What is the effect of low oxygen levels on Lactobacillus?

Lactobacillus is a type of lactic acid bacteria that can tolerate low oxygen environments. While it does not require oxygen for fermentation, it can still perform fermentation even in the presence of low oxygen levels, albeit at a reduced efficiency due to its facultative anaerobic nature. In these low-oxygen conditions, Lactobacillus can survive and ferment various carbohydrates, producing lactic acid as a byproduct. This ability to ferment poorly but survive in low oxygen is key to its role in many fermentation processes, such as the production of yogurt and various fermented beverages.

In contrast, the other options incorrectly characterize the behavior of Lactobacillus in low-oxygen environments. It does not completely stop fermenting, nor does it thrive in low-oxygen conditions, and it certainly does not require high levels of oxygen for its metabolic processes.