IADR Abstract Archives
Isolation of Oral Candidate Phyla Radiation Bacteria
Objectives: Saccharibacteria (TM7) and Absconditabacteria (SR1) are members of the Candidate Phyla Radiation (CPR) group of bacteria which have ultra-small cells and exhibit obligate epibiontic relationships with other bacteria. A strain of TM7, TM7x, has been previously reported to grow in co-culture with Actinomyces odontolyticus. The aim of this study was to culture TM7 and SR1 strains from dental plaque, by co-culture with other oral bacteria.
Methods: Supragingival plaque was collected from 11 healthy volunteers and passed through a 0.2 µm filter. Co-culture host organisms were selected Actinobacteria species and others previously shown to be associated with CPR organisms, including Dialister and Tannerella species. Cultures of CPR and hosts in supplemented complex media were incubated anaerobically and passaged every 48 h with CPR growth monitored by qPCR.
Results: TM7 taxa HMT-955 and HMT-488 (Genus 1) were isolated and successfully maintained in co-culture with Arachnia propionica. TM7 HMT-356 (Genus 5) was detected in co-cultures with Actinomyces sp. HMT-169 and HMT-171 up to 8 d, with a peak copy number of 5.5 x 106 / ml. SR1 was detected in co-culture with Actinomyces sp. HMT-171; growth increased to a peak at day 8 of 2.5 x 106 gene copies but declined thereafter.
Conclusions: CPR bacteria were isolated from plaque samples in co-culture with other oral bacteria. TM7 Genus 1 strains appear to be most receptive to this approach while TM7 Genus 5 and SR1 strains showed some evidence of in-vitro growth which was not maintained. Further method development is required to establish stable cultures of the full range of oral CPR organisms.
Methods: Supragingival plaque was collected from 11 healthy volunteers and passed through a 0.2 µm filter. Co-culture host organisms were selected Actinobacteria species and others previously shown to be associated with CPR organisms, including Dialister and Tannerella species. Cultures of CPR and hosts in supplemented complex media were incubated anaerobically and passaged every 48 h with CPR growth monitored by qPCR.
Results: TM7 taxa HMT-955 and HMT-488 (Genus 1) were isolated and successfully maintained in co-culture with Arachnia propionica. TM7 HMT-356 (Genus 5) was detected in co-cultures with Actinomyces sp. HMT-169 and HMT-171 up to 8 d, with a peak copy number of 5.5 x 106 / ml. SR1 was detected in co-culture with Actinomyces sp. HMT-171; growth increased to a peak at day 8 of 2.5 x 106 gene copies but declined thereafter.
Conclusions: CPR bacteria were isolated from plaque samples in co-culture with other oral bacteria. TM7 Genus 1 strains appear to be most receptive to this approach while TM7 Genus 5 and SR1 strains showed some evidence of in-vitro growth which was not maintained. Further method development is required to establish stable cultures of the full range of oral CPR organisms.