Hydrogen peroxide production by Lactobacillus johnsonii NCC 533 and its role in anti-Salmonella activity

The Anti-parasitic Effect of Probiotic Bacteria via Limiting the Fecundity of Trichinella Spiralis Female Adults

A potential protective effect of probiotic strains against zoonotic Trichinella spiralis infection was investigated in the framework of a new therapeutic strategy aimed at using probiotics to control parasitic zoonoses. The study was focused on the impact of six selected probiotic (bacteriocinogenic) strains on the intensity of T. spiralis infection and female fecundity ex vivo and in vitro. Bacterial strains of different origin (Enterococcus faecium EF55, Enterococcus faecium 2019 = CCM7420, Enterococcus faecium AL41 = CCM8558, Enterococcus durans ED26E/7, Lactobacillus fermentum AD1 = CCM7421, Lactobacillus plantarum 17L/1) were administered daily in a dose of 109 CFU/ml in 100 μl, and mice were infected with 400 T. spiralis larvae on day 7 of treatment. Female adults of T. spiralis were isolated on day 5 post infection (p.i.) and subsequently were used in fecundity test ex vivo. E. faecium CCM8558, E. faecium CCM7420 and E. durans ED26E/7 strains significantly reduced the number of adults in the intestine. The application of L. fermentum CCM7421, L. plantarum 17L/1, E. faecium CCM8558 and E. durans ED26E/7 caused a significant decrease in the number of muscle larvae. The treatment with E. faecium CCM8558 and E. durans ED26E/7 showed the highest inhibitory effect on female fecundity (94 %). The number of newborn larvae (NBL) was also significantly decreased after administration of L. fermentum CCM7421 and L. plantarum 17L/1 (80 %). A direct impact of probiotic strains on female reproductive capacity was examined in vitro in females isolated from untreated infected mice on day 5 p.i. A correlation was found between the inhibitory effect and the concentration of probiotic strains. The reduction effects of the strains manifested as follows: L. fermentum CCM7421 (93 %), E. faecium CCM8558, L. plantarum 17L/1, E. faecium EF55 (about 80 %), E. faecium CCM7420 and E. durans ED26E/7 (about 60 %).

Hydrogen peroxide production by lactobacilli promotes epithelial restitution during colitis

Inflammatory bowel disease (IBD) is a multifactorial chronic inflammatory disease of the gastrointestinal tract, characterized by cycles of acute flares, recovery and remission phases. Treatments for accelerating tissue restitution and prolonging remission are scarce, but altering the microbiota composition to promote intestinal homeostasis is considered a safe, economic and promising approach. Although probiotic bacteria have not yet fulfilled fully their promise in clinical trials, understanding the mechanism of how they exert beneficial effects will permit devising improved therapeutic strategies. Here we probe if one of the defining features of lactobacilli, the ability to generate nanomolar H2O2, contributes to their beneficial role in colitis. H2O2 generation by wild type L. johnsonii was modified by either deleting or overexpressing the enzymatic H2O2 source(s) followed by orally administering the bacteria before and during DSS colitis. Boosting luminal H2O2 concentrations within a physiological range accelerated recovery from colitis, while significantly exceeding this H2O2 level triggered bacteraemia. This study supports a role for increasing H2O2 within the physiological range at the epithelial barrier, independently of the enzymatic source and/or delivery mechanism, for inducing recovery and remission in IBD.

Anti-biofilm Properties of the Fecal Probiotic Lactobacilli Against Vibrio spp

Diarrheal disease caused by Vibrio cholerae is endemic in developing countries including India and is associated with high rate of mortality especially in children. V. cholerae is known to form biofilms on the gut epithelium, and the biofilms once formed are resistant to the action of antibiotics. Therefore agents that prevent the biofilm formation and disperse the preformed biofilms are associated with therapeutic benefits. The use of antibiotics for the treatment of cholera is associated with side effects such as gut dysbiosis due to depletion of gut microflora, and the increasing problem of antibiotic resistance. Thus search for safe alternative therapeutic agents is warranted. Herein, we screened the lactobacilli spp. isolated from the fecal samples of healthy children for their abilities to prevent biofilm formation and to disperse the preformed biofilms of V. cholerae and V. parahaemolyticus by using an in vitro assay. The results showed that the culture supernatant (CS) of all the seven isolates of Lactobacillus spp. used in the study inhibited the biofilm formation of V. cholerae by more than 90%. Neutralization of pH of CS completely abrogated their antimicrobial activities against V. cholera, but had negligible effects on their biofilm inhibitory potential. Further, CS of all the lactobacilli isolates caused the dispersion of preformed V. cholerae biofilms in the range 62–85%; however, pH neutralization of CS reduced the biofilm dispersal potential of the 4 out of 7 isolates by 19–57%. Furthermore, the studies showed that CS of none of the lactobacilii isolates had antimicrobial activity against V. parahaemolyticus, but 5 out of 7 isolates inhibited the formation of its biofilm in the range 62–82%. However, none of the CS dispersed the preformed biofilms of V. parahaemolyticus. The ability of CS to inhibit the adherence of Vibrio spp. to the epithelial cell line was also determined. Thus, we conclude that the biofilm dispersive action of CS of lactobacilli is strain-specific and pH-dependent. As Vibrio is known to form biofilms in the intestinal niche having physiological pH in the range 6–7, the probiotic strains that have dispersive action at high pH may have better therapeutic potential.

Adaptation to Aerobic Environment of Lactobacillus johnsonii/gasseri Strains

Oxygen is considered one of the main factors affecting probiotic bacteria survival due to the induction of oxidative damages caused by the action of reactive oxygen species (ROS). It has been shown that oxidative stress resistance in lactic acid bacteria is strongly dependent on the type of cell metabolism. Shift from fermentative to respiratory metabolism (through the addition of heme and menaquinone and in presence of oxygen) was associated to increase in biomass, long-term survival, and production of antioxidant enzymes. The aim of this work was to investigate the effect of aerobic (presence of oxygen) and respiratory (presence of oxygen, heme, and menaquinone) cultivation on the growth kinetic, catalase production, oxygen uptake, and oxidative stress response of Lactobacillus johnsonii/gasseri strains previously isolated from infant feces. Seven strains showed to consume oxygen under aerobic and respiratory conditions. The strain AL5 showed a catalase activity in both growth conditions, while AL3 showed this activity only in respiratory condition. Respiratory condition improved their tolerance to oxidative compounds (hydrogen peroxide and ROS generators) and further they showed promising probiotic features. The exploration of respiratory competent phenotypes with probiotic features may be extremely useful for the development of competitive starter or probiotic cultures.

Bile-Salt-Hydrolases from the Probiotic Strain Lactobacillus johnsonii La1 Mediate Anti-giardial Activity in Vitro and in Vivo

Giardia duodenalis (syn. G. lamblia, G. intestinalis) is the protozoan parasite responsible for giardiasis, the most common and widely spread intestinal parasitic disease worldwide, affecting both humans and animals. After cysts ingestion (through either contaminated food or water), Giardia excysts in the upper intestinal tract to release replicating trophozoites that are responsible for the production of symptoms. In the gut, Giardia cohabits with the host's microbiota, and several studies have revealed the importance of this gut ecosystem and/or some probiotic bacteria in providing protection against G. duodenalis infection through mechanisms that remain incompletely understood. Recent findings suggest that Bile-Salt-Hydrolase (BSH)-like activities from the probiotic strain of Lactobacillus johnsonii La1 may contribute to the anti-giardial activity displayed by this strain. Here, we cloned and expressed each of the three bsh genes present in the L. johnsonii La1 genome to study their enzymatic and biological properties. While BSH47 and BSH56 were expressed as recombinant active enzymes, no significant enzymatic activity was detected with BSH12. In vitro assays allowed determining the substrate specificities of both BSH47 and BSH56, which were different. Modeling of these BSHs indicated a strong conservation of their 3-D structures despite low conservation of their primary structures. Both recombinant enzymes were able to mediate anti-giardial biological activity against Giardia trophozoites in vitro. Moreover, BSH47 exerted significant anti-giardial effects when tested in a murine model of giardiasis. These results shed new light on the mechanism, whereby active BSH derived from the probiotic strain Lactobacillus johnsonii La1 may yield anti-giardial effects in vitro and in vivo. These findings pave the way toward novel approaches for the treatment of this widely spread but neglected infectious disease, both in human and in veterinary medicine.

Weighing in on the risks and benefits of probiotic use in HIV-infected and immunocompromised populations

Probiotics are used in the prophylaxis and treatment of several conditions, including irritable bowel syndrome, diarrhoea, necrotising enterocolitis (NEC) and colic in infants. Despite the long history of probiotic use in humans, there is still significant debate about their efficacy and safety, particularly in HIV-infected and immunocompromised individuals. Here, we reviewed the safety and adverse event (AE) reporting from clinical trials that have tested probiotics in at risk populations, including HIV-infected individuals, the terminally ill and elderly, and neonates. Our analysis suggests that the benefits of probiotic therapy outweigh their potential risks in HIV-infected populations, and in the treatment of colic and NEC in low birth weight or premature neonates. Most case reports of severe AEs were in the elderly and terminally ill, or in those with additional severe medical conditions. We conclude that probiotic use, as adjunctive treatment, is effective and safe in the majority of patients including HIV-infected individuals, although special care should be taken in individuals with extreme immunosuppression and severe medical conditions in all ages.

Biochemical Features of Beneficial Microbes: Foundations for Therapeutic Microbiology

Commensal and beneficial microbes secrete myriad products which target the mammalian host and other microbes. These secreted substances aid in bacterial niche development, and select compounds beneficially modulate the host and promote health. Microbes produce unique compounds which can serve as signaling factors to the host, such as biogenic amine neuromodulators, or quorum-sensing molecules to facilitate inter-bacterial communication. Bacterial metabolites can also participate in functional enhancement of host metabolic capabilities, immunoregulation, and improvement of intestinal barrier function. Secreted products such as lactic acid, hydrogen peroxide, bacteriocins, and bacteriocin-like substances can also target the microbiome. Microbes differ greatly in their metabolic potential and subsequent host effects. As a result, knowledge about microbial metabolites will facilitate selection of next-generation probiotics and therapeutic compounds derived from the mammalian microbiome. In this article we describe prominent examples of microbial metabolites and their effects on microbial communities and the mammalian host.

Remediation of intramacrophageal Shigella dysenteriae type 1 by probiotic lactobacilli isolated from human infants' stool samples

Background & objectives:

Shigella dysenteriae is one of the most virulent pathogens causing bacillary dysentery and is responsible for high mortality in infants. To reduce the load of antibiotic therapy for treating shigellosis, this study was carried out to assess the ex vivo effect of novel probiotic lactobacilli, isolated from infant's stool samples, on killing S. dysenteriae type 1 residing in the rat macrophages.

Methods:

Stool samples from infants were collected, processed for the isolation of lactobacilli and screened for the probiotic attributes (acid tolerance, bile tolerance, ability to adhere intestinal cells and anti-S. dysenteriae activity). The effect of cell-free supernatant of lactobacilli on Shigella- infected macrophages in terms of phagocytic ability, extent of lipid peroxidation, nitrite, superoxide dismutase and glutathione levels was evaluated.

Results:

Based on the probiotic attributes, three lactobacilli were isolated from the stool samples of infants. Using classical and molecular tools, these isolates were identified as Lactobacillus pentosus, L. Paraplantarum and L. rhamnosus. All the three lactobacilli had the ability to kill intramacrophage S. dysentriae type 1. The anti-Shigella activity of the probiotic lactobacilli was attributed to increased antioxidative ability and decreased free radical production by the infected macrophages.

Interpretation & conclusions:

Probiotic cocktail of L. pentosus, L. paraplantarum and L. rhamnosus showed ex vivo killing of S. dysenteriae residing inside the rat macrophages significantly. This cocktail has the potential to be used as a natural alternative for treating S. dysenteriae infection, especially in infants, however, further studies need to be done to confirm these finding in vivo.

Secretome of Intestinal Bacilli: A Natural Guard against Pathologies

Current studies of human gut microbiome usually do not consider the special functional role of transient microbiota, although some of its members remain in the host for a long time and produce broad spectrum of biologically active substances. Getting into the gastrointestinal tract (GIT) with food, water and probiotic preparations, two representatives of Bacilli class, genera Bacillus and Lactobacillus, colonize epithelium blurring the boundaries between resident and transient microbiota. Despite their minor proportion in the microbiome composition, these bacteria can significantly affect both the intestinal microbiota and the entire body thanks to a wide range of secreted compounds. Recently, insufficiency and limitations of pure genome-based analysis of gut microbiota became known. Thus, the need for intense functional studies is evident. This review aims to characterize the Bacillus and Lactobacillus in GIT, as well as the functional roles of the components released by these members of microbial intestinal community. Complex of their secreted compounds is referred by us as the "bacillary secretome." The composition of the bacillary secretome, its biological effects in GIT and role in counteraction to infectious diseases and oncological pathologies in human organism is the subject of the review.

Probiotic bacteria inhibit the bovine respiratory pathogen Mannheimia haemolytica serotype 1 in vitro

This study evaluated the potential of probiotic bacteria to inhibit growth and cell adhesion of the bovine respiratory pathogen Mannheimia haemoltyica serotype 1. The inhibitory effects of nine probiotic strains (Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus helveticus, Lactobacillus plantarum, Lactobacillus rhamnosus, Lactococcus lactis, Streptococcus thermophilus and two Paenibacillus polymyxa strains) against M. haemolytica were evaluated using a spot-on-lawn method. Probiotic strains were then tested for their adherence to bovine bronchial epithelial (BBE) cells and the ability to displace and compete against M. haemolytica on BBE. Except for S. thermophilus, all probiotic strains inhibited the growth of M. haemolytica, with zones of inhibition ranging between 12 and 19 mm. Lactobacillus strains and Lactococcus lactis displayed greater (P < 0·05) BBE adhesion compared with M. heamolytica (8·3%) and other probiotics (<2·2%). Strains of P. polymyxa and L. acidophilus caused the greatest reduction in M. haemolytica adherence, through both displacement and competition, compared with other probiotics. The results of this study suggest that probiotics may have the potential to colonize the bovine respiratory tract, and exert antagonistic effects against M. haemolytica serotype 1.

SIGNIFICANCE AND IMPACT OF THE STUDY

A common method to control bovine respiratory disease (BRD) in feedlots is through mass medication with antibiotics upon cattle entry (i.e. metaphylaxis). Increasingly, antimicrobial resistance in BRD bacterial pathogens has been observed in feedlots, which may have important implications for cattle health. In this study, probiotic strains were shown to adhere to bovine respiratory cells and inhibit the BRD pathogen M. haemolytica serotype 1 through competition and displacement. Probiotics may therefore offer a mitigation strategy to reduce BRD bacterial pathogens, in place of metaphylactic antimicrobials.

CatB is Critical for Total Catalase Activity and Reduces Bactericidal Effects of Phenazine-1-Carboxylic Acid on Xanthomonas oryzae pv. oryzae and X. oryzae pv. oryzicola

Rice bacterial leaf blight, caused by Xanthomonas oryzae pv. oryzae, and rice bacterial leaf streak, caused by X. oryzae pv. oryzicola, are major diseases of rice. Phenazine-1-carboxylic acid (PCA) is a natural product that is isolated from Pseudomonas spp. and is used to control many important rice diseases in China. We previously reported that PCA disturbs the redox balance, which results in the accumulation of reactive oxygen species in X. oryzae pv. oryzae. In this study, we found that PCA significantly upregulated the transcript levels of catB and katE, which encode catalases, and that PCA sensitivity was reduced when X. oryzae pvs. oryzae and oryzicola were cultured with exogenous catalase. Furthermore, catB deletion mutants of X. oryzae pvs. oryzae and oryzicola showed dramatically decreased total catalase activity, increased sensitivity to PCA, and reduced virulence in rice. In contrast, deletion mutants of srpA and katG, which also encode catalases, exhibited little change in PCA sensitivity. The results indicate that catB in both X. oryzae pvs. oryzae and oryzicola encodes a catalase that helps protect the bacteria against PCA-induced stress.

Antivirulence Properties of Probiotics in Combating Microbial Pathogenesis

Probiotics are nonpathogenic microorganisms that confer a health benefit on the host when administered in adequate amounts. Ample evidence is documented to support the potential application of probiotics for the prevention and treatment of infections. Health benefits of probiotics include prevention of diarrhea, including antibiotic-associated diarrhea and traveler's diarrhea, atopic eczema, dental carries, colorectal cancers, and treatment of inflammatory bowel disease. The cumulative body of scientific evidence that demonstrates the beneficial effects of probiotics on health and disease prevention has made probiotics increasingly important as a part of human nutrition and led to a surge in the demand for probiotics in clinical applications and as functional foods. The ability of probiotics to promote health is attributed to the various beneficial effects exerted by these microorganisms on the host. These include lactose metabolism and food digestion, production of antimicrobial peptides and control of enteric infections, anticarcinogenic properties, immunologic enhancement, enhancement of short-chain fatty acid production, antiatherogenic and cholesterol-lowering attributes, regulatory role in allergy, protection against vaginal or urinary tract infections, increased nutritional value, maintenance of epithelial integrity and barrier, stimulation of repair mechanism in cells, and maintenance and reestablishment of well-balanced indigenous intestinal and respiratory microbial communities. Most of these attributes primarily focus on the effect of probiotic supplementation on the host. Hence, in most cases, it can be concluded that the ability of a probiotic to protect the host from infection is an indirect result of promoting overall health and well-being. However, probiotics also exert a direct effect on invading microorganisms. The direct modes of action resulting in the elimination of pathogens include inhibition of pathogen replication by producing antimicrobial substances like bacteriocins, competition for limiting resources in the host, antitoxin effect, inhibition of virulence, antiadhesive and antiinvasive effects, and competitive exclusion by competition for binding sites or stimulation of epithelial barrier function. Although much has been documented about the ability of probiotics to promote host health, there is limited discussion on the above mentioned effects of probiotics on pathogens. Being in an era of antibiotic resistance, a better understanding of this complex probiotic-pathogen interaction is critical for development of effective strategies to control infections. Therefore, this chapter will focus on the ability of probiotics to directly modulate the infectious nature of pathogens and the underlying mechanisms that mediate these effects.

Effects of the dietary supplementation of mixed probiotic spores of Bacillus amyloliquefaciens 54A, and Bacillus pumilus 47B on growth, innate immunity and stress responses of striped catfish (Pangasianodon hypophthalmus)

The study used the mixed probiotics of Bacillus amyloliquefaciens 54A and B. pumilus 47B isolated from striped catfish (Pangasianodon hypophthalmus) intestine aiming to stimulate growth performance, innate immunity, stress tolerance of striped catfish. The average weight gain (AWG), specific growth rate (SGR), and feed conversion ratio (FCR) were analyzed after fish were fed the mixture of probiotics (B. amyloliquefaciens 54A and B. pumilus 47B) at concentrations of 1 × 10⁸, 3 × 10⁸, and 5 × 10⁸ CFU g^-1 feed for 90 days. Immunity parameters, survival rate of fish challenged with Edwardsiella ictaluri and ammonia tolerance were also investigated. The amounts of B. amyloliquefaciens and B. pumilus were counted and identified by specific primer pairs of Ba1-F/Ba1-R, and 16-F/Bpu-R to confirm the presence of probiotics in fish intestine. The AWG (476.6 ± 7.81 g fish^-1) of fish fed probiotics at 5 × 10⁸ CFU g^-1 was significant higher than the control (390 ± 25.7 g fish^-1) after 90 days of feeding, but there was no significant (P > 0.05) effect of probiotics on FCR and SGR. Fish fed diet containing probiotics at 5 × 10⁸ CFU g^-1 also expressed resistance to E. ictaluri infection and higher immune parameters such as phagocytic activity, respiratory bursts, and lysozyme activity than the control. Stress response with ammonia showed significantly lower mortality rate (25%, 20% and 27%) of fish fed probiotics at all three levels of 1, 3 and 5 × 10⁸ CFU g^-1 than the fish fed control diet (75%). The study also demonstrated that the probiotics survived in the intestine of striped catfish after 90 days of feeding. Therefore, the dietary supplementation of a mixture of B. amyloliquefaciens and B. pumilus at 5 × 10⁸ CFU g^-1 can be used to improve the health and growth rate of striped catfish.

Deconjugated Bile Salts Produced by Extracellular Bile-Salt Hydrolase-Like Activities from the Probiotic Lactobacillus johnsonii La1 Inhibit Giardia duodenalis In vitro Growth

Giardiasis, currently considered a neglected disease, is caused by the intestinal protozoan parasite Giardia duodenalis and is widely spread in human as well as domestic and wild animals. The lack of appropriate medications and the spread of resistant parasite strains urgently call for the development of novel therapeutic strategies. Host microbiota or certain probiotic strains have the capacity to provide some protection against giardiasis. By combining biological and biochemical approaches, we have been able to decipher a molecular mechanism used by the probiotic strain Lactobacillus johnsonii La1 to prevent Giardia growth in vitro. We provide evidence that the supernatant of this strain contains active principle(s) not directly toxic to Giardia but able to convert non-toxic components of bile into components highly toxic to Giardia. By using bile acid profiling, these components were identified as deconjugated bile-salts. A bacterial bile-salt-hydrolase of commercial origin was able to mimic the properties of the supernatant. Mass spectrometric analysis of the bacterial supernatant identified two of the three bile-salt-hydrolases encoded in the genome of this probiotic strain. These observations document a possible mechanism by which L. johnsonii La1, by secreting, or releasing BSH-like activity(ies) in the vicinity of replicating Giardia in an environment where bile is present and abundant, can fight this parasite. This discovery has both fundamental and applied outcomes to fight giardiasis, based on local delivery of deconjugated bile salts, enzyme deconjugation of bile components, or natural or recombinant probiotic strains that secrete or release such deconjugating activities in a compartment where both bile salts and Giardia are present.

Anti-infective activities of lactobacillus strains in the human intestinal microbiota: from probiotics to gastrointestinal anti-infectious biotherapeutic agents

A vast and diverse array of microbial species displaying great phylogenic, genomic, and metabolic diversity have colonized the gastrointestinal tract. Resident microbes play a beneficial role by regulating the intestinal immune system, stimulating the maturation of host tissues, and playing a variety of roles in nutrition and in host resistance to gastric and enteric bacterial pathogens. The mechanisms by which the resident microbial species combat gastrointestinal pathogens are complex and include competitive metabolic interactions and the production of antimicrobial molecules. The human intestinal microbiota is a source from which Lactobacillus probiotic strains have often been isolated. Only six probiotic Lactobacillus strains isolated from human intestinal microbiota, i.e., L. rhamnosus GG, L. casei Shirota YIT9029, L. casei DN-114 001, L. johnsonii NCC 533, L. acidophilus LB, and L. reuteri DSM 17938, have been well characterized with regard to their potential antimicrobial effects against the major gastric and enteric bacterial pathogens and rotavirus. In this review, we describe the current knowledge concerning the experimental antibacterial activities, including antibiotic-like and cell-regulating activities, and therapeutic effects demonstrated in well-conducted, placebo-controlled, randomized clinical trials of these probiotic Lactobacillus strains. What is known about the antimicrobial activities supported by the molecules secreted by such probiotic Lactobacillus strains suggests that they constitute a promising new source for the development of innovative anti-infectious agents that act luminally and intracellularly in the gastrointestinal tract.

PROBIOTIC APPROACHES FOR TARGETING INFLAMMATORY BOWEL DISEASE: AN UPDATE ON ADVANCES AND OPPORTUNITIES IN MANAGING THE DISEASE

Various commensal enteric and pathogenic bacteria may be involved in the pathogenesis of inflammatory bowel diseases (IBDs), a chronic condition with a pathogenic background that involves both immunogenetic and environmental factors. IBDs comprising of Crohn's disease, and ulcerative colitis, and pauchitis are chronic inflammatory conditions, and known for causing disturbed homeostatic balance among the intestinal immune compartment, gut epithelium and microbiome. An increasing trend of IBDs in incidence, prevalence, and severity has been reported during recent years. Probiotic strains have been reported to manage the IBDs and related pathologies, and hence are current hot topics of research for their potential to manage metabolic diseases as well as various immunopathologies. However, the probiotics industry will need to undergo a transformation, with increased focus on stringent manufacturing guidelines and high-quality clinical trials. This article reviews the present state of art of role of probiotic bacteria in reducing inflammation and strengthening the host immune system with reference to the management of IBDs. We infer that t healthcare will move beyond its prevailing focus on human physiology, and embrace the superorganism as a paradigm to understand and ameliorate IBDs.

Lactobacilli with probiotic potential in the prairie vole (Microtus ochrogaster)

Background

Recent research suggests integration of the intestinal microbiota in gut-brain communication which could lead to new approaches to treat neurological disorders. The highly social prairie voles are an excellent model system to study the effects of environmental factors on social behavior. For future studies on the role of probiotics in ameliorating disorders with social withdrawal symptoms, we report the characterization of intestinal Lactobacillus isolates with probiotic potential from voles.

Methods and results

30 bacterial strains were isolated from the vole intestine and found to be distinct but closely related to Lactobacillus johnsonii using 16S rRNA gene sequencing and Random Amplification of Polymorphic DNA fingerprinting. In vitro characterizations including acid and bile tolerance, antimicrobial effects, antibiotic susceptibility, and adherence to intestinal epithelial cells were performed to assess the probiotic potential of selected strains. Since previous studies revealed that mercury ingestion triggers social deficits in voles, mercury resistance of the probiotic candidates was evaluated which could be an important factor in preventing/treating these behavioral changes.

Conclusions

This study demonstrates that lactobacilli with probiotic potential are present in the vole intestine. The Lactobacillus isolates identified in this study will provide a basis for the investigation of probiotic effects in the vole behavioral model system.

Electronic supplementary material

The online version of this article (doi:10.1186/s13099-015-0082-0) contains supplementary material, which is available to authorized users.

Mechanisms and therapeutic effectiveness of lactobacilli

The gut microbiome is not a silent ecosystem but exerts several physiological and immunological functions. For many decades, lactobacilli have been used as an effective therapy for treatment of several pathological conditions displaying an overall positive safety profile. This review summarises the mechanisms and clinical evidence supporting therapeutic efficacy of lactobacilli. We searched Pubmed/Medline using the keyword ‘Lactobacillus’. Selected papers from 1950 to 2015 were chosen on the basis of their content. Relevant clinical and experimental articles using lactobacilli as therapeutic agents have been included. Applications of lactobacilli include kidney support for renal insufficiency, pancreas health, management of metabolic imbalance, and cancer treatment and prevention. In vitro and in vivo investigations have shown that prolonged lactobacilli administration induces qualitative and quantitative modifications in the human gastrointestinal microbial ecosystem with encouraging perspectives in counteracting pathology-associated physiological and immunological changes. Few studies have highlighted the risk of translocation with subsequent sepsis and bacteraemia following probiotic administration but there is still a lack of investigations on the dose effect of these compounds. Great care is thus required in the choice of the proper Lactobacillus species, their genetic stability and the translocation risk, mainly related to inflammatory disease-induced gut mucosa enhanced permeability. Finally, we need to determine the adequate amount of bacteria to be delivered in order to achieve the best clinical efficacy decreasing the risk of side effects.

H2O2 production rate in Lactobacillus johnsonii is modulated via the interplay of a heterodimeric flavin oxidoreductase with a soluble 28 Kd PAS domain containing protein

Host and commensals crosstalk, mediated by reactive oxygen species (ROS), has triggered a growing scientific interest to understand the mechanisms governing such interaction. However, the majority of the scientific studies published do not evaluate the ROS production by commensals bacteria. In this context we recently showed that Lactobacillus johnsonii N6.2, a strain of probiotic value, modulates the activity of the critical enzymes 2,3-indoleamine dioxygenase via H₂O₂ production. L. johnsonii N6.2 by decreasing IDO activity, is able to modify the tryptophan/kynurenine ratio in the host blood with further systemic consequences. Understanding the mechanisms of H₂O₂ production is critical to predict the probiotic value of these strains and to optimize bacterial biomass production in industrial processes. We performed a transcriptome analysis to identify genes differentially expressed in L. johnsonii N6.2 cells collected from cultures grown under different aeration conditions. Herein we described the biochemical characteristics of a heterodimeric FMN reductase (FRedA/B) whose in vitro activity is controlled by LjPAS protein with a typical Per-Arnst-Sim (PAS) sensor domain. Interestingly, LjPAS is fused to the FMN reductase domains in other lactobacillaceae. In L. johnsonii, LjPAS is encoded by an independent gene which expression is repressed under anaerobic conditions (>3 fold). Purified LjPAS was able to slow down the FRedA/B initial activity rate when the holoenzyme precursors (FredA, FredB, and FMN) were mixed in vitro. Altogether the results obtained suggest that LjPAS module regulates the H₂O₂ production helping the cells to minimize oxidative stress in response to environmental conditions.

Probiotic Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 exhibit strong antifungal effects against vulvovaginal candidiasis-causing Candida glabrata isolates

Aims

This study investigates the antagonistic effects of the probiotic strains Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 against vulvovaginal candidiasis (VVC)-causing Candida glabrata.

Methods and Results

Growth inhibitory activities of Lact. rhamnosus GR-1 and Lact. reuteri RC-14 strains against C. glabrata were demonstrated using a spot overlay assay and a plate-based microtitre assay. In addition, these probiotic lactobacilli strains also exhibited potent candidacidal activity against C. glabrata, as demonstrated by a LIVE/DEAD yeast viability assay performed using confocal laser scanning microscopy. The metabolic activities of all C. glabrata strains were completely shut down in response to the challenges by the probiotic lactobacilli strains. In addition, both probiotic lactobacilli strains exhibited strong autoaggregation and coaggregation phenotypes in the presence of C. glabrata, which indicate that these lactobacilli strains may exert their probiotic effects through the formation of aggregates and, thus the consequent prevention of colonization by C. glabrata.

Conclusions

Probiotic Lact. rhamnosus GR-1 and Lact. reuteri RC-14 strains exhibited potent antagonistic activities against all of the tested C. glabrata strains. These lactobacilli exhibited antifungal effects, including those attributed to their aggregation abilities, and their presence caused the cessation of growth and eventual cell death of C. glabrata.

Significance and Impact of the Study

This is the first study to report on the antagonistic effects of these probiotic lactobacilli strains against the non-Candida albicans Candida (NCAC) species C. glabrata.

Mechanisms underlying protective effects of probiotics on intestinal epithelial

Intestinal epithelial cells (IECs), the first line of defense against pathogens, are an initial point of contact between the host and intestinal microbes. Growing evidence suggests that the interactions between the host and intestinal microbes may lead to dysregulated immune responses, while probiotics can reinforce the barrier function and exert a modest stimulation of the immune system to prevent this situation. On one hand, probiotics exert antagonistic functions via competition for nutrients, metabolites, and occupying effect. Therefore, probiotics can regulate the endogenous gastrointestinal flora and restrain exogenous pathogenic bacteria. On the other hand, IECs recognize probiotics and their metabolites through pattern recognition receptors to stimulate the non-specific immune responses. In addition, probiotics can induce IECs to produce the mucus layer covering the entire intestinal tract and prevent attachment and invasion of various bacterial pathogens. Clinical trials have also shown beneficial effects of probiotics as a potential preventive method for inflammatory bowel disease such as Crohn disease and ulcerative colitis.

Postbiotic activities of lactobacilli-derived factors

Probiotics are alive nonpathogenic microorganisms present in the gut microbiota that confer benefits to the host for his health. They act through molecular and cellular mechanisms that contrast pathogen bacteria adhesion, enhance innate immunity, decrease pathogen-induced inflammation, and promote intestinal epithelial cell survival, barrier function, and protective responses. Some of these beneficial effects result to be determined by secreted probiotic-derived factors that recently have been identified as "postbiotic" mediators. They have been reported for several probiotic strains but most available literature concerns Lactobacilli. In this review, we focus on the reported actions of several secretory products of different Lactobacillus species highlighting the available mechanistic data. The identification of soluble factors mediating the beneficial effects of probiotics may present an opportunity not only to understand their fine mechanisms of action, but also to develop effective pharmacological strategies that could integrate the action of treatments with live bacteria.

Lactobacilli inactivate Chlamydia trachomatis through lactic acid but not H2O2

Lactobacillus species dominate the microbiome in the lower genital tract of most reproductive-age women. Producing lactic acid and H2O2, lactobacilli are believed to play an important role in prevention of colonization by and growth of pathogens. However, to date, there have been no reported studies characterizing how lactobacilli interact with Chlamydia trachomatis, a leading sexually transmitted bacterium. In this report, we demonstrate inactivation of C. trachomatis infectivity by culture media conditioned by Lactobacillus crispatus, L. gasseri and L. jensenii, known to be dominating organisms in the human vaginal microbiome. Lactobacillus still cultures produced lactic acid, leading to time- and concentration-dependent killing of C. trachomatis. Neutralization of the acidic media completely reversed chlamydia killing. Addition of lactic acid into Lactobacillus-unconditioned growth medium recapitulated the chlamydiacidal activity of conditioned media. The H2O2 concentrations in the still cultures were found to be comparable to those reported for the cervicovaginal fluid, but insufficient to inactivate chlamydiae. Aeration of Lactobacillus cultures by shaking markedly induced H2O2 production, but strongly inhibited Lactobacillus growth and lactic acid production, and thus severely affected acidification, leading to significantly reduced chlamydiacidal efficiency. These observations indicate lactobacilli inactivate chlamydiae primarily through maintaining acidity in a relatively hypoxic environment in the vaginal lumen with limited H2O2, which is consistent with the notion that women with higher vaginal pH are more prone to sexually transmitted C. trachomatis infection. In addition to lactic acid, formic acid and acetic acid also exhibited potent chlamydiacidal activities. Taken together, our findings imply that lowering the vaginal pH through engineering of the vaginal microbiome and other means will make women less susceptible to C. trachomatis infection.

Potential of cell-free supernatants from cultures of selected lactic acid bacteria and yeast obtained from local fermented foods as inhibitors of Listeria monocytogenes, Salmonella spp. and Staphylococcus aureus

BACKGROUND

Food-borne infections cause huge economic and human life losses worldwide. The most common contaminants of foods include Listeria monocytogenes Salmonellae and Staphylococcus aureus. L. monocytogenes is most notorious due to its tolerance to common food preservation methods and the risks it poses, including higher fatality rates. Safer, more efficacious control methods are thus needed. Along with food-borne pathogens, lactic acid bacteria (LAB) can also be found in foods. Some LAB isolates inhibit pathogenic bacteria by various mechanisms, including by production of antimicrobial metabolites.

METHODS

The potential of cell-free culture supernatants (CFS) derived from broth cultures of selected local LAB and yeast isolates, some of which were subjected to various treatments, were tested for inhibition of L. monocytogenes, Salmonella spp. and S. aureus in in vitro culture by incorporating various proportions of the CFSs into the growth medium concurrently with inoculation (co-cultures) or following limited proliferation after inoculation of the pathogens (delayed cultures). The effects of the CFSs on various growth parameters were assessed.

RESULTS

CFS from the LAB isolates were strongly inhibitory when co-cultured. The inhibitory activities were stable following heat or protease treatment of the CFSs. Inhibitory activity was dependent primarily on active substance(s) secreted into the supernatant. In all co-cultures, CFS proportion-dependent progressive decrease in the number of colonies was observed and both growth rates and number of generations were reduced with significantly fewer numbers of colony forming units, whereas generation times were significantly increased compared to those of controls. Transfer from co-cultures to fresh broth showed inhibited cultures contained bacteria that can re-grow, indicating the presence of viable bacteria that are undetectable by culture. Growth rates in CFS-treated delayed cultures were also reduced to varying degrees with the number of colonies in some cultures being significantly less than the corresponding control values. CFSs were active against both Gram-positive and -negative bacteria.

CONCLUSIONS

Active metabolites produced and secreted by LAB into the growth medium were effective in inhibiting the tested pathogens. Early addition of the CFSs was necessary for significant inhibition to occur. Further studies will help make these findings applicable to food safety.

Impact of genomics on the field of probiotic research: historical perspectives to modern paradigms

For thousands of years, humans have safely consumed microorganisms through fermented foods. Many of these bacteria are considered probiotics, which act through diverse mechanisms to confer a health benefit to the host. However, it was not until the availability of whole-genome sequencing and the era of genomics that mechanisms of probiotic efficacy could be discovered. In this review, we explore the history of the probiotic concept and the current standard of integrated genomic techniques to discern the complex, beneficial relationships between probiotic microbes and their hosts.

H(2)O(2) production in species of the Lactobacillus acidophilus group: a central role for a novel NADH-dependent flavin reductase

Hydrogen peroxide production is a well-known trait of many bacterial species associated with the human body. In the presence of oxygen, the probiotic lactic acid bacterium Lactobacillus johnsonii NCC 533 excretes up to 1 mM H(2)O(2), inducing growth stagnation and cell death. Disruption of genes commonly assumed to be involved in H(2)O(2) production (e.g., pyruvate oxidase, NADH oxidase, and lactate oxidase) did not affect this. Here we describe the purification of a novel NADH-dependent flavin reductase encoded by two highly similar genes (LJ_0548 and LJ_0549) that are conserved in lactobacilli belonging to the Lactobacillus acidophilus group. The genes are predicted to encode two 20-kDa proteins containing flavin mononucleotide (FMN) reductase conserved domains. Reductase activity requires FMN, flavin adenine dinucleotide (FAD), or riboflavin and is specific for NADH and not NADPH. The Km for FMN is 30 ± 8 μM, in accordance with its proposed in vivo role in H(2)O(2) production. Deletion of the encoding genes in L. johnsonii led to a 40-fold reduction of hydrogen peroxide formation. H(2)O(2) production in this mutant could only be restored by in trans complementation of both genes. Our work identifies a novel, conserved NADH-dependent flavin reductase that is prominently involved in H(2)O(2) production in L. johnsonii.

The ABC-type efflux pump MacAB protects Salmonella enterica serovar typhimurium from oxidative stress

Multidrug efflux pumps are integral membrane proteins known to actively excrete antibiotics. The macrolide-specific pump MacAB, the only ABC-type drug efflux pump in Salmonella, has previously been linked to virulence in mice. The molecular mechanism of this link between macAB and infection is unclear. We demonstrate that macAB plays a role in the detoxification of reactive oxygen species (ROS), compounds that salmonellae are exposed to at various stages of infection. macAB is induced upon exposure to H₂O₂ and is critical for survival of Salmonella enterica serovar Typhimurium in the presence of peroxide. Furthermore, we determined that macAB is required for intracellular replication inside J774.A1 murine macrophages but is not required for survival in ROS-deficient J774.D9 macrophages. macAB mutants also had reduced survival in the intestine in the mouse colitis model, a model characterized by a strong neutrophilic intestinal infiltrate where bacteria may experience the cytotoxic actions of ROS. Using an Amplex red-coupled assay, macAB mutants appear to be unable to induce protection against exogenous H₂O₂in vitro, in contrast to the isogenic wild type. In mixed cultures, the presence of the wild-type organism, or media preconditioned by the growth of the wild-type organism, was sufficient to rescue the macAB mutant from peroxide-mediated killing. Our data indicate that the MacAB drug efflux pump has functions beyond resistance to antibiotics and plays a role in the protection of Salmonella against oxidative stress. Intriguingly, our data also suggest the presence of a soluble anti-H₂O₂ compound secreted by Salmonella cells through a MacAB-dependent mechanism.

The ABC-type multidrug efflux pump MacAB is known to be required for Salmonella enterica serovar Typhimurium virulence after oral infection in mice, yet the function of this pump during infection is unknown. We show that this pump is necessary for colonization of niches in infected mice where salmonellae encounter oxidative stress during infection. MacAB is required for growth in cultured macrophages that produce reactive oxygen species (ROS) but is not needed in macrophages that do not generate ROS. In addition, we show that MacAB is required to resist peroxide-mediated killing in vitro and for the inactivation of peroxide in the media. Finally, wild-type organisms, or supernatant from wild-type organisms grown in the presence of peroxide, rescue the growth defect of macAB mutants in H₂O₂. MacAB appears to participate in the excretion of a compound that induces protection against ROS-mediated killing, revealing a new role for this multidrug efflux pump.

Compound(s) secreted by Lactobacillus casei strain Shirota YIT9029 irreversibly and reversibly impair the swimming motility of Helicobacter pylori and Salmonella enterica serovar Typhimurium, respectively

We conducted experiments in order to examine whether the probiotic Lactobacillus casei strain Shirota YIT9029 (LcS) in vitro and in vivo antagonism of Helicobacter pylori and Salmonella, involves inhibition of the swimming motility of these pathogens. We report the irreversible inhibition of the swimming motility of H. pylori strain 1101 and reversible inhibition of Salmonella enterica serovar Typhimurium (S. Typhimurium) strain SL1344 by compound(s) secreted by LcS. In H. pylori 1101, irreversible inhibition results in the helical cells being progressively replaced by cells with 'c'-shaped and coccoid morphologies, accompanied by a loss of FlaA and FlaB flagellin expression. In S. Typhimurium SL1344, transient inhibition develops after membrane depolarization and without modification of expression of FliC flagellin. The inhibitory activity of strain LcS against both S. Typhimurium and H. pylori swimming motilities is linked with a small sized, heat-sensitive, and partially trypsin-sensitive, secreted compound(s), and needed the cooperation of the secreted membrane permeabilizing lactic acid metabolite. The inhibition of S. Typhimurium SL1344 swimming motility leads to delayed cell entry into human enterocyte-like Caco-2/TC7 cells and a strong decrease of cell entry into human mucus-secreting HT29-MTX cells.

Genomic and phenotypic evidence for probiotic influences of Lactobacillus gasseri on human health

Certain lactic acid bacteria (LAB) have the capacity to occupy mucosal niches of humans, including the oral cavity, gastrointestinal tract, and vagina. Among commensal, LAB are species of the acidophilus complex, which have proven to be a substantial reservoir for microorganisms with probiotic attributes. Specifically, Lactobacillus gasseri is an autochthonous microorganism which has been evaluated for probiotic activity based on the availability of genome sequence and species-specific adaptation to the human mucosa. Niche-related characteristics of L. gasseri contributing to indigenous colonization include tolerance of low pH environments, resistance to bile salts, and adhesion to the host epithelium. In humans, L. gasseri elicits various health benefits through its antimicrobial activity, bacteriocin production, and immunomodulation of the innate and adaptive systems. The genomic and empirical evidence supporting use of L. gasseri in probiotic applications is substantiated by clinical trial data displaying maintenance of vaginal homeostasis, mitigation of Helicobacter pylori infection, and amelioration of diarrhea.

Newly Developed Synbiotics and the Chemotherapy-Damaged Gut

Mucositis is a common side-effect of cancer chemotherapy and radiotherapy. Features of mucositis include erythema, ulceration, and inflammation of the gastrointestinal tract accompanied by clinical symptoms of abdominal pain and digestive disturbances. New treatment strategies are required. Experimental evidence is accumulating showing therapeutic promise for new nutraceutical agents including probiotic bacteria, probiotic-derived factors, prebiotics, and plant extracts. However, the targeted development of new combinations of these agents (synbiotics) to combat mucositis remains largely unexplored. The current review addresses the potential for these nutraceutical agents to reduce the severity of chemotherapy-damaged mucositis by strategically aligning their underlying mechanism of action with features of mucositis pathogenesis. The potential for certain plant extracts to act as prebiotics, in combination with probiotics or their derived factors, is further investigated. These unique synbiotic formulations could form the basis of a new naturally sourced adjunctive approach to cancer chemotherapy.

Oxygen relieves the CO2 and acetate dependency of Lactobacillus johnsonii NCC 533

Oxygen relieves the CO₂ and acetate dependency of Lactobacillus johnsonii NCC 533. The probiotic Lactobacillus johnsonii NCC 533 is relatively sensitive to oxidative stress; the presence of oxygen causes a lower biomass yield due to early growth stagnation. We show however that oxygen can also be beneficial to this organism as it relieves the requirement for acetate and CO₂ during growth. Both on agar- and liquid-media, anaerobic growth of L. johnsonii NCC 533 requires CO₂ supplementation of the gas phase. Switching off the CO₂ supply induces growth arrest and cell death. The presence of molecular oxygen overcomes the CO₂ dependency. Analogously, L. johnsonii NCC 533 strictly requires media with acetate to sustain anaerobic growth, although supplementation at a level that is 100-fold lower (120 microM) than the concentration in regular growth medium for lactobacilli already suffices for normal growth. Analogous to the CO₂ requirement, oxygen supply relieves this acetate-dependency for growth. The L. johnsonii NCC 533 genome indicates that this organism lacks genes coding for pyruvate formate lyase (PFL) and pyruvate dehydrogenase (PDH), both CO₂ and acetyl-CoA producing systems. Therefore, C1- and C2- compound production is predicted to largely depend on pyruvate oxidase activity (POX). This proposed role of POX in C2/C1-generation is corroborated by the observation that in a POX deficient mutant of L. johnsonii NCC 533, oxygen is not able to overcome acetate dependency nor does it relieve the CO₂ dependency.

Role of endogenous microbiota, probiotics and their biological products in human health

Although gut diseases such as inflammatory bowel disease, mucositis and the alimentary cancers share similar pathogenetic features, further investigation is required into new treatment modalities. An imbalance in the gut microbiota, breached gut integrity, bacterial invasion, increased cell apoptosis to proliferation ratio, inflammation and impaired immunity may all contribute to their pathogenesis. Probiotics are defined as live bacteria, which when administered in sufficient amounts, exert beneficial effects to the gastrointestinal tract. More recently, probiotic-derived factors including proteins and other molecules released from living probiotics, have also been shown to exert beneficial properties. In this review we address the potential for probiotics, with an emphasis on probiotic-derived factors, to reduce the severity of digestive diseases and further discuss the known mechanisms by which probiotics and probiotic-derived factors exert their physiological effects.

Potential probiotic lactic acid bacteria of human origin induce antiproliferation of colon cancer cells via synergic actions in adhesion to cancer cells and short-chain fatty acid bioproduction

The activities and modes of probiotic action of lactic acid bacteria isolated from infant feces were investigated for alternative application in the prevention and biotherapy of colon cancer. From a total of 81 isolates of Gram-positive rod and cocci bacteria obtained from healthy infants, only 15 isolates had the probiotic criteria which included growth inhibition against eight food-borne pathogens, no blood hemolysis, and tolerance to gastrointestinal tract properties such as pH 2.5 and 0.3 % bile salt. Four probiotic bacteria showed antiproliferation of colon cancer cells with the use of MTT and Trypan blue exclusion assay at the rates of 17-35 %. Through comparison of probiotic 16S rRNA sequences, they were identified as Pediococcus pentosaceus FP3, Lactobacillus salivarius FP25, L. salivarius FP35, and Enterococcus faecium FP51. Finding the mechanism of proliferative inhibition of colon cancer cells in this study indicated synergic induction by probiotic bacteria directly adhered to these cancer cells and triggered the bioproduction of short-chain fatty acids, mainly butyric and propionic acids. This study suggested that the use of these probiotics may be suitable as an alternative bioprophylactic and biotherapeutic strategy for colon cancer.

In vitro and in vivo characterization and strain safety of Lactobacillus reuteri NCIMB 30253 for probiotic applications

Lactobacillus reuteri NCIMB 30253 was shown to have potential as a probiotic by reducing the proinflammatory chemokine interleukin-8. Moreover, this strain was evaluated, by in vitro and in vivo techniques, for its safety for human consumption. The identity of the strain was investigated by metabolic profiling and 16S rRNA gene sequencing, and in vitro safety evaluations were performed by molecular and metabolic techniques. Genetic analysis was confirmed by assessing the minimum inhibitory concentration to a panel of antibiotics, showing that the strain was susceptible to 8 antibiotics tested. The ability of the strain to produce potentially harmful by-products and antimicrobial compounds was evaluated, showing that the strain does not produce biogenic amines and does not show bacteriocin activity or reuterin production. A 28-day repeated oral dose study was conducted in normal Sprague–Dawley rats to support the in vivo strain safety. Oral administration of the strain resulted in no changes in general condition and no clinically significant changes to biochemical and haematological markers of safety relative to vehicle control treated animals. This comprehensive assessment of safety of L. reuteri NCIMB 30253 supports the safety of the strain for use as a probiotic.

Production of bioactive substances by intestinal bacteria as a basis for explaining probiotic mechanisms: bacteriocins and conjugated linoleic acid

The mechanisms by which intestinal bacteria achieve their associated health benefits can be complex and multifaceted. In this respect, the diverse microbial composition of the human gastrointestinal tract (GIT) provides an almost unlimited potential source of bioactive substances (pharmabiotics) which can directly or indirectly affect human health. Bacteriocins and fatty acids are just two examples of pharmabiotic substances which may contribute to probiotic functionality within the mammalian GIT. Bacteriocin production is believed to confer producing strains with a competitive advantage within complex microbial environments as a consequence of their associated antimicrobial activity. This has the potential to enable the establishment and prevalence of producing strains as well as directly inhibiting pathogens within the GIT. Consequently, these antimicrobial peptides and the associated intestinal producing strains may be exploited to beneficially influence microbial populations. Intestinal bacteria are also known to produce a diverse array of health-promoting fatty acids. Indeed, certain strains of intestinal bifidobacteria have been shown to produce conjugated linoleic acid (CLA), a fatty acid which has been associated with a variety of systemic health-promoting effects. Recently, the ability to modulate the fatty acid composition of the liver and adipose tissue of the host upon oral administration of CLA-producing bifidobacteria and lactobacilli was demonstrated in a murine model. Importantly, this implies a potential therapeutic role for probiotics in the treatment of certain metabolic and immunoinflammatory disorders. Such examples serve to highlight the potential contribution of pharmabiotic production to probiotic functionality in relation to human health maintenance.