Changes with time in the oral microflora and dental caries induction in hyposalivated rats fed on sucrose diet.

The effects of hyposalivation on the induction of dental caries and the change in oral microflora were examined at weekly intervals in Sprague-Dawley rats fed on diet 2000 containing 56% sucrose. In hyposalivated rats, significant dental caries was induced within one week and its severity increased with the experimental period. Bacteriological examinations demonstrated that the number of total cultivable microorganisms, lactobacilli and Staphylococcus aureus increased significantly shortly after surgical induction of hyposalivation, while the number of streptococci and yeasts did not increase significantly until the 7th week, beyond which time remarkable gross caries developed. A positive correlation was found between the caries score and the recovery of lactobacilli from mandibles of hyposalivated rats, while there was no statistically significant correlation between the caries score and the recoveries of S. aureus. On the other hand, dental caries was not induced in control rats fed on sucrose diet with no surgically-induced hyposalivation. It was also found that the number of lactobacilli increased significantly shortly after diet 2000 was given to control rats, but S. aureus was rarely recovered from the mandibles of control rats throughout the experiments. The roles of lactobacilli and S. aureus in the induction of dental caries under the hyposalivated condition were discussed and it was suggested that lactobacilli may play some significant role in the induction of dental caries in hyposalivated rats.     

Dental Caries Induction in Experimental Animals by Clinical Strains of Streptococcus mutans Isolated from Japanese Children

Oral implantation and the cariogenic activity of clinical strains of Streptococcus mutans which had been isolated from Japanese children and labeled with streptomycin-resistance were examined in specific pathogen-free Sprague-Dawley rats. All the seven strains tested were easily implanted and persisted during the experimental period. Extensive carious lesions were produced in rats inoculated with clinical strains of S. mutans belonging to serotypes c, d, e, and f, and maintained on caries-inducing diet #2000. Noninfected rats did not develop dental caries when fed diet #2000. Type d S. mutans preferentially induced smooth surface caries in the rats. Strains of other serotypes primarily developed caries of pit and fissure origin. Caries also developed in rats inoculated with reference S. mutans strains BH-TR and FAIR (type b) that had been maintained in the laboratories for many years. However, the cariogenicity of the laboratory strains was found to have decreased markedly. All three S. sanguis strains could be implanted, but only one strain induced definite fissure caries. Two S. salivarius strains could not be implanted well in the rats and therefore they were not cariogenic. Four different species of lactobacilli also failed to induce dental caries in rats subjected to similar caries test regimen on diet #2000. S. mutans strain MT6R (type c) also induce caries in golden hamsters and ICR mice, but of variable degrees.     

Bacteriological Studies of the Effects of Cow's Milk on Dental Plaque and Dental Caries in Rats

The effects of liquid milk and skim milk powder on the bacterial composition of rat dental plaque and dental caries were examined in two separate experiments. First, groups of rats fed a cariogenic diet plus one or other of three types of liquid milk had. after 28 d. similar plaque flora. Those rats receiving reconstituted spray-dried skim milk had a significantly higher incidence of dental caries than those receiving either pasteurized and homogenized milk or ultra-heat treated milk. The differences in caries scores may be related to differences in inorganic phosphate and calcium levels of the milks. Secondly, rats fed a diet containing 65% phosphate-free sucrose plus 32% spray-dried skim milk in powder form had a significantly lower dental caries score than did rats receiving a diet containing 65% sucrose plus 32% autoclaved roller-dried skim milk powder. At the end of this experiment, the plaque flora had changed significantly and the difference in caries incidence was related to the reduction in the percentage of potentially cariogenic bacteria.
These results indicate that the mechanism by which milk reduces dental caries incidence may be (a) by remineralizing incipient carious lesions or (b) by mediating changes in the bacterial composition of dental plaque.     

Inhibition of Rat Dental Caries by Dextranase from a Strain of Spicaria violacea

Dextranase AD17 obtained from a culture liquor of a strain of Spicaria violacea was assessed for its ability to inhibit the development of dental caries in conventional Sprague-Dawley rats which had been infected with one of the Streptococcus mutans strains, MT6R (serotype c), OMZ 176R (d), or MT-703R (e). These experiments showed that caries was significantly inhibited when rats were given cariogenic diet # 2000 and drinking water containing AD17 at a concentration of 10 units/g, as compared to control rats not given dextranase. The inhibitory effects of AD17 were more prominent in smooth surface caries than in total caries. AD17 had a tendency to retard both the establishment of inoculated S. mutans and plaque deposition on tooth surfaces. However, S. mutans could be implanted in the rat oral cavity after repeated inoculation of the bacteria, even in the presence of AD17. These results suggest that the anticaries activity of AD17 is due to not only inhibition of adherence of S. mutans cells on tooth surfaces but also to physicochemical changes of dental plaque formed under the enzymatic action of AD17. Preliminary histopathological examination showed that AD17 had no significant toxicity in rats.     

Anti-cariogenic properties of a water-soluble extract from cacao

The addition of a water-soluble extract from cacao-extracted powder (CEPWS) to a cariogenic model food, a white chocolate-like diet that contains 35% sucrose, significantly reduced caries scores in SPF rats infected with Streptococcus sobrinus 6715, compared to control rats fed a white chocolate-like diet. CEPWS markedly inhibited water-insoluble glucan (WIG) synthesis through crude glucosyltransferases (GTFs) from Streptococcus sobrinus B13N in vitro. GTF-inhibitor(s) in CEPWS was prepared through three-step fractionation, and was termed CEPWS-BT, which is a high molecular weight (>10 kDa) heat-stable matrix of sugar, protein, and polyphenol. When the inhibitory effect of CEPWS-BT on glucan synthesis was examined using the purified GTF-I, GTF-T, and GTF-U enzymes from S. sobrinus B13N, significant reduction in GTF-I and GTF-T activity as a result of adding CEPWS-BT at low concentrations was observed. These results suggest that the addition of CEPWS to cariogenic food could be useful in controlling dental caries.     

Resistance to Antimicrobial Agents in Lactobacilli Isolated from Caper Fermentations

A collection of lactobacilli comprising species of Lactobacillus plantarum (43 isolates), Lactobacillus brevis (9 isolates) and Lactobacillus fermentum (6 isolates) obtained from spontaneous fermentations of capers (the fruits of Capparis spinosa) were investigated for resistance to antimicrobial agents. All isolates were resistant to vancomycin and teicoplanin (MIC > 16 μg/ml). Resistance to ciprofloxacin (MIC > 2 μg/ml) was detected in all isolates of L. brevis and L. fermentum as well as in most isolates of L. plantarum, whilst resistance to levofloxacin showed a much lower incidence. Among L. plantarum and L. brevis isolates, low levels of resistance to tetracycline and/or nitrofurantoin were detected. Higher resistance levels were also detected in some isolates. Resistance to penicillin and rifampicin were also detected among L. plantarum isolates. All isolates were sensitive to ampicillin, erythromycin, chloramphenicol, gentamicin, streptomycin, and quinupristin/dalfopristin.     

<Emphasis Type="Italic">Lactobacillus</Emphasis> spp. associated with early childhood caries

A group of 69 lactobacilli was isolated from caries lesions and root canals of early childhood caries (ECC) affected children treated in the Department of Pedodontics (Children’s Teaching Hospital, Brno, Czech Republic). Biochemical and physiological properties of all strains were characterized by API 50 CH kit and conventional tube tests. The rep-PCR fingerprinting with the (GTG)₅ primer was used for genotypic grouping of the isolates. The (GTG)₅-PCR fingerprinting grouped all analyzed strains into a few clusters in nearly full agreement with phenotype identification results and clarified the taxonomic position of 13 biochemically unidentified strains. In total, 20 strains of Lactobacillus fermentum, 17 L. rhamnosus, 14 L. casei/paracasei, 7 L. gasseri, 7 L. salivarius and 4 L. plantarum were identified. Mixtures of two or even three Lactobacillus spp. were isolated from a few root canal content samples. Results obtained by biotyping and (GTG)₅-PCR were generally comparable except for L. gasseri strains that were not biochemically identified. The (GTG)₅-PCR fingerprinting was shown to be quicker, easier to perform and more reliable than biotyping. Our results imply this molecular method as a good tool for screening and identification of Lactobacillus spp. inhabiting dental plaque.     

Mineral status in selenium-deficient rats compared to selenium-sufficient rats fed vitamin-free casein-based or torula yeast-based diet

To clarify the mineral status in selenium (Se)-deficient rats fed a vitamin-free casein (VFC)-based or torula yeast (TY)-based diet, 24 weanling male Wistar rats were divided into 4 groups fed diets using VFC or TY as the protein source and containing Se at sufficient (0.5 μg/g,⁺Se) or deficient (0.019 μg/g for VFC-based and <0.005 μg/g for TY-based diets,⁻Se) level for 8 wk. TY supplied a larger amount of extra minerals (Na, K, Ca, Mg, Fe, Mn, Zn, and Cu) except Se than VFC. Se concentration and glutathione peroxidase activity were significantly lower in TY-fed rats than in VFC-fed rats, as well as in⁻Se rats compared to⁺Se rats. Compared to⁺Se rats, Fe concentration was higher in liver and muscle of⁻Se rats fed the VFC-based diet and in plasma, heart, liver, and tibia of⁻Se rats fed the TY-based diet. Compared to⁺Se rats, decreases of Mn concentration appeared in plasma, heart, and tibia of VFC-fed⁻Se rats and in brain, heart, liver and tibia of TY-fed⁻Se rats. There was also a little imbalance in Ca, Mg, Na, K, and Cu caused by Se deficiency. The results indicated that Se deficiency induced the mineral imbalance in rats, especially an increase in Fe and decrease in Mn, which was more severe in TY-fed rats than VFC-fed rats. However, TY cannot be used as a model for both Se and other mineral deficiency because of the extra minerals except Se found in TY. Instead, VFC can be employed, which contains fewer minerals except Se than TY and also can produce a severe degree of Se deficiency.     

The caries inhibitory effects of GOS-sugar in vitro and in rat experiments

The caries inhibitory activity of GOS-sugar (panose- and maltose-rich sugar mixture) was examined and compared with that of sucrose, maltose, or glucose in in vitro and in vivo experiments. Streptococcus mutans MT8148R (serotype c) and Streptococcus sobrinus 6715 (g) did ferment GOS-sugar and produce acid in a similar way as with maltose and glucose. However, GOS-sugar could not be a substrate for the glucosyltransferases (GTases) of these mutans streptococci to synthesize the water-insoluble glucan. Also, it significantly inhibited not only the synthesis of water-insoluble glucan from sucrose by the crude GTases but also the sucrose-dependent adherence of these cells to a glass surface. In particular, adherence of growing cells of 6715 was markedly inhibited by the presence of GOS-sugar. GOS-sugar was found to induce significant but minimal dental caries in SPF rats infected with either MT8148R or 6715. Furthermore, the replacement of half of the dietary sucrose content with GOS-sugar resulted in a significant reduction of caries development in rats infected with strain 6715.     

Effect of Lactobacillus fermentum alone, and in combination with zinc(II) propionate on Salmonella enterica serovar Düsseldorf in Japanese quails

The influence of zinc(II) propionate on the efficacy of Lactobacillus fermentum against Salmonella enterica serovar Düsseldorf was tested in Japanese quails. Twenty one 3-day old Japanese quails were divided into 3 groups each consisting of 7 birds and inoculated orally: (i) group A (control) with Rogosa broth; (ii) group B with rifampicin-resistant L. fermentum (2.5 × 10⁷ CFU/animal); and (iii) group C with rifampicin-resistant L. fermentum cultured in Rogosa broth supplemented with zinc(II) propionate (1 g Zn²⁺ /L of broth; i.e. 2.5 × 10⁷ CFU/animal and 0.1 mg Zn²⁺ /animal). After 16 hours all birds were infected with a single dose of S. enterica serovar Düsseldorf (5.8 × 10⁷ CFU /animal). During the next 6 days the chicks received the same inoculations as they had received earlier through the medium of drinking water. The viable counts of Salmonella, rifampicin-resistant lactobacilli and total aerobes in the feces and cecal content, zinc concentration in the cecal content and growth performance were evaluated. L. fermentum alone, and in combination with Zn(II) propionate significantly reduced shedding of Salmonella in the feces and also the amount of salmonellae present in cecal content as compared to control. The numbers of Salmonella in group C in all collections were lower than in group B, but a significant difference (p < 0.05) was noted only 24 h after infection. The viable counts of rifampicin-resistant lactobacilli were similar in groups B and C and numbers of total aerobes were reduced in these groups compared with control. L. fermentum and its combination with zinc(II) propionate increased daily weight gains in the chicks in comparison with control. Zinc concentration in the control and C group was 34.9 ± 6.2 mg · kg⁻¹ and 676.3 ± 106.6 mg · kg⁻¹ of cecal content, respectively. Presented at the Second Probiotic Conference, Košice, 15–19 September 2004, Slovakia.     

Zinc‐Induced Hyperleptinemia Relates to the Amelioration of Sucrose‐Induced Obesity with Zinc Repletion

Objective: Dietary zinc repletion can ameliorate sucrose‐induced obesity. A positive correlation between zinc and leptin has been recently noted, and both are known as important mediators in appetite control. In this study, we examined whether the reported amelioration of sucrose‐induced obesity by zinc repletion was consequent on the changes in circulating leptin levels. Research Methods and Procedures: Mice with obesity that was induced by giving a 32% sucrose solution in addition to a semipurified diet were divided into two groups based on whether they had 20 mg/liter zinc supplementation in their drinking water. Results: As expected, the mice with sucrose‐induced obesity had hyperglycemia, hyperinsulinemia, hypertriglyceridemia, hyperleptinemia, and hypozincemia when compared with the mice given the diet alone. Body weight gain, body fat content, and food and sucrose intake tended to decrease but not with statistical significance in sucrose‐fed obese mice with zinc supplementation. Nevertheless, some serum variables (glucose, insulin, triglycerides, and zinc) in sucrose‐fed obese mice with zinc treatment were approximate to those values of the mice given the diet alone. Moreover, sucrose‐fed obese mice with zinc supplementation had the highest serum values of leptin. Discussion: This study indicates that the amelioration of sucrose‐induced obesity by zinc repletion may be partly attributable to the hyperleptinemia induced by the mineral.     

Mannitol production by heterofermentative <Emphasis Type="BoldItalic">Lactobacillus reuteri</Emphasis> CRL 1101 and <Emphasis Type="BoldItalic">Lactobacillus fermentum</Emphasis> CRL 573 in free and controlled pH batch fermentations

Certain lactic acid bacteria, especially heterofermentative strains, are capable to produce mannitol under adequate culture conditions. In this study, mannitol production by Lactobacillus reuteri CRL 1101 and Lactobacillus fermentum CRL 573 in modified MRS medium containing a mixture of fructose and glucose in a 6.5:1.0 ratio was investigated during batch fermentations with free pH and constant pH 6.0 and 5.0. Mannitol production and yields were higher under constant pH conditions compared with fermentations with free pH, the increase being more pronounced in the case of the L. fermentum strain. Maximum mannitol production and yields from fructose for L. reuteri CRL 1101 (122 mM and 75.7 mol%, respectively) and L. fermentum CRL 573 (312 mM and 93.5 mol%, respectively) were found at pH 5.0. Interestingly, depending on the pH conditions, fructose was used only as an alternative external electron acceptor or as both electron acceptor and energy source in the case of the L. reuteri strain. In contrast, L. fermentum CRL 573 used fructose both as electron acceptor and carbon source simultaneously, independently of the pH value, which strongly affected mannitol production by this strain. Studies on the metabolism of these relevant mannitol-producing lactobacilli provide important knowledge to either produce mannitol to be used as food additive or to produce it in situ during fermented food production.     

Oral Lactobacillus species in type 2 diabetic patients living in southern Thailand

Although lactobacilli are part of normal oral, gastrointestinal and genitourinary flora, they are an uncommon cause of infections in human. Lactobacillus-associated infections have generally occurred in patients with serious underlying conditions e.g. diabetes and cancer that might favour certain microorganisms. The aim of this study was to characterize species and genotypes of lactobacilli isolated from diabetic patients and non-diabetic subjects. One hundred and five type 2 diabetic patients and 103 non-diabetic subjects were recruited in this study. A total of 170 isolates of Lactobacillus were identified using 16S rRNA gene PCR-RFLP and genotyping were performed using AP-PCR by ERIC primers. It was found that type 2 diabetic patients had a significantly higher prevalence (p = 0.008) and level of lactobacilli than non-diabetic controls (p = 0.030). The most frequently isolated Lactobacillus spp. were L. casei/paracasei and L. fermentum in both the diabetic and non-diabetic groups. Strains of L. casei/paracasei and L. fermentum from between and within individuals were genotyped, and the genotyping of Lactobacillus strains showed diversity between individuals. One up to three genotypes of these two species could be found in the same subject. Interestingly, fewer genotypes were found in the diabetic patients than in the non-diabetic subjects.     

Microbiological and chemical analysis of fermented sorghum dough for Kisra production

Summary Sorghum flour was fermented in the traditional way for Kisra production. Wet or dry preparations of fermented sorghum dough from Sudanese households were employed as inocula. Microbiological and chemical analysis was performed throughout the fermentation process. Cell counts reached values of up to 9 × 10⁸ cfu/g and contained >99% lactobacilli. Strains of Lactobacillus fermentum, L. reuteri and L. amylovorus or L. fermentum and L. amylovorus were found as dominant organisms in doughs inoculated with wet or dry sorghum dough preparations, respectively. The ratios of the lactobacilli remained constant after up to four consecutive fermentations. After inoculation with the dry dough preparation the yeast Candida krusei was detected at 10⁶ cfu/g. During the fermentation the pH declined from 5.5 to values of approximately 3.4. The maltose content of the dough decreased continuously, wheraas glucose was accumulated as an intermediate. The relative content of most amino acids in the doughs did not significantly change during the fermentation. However, the concentrations of cysteine and methionine decreased, whereas threonine was enriched in the dough. Correspondence to: R. F. Vogel     

A selected probiotic strain of <Emphasis Type="Italic">Lactobacillus fermentum</Emphasis> CM33 isolated from breast-fed infants as a potential source of β-galactosidase for prebiotic oligosaccharide synthesis

Lactic acid bacteria from healthy breast-fed infants were isolated and screened for β-galactosidase production in MRS broth. Among 49 isolates that exhibited the yellow clear zone on MRS agar supplemented with bromocresol blue, the isolate CM33 was selected as being the highest β-galactosidase producer and was identified as Lactobacillus fermentum based on its morphological characteristics and 16S rDNA nucleotide sequence. L. fermentum CM33 exhibited a good survival rate under the simulated stomach passage model, comparable to known probiotic strains L. gallinarum JCM2011 and L. agilis JCM1187. L. fermentum CM33 was antagonistic to pathogenic bacteria Listeria monocytogenes, Escherichia coli 0157:H7, Salmonella typhi, and Salmonella enteriditis, using the well diffusion method. In addition, the selected lactobacilli exhibited a high growth rate when cultivated in modified MRS containing commercial galactooligosaccharide (GOS) as a sole carbon source, as well as in glucose. A preliminary study on the enzymatic synthesis of oligosaccharide using crude β-galactosidase revealed the capability for oligosaccharide synthesis by the transgalactosylation activity.     

Effect of mutacin administration on Streptococcus mutans-induced dental caries in rats

A bacteriocin from serotype c Streptococcus mutans strain C3603 was examined for its inhibitory effect on experimental dental caries in rats infected with S. mutans MT8148R (serotype c). Significant reduction in the incidence of dental caries was found only when bacteriocin was incorporated both in the drinking water and in the diet at a high concentration. However, caries reduction was not as great as expected and the addition of bacteriocin to drinking water alone had no effect on the recovery of S. mutans, plaque deposition or caries incidence. The bacteriocin activity must have been reduced in the oral cavity of rats, and the reasons were examined. Bacteriocin-resistant mutants were not detected and the bacteriocin was not inactivated by saliva. Whereas the bacteriocin did not kill the S. mutans cells grown in a sucrose-containing medium, it completely killed the cells grown in a sucrose-free medium.     

Antibiotic resistance of potential probiotic bacteria of the genus <Emphasis Type="Italic">Lactobacillus</Emphasis> from human gastrointestinal microbiome

Thirteen Lactobacillus strains isolated from the gastrointestinal microbiome of people from the territory of the former Soviet Union have been studied for resistance to 15 antibiotics of different nature, namely, penicillins, aminoglycosides, macrolides, lincosamides, tetracyclines, chloramphenicol, and rifampicin. The strains included four strains of L. plantarum, four of L. helveticus, three of L. casei/paracasei, one of L. rhamnosus, and one of L. fermentum. All strains showed relative sensitivity to ampicillin, chloramphenicol, rifampicin, roxithromycin, erythromycin, and azithromycin, while none of them were sensitive to all tested antibiotics. L. plantarum strains had the broadest resistance spectra: one strain was resistant to tetracycline and three aminoglycosides and three strains were resistant to tetracycline and five aminoglycosides; one strain demonstrated high resistance to clindamycin and two strains to lincomycin. At the same time, two L. plantarum strains demonstrated resistance to benzylpenicillin coupled with sensitivity to ampicillin, another β-lactam antibiotic. Such resistance was clearly not related to the β-lactamase activity and could be explained by a specific mutation in one of the penicillin-binding proteins of the cell wall. Strains of L. helveticus, L. casei/paracasei, L. rhamnosus, and L. fermentum exhibited cross resistance to two to five different aminoglycosides. A PCR test of the resistance determinants for the widely clinically used antibiotics, tetracycline, chloramphenicol, and erythromycin revealed the presence of the tetM gene of conjugative transposon in L. casei/paracasei and two L. helveticus strains. Nucleotide sequence analysis of the amplified tetM fragments demonstrated their high homology with the tetM genes of Enterococcus faecalis and Streptococcus pneumoniae. The strains carrying tetM were tested for the genes of replication and conjugative transfer of plasmids in lactic acid bacteria. The results indicated that these strains contain genes identical or highly homologous to the rep and trsK genes of the plca36 plasmid and rep gene of the pLH1 and pLJ1 plasmids of lactic acid bacteria. The tetM gene is probably not expressed in strains sensitive to the corresponding antibiotic. However, the investigated lactobacilli cannot be directly used as probiotics, as they may serve as a source of genes for antibiotic resistance in the human microbiome.     

Map-based cloning in crop plants: tomato as a model system II. Isolation and characterization of a set of overlapping yeast artificial chromosomes encompassing the jointless locus

A map-based cloning technique for crop plants is being developed using tomato as a model system. The target gene jointless is a recessive mutation that completely suppresses the formation of flower and fruit pedicel abscission zones. Previously, the jointless locus was mapped to a 3 cM interval between the two molecular markers TG523 and RPD158. Physical mapping of the jointless region by pulsed-field gel electrophoresis demonstrated that TG523 and RPD158 reside on a 600 kb SmaI fragment. In this study, TG523 was used as a probe to screen a tomato yeast artificial chromosome (YAC) library. Six tomato YAC (TY) clones were isolated, ranging from 220 to 380 kb in size. Genetic mapping of YAC ends demonstrated that this set of overlapping YACs encompasses the jointless locus. Two YAC ends, TY159L (L indicates left end) and TY143R (R indicates right end), cosegregate with the jointless locus. Only one of the six YACs (TY142) contained single-copy DNA sequences at both ends that could be mapped. The two ends of TY142 were mapped to either side of the jointless locus, indicating that TY142 contains a contiguous 285 kb tomato DNA fragment that probably includes the jointless locus. Physical mapping of the TY142 clone revealed that TY159L and TY143R reside on a 55 kb SalI fragment. Southern blot hybridization analysis of the DNAs of tomato lines nearly isogenic for the jointless mutation has allowed localization of the target locus to a region of less than 50 kb within the TY142 clone.Communicated by H. Saedler     

Isolation and Characterization of a Plasmid fromLactobacillus fermentumConferring Erythromycin Resistance

Lactobacillus fermentumis a lactic acid bacterial species commonly found in the digestive tracts of pigs and rodents and also present in man. We characterized a 5.7-kb plasmid, pLEM3, conferring erythromycin resistance, which was isolated from a porcine strain ofL. fermentum.Plasmid pLEM3 established efficiently inL. fermentum,conferred high-level erythromycin resistance (MIC > 1 mg/ml), and was segregationally stable. A deletion derivative of pLEM3, called pLEM5, was constructed and found to be as genetically stable as the parent. A multiple cloning site was inserted into pLEM5, generating plasmid pLEM7. Nucleotide sequence determination of pLEM5 revealed similarities with known genes. The replicon itself is a member of the pC194 family of rolling circle plasmids. The region responsible for erythromycin resistance was 98.2% identical to theermgene of conjugative transposon Tn1545.     

Assessment and comparison of probiotic potential of four Lactobacillus species isolated from feces samples of Iranian infants

The probiotic potential of Lactobacillus species isolated from infant feces was investigated. For this study, the antibiotic susceptibility, tolerance in gut‐related conditions, antimicrobial activity, and ability to adhere to a human colorectal adenocarcinoma cell line (Caco‐2 cells) of four common Lactobacillus species (Lactobacillus paracasei [n = 15], Lactobacillus rhamnosus [n = 45], Lactobacillus gasseri [n = 20] and Lactobacillus fermentum [n = 18]) were assessed. Most isolates that which were sensitive to imipenem, ampicillin, gentamycin, erythromycin and tetracycline were selected for other tests. L. gasseri isolates had the greatest sensitivity to gastric and intestinal fluids (<10% viability). L. fermentum (FH5, FH13 and FH18) had the highest adhesion to Caco‐2 cells. The lowest antibacterial activity against pathogenic bacteria was shown by L. gasseri strains in spot tests. Furthermore, non‐adjusted cell‐free culture supernatants with low pH had greater antimicrobial activity, which was related to organic acid. The results showed that some isolates of L. rhamnosus and L. fermentum are suitable for use as a probiotic.