Lactic acid bacteria are hetero- and homo-fermentative. However, this is not straightforward as, under slow growth rates, mixed acids will be formed even with homofermentative bacteria.
It is important to select the strains that are homo-fermentative, have no racemase activity, and are tolerant to inhibitors that are present in industrial by-product streams that have
significant amounts of: starch e.g. starch production and processing plants (potato, cassava, sweet potatoes etc); sugars (e.g. lactose whey permeate); and cellulose (e.g. paper industry streams).