Bifidobacterium
Bifidobacterium is morphologically similar to some Lactobacillus species. It is a gram-positive rod. They exist as single cells or in chains. Cells are non sporeforming non-motile, and anaerobic, although some can tolerate O2 in the presence of CO2.
They grow optimally at 37–41 ◦C, with a growth temperature range of 25–45 ◦C. Usually, they do not grow at a pH above 8.0 or below 4.5.
They can ferment glucose to produce lactic and acetic acids in a 2:3 molar ratio without producing CO2.