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P de Vos

Publications and source records attributed to P de Vos.

12 recordsLinked to original sources
PubMed1996

A polyphasic reassessment of the genus Paenibacillus, reclassification of Bacillus lautus (Nakamura 1984) as Paenibacillus lautus comb. nov. and of Bacillus peoriae (Montefusco et al. 1993) as Paenibacillus peoriae comb. nov., and emended descriptions of P. lautus and of P. peoriae.

Seventy-seven strains representing 10 species in the Paenibacillus polymyxa 16S rRNA group and 3 other species that exhibit phenetic relatedness to members of this group, Bacillus lautus, "Bacillus longisporus," and Bacillus peoriae, were characterized genotypically and phenotypically by performing an amplified ribosomal DNA restriction analysis, a randomly amplified polymorphic DNA analysis, a fatty acid methyl ester analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of whole-cell proteins, pyrolysis mass spectrometry, and API and other routine phenotypic tests. These analyses revealed distinct clusters representing Paenibacillus alvei, Paenibacillus amylolyticus, Paenibacillus azotofixans, Paenibacillus durum, Paenibacillus larvae subsp. larvae, Paenibacillus larvae subsp. pulvifaciens, B. lautus, Paenibacillus macerans, Paenibacillus macquariensis, B. peoriae, P. polymyxa, and Paenibacillus validus, which confirmed the distinctness of these species, but appreciable within-species heterogeneity was observed in P. alvei, B. lautus, P. macerans, P. polymyxa, and P. validus. The type strain of Paenibacillus pabuli did not cluster with other strains of this species, and in several analyses a relationship between strains of P. pabuli and "B. longisporus" was observed. As the analyses showed that B. lautus and B. peoriae are closely related to the genus Paenibacillus, these species are reclassified as members of this genus.

Bacillus↗
PubMed1996

Polyphasic taxonomy, a consensus approach to bacterial systematics.

Over the last 25 years, a much broader range of taxonomic studies of bacteria has gradually replaced the former reliance upon morphological, physiological, and biochemical characterization. This polyphasic taxonomy takes into account all available phenotypic and genotypic data and integrates them in a consensus type of classification, framed in a general phylogeny derived from 16S rRNA sequence analysis. In some cases, the consensus classification is a compromise containing a minimum of contradictions. It is thought that the more parameters that will become available in the future, the more polyphasic classification will gain stability. In this review, the practice of polyphasic taxonomy is discussed for four groups of bacteria chosen for their relevance, complexity, or both: the genera Xanthomonas and Campylobacter, the lactic acid bacteria, and the family Comamonadaceae. An evaluation of our present insights, the conclusions derived from it, and the perspectives of polyphasic taxonomy are discussed, emphasizing the keystone role of the species. Taxonomists did not succeed in standardizing species delimitation by using percent DNA hybridization values. Together with the absence of another "gold standard" for species definition, this has an enormous repercussion on bacterial taxonomy. This problem is faced in polyphasic taxonomy, which does not depend on a theory, a hypothesis, or a set of rules, presenting a pragmatic approach to a consensus type of taxonomy, integrating all available data maximally. In the future, polyphasic taxonomy will have to cope with (i) enormous amounts of data, (ii) large numbers of strains, and (iii) data fusion (data aggregation), which will demand efficient and centralized data storage. In the future, taxonomic studies will require collaborative efforts by specialized laboratories even more than now is the case. Whether these future developments will guarantee a more stable consensus classification remains an open question.

Amino Acid Sequence↗
PubMed1995

Identification of Acinetobacter genomic species by amplified ribosomal DNA restriction analysis.

A total of 53 field and reference strains, including the type strains of the seven named species (nomenspecies) and belonging to the 18 described genomic species (DNA groups) of the genus Acinetobacter, were studied by amplified ribosomal DNA restriction analysis (ARDRA). Restriction analysis with the enzymes AluI, CfoI, MboI, RsaI, and MspI of the enzymatically amplified 16S rRNA genes allowed us to identify all species except the genomic species 4 (Acinetobacter haemolyticus) and 7 (A. johnsonii), 5 (A. junii) and 17, and 10 and 11, which clustered pairwise in three respective groups. Further analysis with the enzyme HaeIII, HinfI, NciI, ScrFI, or TaqI did not allow us to differentiate the species within these three clusters. However, use of a few additional simple phenotypic tests (hemolysis, growth at 37 degrees C, production of acid from glucose, and gelatin hydrolysis) can be used to differentiate between the species within these clusters. ARDRA proved to be a rapid and reliable method for the identification of most of the Acinetobacter genomic species, including the closely related DNA groups 1 (A. calcoaceticus), 2 (A. baumannii), 3, and 13. The results of this study suggest that ARDRA can be used for the identification of Acinetobacter species and as such may help to elucidate the ecology and clinical significance of the different species of this genus. Since ARDRA uses universal 16S rRNA gene primers, it is expected to be applicable to the identification of most bacterial species. Furthermore, ARDRA is less prone to contamination problems than PCR for detection, since the use of cultured organisms results in a large initial quantity of target DNA.

Acinetobacter↗
PubMed1994

The capsular overgrowth on microencapsulated pancreatic islet grafts in streptozotocin and autoimmune diabetic rats.

This study investigates whether capsular overgrowth on alginate-polylysine microencapsulated islets is influenced by (1) the presence of islet tissue, (2) MHC incompatibility between donor and recipient, or (3) the presence of autoimmune diabetes. Encapsulated Albino Oxford (AO, n = 6, isografts) and Lewis (n = 6, allografts) rat islets, and encapsulated human islets (n = 5, xenografts) were implanted intraperitoneally into streptozotocin-diabetic AO rats. Also, encapsulated AO islets were implanted into autoimmune diabetic Bio Breeding/Organon (BB/O) rats (n = 5, allografts). Five isografts, five allografts, and three xenografts in AO recipients and five allografts in BB/O recipients resulted in normoglycemia. Two weeks after implantation, islets containing capsules were retrieved by peritoneal lavage, after which all animals that had become normoglycemic after transplantation returned to a state of hyperglycemia. Recovery rates of the capsules of these successful grafts, expressed as percentages of the initially implanted graft volume, varied from 72% +/- 7% to 80% +/- 9%. The associated pericapsular infiltrates (PCI) were similar in all groups and varied from 3.2% +/- 1.4% to 8.3% +/- 2.6%. Similar recovery rates and PCI were also found with empty capsules. However, the recovery rates of recipients with graft failures were lower and showed more PCI. Immunohistological staining of PCI showed no differences in the types of cells in the PCI on capsules with or without islets. We conclude that this early PCI is a capsule-induced foreign body reaction that is not influenced by MHC incompatibility or by the presence of autoimmune diabetes, and it should be avoided by improving the biocompatibility of the capsules.

Alginates↗
PubMed1991

The efficacy of intraperitoneal pancreatic islet isografts in the reversal of diabetes in rats.

The peritoneal cavity is of renewed interest for pancreatic islet transplantation, since it is the preferable site for transplantation of immunoisolated islets. In this study we investigated the minimum islet graft volume needed to restore normoglycemia after free intraperitoneal isogenic transplantation in streptozotocin diabetic rats. Furthermore, graft function was tested by measuring glucose and insulin response to an intravenous glucose load and spontaneously ingested carbohydrate-rich meal. Three graft volumes were used: 8.0-10.0 (group A); 4.0-5.0 (group B); and 2.0-2.3 microliters (group C); 1 microliter contained about 300 islets. All 10 rats in group A and 7 out of 9 rats in group B became normoglycemic for at least 6 months posttransplant, with blood glucose levels not significantly different from normal control animals. Only 3 out of 9 animals in group C became normoglycemic and never for longer than 3 months. The insulin responses to IVGTT in group A and group B were proportional to the grafted islet volume and always significantly lower than those of normal control rats. The insulin response to the test meal showed a similar tendency, which was found to be associated with the absence of preabsorptive insulin secretion. Maximum postprandial blood glucose levels in group A and group B were 0.8 and 1.5 mM higher than in normal control rats. We conclude that intraperitoneal transplantation of at least 4.0-5.0-microliters islet tissue is needed to reverse blood glucose in streptozotocin diabetic rats, and that glucose and insulin levels on IVGTT and test meal in rats with islet grafts of 8.0-10.0 microliters are not completely normalized. It is suggested that the impaired glucose tolerance is due to an insufficient beta-cell mass and a lack of parasympathetic innervation of the transplanted islet tissue.

Animals↗