Survival of Lactobacillus casei strain Shirota in the intestines of healthy Chinese adults

Lactobacillus casei strain Shirota (LcS) is a widely used probiotic strain with health benefits. In this study, the survival of LcS in the intestines of healthy Chinese adults was assessed and the effects of LcS on stool consistency, stool SCFAs and intestinal microbiota evaluated. Subjects consumed 100 mL per day of a probiotic beverage containing 1.0 × 10⁸ CFU/mL of LcS for 14 days. LcS were enumerated using a culture method and the colony identity confirmed by ELISA. Fourteen days after ingestion, the amount of LcS recovered from fecal samples was between 6.86 ± 0.80 and 7.17 ± 0.57 Log₁₀ CFU/g of feces (mean ± SD). The intestinal microbiotas were analyzed by denaturing gradient gel electrophoresis. Principal component analysis showed that consuming LcS significantly changed fecal microbiota profiles. According to redundancy analysis, the amounts of 25 bacterial strains were significantly correlated with LcS intake (P < 0.05), 11 of them positively and fourteen negatively. Concentrations of acetic acid and propionic acid in feces were significantly lower during the ingestion period than during the baseline period (P < 0.05). These results confirm that LcS can survive passage through the gastrointestinal tract of Chinese people; however, they were found to have little ability to persist once their consumption had ceased. Furthermore, consumption of probiotic beverages containing LcS can modulate the composition of the intestinal microbiota on a long‐term basis, resulting in decreased concentrations of SCFAs in the gut.     

Isolation and phenotypic characterization of Lactobacillus casei and Lactobacillus paracasei bacteriophage-resistant mutants

Aims: To isolate and characterize bacterial strains derived from Lactobacillus casei and Lactobacillus paracasei strains and resistant to phage MLC‐A. Methods and Results: Two of nine assayed strains rendered resistant mutants with recovery efficiencies of 83% (Lact. paracasei ATCC 27092) and 100% (Lact. casei ATCC 27139). DNA similarity coefficients (RAPD–PCR) confirmed that no significant genetic changes occurred while obtaining resistant mutants. Neither parent nor mutant strains spontaneously released phages. Phage‐resistant mutants were tested against phages PL‐1, J‐1, A2 and MLC‐A8. Lactobacillus casei ATCC 27092 mutants showed, overall, lower phage resistance than Lact. paracasei ATCC 27092 ones, but still higher than that of the parent strain. Lactobacillus paracasei ATCC 27092 mutants moderately adsorbed phage MLC‐A only in calcium presence, although their parent strain successfully did it with or without calcium. Adsorption rates for Lact. casei ATCC 27139 and its mutants were highly influenced by calcium. Again, phage adsorption was higher on the original strain. Conclusions: Several isolates derived from two Lact. casei and Lact. paracasei strains showed resistance to phage MLC‐A but also to other Lact. casei and Lact. paracasei phages. Significance and Impact of the Study: This study highlights isolation of spontaneous bacteriophage‐resistant mutants from Lact. casei and Lact. paracasei as a good choice for use in industrial rotation schemes.     

Beneficial effect of oral administration of Lactobacillus casei strain Shirota on insulin resistance in diet-induced obesity mice

Aims: This study aimed at determining whether oral administration of a probiotic strain, Lactobacillus casei strain Shirota (LcS), can improve insulin resistance, which is the underlying cause of obesity‐associated metabolic abnormalities, in diet‐induced obesity (DIO) mice. Methods and Results: DIO mice were fed a high‐fat diet without or with 0·05% LcS for 4 weeks and then subjected to an insulin tolerance test (ITT) or oral glucose tolerance test (OGTT). Oral administration of LcS not only accelerated the reduction in plasma glucose levels during the ITT, but also reduced the elevation of plasma glucose levels during the OGTT. In addition, plasma levels of lipopolysaccharide‐binding protein (LBP), which is a marker of endotoxaemia, were augmented in the murine models of obese DIO, ob/ob, db/db and KK‐A^y and compared to those of lean mice. LcS treatment suppressed the elevation of plasma LBP levels in DIO mice, but did not affect intra‐abdominal fat weight. Conclusions: LcS improves insulin resistance and glucose intolerance in DIO mice. The reduction in endotoxaemia, but not intra‐abdominal fat, may contribute to the beneficial effects of LcS. Significance and Impact of the Study: This study suggests that LcS has the potential to prevent obesity‐associated metabolic abnormalities by improving insulin resistance.     

Microbial products from probiotic bacteria inhibit Salmonella enteritidis 857-induced IL-8 synthesis in Caco-2 cells

Oral administration of Lactobacillus spp. as probiotics is gaining importance in the treatment of intestinal inflammations. However, their mechanism of action is unknown. We investigated whether nonspecific binding Lactobacillus casei Shirota (LcS) and mannose-specific Lactobacillus plantarum 299v (Lp) and their spent culture supernatant (SCS) affect Salmonella enteritidis 857 (Se) growth, IL-8 and Hsp70 syntheses. In one set of experiments human enterocyte-like Caco-2 cells were infected with LcS, Lp or Se at 1–500 bacteria per cell for 1 h. In another set, cells were exposed to Se (0–200 per cell, 1 h) after exposure to lactobacilli (LB) (500 per cell, 30 min) or by co-incubation of Se and LB (1 h). The third set of experiments involved exposure of cells for 1 h to SCS or Se (100 per cell) pretreated (1 h) in SCS. The effect of LB SCS on Se growth was evaluated by agar plate diffusion test. IL-8 and Hsp70 were assessed over 2–24 h using ELISA and Western blotting, respectively. Neither LcS nor Lp affected the Se growth and IL-8 production. In addition, they did not induce Hsp70 expression by Caco-2 cells. Instead, their SCS inhibited the Se growth and IL-8 production and induced the expression of Hsp70 by both crypt- and villus-like cells. The beneficial effect of Lactobacillus spp. to the intestinal inflammations might be associated with a decrease in IL-8 levels. This effect could be mediated, at least in part, via a secreted antimicrobial product(s) either directly against the pathogens or indirectly through the synthesis of Hsp70.     

Anti‐infectious activity of synbiotics in a novel mouse model of methicillin‐resistant Staphylococcus aureus infection

The anti‐infectious activity of synbiotics against methicillin‐resistant Staphylococcus aureus (MRSA) infection was evaluated using a novel lethal mouse model. Groups of 12 mice treated with multiple antibiotics were infected orally with a clinical isolate of MRSA at an inoculum of 10⁸ CFU on day 7 after starting the antibiotics. A dose of 400 mg/kg 5‐fluorouracil (5‐FU) was injected intraperitoneally on day 7 after the infection. A dose of 10⁸ CFU Bifidobacterium breve strain Yakult and 10 mg of galactooligosaccharides (GOS) were given orally to mice daily with the antibiotic treatment until day 28. The intestinal population levels of MRSA in the mice on multiple antibiotics were maintained stably at 10⁸ CFU/g of intestinal contents after oral MRSA infection and the subsequent 5‐FU treatment killed all the mice in the group within 14 days. B. breve administration saved most of the mice, but the synbiotic treatment saved all of the mice from lethal MRSA infection. The synbiotic treatment was effective for the treatment of intestinal infection caused by four MRSA strains with different toxin productions. There was a large difference among the six Bifidobacteria strains that were naturally resistant to the antibacterial drugs used. B. breve in combination with GOS is demonstrated to have valuable preventive and curative effects against even fatal MRSA infections.     

Inhibitory effect of oral Lactobacillus against oral pathogens

Aims: To determine the inhibitory effect of oral Lactobacillus against putative oral pathogens. Methods and Results: Total 357 strains comprising 10 species of oral Lactobacillus, Lactobacillus fermentum (195), Lactobacillus salivarius (53), Lactobacillus casei (20), Lactobacillus gasseri (18), Lactobacillus rhamnosus (14), Lactobacillus paracasei (12), Lactobacillus mucosae (12), Lactobacillus oris (12), Lactobacillus plantarum (11) and Lactobacillus vaginalis (10) were used as producer strains. Inhibitory effect against a panel of indicators, periodontitis‐ and caries‐related pathogens, was assessed. Most oral Lactobacillus was able to inhibit the growth of both periodontitis‐ and caries‐related pathogens. The strongest inhibitory activity was associated with Lact. paracasei, Lact. plantarum, Lact. rhamnosus, Lact. casei and Lact. salivarius. Lactobacillus SD1–SD6, representing the six species with the strong inhibitory effect, inhibited growth of Streptococcus mutans ATCC 25175 in the biofilm model. Also, it was demonstrated that growth of Strep. mutans was inhibited in a mixture with Lact. paracasei SD1. The inhibition was enhanced in acidic condition and 5% glucose. Conclusions: The results have shown that oral Lactobacillus SD1–SD6 showed a strong inhibitory effect against Strep. mutans and Streptococcus sobrinus, as well as, Gram‐negative periodontal pathogens Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans. Significance and Impact of the Study: The results indicated that Lactobacillus may be of benefit as probiotics for the prevention of oral diseases.     

Use of Group-Specific and RAPD-PCR Analyses for Rapid Differentiation of <Emphasis Type="Italic">Lactobacillus</Emphasis> Strains from Probiotic Yogurts

The increasing interest in probiotic lactobacilli implicates the requirement of techniques that allow a rapid and reliable identification of these organisms. In this study, group-specific PCR and RAPD-PCR analyses were used to identify strains of the Lactobacillus casei and Lactobacillus acidophilus groups most commonly used in probiotic yogurts. Group-specific PCR with primers for the L. casei and L. acidophilus groups, as well as L. gasseri/johnsonii, could differentiate between 20 Lactobacillus strains isolated from probiotic yogurts and assign these into the corresponding groups. For identification of these strains to species or strain level, RAPD profiles of the 20 Lactobacillus strains were compared with 11 reference strains of the L. acidophilus and L. casei group. All except one strain could be attributed unambigously to the species L. acidophilus, L. johnsonii, L. crispatus, L. casei, and L. paracasei. DNA reassociation analysis confirmed the classification resulting from the RAPD-PCR.     

Genomic Adaptation of the Lactobacillus casei Group

Lactobacillus casei, L. paracasei, and L. rhamnosus form a closely related taxonomic group (Lactobacillus casei group) within the facultatively heterofermentative lactobacilli. Here, we report the complete genome sequences of L. paracasei JCM 8130 and L. casei ATCC 393, and the draft genome sequence of L. paracasei COM0101, all of which were isolated from daily products. Furthermore, we re-annotated the genome of L. rhamnosus ATCC 53103 (also known as L. rhamnosus GG), which we have previously reported. We confirmed that ATCC 393 is distinct from other strains previously described as L. paracasei. The core genome of 10 completely sequenced strains of the L. casei group comprised 1,682 protein-coding genes. Although extensive genome-wide synteny was found among the L. casei group, the genomes of ATCC 53103, JCM 8130, and ATCC 393 contained genomic islands compared with L. paracasei ATCC 334. Several genomic islands, including carbohydrate utilization gene clusters, were found at the same loci in the chromosomes of the L. casei group. The spaCBA pilus gene cluster, which was first identified in GG, was also found in other strains of the L. casei group, but several L. paracasei strains including COM0101 contained truncated spaC gene. ATCC 53103 encoded a higher number of proteins involved in carbohydrate utilization compared with intestinal lactobacilli, and extracellular adhesion proteins, several of which are absent in other strains of the L. casei group. In addition to previously fully sequenced L. rhamnosus and L. paracasei strains, the complete genome sequences of L. casei will provide valuable insights into the evolution of the L. casei group.     

Evaluation of Numerical Analysis of Random Amplified Polymorphic DNA (RAPD)-PCR as a Method to Differentiate Lactobacillus plantarum and Lactobacillus pentosus

Lactobacillus plantarum and Lactobacillus pentosus grouped into one protein profile cluster at r ≥ 0.70, separate from Lactobacillus casei, Lactobacillus sake, and Lactobacillus curvatus. Similar sugar fermentation reactions were recorded for representative strains of L. plantarum and L. pentosus. Representative strains, including the type of each species, were selected from the different protein profile clusters and their genetic relatedness determined by using numerical analysis of random amplified polymorphic DNA (RAPD)-PCR. The type strains of L. plantarum (ATCC 14917^T) and L. pentosus (NCFB 363^T) displayed different RAPD profiles and grouped into two independent clusters, well separated from L. casei, L. curvatus, and L. sake. Numerical analysis of RAPD-PCR proved a reliable and accurate method to distinguish between strains of L. plantarum and L. pentosus.     

Probiotic Lactobacillus sp. inhibit growth,biofilm formation and gene expression of caries‐inducing Streptococcus mutans

Streptococcus mutans contributes significantly to dental caries, which arises from homoeostasic imbalance between host and microbiota. We hypothesized that Lactobacillus sp. inhibits growth, biofilm formation and gene expression of Streptococcus mutans. Antibacterial (agar diffusion method) and antibiofilm (crystal violet assay) characteristics of probiotic Lactobacillus sp. against Streptococcus mutans (ATCC 25175) were evaluated. We investigated whether Lactobacillus casei (ATCC 393), Lactobacillus reuteri (ATCC 23272), Lactobacillus plantarum (ATCC 14917) or Lactobacillus salivarius (ATCC 11741) inhibit expression of Streptococcus mutans genes involved in biofilm formation, quorum sensing or stress survival using quantitative real‐time polymerase chain reaction (qPCR). Growth changes (OD600) in the presence of pH‐neutralized, catalase‐treated or trypsin‐treated Lactobacillus sp. supernatants were assessed to identify roles of organic acids, peroxides and bacteriocin. Susceptibility testing indicated antibacterial (pH‐dependent) and antibiofilm activities of Lactobacillus sp. against Streptococcus mutans. Scanning electron microscopy revealed reduction in microcolony formation and exopolysaccharide structural changes. Of the oral normal flora, L. salivarius exhibited the highest antibiofilm and peroxide‐dependent antimicrobial activities. All biofilm‐forming cells treated with Lactobacillus sp. supernatants showed reduced expression of genes involved in exopolysaccharide production, acid tolerance and quorum sensing. Thus, Lactobacillus sp. can inhibit tooth decay by limiting growth and virulence properties of Streptococcus mutans.     

Antibiotic Susceptibility of Lactobacillus and Bifidobacterium Species from the Human Gastrointestinal Tract

One hundred and twenty-two strains of Bifidobacterium and Lactobacillus species have been tested against 12 antibiotics and two antibiotic mixtures by a commercial system (Sensititre Anaero3; Treck Diagnostic Systems). The upper limits of some minimum inhibitory concentrations (MICs) were completed on MRS agar plates by the NCCLS procedure. All strains were sensitive to chloramphenicol and imipenem and most of the strains were resistant to metronidazole. Bifidobacteria isolates were susceptible to cefoxitin, whereas about half of the lactobacilli were resistant. Approximately 30% of the Bifidobacterium isolates were resistant to tetracycline, as well as five Lactobacillus strains belonging to four different species. None of the tested Bifidobacterium isolates was resistant to vancomycin, whereas a species-dependent resistance was found among the lactobacilli. Single strains of Bifidobacterium longum, Bifidobacterium pseudocatenulatum, Lactobacillus acidophilus, Lactobacillus rhamnosus, and Lactobacillus brevis were resistant to erythromycin and/or clindamycin. Most of the observed resistances seemed to be intrinsic, but some others could be compatible with transmissible determinants.     

Stimulation of macrophages by immunobiotic Lactobacillus strains: influence beyond the intestinal tract

Lactobacillus rhamnosus CRL1505 (Lr1505), L. rhamnosus CRL1506 (Lr1506) and L. casei CRL431 (Lc431) are able to stimulate intestinal immunity, but only Lr1505 and Lc431 are able to stimulate immunity in the respiratory tract. With the aim of advancing the understanding of the immunological mechanisms involved in stimulation of distant mucosal sites, this study evaluated the effects of orally administered probiotics on the functions of alveolar and peritoneal macrophages. Compared to a control group, these three lactobacilli were able to significantly increase phagocytic and microbicidal activities of peritoneal macrophages. After intraperitoneal challenge with pathogenic Candida albicans, mice treated with immunobiotics had significantly lower pathogen counts in infected organs. Moreover, lactobacilli‐treated mice had a stronger immune response against C. albicans. On the other hand, only Lc1505 and Lc431 were able to improve activity of and cytokine production by alveolar macrophages. Only in these two groups was there better resistance to respiratory challenge with C. albicans, which correlated with improved respiratory immune response. The results of this study suggest that consumption of some probiotic strains could be useful for improving resistance to infections in sites distant from the gut by increasing the activity of macrophages at those sites.     

Genetic screening of wine‐related enzymes in Lactobacillus species isolated from South African wines

Aims: The objective of this study was to investigate the presence of genes coding for enzymes of oenological relevance in wine Lactobacillus strains isolated from South African grape and wine samples during the 2001 and 2002 harvest seasons. Methods and Results: A total of 120 wine lactobacilli isolates belonging to Lactobacillus plantarum, Lactobacillus hilgardii, Lactobacillus brevis, Lactobacillus pentosus, Lactobacillus paracasei, Lactobacillus sakei and Lactobacillus paraplantarum were genetically screened for enzyme‐encoding genes using PCR with primers specific for β‐glucosidase, protease, esterase, citrate lyase and phenolic acid decarboxylase. The results of PCR screening showed that the Lactobacillus strains possessed different combinations of enzymes and that some strains did not possess any of the enzymes tested. Confirmation analysis with gene sequencing also showed high similarity of genes with those available in GenBank database. Conclusion: In this study, we have demonstrated the existence of genes coding for wine‐related enzymes in wine lactobacilli that could potentially hydrolyse wine precursors to positively influence wine aroma. Significance and Impact of the Study: An expansion of knowledge on the genetic diversity of wine‐associated lactic acid bacteria will enable the selection of novel malolactic fermentation starter cultures with desired oenological traits for the improvement of the organoleptic quality of the wine, and hence wine aroma.     

Induction of Immune Responses in Mice after Intragastric Administration of Lactobacillus casei Producing Porcine Parvovirus VP2 Protein

Lactobacillus casei ATCC 393 was selected as an antigen delivery vehicle for mucosal immunization against porcine parvovirus (PPV) infection. A 64-kDa fragment of PPV major protective antigen VP2 protein was used as the parvovirus antigen model. A recombinant Lactobacillus expressing VP2 protein was constructed with plasmid pPG611.1, where expression and localization of the VP2 protein from recombinant Lc393-rPPV-VP2 was detected via sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blotting, and immunofluorescence. Both local mucosal and systemic immune responses against PPV were induced in BALB/c mice immunized orally with the recombinant Lactobacillus expressing VP2 protein. The induced antibodies demonstrated neutralizing effects on PPV infection. These data indicated that the use of recombinant lactobacilli could be a valuable strategy for future vaccine development of PPV.     

Probiotic Lactobacillus casei Expressing Human Lactoferrin Elevates Antibacterial Activity in the Gastrointestinal Tract

In this study, Lactobacillus casei was used to deliver and express human lactoferrin (hLF) to protect the host against bacterial infection. Full-length hLF cDNA was cloned into a Lactobacillus-specific plasmid to produce the L. casei transformants (rhLF/L. casei). Antimicrobial activity of recombinant hLF was examined in inhibition of bacteria growth in vitro. A mouse model was established to test in vivo antibacterial activity and protective effect of orally-administered probiotic L. casei transformant in the gastrointestinal tract. Trials were conducted in which animals were challenged with E. coli ATCC25922. E. coli colony numbers in duodenal fluid from the group fed with rhLF/L. casei were significantly lower than those of the group fed with wild-type L. casei or placebo (P < 0.01). Histopathological analyses of the small intestine, showed both decreased intestinal injury and increased villi length were observed in the mice fed with rhLF/L. casei as compared with the control groups (P < 0.01). Our results demonstrate that L. casei expressing hLF exhibited antibacterial activity both in in vitro and in vivo. It also provides a potentially large-scale production of hLF as applications for treatment of infections caused by clinically relevant pathogens.     

Strain identification of probiotic Lactobacillus casei-related isolates with randomly amplified polymorphic DNA and pulsed-field gel electrophoresis methods

Typing of reference strains and isolates identified as Lactobacillus casei, Lactobacillus paracasei or Lactobacillus rhamnosus was carried out using randomly amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) analyses. Strains of L. paracasei were mainly grouped in the same cluster as those of L. casei. The RAPD fingerprints of strains ATCC 393 and ATCC 15820 differ from those of the L. rhamnosus and L. paracasei/casei strains further supporting classification of these strains as a separate group. The RAPD profiling could be used for classification and discrimination of isolates belonging to the L. casei group.     

The aerobic growth and product formation of Lactobacillus,Leuconostoc, Brochothrix,and Carnobacterium in batch cultures

Summary The aerobic growth and metabolism of eleven homofermentative and three heterofermentative Lactobacillus strains, three Leuconostoc strains, two Brochothrix thermosphacta strains and two Carnobacterium strains were studied in batch cultures at pH 6.0 and 25°C on a complex substrate containing 10.0 g glucose per litre. All strains, except Carnobacterium divergens 69, grew well aerobically. An oxygen consumption was registered for 18 of the strains—the exceptions being Lactobacillus alimentarius DSM 20249^T, Lactobacillus farciminis DSM 20284^T and Lactobacillus sharpeae DSM 20505^T. The homofermentative lactobacilli showed a maximal oxygen consumption during the stationary growth phase and this was coupled with a low final viable count. Leuconostoc strains, heterofermentative lactobacilli, Brochothrix thermosphacta and Carnobacterium strains showed a maximal oxygen consumption during the exponential growth phase together with a high final viable count. The maximum specific growth rate varied from 0.19 to 0.54 h^-1 while the growth yield varied from 19 to 86 g dry weight per mol glucose consumed. In general, homofermentative lactobacilli produced dl-lactic acid, acetic acid and acetoin. The three heterofermentative lactobacilli produced dl-lactic acid and acetic acid, two strains also produced ethanol Leuconostoc spp. formed d-lactic acid, acetic acid, and ethanol. B. thermosphacta produced acetoin, acetic acid, formic acid, isobutyric acid and isovaleric acid but no lactic acid. Carnobacterium produced l-lactic acid, acetic acid and acetoin. All strains accumulated hydrogen peroxide except L. alimentarius DSM 20249^T, Carnobacterium piscicola 3 and B. thermosphacta.née Blickstad     

Effect of culture media onLactobacillus hydrophobicity and electrophoretic mobility

The hydrophobicity of six strains representing three species ofLactobacillus was measured using dextran-polyethylene glycol contact angle measurements. These ranged from 123.6° forLactobacillus casei douche to 26.2° forL. casei RC-17 under identical growth conditions. The results indicated that the nutritional environment affected bacterial hydrophobicity. Electrophoretic mobilities of the lactobacilli were also determined and found to be negative for all specimens, and to vary with growth media, especially when sugars were added to urine. The electrophoretic mobility histograms showed one main peak for all strains, exceptLactobacillus acidophilus T-13 which had two peaks, suggesting two morphological sizes or types within its population. In addition, strain T-13 was more positively charged than the other five strains after growth in agar, urine, and supplemented urine. The use of contact angle and electrophoretic mobility techniques allows examination of cell surface properties of lactobacilli that may have importance in the colonization of mucosal epithelia.     

Shotgun mass mapping of Lactobacillus species and subspecies from caries related isolates by MALDI‐MS

A taxonomical study of 90 isolates of lactobacilli isolated from soft and hard carious dentine of 70 deciduous molars is presented. The Lactobacillus strains were determined by shotgun mass mapping (SMM). This method based on MALDI‐MS analysis of Lactobacillus isolates treated with trypsin followed by database comparison against a library of mass spectra derived from 20 reference strains. The SMM method allowed to discriminate different Lactobacillus subspecies. The method was used to analyse Lactobacillus isolates of unknown identity derived from carious dentine. Application of the SMM method to isolates from hard carious dentine revealed a nearly similar distribution of L. paracasei ss paracasei (29%), L. paracasei ss tolerans (32%) and L. casei ss rhamnosus (23%) as dominant subspecies. On the other hand, samples derived from soft carious dentine showed a clear bias only to L. paracasei ss paracasei (60%), whereas L. paracasei ss tolerans (14%) and L. casei ss rhamnosus (12%) were clear minorities. Compared to existent methods, SMM has unique potential for the analysis of Lactobacillus strains on subspecies level.     

Impact of heat-inactivated <Emphasis Type="Italic">Lactobacillus casei</Emphasis> and <Emphasis Type="Italic">Lactobacillus paracasei</Emphasis> strains on cytokine responses in whole blood cell cultures of children with atopic dermatitis

Heat-inactivated Lactobacillus casei LOCK 0900, L. casei LOCK 0908 and Lactobacillus paracasei LOCK 0919 strains, applied to blood cell cultures obtained from children with atopic dermatitis induced production of anti-allergic T_H1 cytokines (interleukin-12, interleukin-18, interferon-γ, tumor necrosis factor-α) and regulatory transforming growth factor-β₁), but did not stimulate pro-allergic interleukin-5. The lactobacilli-mixture remarkably enhanced the T_H1 response compared to single strains. This synergistic effect was not observed for transforming growth factor-β₁. In contrast, the amount of interleukin-10 was found to be considerably lower when cells were stimulated with lactobacilli-mixture compared to single strains. The mixture of Lactobacillus strains represents a probiotic bacterial preparation modulating in vitro cytokine profile of allergic children towards anti-allergic T_H1 response.