Synthetic Mucins as Glycan-Defined Prebiotics.

Conservation and the microbiome.

Nickel is a heavy metal that has a variety of negative impacts on living organisms and causes different health disorders. Probiotic bacteria have been recently utilized for nickel detoxification through bioremediation strategies. We inspected that the role of probiotic lactic acid bacteria in reducing nickel toxicity has been investigated using two biological methods, including biosorption and bioaccumulation. Seventeen strains of nickel-resistant probiotic lactic acid bacteria isolated from the human microbiome were selected out of 88 strains by three different screening stages comprising disc diffusion, MIC, and biosorption/bioaccumulation tests culminated in four of the most powerful strains in reducing nickel from their culture medium. They were L. brevis 205, L. mocusae 226, L. casei 375, and B. infantis 1001 with the mean nickel biosorption rate of 82%, 66%, 70%, and 74%, respectively. The bioaccumulation test resulted in an approximate rate of accumulated nickel inside the strains cells. L. casei, L. brevis, and L. mocusae had the best rate of about 43% nickel accumulation, followed by B. infantis with a 42% bioaccumulation rate. This study supports that the theory of applying probiotic lactic acid bacteria to food and water detoxification could be a safe, bio-friendly alternative for gut remediation and in edible industries.

Human Microbiota in Health and Disease

Silver nanoparticles (colloidal silver) have a bactericidal effect against a variety of bacteria, fungi and viruses. They are promising for biomedical applications due to the limited toxicity against eukaryotic cells. Important role in the silver nanoparticles production have various microorganisms including lactic acid bacteria of the genus Lactobacillus. Probiotic Lactobacillus species are good candidates for nanoparticles producing in the laboratory and in industrial scale, too. The aim of this work was to test the production of colloidal silver nanoparticles with probiotic species Lactobacillus casei. Nanoparticles production was tested in the reaction mixtures (phosphate buffer, glucose, bacterial cells) upon addition of varying concentrations of AgNO3 (1 - 4mM). Production of the silver nanoparticles was proven by screening of reaction mixtures by Transmission electron microscopy. Level of Ag+ ions utilization to nanoparticles was analysed by optical emission spectrometry. Results showed high efficiency of nanosilver production with narrow size distribution of nanoparticles (12 - 27nm).

Probiotics are defined as living or dead bacteria and their byproducts that maintain the balance of the intestinal microbiome. They are non-toxic, non-pathogenic, and do not release any toxins either within or outside the body. Adequate consumption of probiotics can enhance metabolite production, increase immunity, maintain a balanced intestinal flora, and stimulate growth. Probiotics do not have negative antibiotic effects and help maintain the natural flora in animals in a balanced state or prevent dysbacteriosis. Heyndrickxia coagulans (H. coagulans) is a novel probiotic species that is gradually being used for the improvement of human health. Compared to commonly used probiotic lactic acid bacteria, H. coagulans can produce spores, which provide the species with high resistance to adverse conditions. Even though they are transient residents of the gut, beneficial bacteria can have a significant impact on the microbiota because they can outnumber harmful germs, and vice versa. This article discusses the probiotic mechanisms of H. coagulans and outlines the requirements for a substance to be classified as a probiotic. It also addresses how to assess strains that have recently been discovered to possess probiotic properties.

BackgroundChanges in nutrient availability have dramatic and well-defined impacts on both transcription and translation in bacterial cells. At the same time, the role of post-translational control in adaptation to nutrient-poor environments is poorly understood. Previous studies demonstrate the ability of the glucosyltransferase UgtP to influence cell size in response to nutrient availability. Under nutrient-rich medium, interactions with its substrate UDP-glucose promote interactions between UgtP and the tubulin-like cell division protein FtsZ in Bacillus subtilis, inhibiting maturation of the cytokinetic ring and increasing cell size. In nutrient-poor medium, reductions in UDP-glucose availability favor UgtP oligomerization, sequestering it from FtsZ and allowing division to occur at a smaller cell mass.ResultsIntriguingly, in nutrient-poor conditions UgtP levels are reduced ~ 3-fold independent of UDP-glucose. B. subtilis cells cultured under different nutrient conditions indicate that UgtP accumulation is controlled through a nutrient-dependent post-translational mechanism dependent on the Clp proteases. Notably, all three B. subtilis Clp chaperones appeared able to target UgtP for degradation during growth in nutrient-poor conditions.ConclusionsTogether these findings highlight conditional proteolysis as a mechanism for bacterial adaptation to a rapidly changing nutritional landscape.

The human body harbors ten times more bacterial cells than human cells. These bacterial cells form the human microbiome that plays a vital role in human health. An imbalance in the gut microbiome (i.e., dysbiosis) can result in various pathological conditions. This dysbiosis can be refurbished with the supplement of “probiotics.” Probiotics have thus been defined as non-pathogenic micro-organisms that, when ingested, exert a positive influence on host health or physiology. The most commonly used probiotic bacteria comes from two genera: Lactobacillus and Bifidobacterium. Various research findings have proposed a correlation between the alteration of microbiota (composition/activity/density) with disorders like infectious diarrhea, inflammatory bowel diseases, obesity, to name a few. The ultimate effect of administration of probiotics on health or physiology is either direct or indirect. This chapter summarizes the concept of probiotics, their therapeutic aspect along with possible mechanism of action.

There is a growing interest in non-dairy probiotic products. The main aim of the study was to evaluate the impact of juice prepared from 15 various cultivars of carrot on the growth of representatives of human intestinal microbiota (Bifidobacterium catenulatum, Escherichia coli) and probiotic strains (Lactobacillus acidophilus LA-5, Lactobacillus casei 01). Carrot juice was added to liquid medium at a final concentration of 5.0% and their impact on the bacteria number was assessed by measurement of the turbidity after 24 h of culture. The number of cells was expressed as % of positive control (medium without juice addition). Juices prepared from all tested cultivars of carrot inhibited the growth of Bifidobacterium catenulatum, and the strongest inhibitory effect was observed for juices obtained from the 'Kongo F1' cultivar (3.40 ±2.85% of positive control), 'Rumba F1'(4.17 ±2.27%) and 'Broker F1' (5.35 ±2.14%). The majority of tested juices also inhibited the growth of E. coli, but those prepared from the 'Niland F1', 'Napa F1', 'Afro F1'and 'Samba F1' cultivars stimulated the growth of this bacterium. The probiotic strains were less sensitive to carrot juice impact than intestinal species, however both stimulation and inhibition could be observed. Juices made from the cultivars 'Kongo F1' and 'Deep Purple F1' acted negatively on the growth of both probiotic strains, while juice from 'Bangor F1' cultivar inhibited L. casei 01 growth, but stimulated the growth of LA-5. The obtained results suggest that 'Kongo F1' and 'Deep Purple F1' cultivars are not suitable as an additive or raw material for the production of probiotic products, because of their inhibitory properties against probiotic strains. Concluding, carrots can be used as raw material for the production of probiotic beverages, however both the cultivar of carrot and the strains of probiotic bacteria used for the production should be selected carefully. The most suitable for production of probiotic beverages seems to be the 'Rumba F1', followed by the 'Polka F1' and 'Yellowstone F1' cultivars. They inhibited the growth of intestinal bacteria, which are undesirable in the final product, without negative effect on the probiotic species.

Humans are colonized from birth by bacteria, which form a complex and dynamic consortium of microorganisms known as microbiota. Overall, this complex microbial community outnumbers the somatic and germ cells of the host and collectively contains significantly higher genetic variability than that of the host genome (Backhed et al. 2005). Health-promoting indigenous bacteria, known as probiotic bacteria, represent a significant proportion of the human gut microbiota, whose composition is modulated by several factors including diet (Muegge et al. 2011). Probiotic bacteria are often introduced as live dietary supplements, but they are also present as live microflora in fermented foodstuffs for human consumption. The molecular mechanisms by which probiotics beneficially affect human health include strengthening of the intestinal barrier, modulation of the immune response and antagonism of pathogens through production of antimicrobial compounds or competition for mucosal binding sites (Marco et al. 2006). A significant proportion of the commercialized probiotic bacterial species was originally selected on the basis of their technological stability (e.g., resistance and viability during food processing and storage) or by a variety of easily measurable phenotypes, such as the ability to tolerate bile salts or to survive passage through the gastro-intestinal tract. These features do not necessarily associate with capabilities to provide human health benefits. Regulatory requirements concerning probiotic products are currently undergoing a profound transformation that will require elucidation of the mechanisms by which probiotic microorganisms beneficially influence human health. In order to achieve such fine characterization, the so-called “omics” approaches involving genomics and functional analysis represent an essential tool. In particular, probiogenomics, a recently proposed genomic discipline (Ventura et al. 2009), provides insights into the diversity and the evolution of probiotic microorganisms, thus allowing to clarify the molecular basis of their health-promoting activities. Probiogenomics also includes functional genomics, as well as investigation of microbe–microbe and host-microbe interactions that represent crucial aspects to expand our understanding of the roles of probiotics. The study of probiotic bacteria must necessarily take into account recent advances on the microbial ecology of the human gut. Elucidation of the bacterial biodiversity encompassing such a complex ecosystem is essential to highlight the presence or absence of specific groups of microorganisms (microbial biomarkers) and their association with health/disease conditions. In-depth knowledge of the composition and functionality of the human gut microbiota can also provide molecular criteria to predict individual susceptibility to specific probiotic supplements and could be utilized as a priori criteria for successful probiotic therapy. For all these reasons, we believe that a special issue of Genes & Nutrition devoted to probiotic bacteria and human gut microbiota is extremely appropriate. Two reviews within this special issue deal with the genomics of lactobacilli (Alterman et al.) and bifidobacteria (Pokusaeva et al.), which are considered the golden stars among probiotic bacteria. Probiotics are subject to several stressful conditions during industrial processing as well as in nature, where a fast stress-response is essential for survival (Ventura et al. 2006). Genetic characterization of the molecular players that enable probiotic bacteria to cope with such stressful stimuli are discussed by Ruiz et al. Microbial diversity within the human intestinal community is reported by Gerritsen et al., with special focus on the contribution of the gut microbiota to the health/disease balance. The impact of bacteriophages in modulating gut microbiota, as well as on bacterial survival and thus on the efficacy of probiotic treatments is described by Ventura et al. Prebiotic approaches represent new avenues for manipulating gut microbial composition and host responses to achieve health benefits. Conterno et al. explore the possible relationships between prebiotics and modulation of bifidobacterial and lactobacilli populations in the human gut, as a potential tool for obesity prevention and treatment. The effects of probiotics on human health are further discussed by Taverniti and Guglielmetti, who review the current knowledge on interactions of gut bacteria with the mammalian immune system. Safety is a crucial pre-requisite that probiotic bacteria must possess, and safety validation of probiotics includes exclusion of pathogenic potential. A key food safety issue reviewed by Devirgiliis et al. is the potential presence of horizontally transferable antibiotic resistance genes in probiotic strains naturally present in fermented foods, which can interact with the gut microbiota through the food chain. We wish to thank all authors who provided their manuscripts for this special issue, as well as all reviewers involved in processing the submitted articles. Overall, such a collective effort has provided a clear picture of the rapid progress occurring in the field of biology of probiotic bacteria, with special focus on the health benefits resulting from their interactions with the human host.

Elton's biotic resistance hypothesis, which proposes that diverse plant communities are more resistant to biological invasions, has received considerable experimental support. However, the roles of soil microbes in the diversity–invasibility relationship and how they are influenced by nutrient availability and invader density remain poorly understood in temperate forest ecosystems. We conditioned soils for nearly 1 year using nine individually grown native woody species. We then mixed the soils to create a synthetic diversity gradient of one, three or six species. The invasive plant Phytolacca americana was then grown in pots inoculated with these differently conditioned soils. Each soil treatment was crossed with two nutrient availabilities (fertilised vs. non‐fertilised) and three invader densities (one, two and four plants) to test invasion success. We found that soil treatments did not significantly affect P. americana biomass under low nutrient availability, whereas biomass increased with increasing soil inoculum diversity under high nutrient availability. Soil treatments had no significant effect at invader densities of two and four, whereas P. americana biomass increased with increasing diversity levels at a density of one. Furthermore, among all native species, Quercus acutissima reduced P. americana biomass at an invader density of four, although this suppressive effect disappeared with nutrient addition. Analysis of the soil microbial community suggests that these patterns may reflect diversity‐driven pathogen dilution and a reduction in the relative abundance of saprotrophic fungi associated with Q. acutissima. Overall, our results indicate that the diversity–invasibility relationship is modulated by soil microbes, and this modulation depends on nutrient availability and invader density. By integrating the interactive effects of plant diversity, nutrient conditions and invasion intensity, this study provides a potential microbial pathway to explain context‐dependent shifts in biotic resistance. Furthermore, our findings also highlight the important role that some specific native species can play in enhancing community resistance to invasion in particular ecological contexts. Read the free Plain Language Summary for this article on the Journal blog.

Horizontal gene transfer in the gut: Is it a risk?

ABSTRACTBackgroundLactobacillus GG is a safe probiotic bacterium known to transiently colonize the human intestine. It has been found to be useful in treatment of several gastrointestinal conditions characterized by increased gut permeability. In the current study, the efficacy of Lactobacillus GG was investigated in children with Crohn's disease.MethodsIn this open‐label pilot evaluation viewed as a necessary preliminary step for a possible subsequent randomized placebo‐controlled trial, four children with mildly to moderately active Crohn's disease were given Lactobacillus GG (1010 colony‐forming units [CFU]) in enterocoated tablets twice a day for 6 months. Changes in intestinal permeability were measured by a double sugar permeability test. Clinical activity was determined by measuring the pediatric Crohn's disease activity index.ResultsThere was a significant improvement in clinical activity 1 week after starting Lactobacillus GG, which was sustained throughout the study period. Median pediatric Crohn's disease activity index scores at 4 weeks were 73% lower than baseline. Intestinal permeability improved in an almost parallel fashion.ConclusionsFindings in this pilot study show that Lactobacillus GG may improve gut barrier function and clinical status in children with mildly to moderately active, stable Crohn's disease. Randomized, double‐blind, placebo‐controlled trials are warranted for a final assessment of the efficacy of Lactobacillus GG in Crohn's disease.

Infectious disease in the developing world continues to represent one of the greatest challenges facing humanity. Every year over a million children suffer and die from the sequela of enteric infections, while in 2008 it is estimated almost 2.7 million (UNAIDS 2009 update) adults and children became infected with human immunodeficiency virus (HIV). While oral rehydration therapy for diarrhea, and antiretrovirals (ARV) for HIV are critical, there is a place for adjunctive therapies to improve quality of life. The importance of the human microbiota in retaining health is now recognized, as is the concept of replenishing beneficial microbes through probiotic treatments. Studies have shown that probiotics can reduce the duration of diarrhea, improve gut barrier function, help prevent bacterial vaginosis (BV), and enhance immunity even in HIV-infected subjects. However, many issues remain before the extent of probiotic benefits can be verified, and their application to the developing world realised. This consensus report outlines the potential probiotic, and to a lesser extent prebiotic, applications in resource disadvantages settings, and recommends steps that could bring tangible relief to millions of people. The challenges to both efficacy and effectiveness studies in these settings include a lack of infrastructure and funding for scientists, students and research projects in developing countries; making available clinically proven probiotic and prebiotic products at affordable prices; and undertaking appropriately designed clinical trials. We present a roadmap on how efficacy studies may be conducted in a resource disadvantages setting among persons with chronic diarrhea and HIV. These examples and the translation of efficacy into effectiveness are described.

With technological advancements in the medical field, new discoveries have been unfolded about the human microbiota. A tremendous amount of work has been studied within the last two decades. Some of the human microbiota sites include nonsterile areas such as mouth, skin, gut, nose, and vagina. Additionally, there are bacterial cells in areas that were considered sterile such as lungs and placenta before delivery. Out of all the sites, the gut houses the most with an amount of 100 trillion bacteria (Guinane, 2013). Environmental implications have been known to impact these new areas of medicine. There has been a growing interest by the social epidemiologists on how health inequalities impact the role of human gut microbiota.

Summary. Aim: to determine the viability, proliferative activity, and reactive oxygen species (ROS) production in human breast cancer (BC) cells after their co-cultivation with a human microbiota member Bifidobacterium animalis. Object and methods: the study was conducted in vitro on human BC cells of MCF7, T47D, and MDA-MB-231 lines. Cells were co-cultured with live B. animalis bacteria in direct or metabolite-mediated (contactless co-cultivation in the Insert system) interaction between eukaryotic and bacterial cells. ROS production was assessed by flow cytometry. The expression of proteins associated with the regulation of proliferation and apoptosis in BC cells was evaluated by immunocytochemical analysis. Results: The most pronounced changes in the growth characteristics of human BC cells in vitro are caused by the direct interaction of bacterial and malignant cells, compared to the bacterial metabolite-mediated action. MCF-7 cells of the luminal subtype are most sensitive to the effects of B. animalis. Co-cultivation of BC cells with B. animalis leads to a decrease of Ki-67 expression in malignant cells, an increase in ROS production, and the expression of pro-apoptotic proteins Bax and p21WAF1. Translocalization of p21WAF1 expression from the cytoplasm to the cell nucleus was detected in T47D cells after exposure to B. animalis. Conclusions: the interaction of human BC cells with B. animalis and their secreted metabolites led to inhibition of the malignant cells proliferation, induction of oxidative stress, and apoptosis program activation in BC cells.