title: Effect of smokeless tobacco products on human oral bacteria growth and viability.
abstract: To evaluate the toxicity of smokeless tobacco products (STPs) on oral bacteria, seven smokeless tobacco aqueous extracts (STAEs) from major brands of STPs and three tobacco-specific N-nitrosamines (TSNAs) were used in a growth and viability test against 38 oral bacterial species or subspecies. All seven STAEs showed concentration-dependent effects on the growth and viability of tested oral bacteria under anaerobic culture conditions, although there were strain-to-strain variations. In the presence of 1 mg/ml STAEs, the growth of 4 strains decreased over 0.32-2.14 log10fold, while 14 strains demonstrated enhanced growth of 0.3-1.76 log10fold, and the growth of 21 strains was not significantly affected. In the presence of 10 mg/ml STAEs, the growth of 17 strains was inhibited 0.3-2.11 log10fold, 18 strains showed enhanced growth of 0.3-0.97 log10fold, and 4 strains were not significantly affected. In the presence of 50 mg/ml STAEs, the growth of 32 strains was inhibited 0.3-2.96 log10fold, 8 strains showed enhanced growth of 0.3-1.0 log10fold, and 2 strains were not significantly affected. All seven STAEs could promote the growth of 4 bacterial strains, including Eubacterium nodatum, Peptostreptococcus micros, Streptococcus anginosus, and Streptococcus constellatus. Exposure to STAEs modulated the viability of some bacterial strains, with 21.1-66.5% decrease for 4 strains at 1 mg/ml, 20.3-85.7% decrease for 10 strains at 10 mg/ml, 20.0-93.3% decrease for 27 strains at 50 mg/ml, and no significant effect for 11 strains at up to 50 mg/ml. STAEs from snuffs inhibited more tested bacterial strains than those from snus indicating that the snuffs may be more toxic to the oral bacteria than snus. For TSNAs, cell growth and viability of 34 tested strains were not significantly affected at up to 100 μg/ml; while the growth of P. micros was enhanced 0.31-0.54 log10fold; the growth of Veillonella parvula was repressed 0.33-0.36 log10fold; and the cell viabilities of 2 strains decreased 56.6-69.9%. The results demonstrate that STAEs affected the growth of some types of oral bacteria, which may affect the healthy ecological balance of oral bacteria in humans. On the other hand, TSNAs did not significantly affect the growth of the oral bacteria.
authors.affiliation: Division of Microbiology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, United States; Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China.
authors.forename: Min
authors.initials: M
authors.lastname: Liu
authors.affiliation: Division of Microbiology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, United States.
authors.forename: Jinshan
authors.initials: J
authors.lastname: Jin
authors.affiliation: Division of Microbiology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, United States; Key Laboratory of Marine Ecology & Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.
authors.forename: Hongmiao
authors.initials: H
authors.lastname: Pan
authors.affiliation: Division of Microbiology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, United States; National Engineering Laboratory for Industrial Enzymes, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.
authors.forename: Jinhui
authors.initials: J
authors.lastname: Feng
authors.affiliation: Division of Microbiology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, United States.
authors.forename: Carl E
authors.initials: CE
authors.lastname: Cerniglia
authors.affiliation: Office of Science, Center for Tobacco Products, U.S. Food and Drug Administration, 10903 New Hampshire Ave, Silver Spring, MD, 20993, United States. Electronic address: Maocheng.Yang@fda.hhs.gov.
authors.forename: Maocheng
authors.initials: M
authors.lastname: Yang
authors.affiliation: Division of Microbiology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, United States. Electronic address: Huizhong.Chen@fda.hhs.gov.
authors.forename: Huizhong
authors.initials: H
authors.lastname: Chen
mesh_terms: D045424:Complex Mixtures / Q000494:pharmacology*; D003470:Culture Media / Q000737:chemistry; D005051:Eubacterium / Q000187:drug effects / Q000302:isolation & purification / Q000502:physiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D050296:Microbial Viability / Q000187:drug effects; D064307:Microbiota / Q000187:drug effects* / Q000502:physiology; D009055:Mouth / Q000382:microbiology*; D009602:Nitrosamines / Q000494:pharmacology*; D010462:Peptostreptococcus / Q000187:drug effects / Q000302:isolation & purification / Q000502:physiology; D013045:Species Specificity; D034366:Streptococcus anginosus / Q000187:drug effects / Q000302:isolation & purification / Q000502:physiology; D034365:Streptococcus constellatus / Q000187:drug effects / Q000302:isolation & purification / Q000502:physiology; D014030:Tobacco, Smokeless / Q000032:analysis*; D014678:Veillonella / Q000187:drug effects / Q000302:isolation & purification / Q000502:physiology
chemical_list: D045424:Complex Mixtures; D003470:Culture Media; D009602:Nitrosamines
keywords: Cell viability; Oral bacteria; Smokeless tobacco; Tobacco-specific N-nitrosamines; Toxicology