唾液乳杆菌的研究进展

唾液乳杆菌属于乳杆菌科、乳杆菌属,广泛地存在于人和动物的肠道。近年来,唾液乳杆菌作为益生菌广泛用于人和动物益生菌制剂的生产。在分析与唾液乳杆菌相关的文献和生物信息数据的基础上,就唾液乳杆菌的生物学特征、作用机制、应用及发展前景进行了简要综述,为唾液乳杆菌的研究提供参考。     

Characterization of the three selected probiotic strains for the application in food industry

Previously selected bacterial probiotic strains Enterococcus faecium L3, Lactobacillus plantarum L4 and Lactobacillus acidophilus M92 have shown their potential as functional starter cultures in silage, white cabbage and milk fermentation. Therefore, the phenotypic and genotypic characteristics important for their application in food industry were investigated. Pulsed-field gel electrophoresis (PFGE) of NotI digested genomic DNA, in combination with physiological traits determined by API tests, made a useful tool for identification of these probiotic strains and differentiation among them. Lyophilized probiotic cells remained viable during 75 days of storage at −20, +4 and +15°C, while fresh concentrated cells remained viable only at −20°C with addition of glycerol as cryoprotectant. After the lyophilization with addition of skim milk as lyoprotectant, the viability of L. acidophilus M92, L. plantarum L4 and E. faecium L3 was reduced by only 0.37, 0.44 and 0.50 log, respectively. Furthermore, probiotic strains L. acidophilus M92, L. plantarum L4, and E. faecium L3, demonstrated anti-Salmonella activity, and L. acidophilus M92 having also antilisterial activity demonstrated by in vitro competition test. Overnight cultures and cell-free supernatants of the three probiotic strains exerted also an antagonistic effect against the Gram-positive and Gram-negative test microorganisms examined, demonstrated by the agar-well diffusion test. The inhibition of Listeria monocytogenes, Salmonella typhimurium, Yersinia enterocolitica, and Acinetobacter calcoaceticus obtained, achieved by the neutralized, 5-fold concentrated supernatant of L. plantarum L4, may be the result of its bacteriocinogenic activity. On the basis of these results, the application of the three examined probiotic strains may become a point of great importance in respect of food safety.     

Detection and Specific Enumeration of Multi-Strain Probiotics in the Lumen Contents and Mucus Layers of the Rat Intestine After Oral Administration

Although the detection of viable probiotic bacteria following their ingestion and passage through the gastrointestinal tract (GIT) has been well documented, their mucosal attachment in vivo is more difficult to assess. In this study, we investigated the survival and mucosal attachment of multi-strain probiotics transiting the rat GIT. Rats were administered a commercial mixture of the intestinal probiotics Lactobacillus acidophilus LA742, Lactobacillus rhamnosus L2H and Bifidobacterium lactis HN019 and the oral probiotic Streptococcus salivarius K12 every 12 h for 3 days. Intestinal contents, mucus and faeces were tested 6 h, 3 days and 7 days after the last dose by strain-specific enumeration on selective media and by denaturing gradient gel electrophoresis. At 6 h, viable cells and DNA corresponding to all four probiotics were detected in the faeces and in both the lumen contents and mucus layers of the ileum and colon. Viable probiotic cells of B. lactis and L. rhamnosus were detected for 7 days and L. acidophilus for 3 days after the last dose. B. lactis and L. rhamnosus persisted in the ileal mucus and colon contents, whereas the retention of L. acidophilus appeared to be relatively higher in colonic mucus. No viable cells of S. salivarius K12 were detected in any of the samples at either day 3 or 7. The study demonstrates that probiotic strains of intestinal origin but not of oral origin exhibit temporary colonisation of the rat GIT and that these strains may have differing relative affinities for colonic and ileal mucosa.     

Bacteria competing with the adhesion and biofilm formation by <Emphasis Type="Italic">Staphylococcus aureus</Emphasis>

The activity of antagonistic substances produced by Pseudomonas aeruginosa and Lactobacillus acidophilus against the planktonic and sessile populations of Staphylococcus aureus strains was demonstrated. The strongest effects were caused by probiotic L. acidophilus strain — bacteriocin-like inhibitory substances (BLIS) positive. However, the S. aureus A3 growth, adhesion and biofilm formation was also limited by cell-free supernatant of L. acidophilus H-1 (BLIS negative). Moreover, competitive direct interactions were observed between staphylococci and the above bacteria, which influenced the formation of dualspecies aggregates on the surface.     

Genome of a virulent bacteriophage Lb338-1 that lyses the probiotic Lactobacillus paracasei cheese strain

There is a lack of fundamental knowledge about the influence of bacteriophage on probiotic bacteria and other commensals in the gut. Here, we present the isolation and morphological and genetic characterization of a virulent narrow-host-range bacteriophage, φLb338-1. This phage was isolated from fresh sewage and was shown to infect the probiotic cheese strain Lactobacillus paracasei NFBC 338. Electron microscopy studies revealed that φLb338-1 is a member of the Myoviridae family, with an isometric head, a medium-sized contractile tail, and a complex base plate. Genome sequencing revealed a 142-kb genome with 199 open reading frames. Putative functions could be assigned to 22% of the open reading frames; these had significant homology to genes found in the broad-host-range SPO1-like group of phages which includes the Enterococcus faecalis phage φEF24C, Listeria phage A511, and Lactobacillus plantarum phage LP65. Interestingly, no significant genomic similarity was observed between the phage and the probiotic host strain. Future studies will determine if the presence of bacteriophage φLb338-1 or others in the human or animal gut plays an antagonistic role against the probiotic effect of beneficial bacteria.     

Selecting Lactic Acid Bacteria for Their Safety and Functionality by Use of a Mouse Colitis Model

Studies showed that specific probiotics might provide therapeutic benefits in inflammatory bowel disease. However, a rigorous screening of new probiotics is needed to study possible adverse interactions with the host, particularly when intended for administration to individuals with certain health risks. In this context, the objective of this study was to investigate the role of three lactobacilli (LAB) on intestinal inflammation and bacterial translocation using variations of the mouse model of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced acute colitis. We first compared the in vitro ability of LAB to survive gastrointestinal tract (GIT) conditions and their ability to persist in the GIT of mice following daily oral administration. As a control, we included a nonprobiotic Lactobacillus paracasei strain, previously isolated from an endocarditis patient. Feeding high doses of LAB strains to healthy and to TNBS-treated mice did not induce any detrimental effect or abnormal translocation of the bacteria. Oral administration of Lactobacillus salivarius Ls-33 had a significant preventive effect on colitis in mice, while Lactobacillus plantarum Lp-115 and Lactobacillus acidophilus NCFM did not. None of the three selected LAB strains translocated to extraintestinal organs of TNBS-treated mice. In contrast, L. paracasei exacerbated colitis under severe inflammatory conditions and translocated to extraintestinal organs. This study showed that evaluations of the safety and functionality of new probiotics are recommended. We conclude that not all lactobacilli have similar effects on intestinal inflammation and that selected probiotics such as L. salivarius Ls-33 may be considered in the prevention or treatment of intestinal inflammation.     

The effect of bile salts on survival and morphology of a potential probiotic strain Lactobacillus acidophilus M92

Bile tolerance is an important criterion in the selection of microbial strains for probiotic use. The survival and morphological changes of a potential probiotic strain, Lactobacillus acidophilus M92, in the presence of bile salts were examined. Lactobacillus acidophilus M92 has shown a satisfactory degree of tolerance against oxgall and individual bile salts tested, especially to taurocholate. The higher resistance of L. acidophilus M92 against taurine-conjugated bile salts relative to deconjugated and glycine-conjugated bile salts was attributed to its reaction to the stronger acidity of the former. Furthermore, bile salt hydrolase (BSH) was active when L. acidophilus M92 was grown in the presence of sodium taurocholate. The rate of BSH activity was highest at the exponential growth phase. It was hypothesised that BSH activity may be important for the bile salt resistance of this strain. The colonial and cellular morphology may also be a valuable parameter in the selection of bile salt-resistant Lactobacillus strains for probiotic use. Smooth (S) and rough (R) colonies, appeared in the original L. acidophilus M92 bacterial culture and demonstrated a different degree of bile tolerance. Rough colonies were more sensitive to bile salts than smooth ones. The R colony cells assumed a round form, probably induced by gaps in the cell wall caused by the cytotoxicity of glycodeoxycholate. This revised version was published online in July 2006 with corrections to the Cover Date.     

Antimicrobial activity against Shigella sonnei and probiotic properties of wild lactobacilli from fermented food

Four lactobacilli strains (Lactobacillus paracasei subp. paracasei M5-L, Lactobacillus rhamnosus J10-L, Lactobacillus casei Q8-L and L. rhamnosus GG (LGG), were systematically assessed for the production of antimicrobial substances active towards Shigella sonnei, Escherichia coli and Salmonella typhimurium. Agar-well assay showed that the four lactobacilli strains displayed strong antibacterial activity towards S. sonnei. The nature of antimicrobial substances was also investigated and shown to be dependent on the production of organic acids, in particular the lactic acid. Time-kill assay showed that the viability of the S. sonnei was decreased by 2.7–3.6 log CFU/ml after contact with CFCS (cell-free culture supernatants) of four lactobacilli for 2 h, which confirmed the result of the agar-well assay. Further analysis of the organic acid composition in the CFCS revealed that the content of lactic acid range from 227 to 293 mM. In addition, the aggregations properties, adherence properties and tolerance to simulated gastrointestinal conditions were also investigated in vitro tests. The result suggested that the M5-L, J10-L and Q8-L strains possess desirable antimicrobial activity towards S. sonnei and probiotic properties as LGG and could be potentially used as novel probiotic strains in the food industry.     

Comparative study of Bifidobacteriumanimalis, Escherichiacoli, Lactobacilluscasei and Saccharomycesboulardii probiotic properties

The present work investigates some probiotic properties of four different microorganisms (Bifidobacterium animalis var. lactis BB-12, Escherichia coli EMO, Lactobacillus casei and Saccharomyces boulardii). In vitro and in vivo tests were carried out to compare cell wall hydrophobicity, production of antagonistic substances, survival capacity in the gastrointestinal tract of germ-free mice without pathological consequence, and immune modulation by stimulation of Küpffer cells, intestinal sIgA and IL-10 levels. In vitro antagonism against pathogenic bacteria and yeast was only observed for the probiotic bacteria B. animalis and L. casei. The hydrophobic property of the cell wall was higher for B. animalis and E. coli EMO, and this property could be responsible for a better ability to colonize the gastrointestinal tract of germ-free mice. Higher levels of sIgA were observed mainly for S. boulardii, followed by E. coli EMO and B. animalis, and only S. boulardii induced a significant higher level of IL-10. In conclusion, for a probiotic use, S. boulardii presented better characteristics in terms of immunomodulation, and B. animalis and L. casei for antagonistic substance production. The knowledge of the different probiotic properties could be used to choice the better microorganism depending on the therapeutic or prophylactic application.     

副干酪乳杆菌PC-01全基因组测序及不同副干酪乳杆菌菌株比较基因组学分析

【背景】副干酪乳杆菌(Lactobacillus paracasei)作为乳酸菌中重要菌种之一,常被认为是优良益生菌开发的潜在资源。【目的】以L.paracasei PC-01和L.paracasei Zhang为例,分析不同L.paracasei的基因组差异和遗传背景,为菌株的鉴定和开发奠定基础。【方法】采用PacBioSMRT三代测序技术对L.paracasei PC-01进行全基因组测序,结合2株L.paracasei模式菌株和公开的36株全基因组数据,通过比较基因组学方法揭示39株L.paracasei菌株之间的差异。【结果】L.paracasei PC-01基因组不包含质粒,染色体大小为2 829 251 bp,GC含量为46.64%;L.paracasei Zhang包含一个质粒基因组大小为2 898 456 bp,GC含量为46.51%;不同L.paracasei菌株基因组大小、质粒数及GC含量均存在一定差异。L.paracasei群体为开放式基因组,基因组具有高度多样性。基于核心基因构建系统发育树对于L.paracasei种内区分效果最好,L.paracasei PC-01和L.paracasei Zhang处于不同的进化分支。约占L.paracasei PC-01基因组长度91%的片段与L.paracasei Zhang基因组匹配率大于90%,L.paracasei PC-01注释到10个与转录调节鼠李糖代谢功能相关的特有基因,如agu A、clp B等;L.paracasei Zhang包含msh A、ltr A等特有基因,与糖基转移等功能相关。【结论】通过比较基因组学揭示L.paracasei PC-01和L.paracasei Zhang的遗传信息,解析了不同L.paracasei菌株之间的差异,为L.paracasei的鉴定和应用奠定了遗传学基础。     

Probiotic Characterization of Lactobacillus paracasei subsp. paracasei KNI9 Inhibiting Adherence of Yersinia enterocolitica on Caco-2 Cells In Vitro

The study was aimed to characterize the probiotic properties of Lactobacillus paracasei subsp. paracasei strain KNI9 and its antagonistic activity against Yersinia enterocolitica subsp. enterocolitica. The strain KNI9 was susceptible to antibiotics such as chloramphenicol, tetracycline, erythromycin, and streptomycin recommended by European food safety authority (EFSA). Strain KNI9 exhibited tolerance to simulated oro-gastrointestinal (OGT) condition, adherence to Caco-2 cells, and antimicrobial activity against intestinal enteric pathogens such as Yersinia enterocolitica subsp. enterocolitica, Shigella boydii, and Listeria monocytogenes. Furthermore, the strain KNI9 inhibited the adherence and invasiveness of Y. enterocolitica subsp. enterocolitica to Caco-2 cell line. These results indicate that the L. paracasei subsp. paracasei KNI9 could be further developed into a potential probiotic strain after appropriate in vivo studies.

     

Improved Viability of Microencapsulated Probiotics in a Freeze-Dried Banana Powder During Storage and Under Simulated Gastrointestinal Tract

Freeze-dried banana powder represents an ideal source of nutrients and has not yet been used for probiotic incorporation. In this study, microencapsulation by freeze drying of probiotics Lactobacillus acidophilus and Lactobacillus casei was made using whey protein isolate (WPI), fructooligosaccharides (FOS), and their combination (WPI + FOS) at ratio (1:1). Higher encapsulation yield was found for (WPI + FOS) microspheres (98%). Further, microcapsules of (WPI + FOS) were used to produce a freeze-dried banana powder which was analyzed for bacterial viability under simulated gastrointestinal fluid (SGIF), stability during storage at 4 °C and 25 °C, and chemical and sensory properties. Results revealed that (WPI + FOS) microcapsules significantly increased bacteria stability in the product over 30 days of storage at 4 °C averaging (≥ 8.57 log CFU/g) for L. acidophilus and (≥ 7.61 log CFU/g) for L. Casei as compared to free cells. Bacteria encapsulated in microspheres (WPI + FOS) were not significantly affected by the SGIF, remaining stable up to 7.05 ± 0.1 log CFU/g for L.acidophilus and 5.48 ± 0.1 log CFU/g for L.casei after 90 min of incubation at pH 2 compared to free cells which showed minimal survival. Overall, encapsulated probiotics enriched freeze-dried banana powders received good sensory scores; they can therefore serve as safe probiotics food carriers.

     

马乳酒样乳杆菌马乳酒样亚种及其研究进展

马乳酒样乳杆菌(Lactobacillus kefiranofaciens)是一类革兰氏阳性乳杆菌,其来源广泛,功能多样,安全性好.2020年12月国家卫健委批准马乳酒样乳杆菌马乳酒样亚种作为我国新食品原料.本文主要综述国内外马乳酒样乳杆菌和马乳酒样乳杆菌马乳酒样亚种的菌种形态学和基因组特性、益生功能、主要价值和发展前...     

Identification and antimicrobial susceptibility of porcine bacteria that inhibit the growth of Brachyspira hyodysenteriae in vitro

Aims: To identify bacilli, lactic acid bacteria and bifidobacteria that inhibit the growth of Brachyspira hyodysenteriae. Methods and Results: A total of 80 isolates were obtained from various porcine intestinal compartments using selective conditions and grouped into 15 similarity clusters based on whole‐cell protein profiles. Random amplified polymorphic DNA PCR patterns identified 24 genotypes. 16S rDNA sequencing assigned all genotypes, except eight aerobes, to established species (Bacillus subtilis, Enterococcus faecium, Lactobacillus salivarius, Lactobacillus mucosae, Lactobacillus reuteri, Lactobacillus amylovorus, Bifidobacterium thermophilum). According to their minimum inhibitory concentrations, four strains (Ent. faecium, Lact. reuteri, Lact. amylovorus, Bif. thermophilum) were susceptible to all clinically relevant antibiotics. Two lactobacilli showing multiresistance harboured the erm(B) determinant. A cross‐section of eight representative strains was examined for growth suppression of two strains of Brach. hyodysenteriae, the aetiological agent of swine dysentery, and compared with intestinal strains derived from other animal sources. The Brachyspira strains were inhibited by strains of Lact. salivarius, Bif. thermophilum, Ent. faecium and B. subtilis. Conclusions: Three porcine strains of Ent. faecium, Bif. thermophilum and B. subtilis were found to be suitable as probiotic candidates because of their well‐established identity, antibiotic susceptibility and antagonistic activity. Significance and Impact of the Study: For the first time, antagonistic activity of well‐characterized porcine strains against Brach. hyodysenteriae is presented. These findings suggest that certain intestinal strains might have a potential as probiotic feed additives for prevention of swine dysentery.     

Antagonistic Activity of <Emphasis Type="Italic">Lactobacillus acidophilus</Emphasis> ATCC 4356 on the Growth and Adhesion/Invasion Characteristics of Human <Emphasis Type="Italic">Campylobacter jejuni</Emphasis>

The aim of this research was to determine the potential probiotic activity of Lactobacillus acidophilus ATCC 4356 against several human Campylobacter jejuni isolates. The ability to inhibit the pathogen’s growth was evaluated by co-culture experiments as well as by antimicrobial assays with cell-free culture supernatant (CFCS), while interference with adhesion/invasion to intestinal Caco-2 cells was studied by exclusion, competition, and displacement tests. In the co-culture experiments L. acidophilus ATCC 4356 strain reduced the growth of C. jejuni with variable percentages of inhibition related to the contact time. The CFCS showed inhibitory activity against C. jejuni strains, stability to low pH, and thermal treatment and sensitivity to proteinase K and trypsin. L. acidophilus ATCC 4356 was able to reduce the adhesion and invasion to Caco-2 cells by most of the human C. jejuni strains. Displacement and exclusion mechanisms seem to be the preferred modalities, which caused a significant reduction of adhesion/invasion of pathogens to intestinal cells. The observed inhibitory properties of L. acidophilus ATCC 4356 on growth ability and on cells adhesion/invasion of C. jejuni may offer potential use of this strain for the management of Campylobacter infections.     

Screening for lactobacilli with probiotic properties in the infant gut microbiota

Lactobacilli are believed to be beneficial for the human hosts and are currently being evaluated as potentially probiotic bacteria. In this study, Lactobacillus strains were isolated from infant faeces and were examined in vitro for potential probiotic properties. Faecal specimens from 63 healthy, full-term infants were collected at 4, 30 and 90 days after delivery. Seventy-four Lactobacillus strains were isolated and one or more different phenotypes from each infant (n = 44) were selected for further testing. The bacterial isolates were identified mainly as L. gasseri, L. crispatus, Lactobacillus paracasei, L. salivarius, L. fermentum after amplification and sequencing of 16s rRNA gene. The strains were examined for acid and bile tolerance, adhesion to Caco-2 cells, antibiotic susceptibility and antimicrobial activity against selected enteric pathogens. The great majority of the isolated lactobacilli were susceptible to ampicillin, amoxicillin/clavulanic acid, tetracycline, erythromycin, cephalothin, chloramphenicol and rifampicin. Resistance to vancomycin or bacitracin was detected to 34% of the strains. Twenty strains out of forty-four exhibited significant tolerance to bile salts. Those strains were subsequently tested for resistance to low pH conditions (pH 2 and 3). Interestingly, 85% (17 strains) of the tested lactobacilli remained unaffected at pH 3 after 3 h of incubation, 6 strains were found resistant at pH 2 after 1.5 h and only 2 strains found resistant after 3 h of incubation. Two of the strains were able to adhere to Caco-2 cells. In conclusion, two isolates fulfilled the in vitro probiotic criteria and are good candidates for further in vivo evaluation.     

Supportive Role of Probiotic Strains in Protecting Rats from Ovariectomy-Induced Cortical Bone Loss

Osteoporosis is a major health problem that occurs as a result of an imbalance between bone formation and bone resorption. Different approaches have been established for treating osteoporosis. Recently, because of their health benefits and also low adverse reaction, probiotics have been receiving considerable attention. In this study, we compared the effectiveness of five probiotic strains, Lactobacillus acidophilus, Lactobacillus reuteri, Lactobacillus casei, Bifidobacterium longum, and Bacillus coagulans, in protecting rats from ovariectomized (OVX)-induced bone loss. Forty-nine adult female Sprague-Dawley rats were allocated into seven groups as follows: group 1, control; group 2, OVX; group 3, OVX + Lactobacillus acidophilus; group 4, OVX + Lactobacillus casei; group 5, OVX + Bacillus coagulans; group 6, OVX + Bifidobacterium longum; and group 7, OVX + Lactobacillus reuteri. Probiotics were fed to OVX groups at the concentration of (1 × 10⁹ CFU/ml/day) for 4 weeks. Then, biochemical parameters, including vitamin D, calcium (Ca), phosphorus (P), and alkaline phosphatase (ALP), were assessed. Dual-energy X-ray absorptiometry (DEXA) scans were used that assess bone mineral density (BMD), bone marrow concentration (BMC), and area of global, femur, spine, and tibia. Lactobacillus acidophilus and Lactobacillus casei significantly increased Ca and ALP and decreased P in treated groups. Lactobacillus casei, Lactobacillus reuteri, and Bifidobacterium longum increased vitamin D significantly. Lactobacillus acidophilus and Lactobacillus casei indicated the most effects on BMD. In terms of BMC, and bone area, Lactobacillus acidophilus, Lactobacillus reuteri, and Lactobacillus casei demonstrated the significant enhancement in OVX groups treated with. Among the probiotics used in this study, Lactobacillus acidophilus and Lactobacillus casei showed the most effects in terms of BMD, BMC, bone area, and biochemical parameters. It seems that probiotics effects on bone health are strain dependent, but further studies should be done to prove these findings.

     

Isolation and characterization of bacteriocin‐producing bacteria from the intestinal microbiota of elderly Irish subjects

Aims

To isolate and characterize bacteriocins produced by predominant species of lactic acid bacteria from faeces of elderly subjects.

Methods and Results

Screening over 70 000 colonies, from faecal samples collected from 266 subjects, using the indicator organisms Lactobacillus bulgaricus LMG 6901 and Listeria innocua DPC 3572, identified 55 antimicrobial‐producing bacteria. Genomic fingerprinting following ApaI digestion revealed 15 distinct strains. The antimicrobial activities associated with 13 of the 15 strains were sensitive to protease treatment. The predominant antimicrobial‐producing species were identified as Lactobacillus salivarius, Lactobacillus gasseri, Lactobacillus acidophilus, Lactobacillus crispatus and Enterococcus spp. A number of previously characterized bacteriocins, including ABP‐118 and salivaricin B (from Lact. salivarius), enterocin B (Enterococcus faecium), lactacin B (Lact. acidophilus), gassericin T and a variant of gassericin A (Lact. gasseri), were identified. Interestingly, two antimicrobial‐producing species, not generally associated with intestinally derived microorganisms were also isolated: Lactococcus lactis producing nisin Z and Streptococcus mutans producing mutacin II.

Conclusion

These data suggest that bacteriocin production by intestinal isolates against our chosen targets under the screening conditions used was not frequent (0·08%).

Significance and Impact of the Study

The results presented are important due to growing evidence indicating bacteriocin production as a potential probiotic trait by virtue of strain dominance and/or pathogen inhibition in the mammalian intestine.     

In vivo Testing of Functional Properties of Three Selected Probiotic Strains

Summary Lactobacillus acidophilus M92, Lactobacillus plantarum L4 and Enterococcus faecium L3 were previously selected as probiotic strains on the base of in vitro selection criteria. To investigate functional properties of these three probiotic strains in vivo, Swiss albino mice were used as animal model. Survival, competition, adhesion and colonization were monitored in the gastrointestinal tract, as well as the immunomodulating capability of L. acidophilus M92, L. plantarum L4 and E. faecium L3. During the feeding of mice with probiotic strains with daily dose of 2 × 10¹⁰ rifampicin-resistant cells, the number of lactic acid bacteria in the faeces increased and reduction of enterobacteria and sulphite-reducing clostridia was observed. Rifampicin-resistant colonies of probiotic strains could be reisolated from the faeces of mice fed with the rifampicin-resistant cells. The similar results were obtained in homogenates of small and large intestine of mice on the first and fourteenth days after feeding with L. acidophilus M92, L. plantarum L4 and E. faecium L3. The adherence of the probiotic strains obtained in vitro correlated with their capability to adhere to mouse ileal epithelial cells in vivo. After oral immunization of mice with viable cells of L. acidophilus M92, L. plantarum L4 and E. faecium L3 with a daily dose of 2 × 10¹⁰ cells, the concentrations of serum IgA, IgG and IgM antibodies from all groups of mice were significantly higher in comparison to the control.     

More Protection of Lactobacillus acidophilus Than Bifidobacterium bifidum Probiotics on Azoxymethane-Induced Mouse Colon Cancer

Based on the ability of the probiotics in the gut microflora modification, they can have the beneficial effects on diseases in the short and/or the long term. In previous study, we revealed that unlike Bifidobacterium bifidum, the amount of Lactobacillus acidophilus remained almost unchanged in mice gut microflora in the long term, indicating more stability of L. acidophilus than B. bifidum which can be used to prevent some incurable diseases such as cancer. Thirty-eight male BALB/c mice were divided into four groups, control, azoxymethane (AOM), L. acidophilus, and B. bifidum probiotics, to evaluate the protective effects of the probiotics on AOM-induced mouse colon cancer. Except for the control group, the rest of the animals were weekly given AOM (15 mg/kg, s.c) in three consecutive weeks. Colon lesion incidence was 74% in the AOM group in comparison with the control (0%) (P < 0.05). The lesions were varied from mild to severe dysplasia and colonic adenocarcinoma. Administration of the probiotics inhibited the incidence of colonic lesions by about 57% in L. acidophilus (P < 0.05) and 27% in B. bifidum (P > 0.05) compared to the AOM group. The serum levels of CEA and CA19-9 tumor markers were significantly decreased in L. acidophilus in comparison with the AOM group (P < 0.05). Moreover, the serum levels of IFN-γ and IL-10 and the number of CD4⁺ and CD8⁺ cells were significantly increased in L. acidophilus compared to AOM (P < 0.05). Our study highlighted the more potential effects of L. acidophilus probiotic than B. bifidum on mouse colon cancer.