes were overrepresented in comparison with previous studies. The longitudinal study revealed an association between C. coli (ST-828 complex) infection and elderly patients (>/=60 years). Analysis of exposure factors, determined by a previous case-control study conducted during the seasonal peak in 2002, revealed that the ST-48 complex was significantly (P < 0.05) associated with the tasting or eating of raw minced meat. New and unassigned STs were associated with swimming in natural bodies of water, whereas the ST-677 complex was related to drinking nonchlorinated water from a small water plant or water from natural sources. The ST-45 complex was associated with contact with pet cats and dogs. In 2003, ST-45 occurrence was significantly associated with poultry whereas ST-50 was associated with isolates from humans. In contrast, ST-53, ST-58, ST-61, and ST-883 were significantly associated with isolates from cattle. Further studies are needed to reveal the significance of the observed associations.

Animals↗
PubMed1999

Isolation and characterization of Methanomethylovorans hollandica gen. nov., sp. nov., isolated from freshwater sediment, a methylotrophic methanogen able to grow on dimethyl sulfide and methanethiol.

A newly isolated methanogen, strain DMS1(T), is the first obligately anaerobic archaeon which was directly enriched and isolated from a freshwater sediment in defined minimal medium containing dimethyl sulfide (DMS) as the sole carbon and energy source. The use of a chemostat with a continuous DMS-containing gas stream as a method of enrichment, followed by cultivation in deep agar tubes, resulted in a pure culture. Since the only substrates utilized by strain DMS1(T) are methanol, methylamines, methanethiol (MT), and DMS, this organism is considered an obligately methylotrophic methanogen like most other DMS-degrading methanogens. Strain DMS1(T) differs from all other DMS-degrading methanogens, since it was isolated from a freshwater pond and requires NaCl concentrations (0 to 0.04 M) typical of the NaCl concentrations required by freshwater microorganisms for growth. DMS was degraded effectively only in a chemostat culture in the presence of low hydrogen sulfide and MT concentrations. Addition of MT or sulfide to the chemostat significantly decreased degradation of DMS. Transient accumulation of DMS in MT-amended cultures indicated that transfer of the first methyl group during DMS degradation is a reversible process. On the basis of its low level of homology with the most closely related methanogen, Methanococcoides burtonii (94.5%), its position on the phylogenetic tree, its morphology (which is different from that of members of the genera Methanolobus, Methanococcoides, and Methanohalophilus), and its salt tolerance and optimum (which are characteristic of freshwater bacteria), we propose that strain DMS1(T) is a representative of a novel genus. This isolate was named Methanomethylovorans hollandica. Analysis of DMS-amended sediment slurries with a fluorescence microscope revealed the presence of methanogens which were morphologically identical to M. hollandica, as described in this study. Considering its physiological properties, M. hollandica DMS1(T) is probably responsible for degradation of MT and DMS in freshwater sediments in situ. Due to the reversibility of the DMS conversion, methanogens like strain DMS1(T) can also be involved in the formation of DMS through methylation of MT. This phenomenon, which previously has been shown to occur in sediment slurries of freshwater origin, might affect the steady-state concentrations and, consequently, the total flux of DMS and MT in these systems.

Base Sequence↗