A taxonomic re-evaluation of "Propionibacterium coccoides"

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Date
1998-11
Authors
Van Nieuwholtz, Janine
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University of the Free State
Abstract
English: A study was undertaken to re-evaluate the systematic position of "Propionibacterium coccoides" relative to that of other classical Propionibacterium species. Two "P. coccoides" strains were evaluated by numerically relating them to the type and reference strains of the genus Propionibacterium as well as the type strain of the genus Luteococcus (as outgroup) by comparison of a wide range of phenotypic characters. Numerical clustering revealed five major groups, four of which corresponded to the existing classical species, while the fifth cluster grouped the two "P. coccoides" strains with the type strain of the species Luteococcus japonicus. These results clearly indicated that a higher degree of overall phenotypic similarity existed between L. japonicus and the "P. coccoides" strains than between the latter and the genus Propionibacterium. Using the polymerase chain reaction, the various 16S ribosomal RNA genes of the four Propionibacterium type strains, the two "P. coccoides" strains and the type strain of L. japonicus were successfully amplified. Visual differentiation between the four classical Propionibacterium type strains was possible after restriction endonuclease digestion of the peR products obtained using primers 16sP 1-16sP4 with the restriction endonucleases HaeIII and A/uI. Although a unique pattern was obtained for the two "P. coccoides" and the L. japonicus strains when compared to those as obtained for the four classical Propionibacterium type strains, differentiation between the two "P. coccoides" and the L. japonicus strains, even after the evaluation of numerous restriction endonucleases, was essentially still problematic. Due to the success obtained during the application of ribotyping as a technique to enable species differentiation within the genus Propionibacterium, this technique was also utilised during this study. The combination of the HaeII and Smal restriction endonuclease patterns resulted in the elucidation of the four classical Propionibacterium type strains as well as the two "P. coccoides" and the L. japonicus strains. A unique yet identical ribotyping profile was obtained for the two "P. coccoides" strains and the L. japonicus type strain. In an attempt to justify thephenotypic heterogeneity observed between the two "P. coccoides" strains and the L. japonicus type strain, numerous other restriction endonucleases were also evaluated using ribotyping. The two "P. coccoides" strains and the L. japonicus type strain could only be differentiated after digestion of the genomic DNA with the restriction endonuclease BstEII. The intrageneric phylogenetic relationship of the four classical Propionibacterium type strains, the two "P. coccoides" strains as well as the L. japonicus type strain and various other phylogenetic related genera was determined by comparative analysis of their 16S ribosomal RNA gene sequence data. The "P. coccoides" strains were observed to cluster together with the type strain of the genus Luteococcus in a clade which was phylogenetically clearly delineated from the cluster containing the various Propionibacterium species. This data subsequently confirmed the results obtained during the numerical analysis of the phenotypic characteristics. Finally DNA:DNA probe hybridisation was evaluated as a possible reliable species differentiation technique. Five major DNA:DNA homology groups could be distinguished. Four of these homology groups resembled the various classical Propionibacterium species, while the fifth DNA:DNA homology group consisted out of the "P. coccoides" strains and the L. japonicus type strain. The high degree of DNA:DNA homology between the "P. coccoides" strains and the L. japonicus type strain subsequently confirmed the phylogenetic analysis of the 16S rDNA sequence data. The results of this study subsequently indicate that the proposal by Vorobjeva et al. (1983) to include "P. coccoides" as a new species within the genus Propionibacterium is incorrect due to the higher degree of phenetic, molecular and phylogenetic similarity between Luteococcus japonicus and "P. coccoides" than between the latter and the genus Propionibacterium. It is subsequently proposed that the "P. coccoides" strains be putatively reclassified as Luteococcus japonicus subspecies casei and Luteococcus japonicus subspecies tyrophilus and that the genus description of Luteococcus be revised to include the phenetic and molecular description of these strains.
Afrikaans: 'n Studie was onderneem om die sistematiese posisie van "Propionibacterium coccoides" te herevalueer relatief tot dié van ander klassieke Propionibacterium spesies, Twee "P. coccoides" stamme was geevalueer deur hulle numeriese verwantskappe aan die tipe- en verwysingsstamme van die genus Propionibacterium sowel as the tipe stam van die genus Luteococcus (as buite-groep) te bepaal, deur 'n verskeidenheid fenotipiese karakters te vergelyk. Numeriese groepering het op vyf hoofgroepe gedui, waarvan vier ooreenstem met die bestaande klassieke spesies en die vyfde groepering wat die twee "P. coccoides" stamme saamgroepeer met die tipe stam van die spesie Luteococcus japonicus. Hierdie resultate dui duidelik aan dat 'n hoër graad van algehele ooreenkoms tussen L. japonicus en die "P. coccoides" stamme bestaan, as tussen laasgenoemde en die genus Propionibacterium. Deur gebruik te maak van die polimerase ketting reaksie (PKR), was die verskeie 16S ribosomale RNA gene van die vier Propionibacterium tipe stamme, die twee "P. coccoides" stamme en die tipe stam van L. japonicus suksesvol vermeerder. Visuele differensiasie tussen die vier klassieke Propionbacterium tipe stamme was moontlik na vertering van die PKR produkte verkry, deur gebruik te maak van die voorvoerders 16sPl-16sP4, met die endonukleases HaelII en Alul. Alhoewel 'n unieke profiel verkry is vir die twee "P. coccoides" en die L. japonicus stamme, as dit vergelyk word met dié verkry vir die vier klassieke Propionibacterium tipe stamme, was die differensiasie tussen die twee "P. coccoides" en die L. japonicus stamme, selfs na evaluasie van verskeie restruksie endonukleases, essensieel steeds pro blematies. As gevolg van die sukses behaal gedurende die aanwending van ribotipering as tegniek om spesies differensiasie in staat te stel binne die genus Propionibacterium, was hierdie tegniek ook aangewend gedurende hierdie studie. Die kombinasie van die Haell en Smal restruksie endonuklease pofiele het die verduideliking van die vier klassieke Propionibacterium tipe stamme asook die twee "P. coccoides" en die L. japonicus stamme tot gevolg gehad. 'n Unieke tog identiese ribotiperings profiel was verkry vir die twee "P. coccoides" stamme en die L. japonicus tipe stam. In 'n poging om die fenotipiese heterogenitiet waargeneem tussen die twee "P. coccoides" stamme en die L. japonicus tipe stam te verdedig, was talryke ander restruksie endonukleases ook geevalueer deur die gebruik van ribotipering. Die twee "P. coccoides" stamme en die L. japonicus tipe stam was slegs differensieerbaar na snyding van die genomiese DNA met die restruksie endonuklease BstEII. Die intrageneriese filogenetiese verwantskap van die VIer klassieke Propionibacterium tipe stamme, die twee "P. coccoides" stamme asook die L. japonicus tipe stam en verskeie ander filogeneties verwante genera is bepaal deur vergelykende analise van hulle 16S ribosomale RNA geenopeenvolging. Die "P. coccoides" stamme is bepaalom saam te groepeer met die tipe stam van die genus Luteococcus in 'n groep wat filogeneties duidelik afbeeldbaar was van die groepering wat die verskeie Propionibacterium spesies bevat. Hierdie data bevestig vervolgens die resultate verkry gedurende die numeriese analise van die fenotipiese karaktertrekke. Ten slotte is DNA:DNA kruising ondersoek as 'n moontlike betroubare spesies differensieerbare tegniek. VyfhoofDNA:DNA homologie groepe was onderskeibaar. Vier van hierdie groepe kom met die verskeie klassieke Propionibacterium spesies ooreen, terwyl die vyfde DNA:DNA homologie groep uit die "P. coccoides" stamme en die L. japonicus tipe stam bestaan. Die hoë graad van DNA:DNA homologie tussen die "P. coccoides" stamme en die L. japonicus tipe stam bevestig vervolgens die filogenetiese analise van die 16S rDNA geenopeenvolging data. Die resultate van hierdie studie dui eerstens aan dat die voorstel van Vorobjeva et al. (1983) om "P. coccoides" in te sluit as 'n nuwe spesie binne die genus Propionibacterium verkeerd is as gevolg van die hoë graad van fenetiese, molekulêre en filogenetiese ooreenkomste tussen Luteococcus japonicus en "P. coccoides" as tussen laasgenoemde en die genus Propionibacterium. Gevolglik word dus voorgestel dat die "P. coccoides" stamme putatief heringedeel word as Luteococcus japonicus subspecies casei en Luteococcus japonicus subspecies tyrophilus en dat die genus beskrywing van Luteococcus hersien moet word om die fenetiese en molekulêre beskrywing van hierdie stamme in te sluit.
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Biology -- Classification, Propionibacterium -- Classification, Dissertation (M.Sc. (Microbiology and Biochemistry))--University of the Free State, 1998
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