glucose consumed. Representative homolactic LAB genera include Lactococcus, Enterococcus, Streptococcus, Pediococcus, and group I lactobacilli Heterofermentative LAB use the pentose phosphate pathway, alternatively referred to as the pentose phosphoketolase pathway. One mole of glucose-6-phosphate is initially dehydrogenated to 6-phosphogluconate and subsequently decarboxylated to yield one mole of CO2. The resulting pentose-5-phosphate is cleaved into one mole glyceraldehyde phosphate (GAP) and one mole acetyl phosphate. GAP is further metabolized to lactate as in homofermentation, with the acetyl phosphate reduced to ethanol via acetyl-CoA and acetaldehyde intermediates. In theory, end products (including ATP) are produced in equimolar quantities from the catabolism of one mole of glucose. Obligate heterofermentative LAB include Leuconostoc, Oenococcus, Weissella, and group III lactobacilli Some members of Lactobacillus appear also able to perform aerobic respiration, making them facultative anaerobes, unlike the other members of the order, which are all aerotolerant. Using oxygen helps these bacteria deal with stress. Streptococcus reclassification In 1985, members of the diverse genus Streptococcus were reclassified into Lactococcus, Enterococcus, Vagococcus, and Streptococcus based on biochemical characteristics, as well as molecular features. Formerly, streptococci were segregated primarily based on serology, which has proven to correlate well with the current taxonomic definitions. Lactococci (formerly Lancefield group N streptococci) are used extensively as fermentation starters in dairy production, with humans estimated to consume 1018 lactococci annually. Partly due to their industrial relevance, both L. lactis subspecies (L. l. lactis and L. l. cremoris) are widely used as generic LAB models for research. L. lactis ssp. cremoris, used in the production of hard cheeses, is represented by the laboratory strains LM0230 and MG1363. In similar manner, L. lactis ssp. lactis is employed in soft cheese fermentations, with the workhorse strain IL1403 ubiquitous in LAB research laboratories. In 2001, Bolotin et al. sequenced the genome of IL1403, which coincided with a significant shift of resources to understanding LAB genomics and related applications. Phylogeny The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature and the phylogeny is based on 16S rRNA-based LTP release 106 by 'The All-Species Living Tree' Project. Lactobacillales part 2 (continued) Notes: ♠ Strains found at the National Center for Biotechnology Information, but not listed in the List of Prokaryotic names with Standing in Nomenclature Uses Probiotics Probiotics are products aimed at delivering living, potentially beneficial, bacterial cells to the gut ecosystem of humans and other animals, whereas prebiotics are indigestible