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Glucose 6-Phosphate Dehydrogenase and 6-Phosphogluconate Dehydrogenase Activities and Glucose Utilization by Species within the Genera Bacteroides, Prevotella, and Porphyromonas

BAILEY, GRAHAM D., LOVE, DARIA N.

International Journal of Systematic Bacteriology 1995; 45(2):246 · https://doi.org/10.1099/00207713-45-2-246

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Summary auto-generated

This study compared two detection methods for glucose 6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) enzyme activities in Bacteroides, Prevotella, and Porphyromonas species. The spectrophotometric (SP) method detected enzyme activity in six strains, but the alloenzyme electrophoresis (AE) method failed to detect activity in two of these strains, suggesting SP is more reliable. The results revealed inconsistencies with current genus definitions: Bacteroides levii lacked both enzymes (expected in Bacteroides), while Prevotella heparinolytica, Prevotella zoogleoformans, Porphyromonas canoris, and Porphyromonas salivosa possessed one or both enzymes (contrary to their genus descriptions). Additionally, glucose utilization tests showed that final pH values in glucose-containing media did not always correlate with actual glucose consumption, challenging the use of pH changes as the sole indicator of saccharolytic activity. The authors conclude that genus descriptions for Bacteroides, Prevotella, and Porphyromonas require emendation to reflect variability in enzyme activities and glucose utilization patterns, and suggest that 16S rRNA sequence data may provide more reliable taxonomic classification than physiological characteristics alone.

Key findings

  • Spectrophotometric method detected G6PDH and 6PGDH activities more reliably than alloenzyme electrophoresis, failing to detect activity in two strains that showed activity by spectrophotometry
  • Several species do not conform to their current genus definitions based on enzyme activities: B. levii lacks expected enzymes, while P. heparinolytica, P. zoogleoformans, P. canoris, and P. salivosa possess unexpected enzyme activities
  • Final pH values in glucose media do not directly correlate with glucose utilization; some organisms showed significant glucose reduction with minimal pH change, invalidating pH as sole indicator of saccharolytic activity
  • 16S rRNA sequence data suggest current taxonomic classification based on physiological characteristics should be reconsidered, with some species clustering differently than their genus assignments predict

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Abstract

Members of the genera Bacteroides, Prevotella, and Porphyromonas were investigated for their glucose 6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) activities by using spectrophotometric (SP) and alloenzyme elecrophoresis (AE) detection methods. When the SP and AE methods were compared, the AE method failed to detect activity in two of the six strains which exhibited G6PDH and 6PGDH activities as determined by the SP detection method. On the basis of the results of SP detection, Bacteroides levii ATCC 29147T(T = type strain) (G6PDH and 6PGDH negative) is not a member of the genus Bacteroides as currently defined, which reflects recent 16S rRNA placement, nor do Prevotella heparinolytica ATCC 35895T, Prevotella zoogleoformans ATCC 33285T, Porphyromonas canoris 12835T, and Porphyromonas salivosa NCTC 11632T(all G6PDH and 6PGDH positive) conform to their respective genus descriptions. When these organisms were grown in prereduced peptone-yeast extract broth containing 10% (wt/vol) glucose, the amounts of glucose remaining after 5 days were less than the amounts present initially for members of the genus Bacteroides (Bacteroides fragilis ATCC 25285Tand B. levii) and members of the genus Prevotella (Prevotella melaninogenica ATCC 25845T, Prevotella buccae ATCC 33574T, Prevotella heparinolytica, and Prevotella zoogleoformans). In addition, the glucose levels were lower after 5 days of incubation in broth media containing Porphyromonas asaccharolytica ATCC 25845Tand Porphyromonas salivosa, but not in media containing the other members of the genus Porphyromonas tested (Porphyromonas canoris, Porphyromonas circumdentaria NCTC 12469T, Porphyromonas endodontalis ATCC 35406T, and Porphyromonas gingivalis ATCC 33277T). The reductions in glucose levels were not directly related to the final pH values. Our results suggest that the descriptions of the genera Bacteroides, Prevotella, and Porphyromonas may require emendation to reflect variability in G6PDH and 6PGDH activities and glucose utilization.