Characteristics of Salt-Tolerant Lactic Acid Bacteria, in Particular Lactobacilli, Leuconostocs and Pediococci, Isolated from Salted Raw Milk

Abstract

One hundred and fourty five lactobacilli, leuconostocs and pediococci were isolated from salted raw milks incubated at 30°C for 4 to 21 d. Of 126 lactobacilli isolated, mostly from 9 to 12% salted milk, 115 were identified as homofermentative, nonthermophilic lactobacilli-73 were classified as Lactobacillus plantarum, 31 Lactobacillus casei, 8 strains were motile and 3 Lactobacillus xylosus. The remaining 11 isolates were heterofermentative lactobacilli-8 were Lactobacillus cellobiosus and 3 Lactobacillus brevis-buchneri. Strains of L. plantarum fermented many oligosaccharides, produced DL lactate and gas from L(+) but not from D(−) tartrate and their cell wall peptidoglycan was of the mesodiaminopimelic acid type. Eight strains of L. casei proved to be subsp. pseudoplantarum on the basis of inactive lactic acid production; 8 were subsp. rhamnosus and 2 subsp. alactosus, according to their pattern of sugar fermentation. L. xylosus simulated L. casei morphologically but differed from it in fermentation of xylose. The motile strains fermented arabinose and mostly sucrose but not lactose and produced 73.2 to 94 μmoles ml⁻¹ inactive lactate from 1 % glucose. None of 10 Leuconostoc isolates produced dextran from sucrose but they fermented trehalose and were identified with Leuconostoc paramesenteroides. Three strains belonged to Pediococcus and produced 62 μmoles ml⁻¹ of inactive lactate, whereas other six strains were atypical pediococci. Nineteen strains representing L. plantarum, L. casei, motile strains and Pediococcus gave, on examination for isomers of lactic acid, 32.8 to 171 μmoles ml⁻¹ inactive lactate; the L(+) enanthiomorph generally predominated.