Levels of DNA relatedness were determined for 16 strains of Pediococcus pentosaceus and Pediococcus
acidilactici, and two distinct groups were recognized. The DNA base compositions of the members of one group
ranged from 37.4 to 38.7 mol% guanine plus cytosine and the DNA base compositions of the members of the
other group ranged from 42.7 to 43.5 mol% guanine plus cytosine. The phenotypic characteristics after growth
at 50°C and acid production from maltose correlated with the levels of DNA relatedness and DNA base
compositions. Strains in the first group exhibited high levels of DNA relatedness to the type strain of P.
pentosuceus and were identified as P. pentosuceus strains. Strains in the second group exhibited high levels of
DNA relatedness to authentic reference strains of P. ucidilactici but did not exhibit relatedness to P. acidilactici
JCM 5885= (= NCDO 1859T) (T = type strain). The taxonomic standing of the type strain of P. acidilactici was
examined, and strains in the second group were identified as P. acidilactici. In addition, we request the
replacement of the type strain P. acidilactici with the proposed neotype DSM 20284 (= JCM 8797 = NRIC
0115).