D-109. Complete Genome Sequence of Streptococcus intermedius GIFU 8327 (= NCDO 2227), a Pathogen of Human Purulent Infections

K. Kikuchi, T. Baba, T. Sasaki, K. Kishii, F. Takeuchi, S. Watanabe, M. Sekine, M. Matsuo, L. Cui, T. Ito, K. Hiramatsu;
Juntendo Univ., Tokyo, JAPAN.

Backgrounds: Streptococcus anginosus group (SAG) is now classified into three distinct species as S. anginosus, S. constellatus, and S. intermedius. SAG strains are composed of normal human commensals in the oropharynx, gastrointestinal glands and vagina, and among them, especially S. intermedius strains are often associated with purulent infections. The genome of S. intermedius GIFU 8327 (=NCDO 2227), a type strain, is completely sequenced. Methods: The S. intermedius genome sequence was determined using whole-genome shotgun strategy and was assembled by Optical Mapping. Results: The S. intermedius genome is organized in one circular chromosome of 1,933,610 base pairs without any plasmids. The average of GC content of 37.71% is closed to those of other streptococci like S. pyogenes or S. pneumoniae. The genome encodes 1,706 predicted ORFs. There are four rRNA operons of 5S, 16S, and 23S rRNA genes, which is a same number of S. sanguinis SK36, and 67 tRNA genes. Only one genomic island suspected as a prophage was detected. Most of ORFs are closely related to those in S. sanguinis SK36 and there were only three S. intermedius-specific genes which S. sanguinis SK36 does not have, as sucrose specific ABC transporter, maltose utilization, and intermedilysin genes. Lack of several amino-acid biosynthesis genes as histidine, isoleucine, tryptophan and arginine, in the S. intermedius genome indicated that this species is more fastidious for growth than other streptococci. Conclusion: The complete genome sequence of S. intermedius provides a better understanding of the complexity of this organism and further genome-comparative analysis with other SAG strains will be investigated.