Tsurumi University School of Dental Medicine 2 articles published in JoVE Immunology and Infection Purification of a High Molecular Mass Protein in Streptococcus mutans Takatoshi Murata1, Mamiko Yamashita1, Masao Ishikawa1,2, Koji Shibuya2, Nobuhiro Hanada1 1Department of Translational Research, Tsurumi University School of Dental Medicine, 2Laboratory for Oral Health Science Described here is a simple method for the purification of a gene product in Streptococcus mutans. This technique may be advantageous in the purification of proteins, especially membrane proteins and high molecular mass proteins, and can be used with various other bacterial species. Genetics Generation of a Gene-disrupted Streptococcus mutans Strain Without Gene Cloning Takatoshi Murata1, Ayako Okada1, Khairul Matin1,2,3, Nobuhiro Hanada1 1Department of Translational Research, Tsurumi University School of Dental Medicine, 2Endowed Department of International Oral Health Science (affiliated with Department of Translational Research), Tsurumi University School of Dental Medicine, 3Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University We describe a facile, rapid, and relatively inexpensive method for the generation of gene-disrupted Streptococcus mutans strains; this technique may be adapted for the generation of gene-disrupted strains of various species.