Abstract
Minute 1. Call to order
The Chairman, H. N. Shah, called the closed meeting to order at 14 : 30 on 29 July 2002 in the Palais de Congrès, Paris, France. The minutes of the previous meeting were reviewed and incomplete and controversial areas were highlighted and formed part of the agenda for the current meeting.
Minute 2. Record of attendance
Members present were H. N. Shah (Chairman), I. Olsen (Secretary), K. Bernard, S. M. Finegold, S. E. Gharbia, M. Sakamoto (instead of T. Mitsuoka), A. C. R. Tanner and K. Ueno. Deep-felt sorrow was expressed over the recent deaths of members Daria N. Love and Hannele Jousimies-Somer and Martin A. Claydon, an invited guest at the last meeting in Manchester in 2000. Their immense contributions to taxonomy over the years were gratefully acknowledged.
Minute 3. Changes in membership
Y. Benno (Japan) was nominated in absentia as a possible new subcommittee member to fill the vacant position of T. Mitsuoka.
Minute 4. Status of the subcommittee mandate
Members were of the opinion that the subcommittee should be expanded to include experts with interest in environmental and veterinary anaerobes. Potential candidates will be invited to the next meeting.
Minute 5. Overview of the Bacteroidaceae
H. N. Shah reported that many proposals for speciation in this family have been based on incomplete 16S rDNA sequences and that there was no means of assessing the quality of the data entries into public domains. In deciding the taxonomic status of a species, attention should be focussed on studies where the complete 16S rDNA sequences of several strains are available. Such studies have now confirmed that Bacteroides splanchnicus does not belong to the genus Bacteroides. Its quinone and fatty acid compositions are also distinctive. Bacteroides merdae and Bacteroides distasonis, which resemble other members of Bacteroides phenotypically, are distant on the basis of 16S rDNA sequence analysis.
Prevotella zoogleoformans, which is not inhibited by bile, and Prevotella heparinolytica are phenotypically different from other Bacteroides species and form distinct groups on the basis of 16S rDNA sequence data. Species of the genus Prevotella share a large number of common traits and demonstrate high 16S rDNA sequence similarities, but there are exceptions. Prevotella tannerae, for example, differs from other members in cellular fatty acid composition, shows considerable sequence divergence and is probably not a member of Prevotella, while Bacteroides forsythus was recently transferred to a new genus (see below).
Porphyromonas species form a distinct lineage of the 16S rDNA tree in which species of animal and human origin diverge.
Strains of Rikenella microfusus appear to differ markedly from the type strain and the species needs further investigation.
At present, complete genome sequences of several members of the Bacteroidaceae have nearly been completed, and this was discussed in detail by S. E. Gharbia. It is evident that this will have considerable impact on the taxonomy and classification of many members whose position still remain unclear.
Minute 6. Genomics of Gram-negative anaerobes and relevance to microbial phylogeny
S. E. Gharbia reported that Fusobacterium could be divided in two 16S rDNA gene clusters, but closely related is a group comprising Tissierella, Mitsuokella, Leptotrichia, Streptobacillus, Sebaldella, Propionigenum and Cetobacterium species. Clostridium rectum is related to Fusobacterium mortiferum, while Leptotrichia microbii is closely related to Streptobacillus moniliformis. Leptotrichia microbii was recently transferred to the new genus Sneathia as Sneathia sanguinegens. Current data suggest that Streptobacillus moniliformis and Leptotrichia morbii should be combined into a single genus. Streptobacillus moniliformis is emerging as an important human pathogen and should be investigated further.
The genome of Fusobacterium nucleatum has now been completely sequenced and annotated and the rationale for maintaining the family Bacteroidaceae is supported by such data.
Minute 7. Fusobacterium: restatement of the subspecies
Members of the subcommittee were of the opinion that the published subspecies of F. nucleatum, which have been questioned periodically, are valid and have now been confirmed by sequencing of the spacer region of the 16S23S rDNA.
Minute 8. Bacteroides forsythus: progress in systematics
A. C. R. Tanner reviewed the criteria for establishing B. forsythus as a species and its current taxonomic position. It was quite clear early on that B. forsythus was not compatible with species of the genus Bacteroides. This was confirmed by 16S rDNA sequence analysis and cellular fatty acid profiles. Other distinguishing tests are its possession of menaquinone-12 and other physiological properties. It was suggested that the new name should be amended to Tannerella forsythia (and not Tannerella forsythensis), and this was agreed by the subcommittee.
Minute 9. Overview of Cetobacterium and a new species from faeces
S. M. Finegold reported that these organisms were first isolated from the stools from children with vancomycin-resistant organisms. They were resistant to bile and morphologically similar to F. nucleatum in possessing tapered-ended cells. However, Cetobacterium strains produced lower levels of acetic and propionic acids but not butyric acid. Nitrate was reduced and the urease reaction was positive. Furthermore, their cellular fatty acid composition differed from Fusobacterium and strains could be grown under 2 % oxygen. Complete 16S rDNA sequencing confirmed their difference from F. nucleatum and there was approximately 5 % sequence difference from Cetobacterium ceti.
Minute 10. Minimal species/generic descriptions
Various working groups have been devising minimal descriptions of various taxa. Because of the non-fermentative nature and the paucity of characters of many Gram-negative anaerobes, this is still a distant goal for this subcommittee. However, there was agreement to initiate this process within the Bacteroides, which will then serve as a framework for further species/generic descriptions of other Gram-negative anaerobic rods. The subcommittee will undertake this as a group exercise and seek advice from other experts in the field.
Minute 11. Proposal for a co-operative study by MALDI-TOF-mass spectrometry
Many genera/species of the Bacteroidaceae were proposed several years ago and based on such criteria as lipid analyses, DNADNA hybridization etc., which are not undertaken in most laboratories today. Consequently, a large number of taxa are difficult to identify and new criteria are urgently needed to delineate many non-fermentative species. At present, a number of novel techniques in genomics and proteomics are being introduced into microbiology. As a group study, it was decided to explore one of these, matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), as a means of differentiating members of the genus Porphyromonas, since preliminary data looked promising [see e.g. Shah et al., Clin Infect Dis 35 (2002), 5864].
Minute 12. Future directions
As a rule, the minutes of the subcommittee are published in the International Journal of Systematic and Evolutionary Microbiology. However, an abbreviated version of the last minutes was published for the first time in the journal Anaerobe [Anaerobe 7 (2001), 329331] because of the relevance of Gram-negative anaerobes to readers of this journal. This proved so popular that it was decided to seek the permission of the International Committee on Systematics of Prokaryotes to do so again.
Genera not covered in the meeting, such as Dialister pneumosintes, Streptobacillus moniliformis and Vibrio, will be considered as topics for the next meeting, which will be held in San Francisco in 2005.
Minute 13. Current membership of the subcommittee
H. N. Shah (Chairman; UK), I. Olsen (Secretary; Norway), K. Bernard (Canada), B. I. Duerden (UK), S. M. Finegold (USA), S. E. Gharbia (UK), B. J. Paster (USA), A. C. R. Tanner (USA) and K. Ueno (Japan).
Minute 14. Adjournment
The meeting was adjourned at 18 : 00 on 29 July 2002.