Comparison of the use of the halimeter and the Oral Chroma[TM] in the assessment of the ability of common cultivable oral anaerobic bacteria to produce malodorous volatile sulfur compounds from cysteine and methionine

ABSTRACT

To compare the use of the Halimeter and the Oral Chroma[TM] to assess the ability of common oral anaerobic bacteria isolated from the Kuwaiti population to produce volatile sulfur compounds [VSCs]. Broth cultures of common anaerobes isolated from supragingival plaque were centrifuged and pellets resuspended in phosphate buffer [pH 7.7] with an optical density OD550 of 0.3. 100 micro l of this suspension and 870 micro l of buffer were added in 2 sterile 15-ml head space vials. Reaction was initiated by addition of 30 micro l of 33 mML-methionine and L-cysteine, respectively, in each vial and incubation at 37°C for 90 min. 500 micro l of 3 M phosphoric acid was added to tubes and was kept aside for 10 min. Production of VSCs was measured using the Halimeter and the Oral Chroma. The major VSC producers identified by both Halimeter and Oral Chroma with L-cystenine as substrate were Campylobacter ureolyticus, Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia, Aggregatibacter actinomycetemcomitans and Gemella morbillorum. The concentrations of hydrogen sulfide recorded by both Halimeter and Oral Chroma were essentially identical. With L-methionine as substrate, both Halimeter and Oral Chroma identified different complements of anaerobes with C. ureolyticus, P. gingivalis, Fusobacterium nucleatum and P. intermedia as major VSC producers. The concentrations of methyl mercaptan recorded by the Halimeter were lower compared to those assessed by the Oral Chroma. The results suggest that the Oral Chroma may produce a more comprehensive assessment of VSC production by oral microflora than the Halimeter