ECOLOGICAL COMPETITION AMONG ORAL STREPS

口腔链球菌之间的生态竞争

• 批准号: 3425040
• 负责人: JOHN A MAYO
• 金额: $ 2.07万
• 依托单位: LSU HEALTH SCIENCES CENTER
• 依托单位国家: 美国
• 财政年份: 1986
• 资助国家: 美国
• 起止时间: 1986-02-01 至 1988-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3425040
• 关键词: Streptococcus; Streptococcus mutans; Streptococcus sanguis; arginine; dental caries inhibitor; dental plaque; deoxyglucose; ecology; glucose; growth media; microorganism culture; oral bacteria; preventive dentistry; sucrose

Dental caries is an endemic disease in humans. The primary pathogen of caries on coronal surfaces of teeth is thought to be Streptococcus mutans although other bacteria are implicated in the progression or extension of lesions. Accordingly, measures directed specifically against S. mutans have been included in the many therapies and preventative treatments used against caries. Among the most recent of these have been attempts at the selective replacement of S. mutans in dental plaque by avirulent oral streptococci occupying the same niche on tooth surfaces as S. mutans. Ideally, one would hope to implant a strain or mutant "more fit" for that niche than the originial occupant, namely S. mutans. Thus, it becomes of importance and interest to understand ecological competition among oral streptococci. In this application it is proposed to investigate the roles of uptake systems for glucose, sucrose, and arginine in competition between pairs of oral streptococci grown in mixed culture in a nutrient-limited chemostat. The organisms to be studied are S. mutans Ny344, S. sanguis P4A7, and S. milleri B448. Nutrient-limited chemostats have been chosen as a model for nutrient-limited microbial growth seen in natural ecosystems. Each organism will be grown in a chemostat limited for glucose, sucrose, or arginine, and Km's for uptake of these limiting nutrients will be determined with cells taken from the corresponding chemostats. Then, mixed cultures starting with equal numbers of S. mutans and either S. sanguis or S. milleri will be grown in chemostats limited for glucose, sucrose, or arginine, and the outcome of competition between the two organisms determined by measuring the numbers of the two organisms in the culture as the chemostat comes to a steady state equilibrium. It is expected that the organism having the lower Km for the limiting nutrient will predominate in the mixed culture. This project provides the opportunity to obtain physiological explanations for ecological observations.

龋病是人类的一种地方病。该病的主要病原是 牙齿冠面上的龋病被认为是变形链球菌 尽管其他细菌也牵涉到该疾病的进展或扩展 损伤。因此，专门针对变形链球菌的措施 已被包括在使用的许多疗法和预防性治疗中 预防龋齿。其中最近的一次尝试是在 无毒口服液选择性替代牙菌斑中变形链球菌的研究 与变形链球菌在牙齿表面占据相同生态位的链球菌。 理想情况下，人们会希望植入一种“更适合”的菌株或突变体。 而不是最初的居住者，即变形链球菌。因此，它就成了 理解口腔生态竞争的重要性和趣味性 链球菌。 在这一应用中，建议研究摄取的作用 葡萄糖、蔗糖和精氨酸系统在两对竞争中 在营养有限的恒化器中混合培养的口腔链球菌。 待研究的微生物为变形链球菌Ny344、血链球菌P4A7和链球菌S。 米勒里B448。营养限制型化学药物已被选为 在自然生态系统中看到的营养有限的微生物生长。 每种生物都将在限制葡萄糖、蔗糖或 精氨酸和Km对这些限制性营养物质的吸收将是 用取自相应的化学药物的细胞来确定。然后，混合 以相同数量的变形链球菌和血链球菌或 米勒乳杆菌将在限制葡萄糖、蔗糖或 精氨酸，以及两种生物之间竞争的结果 通过测量培养物中两种微生物的数量确定为 恒化器达到稳态平衡。预计将会有 对极限养分具有较低Km的有机体将在 混合文化。该项目提供了获得 对生态观察的生理学解释。