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.

Identification of salt tolerance-related genes of Lactobacillus plantarum D31 and T9 strains by genomic analysis

“…To date, more than 50 complete genome sequences of L. plantarum strains are available in public databases; nevertheless, little genome information is for the salttolerant LAB. Moreover, only few L. plantarum strains have been reported to tolerate osmotic stress, e.g., L. plantarum ST-III and L. plantarum ATCC 14917 strains (El-Gendy et al 1983;Rao et al 2004;Chen et al 2012;Vasyliuk et al 2014;Xin et al 2014). In this study, for the first time, we evaluated tolerance of L. plantarum D31 and L. plantarum T9 strains, isolated from Chinese traditional fermented food, to different stress conditions (temperatures, acid, osmolality, and artificial gastrointestinal fluids).…”

“…LAB chosen for commercial purposes must challenge adverse conditions encountered in industrial processes, such as heat, cold, acidity, and high concentrations of NaCl (Bucka-Kolendo and Sokolowska 2017). Many fermented food are made with the salt, by which osmotic stress is often a significant challenge for microorganisms surviving in fermentation processes (El-Gendy et al 1983;Yamani et al 1998;Prasad et al 2003;Rao et al 2004). Possible mechanisms of the regulation of intracellular osmotic pressure in LAB have been mentioned, such as (1) exclusion of Na + ion from cells, (2) accumulation of compatible solutes, and (3) changes of cell membrane composition.…”

Bacterial fermentation of meats

“…Rod-shaped LAB are largely used in the preparation of a variety of foods and feed products (Bottazi, 1988). Lactobacillus plantarum is normally associated with meat and vegetable fermentations, and is frequently isolated from white pickled cheese (El-Gendy et al, 1983). Lactobacillus plantarum, L. brevis, L. farciminis, L. alimentarius and L. curvatus are essential for the fermentation of sausages prepared with added sucrose or powdered milk (Reuter, 1970;Kagermeier, 1981).…”

Antifungal Activity of Lactobacillus plantarum ZZUA493 and Its Application to Extend the Shelf Life of Chinese Steamed Buns

“…The growth of ZZUA493 was not affected under the condition of salt at 3 and 6.5%. In the presence of salt, salt-tolerant microorganisms can reproduce, while other salt-sensitive microorganisms are repressed [ 29 ]. In the current study, ZZUA493 could grow in 6.5% salted MRS broth, and this laid the foundation for the application of ZZUA493 in a high-salt environment.…”