What is the current genus name for the saccharolytic group formerly placed within Bacteroides? (Recognize the reclassification of oral anaerobes.)
-
APorphyromonas
-
BBacteroides
-
CPrevotella
-
DNone of these
Answer
Correct Answer: Prevotella
Explanation
Introduction: Black-pigmented oral anaerobes once grouped under “Bacteroides” were reclassified based on biochemical traits and genetics. This question examines knowledge of the modern names attached to saccharolytic taxa.
Given Data / Assumptions:
- “Saccharolytic” indicates carbohydrate-fermenting capability.
- We focus on oral anaerobic rods historically termed “Bacteroides.”
Concept / Approach: Reclassification divided these organisms into Prevotella (saccharolytic) and Porphyromonas (asaccharolytic). Therefore, the saccharolytic group corresponds to Prevotella, while Porphyromonas rely on peptides rather than sugars.
Step-by-Step Solution: Identify trait: saccharolysis implies sugar fermentation. Map trait to genus: saccharolytic → Prevotella; asaccharolytic → Porphyromonas. Select Prevotella as the correct current genus.
Verification / Alternative check: Contemporary oral microbiology references use Prevotella for melaninogenic, sugar-fermenting species such as P. melaninogenica and P. intermedia.
Why Other Options Are Wrong:
- Porphyromonas: Asaccharolytic; not the saccharolytic group.
- Bacteroides: Historical umbrella; not the present correct genus for these oral species.
- None of these: Incorrect because Prevotella fits exactly.
Common Pitfalls: Memorizing names without linking to metabolic traits leads to confusion; remember the saccharolytic vs asaccharolytic split.
Final Answer: Prevotella is the current genus for the saccharolytic group.