Which of the following is a probiotic microorganism commonly associated with maintaining gut flora and inhibiting pathogens?

Study for the Cengage Microbiology Test with helpful multiple choice questions and detailed explanations. Ace your exam with confidence!

Probiotics are live microorganisms that, when consumed in adequate amounts, help support the gut’s resident microbial community and protect against invading pathogens. Lactobacillus species are classic probiotic bacteria that naturally inhabit the human gut and other mucosal sites. They contribute to gut health by producing lactic acid, which lowers the local pH and creates an unfavorable environment for many harmful microbes. They also engage in competitive exclusion, competing for nutrients and attachment sites, and they can generate antimicrobial substances called bacteriocins. Additionally, they can modulate the immune system and help strengthen the gut barrier, all of which support a balanced gut flora and help inhibit pathogens.

Escherichia coli includes many strains, some harmless residents of the gut but others that can cause disease, so it’s not uniformly recognized as a probiotic to maintain gut flora. Staphylococcus aureus is primarily a pathogen associated with infections. Saccharomyces cerevisiae is a yeast; while some yeasts like Saccharomyces boulardii can be probiotic, the classic association with maintaining gut flora and inhibiting pathogens is strongest with Lactobacillus species.