Safety and efficacy of probiotic lactobacilli in promoting growth in post-weaning Swiss mice

Probiotic Potential of Yeast, Mold, and Intermediate Morphotypes of Geotrichum candidum in Modulating Gut Microbiota and Body Physiology in Mice

Geotrichum candidum, a polymorphic fungus, exists in yeast, mold, and intermediate morphotypes, each with varying genome sizes and phenotypic traits. While G. candidum has been studied as a probiotic in dairy cattle and aquaculture, the differential probiotic potential of its morphotypes has not been fully investigated; therefore, the current study was designed to investigate their impact on the modulation of physiological and gut microbial diversity in BALB/c male mice. In this study, four strains of G. candidum were used, comprising two yeast morphotypes (QAUGC01 and UCMA3730), one mold morphotype (UCMA103), and one intermediate morphotype (UCMA91). BALB/c male mice were administered G. candidum yeast, intermediate, and mold morphotypes via drinking water for 4 weeks. After 4 weeks of experimentation, the yeast morphotype (QAUGC01) notably facilitated healthy weight gain compared to other groups. This was accompanied by significant increases in red blood cell count (p = 0.01). Importantly, QAUGC01 showed no detrimental effects on kidney function, as evidenced by significantly reduced CPK levels (77.25 ± 4.87 U/L) and low cholesterol levels (64.75 ± 0.83 mg/dL). Metagenomic analysis revealed that Firmicutes, Bacteroidetes, and Proteobacteria were predominant bacterial phyla, while Ascomycota and Basidiomycota dominated the fungal populations. Lactobacillus and Bifidobacterium were prominent in the gastrointestinal tract of QAUGC01-treated mice, while Lactococcus correlated with intermediate and mold morphotypes. Predictive functional annotation (PICRUSt2) has revealed the maximum relative abundance of metabolic pathways in mold and intermediate-supplemented mice gut. In contrast, the yeast morphotype (UCMA3730) exhibited a higher metabolic pathway activity in the large intestine. Conclusively, yeast morphotypes increase beneficial bacterial diversity, including Brevibacillus and Bacillus, particularly lactic acid bacteria throughout the gastrointestinal tract. These findings suggest that different G. candidum morphotypes have distinct probiotic potentials, with implications for enhancing gut health in food and feed applications.

Evaluation of Acute and Sub-Chronic Toxicity of Lactobacillus rhamnosus GG in Sprague-Dawley Rats

Background

Probiotic-based bacteriotherapy has emerged as a potentially effective strategy for preventing infectious diseases. Lactobacillus strains consumed as probiotics and the safety of these spp. has been questioned due to reported unexpected responses. Hence, the present study has been conducted to evaluate the acute and sub-chronic toxicity of Lactobacillus rhamnosus GG in Sprague-Dawley (SD) rats.

Materials and Methods

The acute and sub-chronic toxicity effect of L. rhamnosus is studied in rats as per the Organization for Economic Cooperation and Development (OECD), test guideline 423 and 407, respectively.

Results

In acute toxicity, L. rhamnosus at 1 × 107, 1 × 108, 1 × 109, and 1 × 1010 CFU/mL don't show any toxic signs. In sub-chronic toxicity, L. rhamnosus at 1 × 106,1 × 107 and 1 × 108 CFU/mL dosages showed dose-depended changes in biochemical and haematological parameters. In this study, one male and one female rat administered with 1 x 108 CFU/mL of L. rhamnosus showed mortality on days 16 and 26, respectively. The animals administered with L. rhamnosus showed no histological changes in the organs such as heart, liver and kidney.

Conclusion

L. rhamnosus exhibited mild-to-moderate toxic effects at the dose levels of 1 × 106 CFU/mL, 1 × 107 and 1 × 108 CFU/mL in rats.

Probiotics and Postbiotics as an Alternative to Antibiotics: An Emphasis on Pigs

Probiotics are being used as feed/food supplements as an alternative to antibiotics. It has been demonstrated that probiotics provide several health benefits, including preventing diarrhea, irritable bowel syndrome, and immunomodulation. Alongside probiotic bacteria-fermented foods, the different structural components, such as lipoteichoic acids, teichoic acids, peptidoglycans, and surface-layer proteins, offer several advantages. Probiotics can produce different antimicrobial components, enzymes, peptides, vitamins, and exopolysaccharides. Besides live probiotics, there has been growing interest in consuming inactivated probiotics in farm animals, including pigs. Several reports have shown that live and killed probiotics can boost immunity, modulate intestinal microbiota, improve feed efficiency and growth performance, and decrease the incidence of diarrhea, positioning them as an interesting strategy as a potential feed supplement for pigs. Therefore, effective selection and approach to the use of probiotics might provide essential features of using probiotics as an important functional feed for pigs. This review aimed to systematically investigate the potential effects of lactic acid bacteria in their live and inactivated forms on pigs.

Cholesterol-lowering effects and safety assessment of Lactobacillus spp. in vivo and in vitro testing for human use as probiotic from the dairy product in Egypt

BACKGROUND

The toxicity profile of lactobacilli may be strain dependent, so it should be considered for safe utilization of probiotics. Further, in vivo studies are necessary to evaluate their safety.

RESULT

The ability of various probiotic strains to hydrolyze bile salts has been confirmed without noticeable hemolytic activity. Results revealed the presence of α-glucosidase, β-glucosidase, α-galactosidase, and β-galactosidase activity in all investigated isolates, while none of the isolates produced the carcinogenic enzyme β-glucuronidase. The probiotic strains exhibited remarkable cholesterol-lowering impact. Also, we found no evidence of chronic toxicity under the experimental conditions based on gross pathological examination of the viscera and study of the spleen and liver weight ratios. These findings indicated that the investigated strains, either alone or combined with their metabolites, had no obvious adverse effect on the mice's general health status.

CONCLUSION

There is prove that the investigated probiotic strains are safe to be utilized for enhancing of the growth performance and are free of adverse side effects.

Dietary Supplementation of Chitosan Oligosaccharide–Clostridium butyricum Synbiotic Relieved Early-Weaned Stress by Improving Intestinal Health on Pigeon Squabs (Columba livia)

According to a previous study, we had found that early weaning causes harm to growth performance, intestinal morphology, activity of digestive enzymes, and antioxidant status in pigeon squabs (Columba livia). Chitosan oligosaccharides (COS) and Clostridium butyricum have been reported to have great potential to improve the growth performance and intestinal health of early-weaned animals. Therefore, the aim of this study is to explore whether dietary supplementation with COS-C. butyricum synbiotic could relieve early-weaned stress by evaluating its effects on growth performance and intestinal health in pigeon squabs. A total of 160 squabs (weaned at 7 days of age) were randomly divided into 5 groups: the control group, fed with artificial crop milk; the COS supplementation group, fed with artificial crop milk + 150 mg/kg COS; and three synbiotic supplementation groups, fed with artificial crop milk + 150 mg/kg COS + 200, 300, and 400 mg/kg C. butyricum. The results showed that a diet supplemented with COS-C. butyricum synbiotic benefitted the growth performance of early-weaned squabs; even so the differences were not significant among the five groups (p > 0.05). In addition, dietary supplementation of 150 mg/kg COS + 300~400 mg/kg C. butyricum significantly improved the intestinal morphology (especially villus surface area and the ratio of villus height to crypt depth), the activity of digestive enzymes (lipase, trypsin, and leucine aminopeptidase) in duodenum contents, and the production of total short-chain fatty acids and acetic acid in ileum content (p < 0.05). Additionally, dietary supplementation of 150 mg/kg COS + 400 mg/kg C. butyricum benefitted gut health by improving the antioxidant capacity (glutathione peroxidase and total antioxidant capacity) and cytokine status (IL-4 and IL-10) (p < 0.05), as well as by improving the intestinal microbiota diversity. In conclusion, our results revealed that dietary supplementation with synbiotic (150 mg/kg COS + 300~400 mg/kg C. butyricum) could relieve early-weaned stress by maintaining intestinal health in pigeon squabs.

Lactobacillus reuteri and Enterococcus faecium from Poultry Gut Reduce Mucin Adhesion and Biofilm Formation of Cephalosporin and Fluoroquinolone-Resistant Salmonella enterica

Non-typhoidal Salmonella (NTS) can cause infection in poultry, livestock, and humans. Although the use of antimicrobials as feed additives is prohibited, the previous indiscriminate use and poor regulatory oversight in some parts of the world have resulted in increased bacterial resistance to antimicrobials, including cephalosporins and fluoroquinolones, which are among the limited treatment options available against NTS. This study aimed to isolate potential probiotic lactic acid bacteria (LAB) strains from the poultry gut to inhibit fluoroquinolone and cephalosporin resistant MDR Salmonella Typhimurium and S. Enteritidis. The safety profile of the LAB isolates was evaluated for the hemolytic activity, DNase activity, and antibiotic resistance. Based on the safety results, three possible probiotic LAB candidates for in vitro Salmonella control were chosen. Candidate LAB isolates were identified by 16S rDNA sequencing as Lactobacillus reuteri PFS4, Enterococcus faecium PFS13, and Enterococcus faecium PFS14. These strains demonstrated a good tolerance to gastrointestinal-related stresses, including gastric acid, bile, lysozyme, and phenol. In addition, the isolates that were able to auto aggregate had the ability to co-aggregate with MDR S. Typhimurium and S. Enteritidis. Furthermore, LAB strains competitively reduced the adhesion of pathogens to porcine mucin Type III in co-culture studies. The probiotic combination of the selected LAB isolates inhibited the biofilm formation of S. Typhimurium FML15 and S. Enteritidis FML18 by 90% and 92%, respectively. In addition, the cell-free supernatant (CFS) of the LAB culture significantly reduced the growth of Salmonella in vitro. Thus, L. reuteri PFS4, E. faecium PFS13, and E. faecium PFS 14 are potential probiotics that could be used to control MDR S. Typhimurium and S. Enteritidis in poultry. Future investigations are required to elucidate the in vivo potential of these probiotic candidates as Salmonella control agents in poultry and animal feed.

Effects of dietary inactivated probiotics on growth performance and immune responses of weaned pigs

This experiment was performed to verify whether dietary heat-killed Lactobacillus rhamnosus (LR) improves growth performance and modulates immune responses of weaned pigs. Ninety-six weaned pigs ([Landrace × Yorkshire] × Duroc; 6.95 ± 0.25 kg body weight [BW]; 28 d old) were randomly allocated to four treatments: 1) a basal diet without heat-killed LR (CON), 2) T1 (CON with 0.1% heat-killed LR), 3) T2 (CON with 0.2% heat-killed LR), and 4) T3 (CON with 0.4% heat-killed LR). Each treatment had six pens with four pigs (6 replicates per treatment) in a randomized completely block design. The heat-killed LR used in this study contained 1 × 10⁹ FU/g of LR in a commercial product. Pigs were fed each treatment for four weeks using a two-phase feeding program to measure growth performance and frequency of diarrhea. During the last week of this study, all diets contained 0.2% chromic oxide as an indigestible marker. Fecal sampling was performed through rectal palpation for the consecutive three days after the four adaptation days to measure apparent total tract digestibility (ATTD) of dry matter, crude protein, and gross energy (GE). Blood sampling was also performed on day 1, 3, 7, and 14 after weaning to measure immune responses such as serum tumor necrosis factor-α (TNF-α), transforming growth factor-β1 (TGF-β1), C-reactive protein (CRP), and cortisol. The heat-killed LR increased (p < 0.05) growth rate, feed efficiency, and ATTD of GE for overall experimental period compared with CON, but reduced (p < 0.05) post-weaning diarrhea. In addition, pigs fed diets contained heat-killed had lower concentrations of serum TNF-α (d 7; p < 0.05), TGF-β1 (d 7; p < 0.10), and cortisol (d 3 and 7; p < 0.05) than pigs fed CON. In conclusion, dietary heat-killed LR improved growth rate, modified immune responses of weaned pigs, and alleviated post-weaning diarrhea.

Barley-based probiotic food mixture: health effects and future prospects

Consumers around the globe are increasingly aware of the relation between nutrition and health. In this sense, food products that can improve gastrointestinal health such as probiotics, prebiotics and synbiotics are the most important segment within functional foods. Cereals are the potential substrates for probiotic products as they contain nutrients easily assimilated by probiotics and serve as the transporters of Lactobacilli through the severe conditions of gastrointestinal tract. Barley is one of the important substrates for the probiotic formulation because of its high phenolic compounds, β-glucans and tocols. The purpose of this review is to examine recent information regarding barley-based probiotic foods with a specific focus on the potential benefits of barley as a substrate for probiotic microorganisms in the development of dairy and nondairy based food products, and to study the effects of food matrices containing barley β-glucans on the growth and features of Lactobacillus strains after fermentation.

Lactobacillus animalis pZL8a: a potential probiotic isolated from pig feces for further research

This study aimed to screen a potential anti-diarrheal probiotic for pigs to meet the growing demand for antibiotic alternatives in livestock. Six intestinal pathogens, Escherichia coli (O157: H7) ATCC 43888, Staphylococcus aureus ATCC 6538, Listeria monocytogenes ATCC 19115, Salmonella Typhimurium ATCC 14028, Shigella boydii ATCC 9207, and Staphylococcus haemolyticus ZSY2 were employed as indicator bacteria. Our result showed that Lactobacillus animalis pZL8a isolated from pig feces had extensive and higher antibacterial activity against indicator pathogens among 9 tested strains. In addition, valuable attributes of pZL8a such as great tolerance of low pH (3.0) and bile salts (0.3%), high-level adhesion to Caco-2 cells, and similar susceptibility to the reference strain Lactobacillus rhamnosus GG (LGG) were observed. Compared with control, pZL8a supplement significantly improved the level of immunoglobulin G (IgG), immunoglobulin M (IgM), and interleukin-2 (IL-2) in mouse serum. Therefore, L. animalis pZL8a was proposed as a potential probiotic for further research and hope to reduce or replace the application of antibiotics in animal production.

Oral microbiome and obesity in a large study of low-income and African-American populations

Few studies have evaluated the relationship of oral microbiome with obesity. We investigated the oral microbiome among 647 obese and 969 non-obese individuals from the Southern Community Cohort Study, through 16S rRNA gene sequencing in mouth rinse samples. We first investigated 16 taxa in two probiotic genera, Bifidobacterium and Lactobacillus. Among them, eight showed nominal associations with obesity (P < 0.05). Especially, Bifidobacterium (odds ratio [OR] = 0.67, 95% confidence interval [CI]:0.54, 0.83) and Bifidobacterium longum (OR = 0.57, 95% CI: 0.45, 0.73) were significantly associated with decreased obesity prevalence with false-discovery rate (FDR)-corrected P of 0.01 and 5.41 × 10-4, respectively. Multiple other bacterial taxa were also significantly associated with obesity prevalence at FDR-corrected P < 0.05. Among them, five in Firmicutes and two respectively in Actinobacteria and Proteobacteria were significantly associated with increased obesity prevalence. Significant associations with decreased obesity prevalence were observed for two taxa respectively in Actinobacteria and Firmicutes. Most of these taxa were associated with body mass index at study enrollment and weight gain during adulthood. Also, most of these associations were observed in both European- and African-Americans. Our findings indicate that multiple oral bacterial taxa, including several probiotic taxa, were significantly associated with obesity.

Evaluation of safety and antifungal activity of Lactobacillus reuteri and Pediococcus diacetilactis isolates against aflatoxigenic Aspergillus flavus

Biocontrol of moulds by lactic acid bacteria (LAB) instead of antibiotics and chemical preservatives is a new approach in veterinary medicine. The aims of present research were to perform molecular identification of dominant sourdough LAB isolates and to evaluate their in vivo safety and in vitro antifungal properties for using as biopreservative agents. Sequencing results of PCR products led to identification of Lactobacillus reuteri and Pediococcus diacetilactis as LAB isolates. Antifungal activity of the isolates and their cell-free culture filtrate (CCF) were also confirmed against aflatoxigenic Aspergillus flavus, respectively by overlay and spore spot methods. Accordingly, antagonistic effect of P. diacetilactis and its CCF were significantly (P<0.05) higher than L. reuteri and CCF of mentioned LAB isolate. Clinical chemistry and haematological findings in mice fed LAB demonstrated also insignificant difference vs control mice and were in the normal range, which confirmed the safety of LAB isolates. By considering the importance of safe, food grade biocontrol agents, L. reuteri and P. diacetilactis isolates and their CCF may be considered as an alternative for antibiotics and other chemical preservatives in food and feed processing chain

Safety Evaluation of a Novel Strain of Bacteroides fragilis

Commensal non-toxigenic Bacteroides fragilis confers powerful health benefits to the host, and has recently been identified as a promising probiotic candidate. We previously isolated B. fragilis strain ZY-312 and identified it as a novel strain based on 16S rRNA sequencing and morphological analyses. We also determined that ZY-312 displayed desirable probiotic properties, including tolerance to simulated digestive fluid, adherence, and in vitro safety. In this study, we aim to investigate whether ZY-312 meets the safety criteria required for probiotic bacteria through comprehensive and systematic evaluation. Consequently, the fatty acid profile, metabolite production, and biochemical activity of strain ZY-312 were found to closely resemble descriptions of B. fragilis in Bergey’s manual. Taxonomic identification of strain ZY-312 based on whole genome sequencing indicated that ZY-312 and ATCC 25285 showed 99.99% similarity. The 33 putative virulence-associated factors identified in ZY-312 mainly encoded structural proteins and proteins with physiological activity, while the lack of bft indicated that ZY-312 was non-toxigenic. In vivo safety was proven in both normal and immune-deficient mice. The 11 identified antibiotic resistance genes were located on the chromosome rather than on a plasmid, ruling out the risk of plasmid-mediated transfer of antibiotic resistance. In vitro, ZY-312 showed resistance to cefepime, kanamycin, and streptomycin. Finally, and notably, ZY-312 exhibited high genetic stability after 100 passages in vitro. This study supplements the foundation work on the safety evaluation of ZY-312, and contributes to the development of the first probiotic representative from the dominant Bacteroidetes phylum.

The Role of Probiotics on the Microbiota: Effect on Obesity

The microbiota and the human host maintain a symbiotic association. Nowadays, metagenomic analyses are providing valuable knowledge on the diversity and functionality of the gut microbiota. However, with regard to the definition of a "healthy microbiota" and the characterization of the dysbiosis linked to obesity, there is still not a clear answer. Despite this fact, attempts have been made to counteract obesity through probiotic supplementation. A literature search of experimental studies relevant to the topic was performed in PubMed database with the keywords "probiotic" and "obesity" and restricted to those with "Lactobacillus" or "Bifidobacterium" in the title. So far, evidence of an antiobesity effect of different lactobacilli and bifidobacteria has been mainly obtained from animal models of dietary-induced obesity. Using these experimental models, a substantial number of studies have reported reductions in weight gain and, in particular, fat tissue mass at different locations following administration of bacteria, as compared with controls. Antiatherogenic and anti-inflammatory effects-including regulation of expression of lipogenic and lipolytic genes in the liver, reduction in liver steatosis, improvement of blood lipid profile and glucose tolerance, decreased endotoxemia, and regulation of inflammatory pathways-are also reported in many of them. The number of human studies focused on probiotic administration for obesity management is still very scarce, and it is too soon to judge their potential efficacy, especially when considering the fact that the actions of probiotics are always strain specific and the individual response varies according to intrinsic factors, the overall composition of diet, and their interactions.

Dietary Lactobacillus rhamnosus GG Supplementation Improves the Mucosal Barrier Function in the Intestine of Weaned Piglets Challenged by Porcine Rotavirus

Lactobacillus rhamnosus GG (LGG) has been regarded as a safe probiotic strain. The aim of this study was to investigate whether dietary LGG supplementation could alleviate diarrhea via improving jejunal mucosal barrier function in the weaned piglets challenged by RV, and further analyze the potential roles for apoptosis of jejunal mucosal cells and intestinal microbiota. A total of 24 crossbred barrows weaned at 21 d of age were assigned randomly to 1 of 2 diets: the basal diet and LGG supplementing diet. On day 11, all pigs were orally infused RV or the sterile essential medium. RV infusion increased the diarrhea rate, increased the RV-Ab, NSP4 and IL-2 concentrations and the Bax mRNA levels of jejunal mucosa (P<0.05), decreased the villus height, villus height: crypt depth, the sIgA, IL-4 and mucin 1 concentrations and the ZO-1, occludin and Bcl-2 mRNA levels of jejunal mucosa (P<0.05), and affected the microbiota of ileum and cecum (P<0.05) in the weaned pigs. Dietary LGG supplementation increased the villus height and villus height: crypt depth, the sIgA, IL-4, mucin 1 and mucin 2 concentrations, and the ZO-1, occludin and Bcl-2 mRNA levels of the jejunal mucosa (P<0.05) reduced the Bax mRNA levels of the jejunal mucosa (P<0.05) in weaned pigs. Furthermore, dietary LGG supplementation alleviated the increase of diarrhea rate in the weaned pigs challenged by RV (P<0.05), and relieve the effect of RV infection on the villus height, crypt depth and the villus height: crypt depth of the jejunal mucosa (P<0.05), the NSP4, sIgA, IL-2, IL-4, mucin 1 and mucin 2 concentrations of jejunal mucosa (P<0.05), the ZO-1, occludin, Bax and Bcl-2 mRNA levels of the jejunal mucosa (P<0.05), and the microbiota of ileum and cecum (P<0.05) in the weaned pigs challenged by RV. These results suggest that supplementing LGG in diets alleviated the diarrhea of weaned piglets challenged by RV via inhibiting the virus multiplication and improving the jejunal mucosal barrier function, which was possibly due to the decreasing apoptosis of jejunal mucosal cells and the improvement of intestinal microbiota.

Exercise prevents weight gain and alters the gut microbiota in a mouse model of high fat diet-induced obesity

Background

Diet-induced obesity (DIO) is a significant health concern which has been linked to structural and functional changes in the gut microbiota. Exercise (Ex) is effective in preventing obesity, but whether Ex alters the gut microbiota during development with high fat (HF) feeding is unknown.

Objective

Determine the effects of voluntary Ex on the gastrointestinal microbiota in LF-fed mice and in HF-DIO.

Methods

Male C57BL/6 littermates (5 weeks) were distributed equally into 4 groups: low fat (LF) sedentary (Sed) LF/Sed, LF/Ex, HF/Sed and HF/Ex. Mice were individually housed and LF/Ex and HF/Ex cages were equipped with a wheel and odometer to record Ex. Fecal samples were collected at baseline, 6 weeks and 12 weeks and used for bacterial DNA isolation. DNA was subjected both to quantitative PCR using primers specific to the 16S rRNA encoding genes for Bacteroidetes and Firmicutes and to sequencing for lower taxonomic identification using the Illumina MiSeq platform. Data were analyzed using a one or two-way ANOVA or Pearson correlation.

Results

HF diet resulted in significantly greater body weight and adiposity as well as decreased glucose tolerance that were prevented by voluntary Ex (p<0.05). Visualization of Unifrac distance data with principal coordinates analysis indicated clustering by both diet and Ex at week 12. Sequencing demonstrated Ex-induced changes in the percentage of major bacterial phyla at 12 weeks. A correlation between total Ex distance and the ΔCt Bacteroidetes: ΔCt Firmicutes ratio from qPCR demonstrated a significant inverse correlation (r² = 0.35, p = 0.043).

Conclusion

Ex induces a unique shift in the gut microbiota that is different from dietary effects. Microbiota changes may play a role in Ex prevention of HF-DIO.

Related actions of probiotics and antibiotics on gut microbiota and weight modification

Antibiotics and probiotics are widely used as growth promoters in agriculture. Most antibiotics prescribed in clinical practice are natural products that originate from Streptomyces spp, which were first used as agricultural probiotics. Antibiotics and probiotics both modify the gut microbiota. The effect of a probiotic species on the digestive flora depends on the strain and is largely determined by bacteriocin production. In human beings, as in animals, specific probiotics are associated with weight gain or loss. Improved understanding of the ability of specific probiotics to harvest energy from the host diet might lead to development of new treatments for obesity and malnutrition. In this Review, we present the effects of probiotics and antibiotics on the gut microbiota of human beings and animals and discuss their potential therapeutic use as interventions for weight gain and loss in human beings.

Genotoxicity assessment of multispecies probiotics using reverse mutation, mammalian chromosomal aberration, and rodent micronucleus tests

Genotoxicity assessment is carried out on freeze dried powder of cultured probiotics containing Lactobacillus rhamnosus LCR177, Bifidobacterium adolescentis BA286, and Pediococcus acidilactici PA318. Ames tests, in vitro mammalian chromosome aberration assay, and micronucleus tests in mouse peripheral blood are performed. For 5 strains of Salmonella Typhimurium, the Ames tests show no increased reverse mutation upon exposure to the test substance. In CHO cells, the frequency of chromosome aberration does not increase in responding to the treatment of probiotics. Likewise, the frequency of micronucleated reticulocytes in probiotics-fed mice is indistinguishable from that in the negative control group. Taken together, the toxicity assessment studies suggest that the multispecies probiotic mixture does not have mutagenic effects on various organisms.

An evaluation of the effects of Lactobacillus ingluviei on body weight, the intestinal microbiome and metabolism in mice

BACKGROUND

Food can modify the intestinal flora, and Lactobacillus ingluviei has been shown to cause weight gain in chicks and ducks but not in mammals.

METHODOLOGY

Female BALB/c mice were divided into a control and two experimental groups and were inoculated either once or twice with L. ingluviei or with PBS. Faecal samples were collected and tested using qPCR in order to detect and quantify Lactobacillus spp., Bacteroidetes spp. and Firmicutes spp. Gene expression was examined in liver and adipose tissue by microarray and qPCR. Metabolic indicators in the plasma were also measured.

RESULTS

Mice that were inoculated with 4 × 10(10) L. ingluviei presented a significant increase in weight gain and liver weight and significant increases in Lactobacillus spp. and Firmicutes DNA copy numbers in their faeces. The mRNA levels of fatty acyl synthase (Fas), sterol regulatory element binding factor 1 (Srebp1c), tumour necrosis factor alpha (Tnf), cytochrome P450 2E1 (Cyp2e1), 3-phosphoinositide-dependent protein kinase-1 (Pdpk1), acyl-Coenzyme A dehydrogenase 11 (Acad11), ATP-binding cassette sub family member G (ABCG2) and DEAD box polypeptide 25 (Ddx25) were significantly elevated in the liver tissues of animals in the experimental group. In gonadal adipose tissue, the expression levels of leptin, peroxisome proliferator-activated receptor γ (Pparg) and Srebp1c were significantly higher in animals from the experimental group, whereas the expression of adiponectin was significantly lower in these animals.

CONCLUSIONS

The inoculation of L. ingluviei in mice resulted in alterations in the intestinal flora, increased weight gain and liver enlargement, accelerated metabolism and increased inflammation.

In vitro and in vivo safety evaluation of the bacteriocin producer Streptococcus macedonicus ACA-DC 198

Streptococcus macedonicus ACA-DC 198, a bacteriocin producer isolated from Greek Kasseri cheese, was used in a series of in vitro and in vivo experiments in order to evaluate its pathogenic potential. The strain was examined in vitro for haemolytic activity, antibiotic resistance and presence of pathogenicity genes encountered in Streptococcus pyogenes. Subsequently, the strain was orally administered to mice (8.9 log cfu daily), continuously over a period of 12 weeks, in order to ascertain the effects of its long term consumption on animal health and gastric inflammation. S. macedonicus ACA-DC 198 was found to be non-haemolytic and sensitive to ampicillin, chloramphenicol, ciprofloxacin, erythromycin, streptomycin, tetracycline, and vancomycin, with the only resistance observed against kanamycin. PCR amplification and DNA-DNA hybridization did not reveal the presence of any of the S.pyogenes pathogenicity genes examined, namely emm, scpA, hasA, speB, smez2, speJ, sagAB, hylA, ska, speF, speG, slo, hylP2 and mga. In the mouse study, no detrimental effects were observed in the behaviour, general well being, weight gain and water consumption of the animals receiving S. macedonicus ACA-DC 198. Histologic analysis showed no evidence of inflammation in the stomach of the animals receiving S. macedonicus ACA-DC 198, while faecal microbiological analysis revealed that the strain retained its viability passing through the mouse gastrointestinal tract. Finally, no evidence of translocation to the liver, spleen and mesenteric lymph nodes was observed. In conclusion, none of the examined virulence determinants were detected in S. macedonicus ACA-DC 198 and its long term, high dosage oral administration did not appear to induce any pathogenic effect in mice.

Effects of Lactobacillus plantarum MA2 isolated from Tibet kefir on lipid metabolism and intestinal microflora of rats fed on high-cholesterol diet

The objective of this study was to evaluate the effects of Lactobacillus plantarum MA2, an isolate from Chinese traditional Tibet kefir, on cholesterol-lowering and microflora of rat in vivo. Rats were fed on cholesterol-enriched experimental diet, supplemented with lyophilized L. plantarum MA2 powder, with a dose of 10(11) cells/day per mice. The results showed that L. plantarum MA2 feeding significantly lowered serum total cholesterol, low-density lipoprotein cholesterol, and triglycerides level, while there was no change in high-density lipoprotein cholesterol. In addition, liver total cholesterol and triglycerides was also decreased. However, fecal cholesterol and triglycerides was increased significantly (P < 0.05) in comparison with the control. Also, L. plantarum MA2 increased the population of lactic acid bacteria and bifidobacteria in the fecal, but it did not change the number of Escherichia coli as compared to control. Moreover, pH, moisture, and organic acids in the fecal were also measured. The present results indicate the probiotic potential of the L. plantarum MA2 strain in hypocholesterolemic effect and also increasing the probiotic count in the intestine.

Age-related effects of the probiotic bacterium Lactobacillus plantarum 299v on gastrointestinal function in suckling rats

The effect of a probiotic bacterium on gut function was studied in neonatal animals by using a model with suckling rats. Lactobacillus plantarum 299v (Lp299v) or saline (controls) was fed (3.0 x 10(6) CFU/g b.wt per day) for one week to rats aged either 3, 7 or 14 days, after which bacterial colonization, gut growth, and functional parameters were analyzed. In rats fed with Lp299v from 3 to 10 days of age, an increase in ceacal lactobacilli was correlated with reduced intestinal macromolecular permeability and increased mucosal protein compared to age-matched controls. Pups treated from 7 to 14 days of age showed a decrease in pancreas weight and protein content, whereas pups treated from 14 to 21 days of age showed little effect of the Lp299v treatment. The results indicated that the bacterial exposure affected the gut function, where the effects were age-related and the youngest rats appeared most sensitive.

Maternal consumption of Lactobacillus plantarum 299v affects gastrointestinal growth and function in the suckling rat

After birth, the gastrointestinal (GI) tract undergoes vast structural and functional adaptations to be able to digest mother's milk and later, during the weaning period, solid food. Studies on germ-free animals have shown the role of the gut microbiota for stimulating GI maturation, but which groups are involved is unclear. In the present study, we administered the probiotic bacterium, Lactobacillus plantarum 299v (Lp299v), in the drinking water to pregnant and lactating rat dams until their pups had reached an age of 14 d. It was found that Lp299v colonizing the mothers were also able to colonize the pups, which had an impact on their gut growth and function. The small intestine, pancreas and liver weighed more in the 14 d-old pups born from dams exposed to Lp299v than in the control pups from dams given only water. Furthermore, the Lp299v pups showed decreased gut permeability. Despite a heavier spleen in the Lp299v pups, as compared to the control pups, no significant increase in the acute-phase protein, haptoglobin, was found. In conclusion, the results reported here clearly show that manipulating the maternal microflora by exposing expecting mothers to a Gram-positive, probiotic bacterium prior to parturition and during lactation impacts the gut growth and function in the offspring.

Safety evaluation of Bifidobacterium pseudocatenulatum G4 as assessed in BALB/c mice

AIMS

To assess the safety of Bifidobacterium pseudocatenulatum G4 in BALB/c mice that involves examination of bacterial translocation, changes in the internal organs and histology of the intestinal lining.

METHODS AND RESULTS

Forty male BALB/c mice were randomly assigned into five groups (n = 8). Three groups were orally fed with 50 microl of three different concentrations of B. pseudocatenulatum G4 (2 x 10(4), 1 x 10(8) and 1 x 10(11) CFU day(-1)) for 4 weeks. One group was orally administered with 50 microl of 1 x 10(8) CFU B. longum BB536 per day for 4 weeks and last group was used as a nonbifidobacterial treatment control, which received 50 microl of skim milk. The administered strains did not affect the general health of mice and incapable of carrying out translocation to blood or liver. There were no significant differences in the internal organ (liver, heart, kidney and spleen) indices, serum enzymes of liver (aspartate aminotransferase, alkaline phosphate, alanine aminotransferase) and kidney (urea and creatinine) and histology (villi height, crypts height, mucosa thickness and epithelial cell height) of caecum, ileum and colon.

CONCLUSION

Administration of high dose of up to 1 x 10(11) CFU B. pseudocatenulatum G4 per day to mice did not show any health threatening symptoms.

SIGNIFICANCE AND IMPACT OF THE STUDY

Bifidobacterium pseudocatenulatum G4 is none pathogenic to BALB/c mice and could be safe probiotic for human consumption.

Meta-analysis: Lactobacillus GG for treating acute diarrhoea in children

AIM

To review evidence for the effectiveness of Lactobacillus GG (LGG) in treating acute infectious diarrhoea in children.

METHODS

The following electronic databases were searched through August 2006 for studies relevant to acute infectious diarrhoea and LGG: MEDLINE, EMBASE, CINAHL and The Cochrane Library; additional references were obtained from reviewed articles. Only randomized-controlled trials (RCTs) were included.

RESULTS

Eight RCTs (988 participants) met the inclusion criteria. Compared with controls, LGG had no effect on the total stool volume (two RCTs, n = 303). However, LGG was associated with a significant reduction in diarrhoea duration (seven RCTs, 876 infants, weighted mean difference, WMD -1.1 days (95% confidence interval, CI -1.9 to -0.3), particularly of rotavirus etiology (WMD -2.1 days, 95% CI -3.6 to -0.6), risk of diarrhoea >7 days (one RCT, n = 287, relative risk 0.25, 95% CI 0.09-0.75) and duration of hospitalization (three RCTs, n = 535, WMD -0.58, 95% CI -0.8 to -0.4; significance was lost in the random effect model). There was no reduction in the number of stools at any time interval.

CONCLUSIONS

The use of LGG is associated with moderate clinical benefits in the treatment of acute diarrhoea in children. These findings should be interpreted with caution due to the important methodological limitations and heterogeneity of most of the studies.

Fermented infant formulae without live bacteria

Infant and follow-on (or "follow-up") formulae fermented with lactic acid-producing bacteria during the production process contain no viable bacteria in the final product due to their inactivation by heat or other means. In this article the ESPGHAN Committee on Nutrition reviews published information on their clinical evaluation. In a systematic literature review, 2 randomized clinical trials including 933 infants were identified as meeting our predefined inclusion criteria. Our analysis reveals that only limited published data are available on the effects of fermented infant formulae. There are indications from 2 studies that some fermented infant formulae may reduce the occurrence or severity of infectious diarrhea in infants. It is recommended that the effects of fermented infant formulae on infectious diarrhea and other relevant outcomes should be assessed in further randomized controlled trials according to current scientific standards. The available data do not allow general conclusions to be drawn on the use and effects of fermented formulae for infants.

Probiotics in gastrointestinal diseases in children: hard and not-so-hard evidence of efficacy

The use of probiotics, once discussed primarily in the context of alternative medicine, is now entering mainstream medicine. However, only a few of the potential health benefits attributed to probiotics have been confirmed in well-designed, well-conducted, randomized, controlled trials. This is especially true in the pediatric population. We review here the available evidence on efficacy of probiotics in children in the prevention and treatment of gastrointestinal diseases. Although we restrict our analysis to the pediatric age, whenever potentially relevant information is available only from adult studies, they are examined as well. Probiotics have been most extensively studied in the treatment of diarrheal diseases, where their efficacy can be considered well established. Studies documenting effects in other childhood gastrointestinal illnesses are few, although some preliminary results are promising. Furthermore, only a limited number of probiotic strains have been tested, and, as the effects of different probiotic microorganisms are not equivalent, results cannot be generalized. Thus, at present, we have some positive certainties, lots of exciting promises and many unanswered questions.

Use of probiotics in children with acute diarrhea

Probiotics, defined as microbial cell preparations or components of microbial cells that have a beneficial effect on the health and well being of the host, have traditionally been used to treat and prevent a variety of infections. Beneficial effects of probiotics in acute infectious diarrhea in children seem to be: (i) moderate; (ii) strain-dependent; (iii) dose dependent; (iv) significant in watery diarrhea and viral gastroenteritis, but non-existent in invasive, bacterial diarrhea; and (v) more evident when treatment with probiotics is initiated early in the course of disease. Three large, randomized controlled trials (RCTs) provide evidence of a very modest effect (statistically significant, but of questionable clinical importance) of some probiotic strains (Lactobaccillus GG, Lactobaccillus reuteri, Bifodobacterium lactis) on the prevention of community-acquired diarrhea. We have found conflicting evidence from four RCTs on the efficacy of Lactobacillus GG and B. bifidum and Streptococcus thermophilus in the prevention of nosocomial diarrhea in children. Two RCTs in children provide evidence of a moderate beneficial effect of Lactobacillus GG in the prevention of antibacterial-associated diarrhea (AAD), but results in adults are conflicting. Data on the efficacy of other probiotic strains in AAD in children are very limited. In conclusion, to date, the most extensively studied and best documented clinical application of probiotics in children is for the treatment of acute watery diarrhea of rotaviral or presumably viral etiology. Studies documenting effects in other types of diarrheal diseases in children are limited, although some preliminary results are promising. The effects of different probiotic microorganisms are not equal. Only very few probiotic strains have been tested rigorously in RCTs. Many questions remain to be answered. Future clinical trials should evaluate carefully selected, precisely defined probiotic strains and address clinically important endpoints.

Probiotics for preterm infants?

Infants nursed in special care baby units develop an abnormal pattern of microbial colonisation, which may contribute to disease. Enteric feeding of live microbial supplements (probiotics) may provide benefit to such infants and help to prevent diseases such as neonatal necrotising enterocolitis.