Tumor micro-environments are at low pH mainly because cancer cells make a lot of this (*)  acid.
Streptococcus  is a member of a bacterial order conventionally named for this compound. The co-polymer between this compound and glycolic acid is commonly used in surgical implants. Ringer's solution, used for IV replacement, is named for being supplemented with this organic compound. Tumor micro-environments are at low pH mainly because cancer cells make a lot of this (*)  acid. In the Cori cycle, this compound moves to the liver, then is oxidized and converted into glucose via gluconeogenesis. This compound, which has the formula C3H6O3, forms when NADH reduces pyruvate at the end of glycolysis. For 10 points, name this byproduct of mammalian anaerobic fermentation, which accumulates in the muscles after a vigorous workout, and was first discovered in sour milk.
Streptococcus  is a member of a bacterial order conventionally named for this compound.
lactic  acid [or  lactate ] 