Final answer:
The tongue predominantly harbors bacteria from the Streptococcus and Fusobacterium genera due to its anaerobic conditions. These bacteria's overgrowth can lead to oral health issues like dental caries and gingivitis, while yeast like Candida albicans can cause oral thrush.
Step-by-step explanation:
The most common oral bacteria that reside on the tongue are species from the genera Streptococcus and Fusobacterium. The human tongue, with its crevices and moist environment, provides a unique niche for these microorganisms. While the inner surface of the cheek has a predominance of Streptococcus due to its exposure to oxygen, areas like the tongue and spaces between teeth, which have limited oxygen exposure, harbor a more diverse range of microbiota, including anaerobic bacteria such as Bacteroides and Fusobacterium. Oral health issues such as dental caries and gingivitis are often associated with overgrowth of bacteria like Streptococcus and Actinomyces due to inadequate dental hygiene. Additionally, conditions such as oral thrush, which is caused by overgrowth of the yeast Candida albicans, can develop when the balance of the oral microbiota is disrupted.