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PubMed1992

Taxonomic study of the Lactobacillus acidophilus group, with recognition of Lactobacillus gallinarum sp. nov. and Lactobacillus johnsonii sp. nov. and synonymy of Lactobacillus acidophilus group A3 (Johnson et al. 1980) with the type strain of Lactobacillus amylovorus (Nakamura 1981).

Biochemical properties and DNA-DNA reassociation studies of Lactobacillus acidophilus strains isolated from humans and animals indicate that these include six genomospecies. Two new species can be differentiated from the established species of the genus Lactobacillus: L. gallinarum sp. nov. (type strain, ATCC 33199) and L. johnsonii sp. nov. (type strain, ATCC 33200). Furthermore, it was clarified that L. acidophilus group A3 (Johnson et al. 1980) is synonymous with L. amylovorus.

DNA, Bacterial↗
PubMed2000

Characterization and purification of a bacteriocin produced by a potential probiotic culture, Lactobacillus acidophilus 30SC.

Lactobacillus acidophilus 30SC was tested for its potential as a probiotic culture. The strain exhibited good acid tolerance in an artificial gastric solution as well as bile resistance in media containing 0.3% bile acids. The strain produced a heat-stable antimicrobial compound that was shown to be proteinaceous in nature and, therefore, referred to as a bacteriocin. The bacteriocin was active over a wide pH range and inhibited a number of gram-positive bacteria including Listeria ivanovii and pathogenic strains. The bacteriocin was purified by 50% ammonium sulfate precipitation followed by hydrophobic interaction column chromatography. The SDS-PAGE of the active fractions resulted in a single band with estimated molecular mass of 3.5 kDa. These results demonstrate the potential of L. acidophilus 30SC as a probiotic culture that can be utilized in the manufacturing of dairy foods and dietary supplements.

Bacteriocins↗
PubMed1989

Characterization of the temperate bacteriophage phi adh and plasmid transduction in Lactobacillus acidophilus ADH.

Lactobacillus acidophilus ADH is lysogenic and harbors an inducible prophage, phi adh. Bacteriophage were detected in cell lysates induced by treatment with mitomycin C or UV light. Electron microscopy of lysates revealed phage particles with a hexagonal head (62 nm) and a long, noncontractile, flexible tail (398 nm) ending in at last five short fibers. Phage phi adh was classified within Bradley's B1 phage group and the Siphoviridae family. The phi adh genome is a linear double-stranded DNA molecule of 41.7 kilobase pairs with cohesive ends: a physical map of the phi adh genome was constructed. A prophage-cured derivative of strain ADH, designated NCK102, was isolated from cells that survived UV exposure. NCK102 did not exhibit mitomycin C-induced lysis, but broth cultures lysed upon addition of phage. Phage phi adh produced clear plaques on NCK102 in media containing 10 mM CaCl2 at pH values between 5.2 and 5.5. A relysogenized derivative (NCK103) of NCK102 was isolated that exhibited mitomycin C-induced lysis and superinfection immunity to phage phi adh. Hybridization experiments showed that the phi adh genome was present in the ADH and NCK103 chromosomes, but absent in NCK102. These results demonstrated classic lytic and lysogenic cycles of replication for the temperate phage phi adh induced from L. acidophilus ADH. Phage phi adh also mediates transduction of plasmid DNA. Transductants of strain ADH containing pC194, pGK12, pGB354, and pVA797 were detected at frequencies in the range of 3.6 x 10(-8) to 8.3 x 10(-10) per PFU. Rearrangements or deletions were not detected in these plasmids as a consequence of transduction. This is the first description of plasmid transduction in the genus Lactobacillus.

Bacteriophages↗
PubMed1998

Isolation and characterization of two bacteriocins of Lactobacillus acidophilus LF221.

Lactobacillus acidophilus LF221 produced bacteriocin-like activity against different bacteria including some pathogenic and food-spoilage species. Besides some lactic acid bacteria, the following species were inhibited: Bacillus cereus, Clostridium sp., Listeria innocua, Staphylococcus aureus, Streptococcus D. L. acidophilus LF221 produced at least two bacteriocins, acidocin LF221 A and acidocin LF221 B, which were purified by ammonium sulphate precipitation, ion-exchange chromatography, hydrophobic interaction and reverse-phase FPLC. The antibacterial substances were heat-stable, sensitive to proteolytic enzymes (trypsin, pepsin, pronase, proteinase K) and migrated as 3500- to 5000-Da proteins on sodium dodecyl sulphate/polyacrylamide gel electrophoresis. The sequences of 46 amino-terminal amino acid residues of peptide A and 35 of peptide B were determined. Among the residues identified, no modified amino acids were found. No significant homology was found between the amino acid sequences of acidocin LF221 A and other bacteriocins of lactic acid bacteria and 26% homology was found between acidocin LF221 B and brevicin 27. L. acidophilus LF221 may be of interest as a probiotic strain because of its human origin and inhibition of pathogenic bacteria, especially clostridium difficile.

Amino Acid Sequence↗
PubMed2005

Complete genome sequence of the probiotic lactic acid bacterium Lactobacillus acidophilus NCFM.

Lactobacillus acidophilus NCFM is a probiotic bacterium that has been produced commercially since 1972. The complete genome is 1,993,564 nt and devoid of plasmids. The average GC content is 34.71% with 1,864 predicted ORFs, of which 72.5% were functionally classified. Nine phage-related integrases were predicted, but no complete prophages were found. However, three unique regions designated as potential autonomous units (PAUs) were identified. These units resemble a unique structure and bear characteristics of both plasmids and phages. Analysis of the three PAUs revealed the presence of two R/M systems and a prophage maintenance system killer protein. A spacers interspersed direct repeat locus containing 32 nearly perfect 29-bp repeats was discovered and may provide a unique molecular signature for this organism. In silico analyses predicted 17 transposase genes and a chromosomal locus for lactacin B, a class II bacteriocin. Several mucus- and fibronectin-binding proteins, implicated in adhesion to human intestinal cells, were also identified. Gene clusters for transport of a diverse group of carbohydrates, including fructooligosaccharides and raffinose, were present and often accompanied by transcriptional regulators of the lacI family. For protein degradation and peptide utilization, the organism encoded 20 putative peptidases, homologs for PrtP and PrtM, and two complete oligopeptide transport systems. Nine two-component regulatory systems were predicted, some associated with determinants implicated in bacteriocin production and acid tolerance. Collectively, these features within the genome sequence of L. acidophilus are likely to contribute to the organisms' gastric survival and promote interactions with the intestinal mucosa and microbiota.

Bacterial Adhesion↗
PubMed1983

Purification and properties of the inhibitory protein isolated from Lactobacillus acidophilus AC1.

Lactobacillus acidophilus AC1 was found to produce a proteinic inhibitor having a molecular weight of 5.4 kd, active against both Gram-positive and Gram-negative bacteria. Some of the sensitive bacteria were found to be resistant to most of the commonly employed drugs and antibiotics. Sodium dodecyl sulphate polyacrylamide gel electrophoresis of the purified inhibitor showed the presence of a single polypeptide. The inhibitor was active over a wide pH range from 4.0 to 7.5. It was heat sensitive, and complete inactivation occurred within 20 min at 50 degrees C. The purified inhibitor lost 50% of its activity within 24 h at room temperature and after 5 days at 4 degrees-8 degrees C. The inhibitory protein was readily distinguished from other inhibitors in lactic cultures by its immunological cross-reactivity.

Anti-Bacterial Agents↗
PubMed2000

Use of the DNA sequence of variable regions of the 16S rRNA gene for rapid and accurate identification of bacteria in the Lactobacillus acidophilus complex.

The Lactobacillus acidophilus complex includes Lact. acidophilus, Lactobacillus amylovorus, Lactobacillus crispatus, Lactobacillus gallinarum, Lactobacillus gasseri and Lactobacillus johnsonii. The objective of this work was to develop a rapid and definitive DNA sequence-based identification system for unknown isolates of the Lact. acidophilus complex. A approximately = 500 bp region of the 16S rRNA gene, which contained the V1 and V2 variable regions, was amplified from the isolates by the polymerase chain reaction. The sequence of this region of the 16S rRNA gene from the type strains of the Lact. acidophilus complex was sufficiently variable to allow for clear differentiation amongst each of the strains. As an initial step in the characterization of potentially probiotic strains, this technique was successfully used to identify a variety of unknown human intestinal isolates. The approach described here represents a rapid and definitive method for the identification of Lact. acidophilus complex members.

Base Sequence↗
PubMed2006

Immune enhancing effects of Lactobacillus acidophilus LAFTI L10 and Lactobacillus paracasei LAFTI L26 in mice.

The immune enhancing properties of Lactobacillus acidophilus LAFTI L10 and Lactobacillus paracasei LAFTI L26 in mice were investigated. Each mouse (BALB/c) was orally fed with cultures of either L. acidophilus or L. paracasei at 10(8) CFU/50 mul per day for 14 days. The effect of these strains on immunoglobulin A, interleukin-10 and interferon gamma producing cells in the gut immune system was determined by immunofluorescence assays. Systemic immune responses were analysed in mice serum upon euthanising after a 14-day feeding trial to estimate cytokines such as IL-10 and IFN-gamma by enzyme-linked immunosorbent assays. L. acidophilus and L. paracasei strains demonstrated an increase in the number of IgA producing cells, IL-10 and IFN-gamma cytokine producing cells in the small intestine. In the systemic immune response, mice fed with L. acidophilus or L. paracasei also enhanced the secretion of anti-inflammatory cytokine (IL-10) and pro-inflammatory cytokine (IFN-gamma). The results of this study suggest that L. acidophilus and L. paracasei were able to enhance specific gut and systemic immune responses in mice.

Animals↗
PubMed1987

Conjugal Transfer of Plasmid-Encoded Determinants for Bacteriocin Production and Immunity in Lactobacillus acidophilus 88.

Lactobacillus acidophilus 88 produced a bacteriocin, designated lactacin F, that demonstrated inhibitory activity toward L. acidophilus 6032, L. lactis 970, L. helveticus 87, L. bulgaricus 1489, L. leichmanii 4797, L. fermentum 1750, and Streptococcus faecalis 19433. Production of lactacin F was pH dependent and could be maximized in MRS broth cultures maintained at pH 7.0. Lactacin F was heat stable and sensitive to ficin, proteinase K, trypsin, and Bacillus subtilis protease. L. acidophilus 88 harbored plasmids of 4 and 27 megadaltons. Variants of L. acidophilus 88 which were deficient in lactacin F production (Laf) and lactacin F immunity (Laf) retained the two resident plasmids. A Laf Laf derivative, L. acidophilus 89, was used as a recipient in agar surface mating experiments with L. acidophilus 88 (Laf Laf). Two types of Laf Laf transconjugants were recovered. One type (T-E) had acquired two plasmids of 68 (pPM68) and 52 (pPM52) megadaltons that were not detected in either the conjugal donor or the other type of Laf Laf transconjugants (T-89). Laf and Laf were unstable in the plasmid-bearing transconjugant. Plasmid analysis of Laf Laf variants revealed that pPM52 and pPM68 were cured with loss of Laf and Laf. Bacteriocin production and immunity phenotypes were genetically stable in Laf Laf transconjugants not harboring pPM52 and pPM68, suggesting chromosomal integration of the transferred determinants. The data demonstrated intragenic conjugation in L. acidophilus and provided direct evidence for involvement of transient plasmid determinants in Laf and Laf.

Journal Article↗
PubMed1998

Characterization of natural isolate Lactobacillus acidophilus BGRA43 useful for acidophilus milk production.

Lactobacillus acidophilus BGRA43 was selected from a set of human origin isolates of Lact. acidophilus strains for the highest growth rates and antagonistic effect against both Gram-positive and Gram-negative bacteria. The strain BGRA43 also exhibited an inhibitory effect on the growth of Clostridium sporogenes. Inhibition of this strain seems to be due to lactic acid production rather than hydrogen peroxide or bacteriocin. Growth of Lact. acidophilus BGRA43 in non-fat skim milk for 6 h at 37 degrees C resulted in a lowering of the pH value to 4.53. Besides the fast acidification, this strain generated a high viscosity of skim milk. These characteristics make the strain BGRA43 attractive for acidophilus milk production. Lactobacillus acidophilus BGRA43 produces an extracellular proteinase. Whole cells efficiently degraded casein for 3 h at 37 degrees C especially alpha- and beta-casein fractions. Total DNA isolated from the strain BGRA43 did not show any hybridization with lactococcal proteinase probes indicating that this strain produces a distinctive proteinase.

Animals↗
PubMed1998

[Lactobacillus acidophilus endocarditis].

BACKGROUND: Lactobacillus is a commensal germ found in the buccal cavity, the digestive tract and the vagina. Usually non-pathogenic except in case of dental caries, it can occasionally be the causal agent in severe endocarditis. CASE REPORT: A 70-year-old woman developed endocarditis on an aortic valve bioprosthesis. Lactobacillus acidophilus was isolated from blood cultures of the valve after surgery. COMMENTS: Forty-four cases of Lactobacillus endocarditis have been reported in the literature to date. Mortality is high (26%). The main difficulty in treatment is germ tolerance to penicillin and aminosides found in all cases. Cure requires high dose parenteral antibiotics and surgery in many cases (26%).

Aged↗
PubMed2000

Production kinetics of acidophilin 801, a bacteriocin produced by Lactobacillus acidophilus IBB 801.

Lactobacillus acidophilus IBB 801 produces a small bacteriocin, designated acidophilin 801. Studying the relationship between growth and bacteriocin biosynthesis revealed primary metabolite kinetics of bacteriocin production with a peak activity at the end of the exponential growth phase followed by a decrease during the stationary phase. Both microbial growth and bacteriocin production was inhibited by lactic acid. Whereas volumetric bacteriocin production (activity units (AU) ml(-1)) was favoured under pH-controlled conditions, bacteriocin titres rapidly decreased because of strong adsorption of the bacteriocin molecules to the producing cells under less acidic conditions.

Bacteriocins↗