A 2004 genomic study found an unexpectedly large diversity of lactic acid bacteria in sauerkraut, and that previous studies had oversimplified this diversity. Weissella was found to be a major organism in the initial, heterofermentative stage, up to day 7. It was also found that Lactobacillus brevis and Pediococcus pentosaceus had smaller population numbers in the first 14 days than previous studies had reported.[14]