Katrien Vandemeulebroecke

Re-examination of the genus Acetobacter, with descriptions of Acetobacter cerevisiae sp. nov. and Acetobacter malorum sp. nov

Thirty-four Acetobacter strains, representing Acetobacter aceti, Acetobacter pasteurianus, Acetobacter pomorum, Acetobacter peroxydans, Acetobacter lovaniensis, Acetobacter estunensis, Acetobacter orleanensis, Acetobacter indonesiensis and Acetobacter tropicalis, were subjected to a polyphasic study that included DNA-DNA hybridizations, DNA base ratio determinations, 16S rDNA sequence analysis and phenotypic characterization. Two novel species are proposed, Acetobacter cerevisiae sp. nov. and Acetobacter malorum sp. nov. The type strains of these species are respectively LMG 1625T (= DSM 14362T = NCIB 8894T = ATCC 23765T) and LMG 1746T (= DSM 14337T).

Genomic diversity amongst Vibrio isolates from different sources determined by fluorescent amplified fragment length polymorphism.

The genomic diversity among 506 strains of the family Vibrionaceae was analysed using Fluorescent Amplified Fragments Length Polymorphisms (FAFLP). Isolates were from different sources (e.g. fish, mollusc, shrimp, rotifers, artemia, and their culture water) in different countries, mainly from the aquacultural environment. Clustering of the FAFLP band patterns resulted in 69 clusters. A majority of the actually known species of the family Vibrionaceae formed separate clusters. Certain species e.g. V. alginolyticus, V. cholerae, V. cincinnatiensis, V. diabolicus, V. diazotrophicus, V. harveyi, V. logei, V. natriegens, V. nereis, V. splendidus and V. tubiashii were found to be ubiquitous, whereas V. halioticoli, V. ichthyoenteri, V. pectenicida and V. wodanis appear to be exclusively associated with a particular host or geographical region. Three main categories of isolates could be distinguished: (1) isolates with genomes related (i.e. with > or =45% FAFLP pattern similarity) to one of the known type strains; (2) isolates clustering (> or =45% pattern similarity) with more than one type strain; (3) isolates with genomes unrelated (<45% pattern similarity) to any of the type strains. The latter group consisted of 236 isolates distributed in 31 clusters indicating that many culturable taxa of the Vibrionaceae remain as yet to be described.

Surface Microflora of Four Smear-Ripened Cheeses

ABSTRACT The microbial composition of smear-ripened cheeses is not very clear. A total of 194 bacterial isolates and 187 yeast isolates from the surfaces of four Irish farmhouse smear-ripened cheeses were identified at the midpoint of ripening using pulsed-field gel electrophoresis (PFGE), repetitive sequence-based PCR, and 16S rRNA gene sequencing for identifying and typing the bacteria and Fourier transform infrared spectroscopy and mitochondrial DNA restriction fragment length polymorphism (mtDNA RFLP) analysis for identifying and typing the yeast. The yeast microflora was very uniform, and Debaryomyces hansenii was the dominant species in the four cheeses. Yarrowia lipolytica was also isolated in low numbers from one cheese. The bacteria were highly diverse, and 14 different species, Corynebacterium casei, Corynebacterium variabile, Arthrobacter arilaitensis, Arthrobacter sp., Microbacterium gubbeenense, Agrococcus sp. nov., Brevibacterium linens, Staphylococcus epidermidis, Staphylococcus equorum, Staphylococcus saprophyticus, Micrococcus luteus, Halomonas venusta, Vibrio sp., and Bacillus sp., were identified on the four cheeses. Each cheese had a more or less unique microflora with four to nine species on its surface. However, two bacteria, C. casei and A. arilaitensis, were found on each cheese. Diversity at the strain level was also observed, based on the different PFGE patterns and mtDNA RFLP profiles of the dominant bacterial and yeast species. None of the ripening cultures deliberately inoculated onto the surface were reisolated from the cheeses. This study confirms the importance of the adventitious, resident microflora in the ripening of smear cheeses.

Sources of the adventitious microflora of a smear‐ripened cheese

Aims:  To determine the relationships between the major organisms from the cheese‐making personnel and environment and the surface of a smear cheese.

Phylogeny and Identification of Enterococci by atpA Gene Sequence Analysis

ABSTRACT The relatedness among 91 Enterococcus strains representing all validly described species was investigated by comparing a 1,102-bp fragment of atpA, the gene encoding the alpha subunit of ATP synthase. The relationships observed were in agreement with the phylogeny inferred from 16S rRNA gene sequence analysis. However, atpA gene sequences were much more discriminatory than 16S rRNA for species differentiation. All species were differentiated on the basis of atpA sequences with, at a maximum, 92% similarity. Six members of the Enterococcus faecium species group (E. faecium, E. hirae, E. durans, E. villorum, E. mundtii, and E. ratti) showed >99% 16S rRNA gene sequence similarity, but the highest value of atpA gene sequence similarity was only 89.9%. The intraspecies atpA sequence similarities for all species except E. faecium strains varied from 98.6 to 100%; the E. faecium strains had a lower atpA sequence similarity of 96.3%. Our data clearly show that atpA provides an alternative tool for the phylogenetic study and identification of enterococci.

Ability of biolog and biotype-100 systems to reveal the Taxonomic diversity of the pseudomonads

Summary A total of 224 strains of the genus Pseudomonas sensu lato were studied by 99 carbon source utilization tests using BioMerieux Biotype-100 strips and 96 substrate oxidation tests using the Biolog GN Micro Plate system. Biotype-100 and Biolog data were computer analyzed using programs of the Taxotron package (Institut Pasteur) and the Bionum software (Biolog), respectively. Unweighted pair group method of averages (UPGMA) yielded 34 Biotype phenons and 36 Biolog phenons. A total of 18 phenons had identical composition in both systems. Six phenons were almost identical in structure whereas some phenons in one system were lumped in the other system. Some species (represented by at least three strains) constituted homogeneous phenons in both Biotype-100 and Biolog systems: Pseudomonas aeruginosa, P. tolaasii, P. mendocina, P. cichorii, P. viridif lava, P. fragi, P. stutzeri, P. agarici, P. alcaligenes, and P. pseudoalcaligenes . None of the two systems could discriminate P. fuscovaginae from P. asplenii, and P caricapapayae from P corona f aciens. P. corrugata was a tight subphenon in both systems. Strains labeled P. f luorescens were found in six phenons with either Biotype-100 or Biolog systems. Strains of P. putida were found in three (Biolog) or four (Biotype) phenons. Strains of P marginalis were distributed over five phenons in both systems. The use of Biotype-100 strips for Pseudomonas characterization was also validated by comparison with published carbon source utilization data.

Vibrio trachuri Iwamoto et al. 1995 is a junior synonym of Vibrio harveyi (Johnson and Shunk 1936) Baumann et al. 1981

The taxonomic position of Vibrio trachuri was examined through a polyphasic approach using 16S rDNA sequencing, fluorescent amplified fragment length polymorphisms (FAFLP), DNA-DNA hybridization experiments, G+C content of DNA and phenotypical tests. Phylogenetic analysis showed that Vibrio harveyi is the closest neighbour of V. trachuri, sharing about 98.8% similarity in the 16S rDNA gene. Moreover, numerical analysis of the FAFLP patterns revealed that both species have highly related genomes, sharing 55% pattern similarity. DNA-DNA hybridization experiments and G+C content measurements reinforced these results, since V. trachuri and V. harveyi had at least 74% DNA similarity and 44.5-45.2 mol % G+C. Phenotypical features of both species were also very similar, except that V. trachuri utilized itaconic acid, whereas V. harveyi did not. Therefore, it is proposed that the species V. trachuri should be reclassified as V. harveyi.

Erwinia oleae sp. nov., isolated from olive knots caused by Pseudomonas savastanoi pv. savastanoi

Three endophytic bacterial isolates were obtained in Italy from olive knots caused by Pseudomonas savastanoi pv. savastanoi. Phenotypic tests in combination with 16S rRNA gene sequence analysis indicated a phylogenetic position for these isolates in the genera Erwinia or Pantoea, and revealed two other strains with highly similar 16S rRNA gene sequences (>99 %), CECT 5262 and CECT 5264, obtained in Spain from olive knots. Rep-PCR DNA fingerprinting of the five strains from olive knots with BOX, ERIC and REP primers revealed three groups of profiles that were highly similar to each other. Multilocus sequence analysis (MLSA) based on concatenated partial atpD, gyrB, infB and rpoB gene sequences indicated that the strains constituted a single novel species in the genus Erwinia. The strains showed general phenotypic characteristics typical of the genus Erwinia and whole genome DNA-DNA hybridization data confirmed that they represented a single novel species of the genus Erwinia. The strains showed DNA G+C contents ranging from 54.7 to 54.9 mol%. They could be discriminated from phylogenetically related species of the genus Erwinia by their ability to utilize potassium gluconate, l-rhamnose and d-arabitol, but not glycerol, inositol or d-sorbitol. The name Erwinia oleae sp. nov. (type strain DAPP-PG 531(T)= LMG 25322(T) = DSM 23398(T)) is proposed for this novel taxon.

Paenibacillus (formerly Bacillus) gordonae (Pichinoty et al. 1986) Ash et al. 1994 is a later subjective synonym of Paenibacillus (formerly Bacillus) validus (Nakamura 1984) Ash et al. 1994: emended description of P. validus.

A polyphasic study in which we performed an amplified ribosomal DNA restriction analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of whole-cell proteins, a gas chromatographic analysis of methylated fatty acids, pyrolysis mass spectrometry, a random amplified polymorphic DNA analysis, a phenotypic analysis, and an analysis of the levels of DNA binding of Paenibacillus gordonae and Paenibacillus validus strains (including both type strains) showed that these organisms form a homogeneous group and that the names P. gordonae and P. validus are therefore synonyms. P. validus has nomenclatural priority, and an emended description of this species is given; the type strain is strain LMG 11161 (= ATCC 43897).

Effect of Resveratrol on Cultured Skin Fibroblasts from Patients with Oxidative Phosphorylation Defects

Few therapeutic options are available to patients with oxidative phosphorylation disorders. Administering pharmacological agents that are able to stimulate mitochondrial biogenesis have been put forward as a possible treatment, yet the approach remains in need of thorough testing. We investigated the effect of resveratrol in an in vitro setting. Mitochondrial enzymatic activities were tested in cultured skin fibroblasts from patients harboring a nuclear defect in either complex II or complex IV (n = 11), and in fibroblasts from healthy controls (n = 11). In the latter, preincubation with resveratrol resulted in a significant increase of citrate synthase, complex II and complex IV enzyme activity. In patients with complex II or complex IV deficiency, however, activity of the deficient complex could not be substantially augmented, and response was dependent upon the residual activity. We conclude that resveratrol is not capable of normalizing oxidative phosphorylation activities in deficient cell lines. Copyright