Final answer:
Individuals with chronic periodontitis exhibit a significantly greater microbial diversity in their oral microbiota compared to those without the disease, due to the anaerobic conditions that favor a wider variety of microbes. The correct answer is option a.
Step-by-step explanation:
Individuals with chronic periodontitis tend to have a significantly greater microbial diversity than those without the condition. The human oral cavity hosts a diverse array of microbiota, with different species preferring various niches within the mouth. These species can range from those preferring the oxygen-rich surfaces to those thriving in the anaerobic spaces between teeth and the crypts of the tongue. Periodontitis is a more severe form of gum disease that follows gingivitis, characterized by inflammation that spreads deeper into the tissues.
The progression from the bacterial colonization of plaque on the teeth to chronic periodontitis includes a transition to an anaerobic environment conducive to a diverse array of microbes. These include bacteria such as Porphyromonas, Streptococcus, Actinomyces, and possibly archaeans like Methanobrevibacter oralis. This diverse microbial community is involved in the tissue damage and chronic inflammation observed in periodontitis.
Therefore, the correct choice in the context of this question about chronic periodontitis and microbial diversity is option (a): significantly greater microbial diversity than those without.