Differentiation of Campylobacter coli and C. jejuni by length and DNA sequence of the 16S-23S rRNA internal spacer region.
(17/3473)
The internal spacer region (ISR) between the 16S and 23S rRNA genes of Campylobacter was investigated by PCR fragment length typing and DNA sequencing of clinical and chicken wild-type isolates. PCR fragment length typing showed one fragment of 859 nt in length for the 12 strains of Campylobacter coli investigated. Thirty-six of the Campylobacter jejuni subsp. jejuni strains possessed one fragment, which varied in size between 727 and 802 nt. Three strains showed two fragments between 501 and 923 nt. Strains of C. jejuni subsp. doylei, Campylobacter lari and Campylobacter upsaliensis possessed one or two fragments with lengths different from those of C. coli and C. jejuni subsp. jejuni. DNA sequences were obtained from 54 nt downstream of rrs up to rrl of four strains of C. coli, eight strains of C. jejuni subsp. jejuni, and one strain each of C. jejuni subsp. doylei and C. lari, selected to represent the different biotypes of Campylobacter. ISR lengths determined by PCR fragment length typing and DNA sequencing corresponded for 12 strains. For two strains of C. coli, PCR fragment length typing underestimated ISR lengths by 159 and 193 nt, probably related to incomplete resolution of the distal helical structures, which were not fully denatured during PAGE. For the 14 strains and the published C. jejuni subsp. jejuni sequence, the first 206-211 nt were conserved and included the two tRNA genes in the characteristic tRNA(Ala) to tRNA(Ile) order separated by a short 8-9 nt spacer region. Within the region downstream of tRNA(Ile) conserved regions were identified which allowed a separation of C. lari from C. coli and C. jejuni but not separation of C. coli from C. jejuni. The 69-282 nt longer variable regions in C. coli strains allowed separation of this species from C. jejuni, confirming results obtained by PCR typing. Certain nucleic acid positions in variable regions were related to the Lior biotypes. Sequence information from ISRs of more strains is needed to ascertain if separation of species and biotypes will be possible for diagnostic purposes. (+info)
Structure and organization of the rrnD operon of 'Brevibacterium lactofermentum': analysis of the 16S rRNA gene.
(18/3473)
Five rRNA operons (rrn) were found by hybridization in the genome of 'Brevibacterium lactofermentum' ATCC 13869 and Corynebacterium glutamicum ATCC 13032. 'B. lactofermentum' DSM 20412 differed from the other corynebacteria tested in showing six hybridizing BamHI bands. Two of the rrn operons (rrnD and rrnE) were located in a single cosmid. Sequencing of the rrnD operon showed that it contains a complete 16S rRNA-23S RNA-5S rRNA gene cluster. Phylogenetic studies using the complete 16S rRNA sequence showed that 'B. lactofermentum' is closely related to several species of the genus Corynebacterium but only distantly related to the type species Brevibacterium linens and the authors suggest that it should be reclassified as Corynebacterium lactofermentum. The 5' end of mature 16S rRNA was identified by primer extension. Sequence elements similar to those of mycobacteria implicated in transcription antitermination (Boxes A, B, C) and in processing of the pre-rRNA to 16S rRNA were identified. An open reading frame encoding an rpoD-like sigma factor (named SigC) different from the previously reported SigA and SigB proteins was found upstream of rrnD in the opposite orientation. Both rpoD and sigC seem to be expressed from a bidirectional promoter region. (+info)
Desulfobacca acetoxidans gen. nov., sp. nov., a novel acetate-degrading sulfate reducer isolated from sulfidogenic granular sludge.
(19/3473)
A mesophilic sulfate reducer, strain ASRB2T, was isolated with acetate as sole carbon and energy source from granular sludge of a laboratory-scale upflow anaerobic sludge bed reactor fed with acetate and sulfate. The bacterium was oval-shaped, 1.3 x 1.9-2.2 microns, non-motile and Gram-negative. Optimum growth with acetate occurred around 37 degrees C in freshwater medium (doubling time: 1.7-2.2 d). Enzyme studies indicated that acetate was oxidized via the carbon monoxide dehydrogenase pathway. Growth was not supported by other organic acids, such as propionate, butyrate or lactate, alcohols such as ethanol or propanol, and hydrogen or formate. Sulfite and thiosulfate were also used as electron acceptors, but sulfur and nitrate were not reduced. Phylogenetically, strain ASRB2T clustered with the delta subclass of the Proteobacteria. Its closest relatives were Desulfosarcina variabilis, Desulfacinum infernum and Syntrophus buswellii. Strain ASRB2T is described as the type strain of Desulfobacca acetoxidans gen. nov., sp. nov. (+info)
Thermococcus barophilus sp. nov., a new barophilic and hyperthermophilic archaeon isolated under high hydrostatic pressure from a deep-sea hydrothermal vent.
(20/3473)
A novel barophilic, hyperthermophilic, anaerobic sulfur-metabolizing archaeon, strain MPT (T = type strain), was isolated from a hydrothermal vent site (Snakepit) on the Mid-Atlantic Ridge (depth, 3550 m). Enrichments and isolation were done under 40 MPa hydrostatic pressure at 95 degrees C. Strain MPT was barophilic at 75, 80, 85, 90, 95 and 98 degrees C, and was an obligate barophile between 95 and 100 degrees C (Tmax). For growth above 95 degrees C, a pressure of 15.0-17.5 MPa was required. The strain grew at 48-95 degrees C under atmospheric pressure. The optimal temperature for growth was 85 degrees C at both high (40 MPa) and low (0.3 MPa) pressures. The growth rate was twofold higher at 85 degrees C under in situ hydrostatic pressure compared to at low pressure. Strain MPT cells were motile, coccoid, 0.8-2.0 microns in diameter and covered by a hexagonal S-layer lattice. The optimum pH and NaCl concentration for growth at low pressure were 7.0 and 20-30 g l-1, respectively. The new isolate was an obligate heterotroph and utilized yeast extract, beef extract and peptone for growth. Growth was optimal in the presence of elemental sulfur. Rifampicin and chloramphenicol inhibited growth. The core lipids consisted of a major archaeol and a complex lipid pattern consisting of a major phospholipid. The DNA G + C content was 37.1 mol%. Sequencing of the 16S rRNA gene revealed that strain MPT belonged to the genus Thermococcus and it is proposed that this isolate should be designated as a new species, Thermococcus barophilus. (+info)
Corynebacterium sundsvallense sp. nov., from human clinical specimens.
(21/3473)
Three strains of a previously undescribed catalase-positive non-lipophilic coryneform bacterium isolated from human clinical specimens were characterized by phenotypic and molecular taxonomic methods. Morphologically the unknown bacterium consisted of pleomorphic rods, some of which displayed bulges/knobs at their ends. All three strains were similar in that they produced acid from fructose, glucose, maltose and sucrose and were urease-positive. Chemotaxonomic investigations revealed the presence of meso-diaminopimelic acid and short-chain mycolic acids consistent with the genus Corynebacterium sensu stricto. Comparative 16S rRNA gene sequencing showed that the three strains are genealogically highly related and constitute a new subline within the genus Corynebacterium, displaying > 3% sequence divergence with recognized species. The unknown bacterium was distinguished from currently validly published Corynebacterium species by phenotypic tests, including electrophoretic analysis of whole-cell proteins. Based on phylogenetic and phenotypic evidence, it is proposed that the unknown bacterium from clinical specimens be classified as Corynebacterium sundsvallense sp. nov. The type strain is CCUG 36622T. (+info)
Marinobacter aquaeolei sp. nov., a halophilic bacterium isolated from a Vietnamese oil-producing well.
(22/3473)
Several strains of moderately halophilic and mesophilic bacteria were isolated at the head of an oil-producing well on an offshore platform in southern Vietnam. Cells were Gram-negative, non-spore-forming, rod-shaped and motile by means of a polar flagellum. Growth occurred at NaCl concentrations between 0 and 20%; the optimum was 5% NaCl. One strain, which was designated VT8T, could degrade n-hexadecane, pristane and some crude oil components. It grew anaerobically in the presence of nitrate on succinate, citrate or acetate, but not on glucose. Several organic acids and amino acids were utilized as sole carbon and energy sources. The major components of its cellular fatty acids were C12:0 3-OH, C16:1, omega 9c, C16:0 and C18:1 omega 9c. The DNA G + C content was 55.7 mol%. 16S rDNA sequence analysis indicated that strain VT8T was closely related to Marinobacter sp. strain CAB (99.8% similarity) and Marinobaster hydrocarbonoclasticus (99.4% similarity). Its antibiotic resistance, isoprenoid quinones and fatty acids were similar to those of Marinobacter hydrocarbonoclasticus and Pseudomonas nautica. However, the whole-cell protein pattern of VT8T differed from that of other halophilic marine isolates, including P. nautica. DNA-DNA hybridization indicated that the level of relatedness to Marinobacter hydrocarbonoclasticus was 65% and that to P. nautica was 75%. Further differences were apparent in Fourier-transformed IR spectra of cells and lipopolysaccharide composition. It is proposed that VT8T should be the type strain of a new species and should be named Marinobacter aquaeolei. P. nautica may have been misclassified, as suggested previously, and may also belong to the genus Marinobacter. (+info)
Reclassification of non-pigmented Erwinia herbicola strains from trees as Erwinia billingiae sp. nov.
(23/3473)
Twenty-two Erwinia-like strains, isolated from trees since the late fifties and belonging to a distinct phenotypic group with resemblance to Pantoea agglomerans, were further characterized by conventional biochemical tests, the BIOLOG metabolic fingerprinting system and fatty acid analysis. Their phylogenetic positions were determined by comparing the 16S rRNA gene sequence of a representative strain to available sequences of Erwinia, Pantoea, Pectobacterium and Brenneria species. The strains were shown to belong to the genus Erwinia, with Erwinia rhapontici and Erwinia persicina as the closest phylogenetic relatives. The name Erwinia billingiae sp. nov. is proposed (type strain LMG 2613T) and a description of the species is given. (+info)
Thiomicrospira kuenenii sp. nov. and Thiomicrospira frisia sp. nov., two mesophilic obligately chemolithoautotrophic sulfur-oxidizing bacteria isolated from an intertidal mud flat.
(24/3473)
Two new members of the genus Thiomicrospira were isolated from an intertidal mud flat sample with thiosulfate as the electron donor and CO2 as carbon source. On the basis of differences in genotypic and phenotypic characteristics, it is proposed that strain JB-A1T (= DSM 12350T) and strain JB-A2T (= DSM 12351T) are members of two new species, Thiomicrospira kuenenii and Thiomicrospira frisia, respectively. The cells were Gram-negative vibrios or slightly bent rods. Strain JB-A1T was highly motile, whereas strain JB-A2T showed a much lower degree of motility combined with a strong tendency to form aggregates. Both organisms were obligately autotrophic and strictly aerobic. Nitrate was not used as electron acceptor. Chemolithoautotrophic growth was observed with thiosulfate, tetrathionate, sulfur and sulfide. Neither isolate was able to grow heterotrophically. For strain JB-A1T, growth was observed between pH values of 4.0 and 7.5 with an optimum at pH 6.0, whereas for strain JB-A2T, growth was observed between pH 4.2 and 8.5 with an optimum at pH 6.5. The temperature limits for growth were between 3.5 and 42 degrees C and 3.5 and 39 degrees C, respectively. The optimum growth temperature for strain JB-A1T was between 29 and 33.5 degrees C, whereas strain JB-A2T showed optimal growth between 32 and 35 degrees C. The mean maximum growth rate on thiosulfate was 0.35 h-1 for strain JB-A1T and 0.45 h-1 for strain JB-A2T. (+info)