Tohoku J. Exp. Med., 2015 September, 237(1)

Porphyromonas bronchialis sp. nov. Isolated from Intraoperative Bronchial Fluids of a Patient with Non-Small Cell Lung Cancer

TAKUICHI SATO,¹ JUNKO TOMIDA,² TAKASHI NAKA,³ NAGATOSHI FUJIWARA,⁴ AYAKO HASEGAWA,^1,2 YASUSHI HOSHIKAWA,⁵ JUNKO MATSUYAMA,⁶ NAOKO ISHIDA,¹ TAKASHI KONDO,⁵ KAORI TANAKA,⁷ NOBUHIRO TAKAHASHI¹ and YOSHIAKI KAWAMURA²

¹Division of Oral Ecology and Biochemistry, Tohoku University Graduate School of Dentistry, Sendai, Miyagi, Japan
²Department of Microbiology, School of Pharmacy, Aichi Gakuin University, Nagoya, Aichi, Japan
³MBR Co., Ltd., Ibaraki, Osaka, Japan
⁴Department of Food and Nutrition, Faculty of Contemporary Human Life Science, Tezukayama University, Nara, Nara, Japan
⁵Department of Thoracic Surgery, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Miyagi, Japan

Porphyromonas strains, including Porphyromonas-like strains, have been isolated from oral and various other systemic infections. The characterization of such strains is a crucial issue, because such information contributes to both the taxonomy of anaerobic bacteria and the clinical aspects of infectious diseases. We previously isolated four Porphyromonas-like strains from intraoperative bronchial fluids of a patient with non-small cell lung cancer. This study aimed to characterize the genetic, biochemical and chemotaxonomic aspects of these isolates. Each strain only grew under anaerobic conditions and their colony morphology was convex, 0.1-1.0 mm in diameter, light gray, and slightly glistening colony, with no black or brown pigmentation on blood agar plates after five-day incubation. The pigmentation was helpful to differentiate the isolates from other Porphyromonas, as most of Porphyromonas species show the pigmentation. In the 16S rRNA gene phylogenetic analysis (98% sequence identity of isolates indicates the same species), the four isolates were closely related to one another (99.7-100.0%), but not related to Porphyromonas (P.) catoniae, the closest species (96.9%). In addition, the DNA-DNA hybridization data revealed less than 16% similarity values between a representative isolate and the P. catoniae, indicating that the strains were genetically independent. Biochemically, the isolates could be differentiated from closely related species, i.e., P. catoniae, P. gingivalis, P. gulae, and P. pogonae, with trypsin activity (negative only in the isolates) and leucine arylamidase activity (positive only in the isolates). We therefore propose a new species to include these isolates: Porphyromonas bronchialis sp. nov.

keywords —— bronchial fluids; DNA-DNA hybridization; human clinical specimen; Porphyromonas; 16S rRNA sequence

© 2015 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2015, 237, 31-37

Correspondence: Takuichi Sato, Division of Oral Ecology and Biochemistry, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan.

e-mail: tak@m.tohoku.ac.jp