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PubMed2026

Lactobacillus iners at the nexus of microbiota, immunity, and pregnancy.

Pregnancy induces a dynamic reconfiguration of the vaginal microbiome, typically marked by increased dominance of Lactobacillus species and reduced microbial diversity. Among these bacteria, Lactobacillus iners stands out for its unique genomic traits, controversial associations with vaginal health, and frequent presence across all stages of gestation. This review synthesizes current literature on the maternal microbiome with a focus on L. iners, exploring its strain-level diversity, metabolic idiosyncrasies, and inflammatory potential. We discuss how host factors such as ethnicity, sexual activity, maternal age, and especially obesity, influence microbial composition, and evaluate conflicting data surrounding L. iners in contexts like in vitro fertilization, preterm birth, and postpartum recovery. Emerging evidence suggests that L. iners may act as a transitional species, whose effect on pregnancy outcomes depends on its abundance, genetic features, and interactions with the host immune system. We also assess limitations of current animal models and propose future directions for understanding this enigmatic bacterium. Unraveling the role of L. iners will be essential to predicting, preventing, and managing adverse pregnancy outcomes in diverse populations.

Humans↗
PubMed2003

Partial purification and characterization of the bacteriocin produced by Lactobacillus acidophilus YIT 0154.

One strain of Lactobacillus acidophilus was found to produce a bacteriocin-like substance in the culture filtrate. The substance was produced in a growth-associated manner, showed heat stability at neutral and acidic pH and exhibited antibacterial activity against various species of Lactobacillus including L. acidophilus itself. The molecular weight of the substance was in the range of 6.2-95 kDa. N-terminal amino acid sequence analysis suggests that the substance may belong to class IIb bacteriocin.

Bacteria↗
PubMed2004

Effects of ingesting Lactobacillus- and Bifidobacterium-containing yogurt in subjects with colonized Helicobacter pylori.

BACKGROUND: Evidence suggests that ingesting lactic acid bacteria exerts a suppressive effect on Helicobacter pylori infection in both animals and humans. Supplementing with Lactobacillus- and Bifidobacterium-containing yogurt (AB-yogurt) was shown to improve the rates of eradication of H. pylori in humans. OBJECTIVE: We administered AB-yogurt to subjects with asymptomatic H. pylori to test whether the yogurt could inhibit H. pylori growth. DESIGN: The in vitro inhibition of H. pylori growth was determined by inoculating Lactobacillus acidophilus La5 or Bifidobacterium lactis Bb12 on plates that were inoculated with H. pylori. Assessment of the viability of H. pylori was performed by the mixed culture method with La5 or Bb12. In an intervention study, 59 adult volunteers infected with H. pylori were given AB-yogurt (10(7) colony-forming units of both La5 and Bb12/mL) twice daily after a meal for 6 wk. Eleven subjects positive for H. pylori infection were treated with milk placebo as control subjects. H. pylori bacterial loads were determined with use of the (13)C-urea breath test, which was performed before and 4 and 8 wk after the start of AB-yogurt supplementation. RESULTS: Bb12 exerted an in vitro inhibitory effect against H. pylori, whereas La5 did not show an effect. Administration of AB-yogurt decreased the urease activity of H. pylori after 6 wk of therapy (P < 0.0001). CONCLUSION: Regular intake of yogurt containing Bb12 and La5 effectively suppressed H. pylori infection in humans.

Adult↗
PubMed1999

Characterization and production of amylovorin L471, a bacteriocin purified from Lactobacillus amylovorus DCE 471 by a novel three-step method.

The strongly hydrophobic bacteriocin amylovorin L471 from Lactobacillus amylovorus DCE 471 was isolated and purified to homogeneity from complex culture broth by a novel, rapid and simple three-step protocol including (i) ammonium sulphate precipitation, (ii) chloroform/methanol extraction/precipitation and (iii) reversed-phase HPLC, the only chromatographic step involved. The molecular mass of the peptide was determined to be 4876.9 Da by electrospray mass spectrometric analysis. N-terminal amino acid sequencing identified 35 amino acid residues as being identical to the N-terminal sequence of lactobin A, a bacteriocin from another L. amylovorus strain. These non-identical strains produce bacteriocins that display small differences in molecular mass and inhibitory spectrum. The amino acid sequence of amylovorin L471 shared significant homology with lactacin X, one of the two bactericidal peptides produced by Lactobacillus johnsonii VPI11088. A purified amylovorin L471 preparation permitted confirmation of the inhibitory spectrum previously established with a crude extract. It displayed a bactericidal mode of action on lactobacilli after an extremely rapid adsorption to the target cells. Two Listeria spp. were only weakly sensitive. Amylovorin L471 appears to be produced constitutively. Ethanol not only stimulated specific bacteriocin production but also prevented adsorption of the bacteriocin molecules to the producer cells upon prolonged fermentation. The latter result supports the hypothesis that the apparent inactivation of bacteriocin observed during the stationary phase of batch fermentations is due to adsorption.

Amino Acid Sequence↗
PubMed1987

Characterization and DNA homology of Lactobacillus strains isolated from pig intestine.

Twenty strains of the genus Lactobacillus were isolated from pig intestines and characterized with phenotypic tests. Eleven of these strains, together with selected reference strains, were subjected to DNA homology studies. Three major groups could be distinguished by biochemical/physiological tests and by DNA homology studies: one homofermentative group of the subgenus Thermobacterium and two heterofermentative groups. The DNA homology studies revealed that strains from the homofermentative group were related to Lactobacillus acidophilus strain VPI 1754, but showed a low relationship to the type strain of Lact. acidophilus. One One group of the heterofermentative strains was related to the type strain of Lact. reuteri; the other group, consisting of three strains, showed a low relationship to all reference strains used. These three strains had the unusual property of producing succinic acid in large amounts.

Animals↗
PubMed1996

Effect of adherent Lactobacillus spp. on in vitro adherence of salmonellae to the intestinal epithelial cells of chicken.

Single strains of Lactobacillus acidophilus and Lact. fermentum, isolated from chicken intestine, were used to study in vitro interactions with Salmonella enteritidis, Salm. pullorum or Salm. typhimurium in an ileal epithelial cell (IEC) radioactive assay. Exclusion, competition and displacement phenomena were investigated by respectively incubating (a) lactobacilli and IEC together, prior to addition of salmonellae, (b) lactobacilli, IEC and salmonellae together, and (c) salmonellae and IEC, followed by the lactobacilli. Lactobacilli were selected for study because of their strong ability to adhere to IEC and poor aggregation with salmonellae. The results demonstrated that Lact. acidophilus significantly reduced (P < 0.05) the attachment of Salm. pullorum to IEC in the tests for exclusion and competition, but not in the displacement tests. Lactobacillus fermentum was found to have some ability to reduce the attachment of Salm. typhimurium to IEC under the conditions of exclusion (P < 0.08), competition (P < 0.09), but not displacement. However, both Lact. acidophilus and Lact. fermentum were unable to reduce the adherence of Salm. enteritidis to IEC under any of the conditions.

Animals↗
PubMed1981

Lactobacillus prophylaxis for diarrhea due to enterotoxigenic Escherichia coli.

In vitro and animal experiments indicated that lactobacilli might prevent Escherichia coli from colonizing the intestine and may produce substances counteracting enterotoxin. Lactinex, a commercial preparation of dried Lactobacillus acidophilus and L. bulgaricus, is marketed for uncomplicated diarrhea. Preliminary experiments in nonfasting volunteers indicated that lactobacilli in this preparation colonized the small intestine for up to 6 h. To evaluate the protective efficacy of Lactinex, a double-blind randomized study was carried out in which 48 volunteers (23 receiving Lactinex and 25 receiving placebos) were challenged with E. coli strains that produced heat-stable or heat-labile enterotoxins or both. No significant differences between the two groups were noted with respect to attack rate, incubation period, duration of diarrhea, volume and number of liquid stools, and coproculture yields. These data suggest that this lactobacillus preparations does not prevent or alter the course of enterotoxigenic E. coli diarrhea in adults. Lack of efficacy occurred despite efforts to maximize small bowel colonization, including administration of Lactinex in milk and in a 6-hour-interval regimen during 36 h before and 96 h after challenge.

Adolescent↗
PubMed1999

Cell surface-associated lipoteichoic acid acts as an adhesion factor for attachment of Lactobacillus johnsonii La1 to human enterocyte-like Caco-2 cells.

The influence of pH on the adhesion of two Lactobacillus strains to Caco-2 human intestinal cells was investigated. One strain, Lactobacillus johnsonii La1, was adherent at any pH between 4 and 7. The other one, L. acidophilus La10, did not attach to this cell line under the same experimental conditions. On the basis of these results, we used the monoclonal antibody technique as a tool to determine differences on the surface of these bacteria and to identify a factor for adhesion. Mice were immunized with live La1, and the hybridomas produced by fusion of spleen cells with ONS1 cells were screened for the production of antibodies specific for L. johnsonii La1. A set of these monoclonal antibodies was directed against a nonproteinaceous component of the L. johnsonii La1 surface. It was identified as lipoteichoic acid (LTA). This molecule was isolated, chemically characterized, and tested in adhesion experiments in the same system. The adhesion of L. johnsonii La1 to Caco-2 cells was inhibited in a concentration-dependent way by purified LTA as well as by L. johnsonii La1 culture supernatant that contained LTA. These results showed that the mechanism of adhesion of L. johnsonii La1 to human Caco-2 cells involves LTA.

Animals↗
PubMed2001

16S ribosomal DNA terminal restriction fragment pattern analysis of bacterial communities in feces of rats fed Lactobacillus acidophilus NCFM.

16S ribosomal DNA terminal restriction fragment patterns from rat fecal samples were analyzed to track the dynamics of Lactobacillus acidophilus NCFM and discern bacterial populations that changed during feeding with NCFM. Lactobacillus johnsonii and Ruminococcus flavefaciens were tentatively identified as such bacterial populations. The presence of L. johnsonii was confirmed by isolation from feces.

Animal Nutritional Physiological Phenomena↗
PubMed1991

Cloning, phenotypic expression, and DNA sequence of the gene for lactacin F, an antimicrobial peptide produced by Lactobacillus spp.

Lactacin F is a heat-stable bacteriocin produced by Lactobacillus acidophilus 11088. A 63-mer oligonucleotide probe deduced from the N-terminal lactacin F amino acid sequence was used to clone the putative laf structural gene from plasmid DNA of a lactacin F-producing transconjugant, L. acidophilus T143. One clone, NCK360, harbored a recombinant plasmid, pTRK160, which contained a 2.2-kb EcoRI fragment of the size expected from hybridization experiments. An Escherichia coli-L. acidophilus shuttle vector was constructed, and a subclone (pTRK162) containing the 2.2-kb EcoRI fragment was introduced by electroporation into two lactacin F-negative strains, L. acidophilus 89 and 88-C. Lactobacillus transformants containing pTRK162 expressed lactacin F activity and immunity. Bacteriocin produced by the transformants exhibited an inhibitory spectrum and heat stability identical to those of the wild-type bacteriocin. An 873-bp region of the 2.2-kb fragment was sequenced by using a 20-mer degenerate lactacin F-specific primer to initiate sequencing from within the lactacin F structural gene. Analysis of the resulting sequence identified an open reading frame which could encode a protein of 75 amino acids. The 25 N-terminal amino acids for lactacin F were identified within the open reading frame along with an N-terminal extension, possibly a signal sequence. The lactacin F N-terminal sequence, through the remainder of the open reading frame (57 amino acids; 6.3 kDa), correlated extremely well with composition analyses of purified lactacin F which also predicted a size of 51 to 56 amino acid residues. Molecular characterization of lactacin F identified a small hydrophobic peptide that may be representative of a common bacteriocin class in lactic acid bacteria.

Amino Acid Sequence↗
PubMed1961

Phthiocol and menadione as acetate-replacing factors for Lactobacillus delbrueckii.

MaciasR, Frank M. (Northrop Corporation, Hawthorne, Calif.). Phthiocol and menadione as acetate-replacing factors for Lactobacillus delbrueckii. J. Bacteriol. 82:657-661. 1961.-Lactobacillus delbrueckii (ATCC 9649), when cultured under nitrogen, or in ferrous iron-containing media exposed to air, requires, for the initiation of growth, compounds that are known to behave as electron acceptors. The ferrous iron probably induces what amounts to anaerobic conditions; that is, it blocks access of the organism to oxygen. Several electron carriers, such as methylene blue and naphthoquinones, stimulate growth of the organism in acetate-free media exposed to air. The most active acetate-replacing agent found is phthiocol. Methylene blue does not stimulate growth under nitrogen. It is suggested that the naphthoquinones bring about the initial oxidations required for growth by transferring the electrons to some other constituent of the medium. Growth of the organism in acetate-free media under CO(2) indicates that CO(2) or its fixation product can behave also as an initial oxidant.

Acetates↗
PubMed1963

EXTRACELLULAR POLYSACCHARIDE OF MUCOID LACTOBACILLUS BIFIDUS.

Wang, Marian (University of Pennsylvania, Philadelphia), Edward Steers, and Robert F. Norris. Extracellular polysaccharide of mucoid Lactobacillus bifidus. J. Bacteriol. 86:898-903. 1963.-The extracellular polysaccharide produced by the "Jackson-mucoid" strain of Lactobacillus bifidus was isolated and purified by three different procedures. The component sugars of the polysaccharide were identified by paper chromatography and confirmed by infrared analysis. Galacturonic acid, galactose, glucose, and 6-deoxy-talose were identified. Contrary to a previous report from this laboratory, fucose was not found to be a component of this polysaccharide.

Fucose↗
PubMed1963

QUANTITATIVE STUDIES ON GLYCOLYTIC ENZYMES IN LACTOBACILLUS PLANTARUM. I. CONCENTRATION OF INORGANIC IONS AND COENZYMES IN FERMENTING CELLS.

Mizushima, Shôji (University of Tokyo, Tokyo, Japan), Yoshiaki Machida, and Kakuo Kitahara. Quantitative studies on glycolytic enzymes in Lactobacillus plantarum. I. Concentration of inorganic ions and coenzymes in fermenting cells. J. Bacteriol. 86:1295-1300. 1963.-An attempt was made to summarize the intracellular conditions of Lactobacillus plantarum in which a lactic acid fermentation proceeded at a steady state. The structure of the fermenting cell was studied by fractionating the cell constituents and measuring the volume of each constituent by the inulin space method. The pH value in the cell was estimated to be 5.4. The intracellular concentrations of inorganic ions and coenzymes and their changes during the fermentation are also presented.

Adenine Nucleotides↗
PubMed1964

NUTRITIONAL REQUIREMENTS OF LACTOBACILLUS 30A FOR GROWTH AND HISTIDINE DECARBOXYLASE PRODUCTION.

Guirard, Beverly M. (University of California, Berkeley), and Esmond E. Snell. Nutritional requirements of Lactobacillus 30a for growth and histidine decarboxylase production. J. Bacteriol. 87:370-376. 1964.-The nutritional requirements of Lactobacillus 30a include each of the naturally occurring amino acids, several B vitamins, ascorbic acid, glucose, acetate, and oleate. The nutritional requirements for optimal histidine decarboxylase production (up to 900 muliters of CO(2) per hr per mg of cells) differ to some extent from those for optimal growth. Wholly synthetic and partially defined media are described which produce high enzyme activity, together with rapid and luxuriant growth.

Amino Acids↗
PubMed1964

METABOLISM OF MEVALONIC ACID BY LACTOBACILLUS PLANTARUM.

Durr, I. F. (American University of Beirut, Beirut, Lebanon), and A. N. Shwayri. Metabolism of mevalonic acid by Lactobacillus plantarum. J. Bacteriol. 88:361-366. 1964.-Lactobacillus plantarum strain 8014-H(2), unlike other lactobacilli studied, does not require mevalonic acid for growth, but growing and resting cells utilize it only for the synthesis of nonsaponifiable lipids. Upon the incubation of washed cells with mevalolactone-2-C(14), the label appeared in the lipids but not in CO(2). On the other hand, when mevalolactone-1-C(14) was used, the label appeared in CO(2) but not in lipids. For every mole of CO(2) liberated, 1 mole of radioactive carbon was introduced in the lipids, suggesting that terpenic polymers were synthesized. Amino acids did not stimulate the utilization of mevalonic acid. Starved cells could not synthesize nonsaponifiable lipids from mevalonic acid unless glucose was supplied. Sodium fluoride (0.14 m), 2,4-dinitrophenol (0.003 m), p-hydroxymercuribenzoate (0.0013 m), potassium phosphate (0.1 m), and ammonium formate (0.04 m) were potent inhibitors. Cells metabolized only one isomer of dl-mevalonic, and utilized the salt form at least twice as efficiently as the lactone. Optimal synthesis of lipids from mevalonic acid occurred aerobically, at pH 5 and 30 C.

2,4-Dinitrophenol↗
PubMed1965

ISOLATION AND CHARACTERIZATION OF THE CYANIDE-RESISTANT AND AZIDE-RESISTANT CATALASE OF LACTOBACILLUS PLANTARUM.

Johnston, M. A. (Cornell University, Ithaca, N.Y.), and E. A. Delwiche. Isolation and characterization of the cyanide-resistant and azide-resistant catalase of Lactobacillus plantarum. J. Bacteriol. 90:352-356. 1965.-Lactobacillus plantarum T-1403-5 has been shown to possess a very active cyanide- and azide-resistant catalase. By means of fractional ammonium sulfate precipitation, removal of nucleic acids with protamine sulfate, adsorption on calcium phosphate gel, and pH gradient chromatography on diethylaminoethyl cellulose, the catalase "activity" was purified approximately 14-fold. The purified enzyme preparation was insensitive to the heme poisons cyanide and azide, the metal chelating agents ethylenediaminetetraacetate and o-phenanthroline, and the sulfhydryl binding agent p-chloromercuribenzoate. The purified enzyme moved at a uniform rate in the electrophoretic field (isoelectric point, pH 4.7). The ultraviolet-light absorption spectrum was negative for heme-iron components, and fluorescence measurements yielded negative results with regard to flavin components. Acriflavin and Atabrine had no effect on enzyme activity. The nonheme catalase displayed a much broader pH range of activity than the heme-iron catalase of a control culture of Escherichia coli and the azide-sensitive catalase developed by L. plantarum NZ48 when grown in the presence of preformed hematin. The nonheme catalase was more resistant to heat inactivation. No retention of the enzyme on a chromatographic column could be obtained with Sephadex 200, nor could the enzyme be separated from crystalline beef-liver catalase by the gel filtration technique. Sedimentation was obtained in a centrifugal field of 144,000 x g for 12 hr.

Animals↗
PubMed2026

Expanding vaginal microbiome pangenomes via a custom MIDAS database reveals Lactobacillus crispatus accessory genes associated with cervical dysplasia.

The vaginal microbiome plays a central role in reproductive health. Vaginal microbiome dysbiosis is associated with many adverse reproductive health outcomes, but most studies have focused on associations at the species level. The potential contribution of intraspecies microbial variation, especially gene content differences across bacterial strains, remains underexplored in reproductive health contexts. The Metagenomic Intra-Species Diversity Analysis (MIDAS) framework enables such analyses, but depends on comprehensive reference databases. We constructed a MIDAS-compatible pangenome database from over 18,000 genomes in the Vaginal Microbiome Genome Collection (VMGC). Compared to the Genome Taxonomy Database (GTDB)-derived reference, the VMGC-derived database expanded the pangenomes of prevalent vaginal species, better capturing vaginal-specific intraspecies diversity. Applying this database to vaginal samples from a cervical dysplasia cohort, we identified 13 Lactobacillus crispatus accessory genes significantly associated with cervical dysplasia, including a HicAB toxin-antitoxin system, three transcriptional regulators, and three phage-derived genes. These findings highlight the utility of body site-specific reference resources and shotgun metagenomic sequencing for uncovering intraspecies microbial variation relevant to reproductive health.IMPORTANCEThe vaginal microbiome plays a critical role in reproductive health, and different bacteria from the same species can carry different genes that influence how the strains interact with the host and other microbes. These strain-level differences are often overlooked when microbiomes are analyzed only at the species level. Existing genomic reference databases are heavily biased toward gut and environmental bacteria, leaving the genetic diversity of vaginal microbes understudied. We built a specialized reference database from over 18,000 vaginal bacterial genomes that better reflects this diversity. We then applied this resource to quantify gene-level variation in vaginal samples from a cervical dysplasia cohort. Focusing on Lactobacillus crispatus, a prevalent and often beneficial vaginal species, we identified 13 genes that were more common in women with cervical dysplasia than in controls. This work demonstrates that body site-specific genomic resources are essential for uncovering strain-level bacterial differences relevant to reproductive health.

Lactobacillus crispatus↗
PubMed2025

Pangenome analysis of Lactobacillus mulieris strains reveals distinct subspecies clusters with defined ecological adaptations.

Lactobacillus mulieris is a recently described species, reportedly isolated from human urine, vagina, and gut. Previous genomic studies of L. mulieris highlighted significant genetic diversity among its strains. To gain a deeper understanding of this genomic diversity, we conducted a comprehensive genomic comparison of 70 L. mulieris strains from diverse sources. Phylogenomic and genome relatedness analysis identified three distinct clades, each representing a potential subspecies cluster. Pangenome analysis revealed distinct gene clusters shaping the functional characteristics and unique ecological adaptations of each clade. Clade 1 demonstrated a generalist lifestyle, with strains isolated from diverse sources and enriched in serine/threonine protein kinases, suggesting adaptive versatility. Clade 2, predominantly composed of urinary isolates, displayed enrichment in genes facilitating nutrient acquisition and osmotic regulation, enabling survival in the nutrient-limited and high osmolarity conditions of the urinary tract. Clade 3, exclusively composed of vaginal isolates, exhibited significant enrichment in genes supporting glycogen metabolism, carbohydrate transport, and capsular polysaccharide biosynthesis-features indicative of adaptation to the vaginal environment. Collectively, our findings provide essential genomic insights into the ecological specialization of L. mulieris, shedding light on their genetic variability and adaptive traits within their respective ecological niches.IMPORTANCERecognizing the genomic diversity within Lactobacillus mulieris is essential for understanding its ecological specialization and adaptation strategies across distinct human-associated environments. By identifying three distinct clades with unique functional traits, our study highlights the critical role of niche-specific genetic adaptations in microbial survival. The presence of specialized gene functions within each clade underscores how evolutionary pressures shape bacterial resilience in different environments. Despite their coexistence in overlapping environments, these clades exhibit distinct genomic profiles that may influence their colonization potential and interactions with the host and within the host-associated microbiota. Our findings emphasize the need for a classification framework that accounts for these genetic and functional differences and the necessity for further investigation to understand their distinct roles and impact on human health.

Humans↗