Final answer:
Lactose-fermenting bacteria found in the colon include Escherichia coli (E. coli) and Bifidobacterium spp., which play a beneficial role in the human gut microbiota and are involved in producing vitamins and maintaining good digestive health.
Step-by-step explanation:
Some lactose-fermenting bacteria that are found in the colon include Escherichia coli (E. coli) and members of the genus Bifidobacterium. These bacteria are part of the Enterobacteriaceae family or Lactobacillales order and can completely ferment lactose producing acid and gas. E. coli is typically considered a beneficial member of the gut microbiota, although some strains can be pathogenic, while Bifidobacterium spp. are substantial components of the human gut microbiota and can confer positive health benefits, including the synthesis of essential vitamins.
The genus Bifidobacterium includes filamentous anaerobes that are commonly found in the gastrointestinal tract and are used both as probiotics and in yogurt production. The Lactobacillales order includes bacteria that are primarily known for fermenting milk into yogurt, such as Lactobacillus and Bifidobacterium, which are associated with promoting good digestive health and a well-balanced immune response.