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At least 19 recordsLinked to original sources
PubMed1979

[Biological properties of antibiotic-resistant strains of lactic acid bacteria].

Lactic-acid bacteria (L. fermenti, L. acidophilus, L. delbruecki), when developing resistance to antibiotics, did not change their main biochemical, antagonistic properties and did not lose capacity for acid production. Only a decrease in their growth rate and a change in their sensitivity to the action of ultraviolet radiation were observed. Both initial and antibiotic-resistant strains were capable of taking on the mucous membrane of the large and small intestines in CBA mice.

Animals↗
PubMed2026

Fructophilic lactic acid bacteria as a window into multi-scale convergent evolution.

Fructophilic lactic acid bacteria (FLAB) are a group of lactic acid bacteria with unique growth characteristics, that is, poor growth on glucose. Their growth is enhanced in the presence of fructose or external electron acceptors. These organisms inhabit fructose-rich environments such as flowers, fruits, and pollinating insects, particularly honey bees. Apilactobacillus spp. and Fructobacillus spp. are representatives of FLAB, although they belong to phylogenetically distant clades. These organisms commonly possess markedly small genomes with a low number of coding DNA sequences. Furthermore, their genomes are characterized by a markedly reduced number of genes involved in carbohydrate transport and metabolism. Genome reduction in FLAB reflects convergent adaptation to fructose-rich environments rather than general genome streamlining. The two distinct FLAB genera, Fructobacillus and Apilactobacillus, independently lost more than 100 genes in statistically similar orders. In contrast, genes involved in carbohydrate and amino acid metabolism exhibited reversed orders of loss between the two genera. Furthermore, FLAB genomes lack an intact bifunctional alcohol/aldehyde dehydrogenase gene (adhE), which causes their poor growth on glucose. A comparative genomic study suggested the evolutionary process underlying adhE gene decay during adaptation to the fructose-rich environments, including pollinating insects. In conclusion, FLAB represent a unique example of habitat-driven convergent reductive evolution that can be investigated across multiple biological scales - from individual genes to whole genomes - in the diverse LAB group with a wide range of habitats, and partially share the fructophilic evolution with eukaryotic yeasts found in fructose-rich habitats.

Fructose↗
PubMed1979

[Lactic acid bacteria and streptococci of the human stomach normally and in pathological processes].

Lactic acid bacteria were either absent or present in negligent quantities in the stomach of apparently healthy man. But in case of various pathological processes in the stomach and duodenum lactic acid bacteria accumulated (up to a million cells per 1 ml of gastric contents). Under these conditions coccal forms sharply prevailed over the bacillary ones. In patients with chronic gastritis and peptic ulcer of the stomach the most frequent were Streptococcus faecalis and its variants; in oncological patients--Str. faecium, strains affiliated to Leuconostoc mesenteroides, and sometimes Str. durans.

Adult↗
PubMed1979

Lipoquinones of some spore-forming rods, lactic-acid bacteria and actinomycetes.

The respiratory quinones of 73 strains of Gram-positive bacteria including spore-forming rods, lactic-acid bacteria and actinomyctes were examined. Menaquinones with seven isoprenoid units (MK-7) were the main quinone type found in representatives of the genus Bacillus and in Sporolactobacillus inulinus. However, a strain of B. thuringiensis produced MK-8 in addition to MK-7, and strains of B. lentus and B. pantothenticus appeared to produce MK-9 and MK-8, respectively, with no MK-7. In the clostridia and lactic-acid bacteria, no quinones were found, except in Pediococcus cerevisiae NCTC 8066 and Lactobacillus casei subsp. rhamnosus ATCC 7469, which contained menaquinones, and Streptococcus faecalis NCTC 775 and HIM 478-1, which contained demethylmenaquinones, in relatively low concentrations. Menaquinones were also found in the actinomycetes (except Actinomyces odontolyticus and Bifidobacterium bifidum which did not produce any quinones) and in Protaminobacter alboflavus ATCC 8458, the so-called Actinobacillus actinoides ATCC 15900 and Noguchia granulosis NCTC 10559.

Actinomycetales↗
PubMed1977

Comparative studies of lactic acid dehydrogenases in lactic acid bacteria. I. Purification and kinetics of the allosteric L-lactic acid dehydrogenase from Lactobacillus casei ssp. casei and Lactobacillus curvatus.

The stability, pH-dependence and kinetic properties of the Mn2+ and FDP-activated NAD-dependent lactic acid dehydrogenases from Lactobacillus casei ssp. casei (ATCC 393) and L. curvatus (DSM 20010) were studied after the enzymes were purified to homogeneity by affinity chromatography. Both enzymes are virtually unidirectional, catalysing efficiency only the reduction of pyruvate. They are similar with respect to the effector requirement and pH-optimum. They differ, however, in their electrophoretic mobility, heat stability, pH-dependence of the Mn2+ requirement and several kinetic properties. It is suggested that most of these differences are caused by differences of the negative charges in the vicinity of the FDP-binding site or the site responsible for the interaction of the subunits of the enzymatically active oligomeres.

Allosteric Regulation↗
PubMed1976

Aldolases of the lactic acid bacteria. Demonstration of immunological relationships among eight genera of Gram positive bacteria using an anti-pediococcal aldolase serum.

Reciprocal qualitative and quantitative immunological experiments employing an anti-Pediococcus cerevisiae aldolase serum confirmed many of the interspecific relationships demonstrated previously among lactic acid bacteria with antisera prepared against the Streptococcus faecalis fructose diphosphate aldolase. The extent of immunological relatedness observed between the Lactobacillus and Pediococcus aldolases was markedly gses indicating that the pediococci share closer phylogenetic ties with the rod-shaped lacotbacilli than with their spherical counterparts in the streptococci. In addition to confirming the existence of definitive, but distant, relationships between the lactic acid bacteria and certain gram positive nonsporeforming anaerobes, immunological cross-reactivity was also demonstrated between the pediococcal aldolases and those of Aerococcus viridans.

Biological Evolution↗
PubMed1976

Citric acid metabolism in hetero- and homofermentative lactic acid bacteria.

The effect of citrate on production of diacetyl and acetoin by four strains each of heterofermentative and homofermentative lactic acid bacteria capable of utilizing citrate was studied. Acetoin was quantitatively the more important compound. The heterofermentative bacteria produced no acetoin or diacetyl in the absence of citrate, and two strains produced traces of acetoin in its presence. Citrate stimulated the growth rate of the heterofermentative lactobacilli. Acidification of all heterofermentative cultures with citric acid resulted in acetoin production. Destruction of accumulated acetoin appeared to coincide with the disappearance of citrate. All homofermentative bacteria produced more acetoin and diacetyl in the presence of citrate than in its absence. Citrate utilization was begun immediately by the streptococci but was delayed until at least the middle of the exponential phase in the case of the lactobacilli.

Acetoin↗
PubMed2026

Genomic determinants underlying biogenic amine detoxification phenotypes in food-associated lactic acid bacteria: Mechanism, evolutionary origin, and relevance to fermented food safety.

Biogenic amines (BAs) are toxic metabolites that accumulate in fermented foods and pose significant food safety concerns. Although several lactic acid bacteria (LAB) have previously been reported to exhibit strain-specific BA-degrading phenotypes, the genetic determinants underlying these activities have remained largely uncharacterized. Here, we analyzed 8251 LAB genomes to validate BA-degrading phenotypes. We predicted five BA-associated genes, including two direct biogenic amine-degrading genes (BADGs), mco and patA, and three polyamine-modifying genes (PMGs), speG, paiA, and bltD. Among BADGs, mco was broadly distributed across LAB and strongly enriched across food-associated niches. patA, organized within a conserved potD-glnB-potABC-patA cassette, is a putative, functionally distinct BADG in LAB, revealing a nitrogen-responsive polyamine uptake-catabolism module. Phylogenomics, phylogenetic reconciliation, and synteny analysis established that all five genes entered the LAB through episodic horizontal gene transfer followed by lineage-specific fixation. GC compositional bias and mobile genetic element association further corroborated the horizontal origin of the two BADGs. Structural analysis confirmed the conservation of catalytic core residues of BADGs across LAB, indicating strong purifying selection. Phenotype-to-genotype correlation with experimentally reported LAB suggested mco as a reliable genomic predictor of degrading phenotype. Integration of degradation and biosynthetic profiles predicted multiple LAB species capable of both synthesizing and degrading BA, along with 1823 genomes with degradation potential but lacking detectable BA biosynthesis genes. This study provides the first large-scale genome framework linking BA-degrading phenotypes with their genetic determinants in LAB and offers a rational basis for selecting BA-detoxifying strains for fermented food applications.

Biogenic Amines↗
PubMed2026

Whole-genome sequencing reveals hidden antimicrobial resistance genes in phenotypically susceptible probiotic candidate lactic acid bacteria.

Phenotypic assays commonly used to evaluate probiotic safety may fail to detect clinically relevant antimicrobial resistance (AMR), potentially allowing genetically concerning strains to appear acceptable based on MIC testing alone. To explore this issue, we applied whole-genome sequencing (WGS) to three lactic acid bacteria (LAB) isolates previously identified as probiotic candidates based on acid and bile tolerance, antagonism against enteric pathogens, and biofilm formation in vitro: Lactiplantibacillus plantarum L25F and L22F (from pigs) and Ligilactobacillus salivarius AF2319 (from a chicken). Genome annotation identified extensive repertoires of probiotic-associated genes (46-47 per strain) linked to stress tolerance, adhesion, immunomodulation, and quorum sensing, supporting functional potential. The two L. plantarum strains exhibited broader predicted metabolic capacities than L. salivarius AF2319. However, genomic analysis revealed acquired AMR genes with complex genotype-phenotype relationships not fully apparent from phenotypic testing. The L. plantarum strains harbored lnu(A) (99.79% identity) on extrachromosomal DNA, conferring the L-phenotype (lincomycin resistance, clindamycin susceptibility); clindamycin MICs (1 mg/L) were concordant with this genotype, though lincomycin MICs were not determined. L. salivarius AF2319 carried tet(M), tet(L), and erm(C) (99.48%, 99.49%, and 99.45% identity by ResFinder, respectively) on extrachromosomal DNA; notably, the erythromycin MIC (1 mg/L) was precisely at the EFSA breakpoint (≤ 1 mg/L), representing borderline genotype-phenotype discordance potentially due to silent gene expression. Under current EFSA QPS criteria, these acquired ARGs would preclude all three strains from approval as probiotic feed additives despite favorable functional profiles, underscoring the indispensable role of WGS-based AMR gene detection in modern probiotic safety evaluation.

Probiotics↗
PubMed1976

Acetaldehyde: an intermediate in the formation of ethanol from glucose by lactic acid bacteria.

Group N streptococci formed acetaldehyde and ethanol from glucose. As the enzymes aldehyde dehydrogenase, phosphotransacetylase and acetate kinase were present this would enable these organisms to reduce acetyl-CoA to acetaldehyde and convert acetyl-CoA to acetyl phosphate and acetate. A pentose phosphate pathway which converted ribose-5-phosphate to glyceraldehyde-3-phosphate was also present. Acetaldehyde could not be formed via the hexose monophosphate shunt or by direct decarboxylation of pyruvate, as the enzymes phosphoketolase and alpha-carboxylase were absent. Phosphoketolase activity was induced in Streptococcus lactis subsp. diacetylactis after growth on D-xylose. Group N streptococci also contained an NAD-dependent alcohol dehydrogenase which reduced acetaldehyde to ethanol while both NAD- and NADP-dependent alcohol dehydrogenase activities were found in Leuconostoc cremoris.

Acetaldehyde↗
PubMed1977

Comparative studies of lactate dehydrogenases in lactic acid bacteria. Amino-acid composition of an active-site region and chemical properties of the L-lactate dehydrogenase of Lactobacillus casei, Lactobacillus curvatus, Lactobacillus plantarum, and Lactobacillus acidophilus.

The molecular weight, the amino acid composition and the N-terminal and C-terminal amino acids of two allosteric (Lactobacillus casei, L. curvatus) and two non-allosteric (L. plantarum, L. acidophilus) L-lactate dehydrogenases, purified to homogeneity by affinity chromatography, were determined. The amino acid composition of the only tryptic peptide unequivocally common to the fingerprints of the 4 enzymes is virtually identical with that of the arginine peptide, called Arg6 of the the substratebinding site of the L-lactate dehydrogenase dehydrogenase of several animals. However, the 'essential' cysteine residue 165 is replaced by threonine, as it is in the L-lactate dehydrogenase of lobster. In addition, the 4 bacterial peptides differ by one or two changes in single amino acid residues from each other as well as from those of animals. The data indicate that not only the animal L-lactate dehydrogenases, but also the allosteric and lactate dehydrogenases from bacterial sources may have evolved from a common gene.

Amino Acids↗
PubMed1976

Grouping and cross-reacting antigens of oral lactic acid bacteria.

The grouping antigens from five of the seven serological groups of lactobacilli have been defined with respect to the carbohydrate units responsible for serological specificity. When the antigens are polysaccharides, specificity is more absolute than with the teichoic acids where cross-reactions may occur because of the same or similar carbohydrate substituents, or more particularly because of the common "backbone" structure of the glycerol teichoic acids. This glycerol phosphate "backbone" accounts for a number of reports on the presence of a "common antigen" in gram-positive organisms and their culture fluids, with the amount of extracellular material being particularly high for S mutans strains.

Animals↗
PubMed1977

Transport and metabolism of vitamin B6 in lactic acid bacteria.

Streptococcus faecalis 8043 concentrates extracellular [3H]pyridoxal or [3H]pyridoxamine primarily as the corresponding 5'-phosphates. Accumulation of pyridoxamine requires an exogenous energy source and is inhibited by glycolysis inhibitors. A membrane potential is not required for transport of pyridoxamine, and an artificially generated potential does not drive uptake in this organism. Based on this and other evidence, it is concluded that S. faecalis accumulates pyridoxamine by facilitated diffusion in conjunction with trapping by pyridoxal kinase. Pyridoxamine-P is not concentrated, but equilibrates with that provided externally. Lactobacillus casei 7469 concentrates radioactivity only from pyridoxal, which appears internally as pyridoxal-P, suggesting that it too absorbs the vitamin by facilitated diffusion plus trapping. The specificity of the growth requirement of S. faecalis and L. casei for vitamin B6 parallels the specificity of the transport systems for this vitamin in these organisms. Lactobacillus delbrueckii 7469, however, which specifically requires pyridoxamine-P or pyridoxal-P for growth, accumulates both these compounds and pyridoxine-P from the medium, apparently by active transport, but not pyridoxine, pyridoxamine, or pyridoxal. While pyridoxal-P and pyridoxamine-P are interconvertible in this organism, pyridoxine-P is not further metabolized, thus accounting for the specificity of the growth requirement. These and previous results show (a) that different organisms may employ quite different transport machinery in utilization of a given external nutrient, and (b) that the specificity of the growth requirement for a given form of a vitamin frequently arises from the specificity of transport, but that internal metabolism of the compounds also plays a significant role in some organisms.

Biological Transport, Active↗