IDENTIFICATION OF LACTOBACILLI FROM SOURDOUGH AND DESCRIPTION OF LACTOBACILLUS-PONTIS SP-NOV

The microflora of sourdough preparations was investigated by examining the physiological characteristics, whole-cell protein patterns, and 1 6S rRNA sequences of lactobacillus isolates. Strains isolated from sou rdough were placed in the species Lactobacillus brevis, Lactobacillus sanfrancisco, and Lactobacillus reuteri. 16S rRNA sequences were deter mined for L. brevis, Lactobacillus fructivorans, Lactobacillus ferment um, L. sanfrancisco, and L. reuteri, and oligonucleotide probes for fa st specific identification of these sourdough lactobacilli were deduce d. The physiological characteristics, protein patterns, and 16S rRNA s equences of these organisms were compared with data for other sourdoug h lactobacilli and additional reference strains. Strains of a Lactobac illus species were isolated from rye sourdough; these strains may acco unt for most of the flora in sourdough made from wheat or rye. These o rganisms were differentiated from other sourdough lactobacilli by thei r protein pattern, 16S rRNA sequence, G+C content, and physiological p roperties. The 16S rRNA sequence of this species was determined, and w e constructed a phylogenetic tree which reflected the relationships of this species to other lactobacilli. This organism is closely related to L. reuteri. A new Lactobacillus species, Lactobacillus pontis, is p roposed. The type strain is L. pontis LTH 2587 (= DSM 8475 = LMG 14187 ). We describe a general strategy in which a polyphasic approach was u sed to characterize a new species.