Ultrastructure of Bacteroides capillus, B. buccae, B. pentosaceus, B. oris, B. oralis, B. veroralis, and Pentose Sugar-Fermenting Bacteroides sp. from Humans with Periapical Osteitis: Occurrence of External Proteinaceous Cell Wall Layer

We describe the comparative ultrastructures of bile-sensitive Bacteroides species which were isolated from oral cavities and ferment xylose and arabinose. Reference strains Bacteroides buccae ATCC 33574T(T = type strain), Bacteroides capillus ATCC 33690Tand ATCC 33691, and Bacteroides pentosaceus NP333Tand WPH61 and Bacteroides sp. strains ES42 and ES57 all had an extra surface layer (S-layer) outside the outer membrane. No S-layer was detected in Bacteroides oris ATCC 33573Tand ATCC 27518, Bacteroides oralis, Bacteroides veroralis, or Bacteroides sp. strains ES2759 and ES2834. The deoxyribonucleic acid guanine-plus-cytosine contents and both the malate dehydrogenase and glutamate dehydrogenase mobilities of the strains with an S-layer were identical. We suggest that the oral pentose-fermenting Bacteroides isolates with an S-layer may belong to the same species.