What is the most common resident biota of mouth surfaces?

Streptococcus is the most common resident biota of mouth surfaces due to its ability to form biofilms and adapt to the oral environment. This genus, particularly Streptococcus mutans, plays a crucial role in dental health, as it can adhere to teeth and contribute to the formation of dental plaque.

Streptococcus species are masters at colonizing the oral cavity, thriving on sugars and producing acids as metabolic byproducts, which are significant factors in tooth decay. Their prevalence in the mouth is a result of both their adaptability and the specific niche they occupy, as they can survive the variations in temperature, pH, and oxygen levels typical of the oral environment.

In contrast, other genera like Staphylococcus are more commonly found on skin surfaces and in other areas of the body rather than in the oral cavity. Escherichia is generally associated with the intestines and does not thrive as effectively in the oral environment. Bacteroides, while it does have a presence in the mouth and is known for its role in the gut microbiome, is more predominant in the intestines than in the oral cavity.

Therefore, the dominance of Streptococcus in the mouth is attributed to its unique characteristics which allow it to effectively colon