Emerging trends in 'smart probiotics' : functional consideration for the development of novel health and industrial applications

The link between gut microbiota and human health is well-recognized and described. This ultimate impact on the host has contributed to explain the mutual dependence between humans and their gut bacteria. Gut microbiota can be manipulated through passive or active strategies. The former includes diet, lifestyle, and environment, while the latter comprise antibiotics, pre- and probiotics. Historically, conventional probiotic strategies included a phylogenetically limited diversity of bacteria and some yeast strains. However, biotherapeutic strategies evolved in the last years with the advent of fecal microbiota transplant (FMT), successfully applied for treating CDI, IBD, and other diseases. Despite the positive outcomes, long-term effects resulting from the uncharacterized nature of FMT are not sufficiently studied. Thus, developing strategies to simulate the FMT, using characterized gut colonizers with identified phylogenetic diversity, may be a promising alternative. As the definition of probiotics states that the microorganism should have beneficial effects on the host, several bacterial species with proven efficacy have been considered next generation probiotics. Non-conventional candidate strains include Akkermansia muciniphila, Faecalibacterium prausnitzii, Bacteroides fragilis, and members of the Clostridia clusters IV, XIVa, and XVIII. However, viable intestinal delivery is one of the current challenges, due to their stringent survival conditions. In this review, we will cover current perspectives on the development and assessment of next generation probiotics and the approaches that industry and stakeholders must consider for a successful outcome

Dysbiosis by neutralizing commensal mediated inhibition of pathobionts

Dysbiosis in the periodontal microbiota is associated with the development of periodontal diseases. Little is known about the initiation of dysbiosis. It was hypothesized that some commensal bacteria suppress the outgrowth of pathobionts by H2O2 production. However, serum and blood components released due to inflammation can neutralize this suppressive effect, leading to the initiation of dysbiosis. Agar plate, dual-species and multi-species ecology experiments showed that H2O2 production by commensal bacteria decreases pathobiont growth and colonization. Peroxidase and blood components neutralize this inhibitory effect primarily by an exogenous peroxidase activity without stimulating growth and biofilm formation of pathobionts directly. In multi-species environments, neutralization of H2O2 resulted in 2 to 3 log increases in pathobionts, a hallmark for dysbiosis. Our data show that in oral biofilms, commensal species suppress the amounts of pathobionts by H2O2 production. Inflammation can neutralize this effect and thereby initiates dysbiosis by allowing the outgrowth of pathobionts

Assessing the viability of a synthetic bacterial consortium on the in vitro gut host-microbe interface

The interplay between host and microbiota has been long recognized and extensively described. The mouth is similar to other sections of the gastrointestinal tract, as resident microbiota occurs and prevents colonisation by exogenous bacteria. Indeed, more than 600 species of bacteria are found in the oral cavity, and a single individual may carry around 100 different at any time. Oral bacteria possess the ability to adhere to the various niches in the oral ecosystem, thus becoming integrated within the resident microbial communities, and favouring growth and survival. However, the flow of bacteria into the gut during swallowing has been proposed to disturb the balance of the gut microbiota. In fact, oral administration of P. gingivalis shifted bacterial composition in the ilea! microflora. We used a synthetic community as a simplified representation of the natural oral ecosystem, to elucidate the survival and viability of oral bacteria subjected to simulated gastrointestinal transit conditions. Fourteen species were selected, subjected to in vitro salivary, gastric, and intestinal digestion processes, and presented to a multicompartment cell model containing Caco-2 and HT29-MTX cells to simulate the gut mucosal epithelium. This model served to unravel the impact of swallowed bacteria on cells involved in the enterohepatic circulation. Using synthetic communities allows for controllability and reproducibility. Thus, this methodology can be adapted to assess pathogen viability and subsequent inflammation-associated changes, colonization capacity of probiotic mixtures, and ultimately, potential bacterial impact on the presystemic circulation

In vitro increased respiratory activity of selected oral bacteria may explain competitive and collaborative interactions in the oral microbiome

Understanding the driving forces behind the shifts in the ecological balance of the oral microbiota will become essential for the future management and treatment of periodontitis. As the use of competitive approaches for modulating bacterial outgrowth is unexplored in the oral ecosystem, our study aimed to investigate both the associations among groups of functional compounds and the impact of individual substrates on selected members of the oral microbiome. We employed the Phenotype Microarray high-throughput technology to analyse the microbial cellular phenotypes of 15 oral bacteria. Multivariate statistical analysis was used to detect respiratory activity triggers and to assess similar metabolic activities. Carbon and nitrogen were relevant for the respiration of health-associated bacteria, explaining competitive interactions when grown in biofilms. Carbon, nitrogen, and peptides tended to decrease the respiratory activity of all pathobionts, but not significantly. None of the evaluated compounds significantly increased activity of pathobionts at both 24 and 48 h. Additionally, metabolite requirements of pathobionts were dissimilar, suggesting that collective modulation of their respiratory activity may be challenging. Flow cytometry indicated that the metabolic activity detected in the Biolog plates may not be a direct result of the number of bacterial cells. In addition, damage to the cell membrane may not influence overall respiratory activity. Our methodology confirmed previously reported competitive and collaborative interactions among bacterial groups, which could be used either as marker of health status or as targets for modulation of the oral environment

Growing media constituents determine the microbial nitrogen conversions in organic growing media for horticulture

Vegetables and fruits are an important part of a healthy food diet, however, the eco-sustainability of the production of these can still be significantly improved. European farmers and consumers spend an estimated Euro15.5 billion per year on inorganic fertilizers and the production of N-fertilizers results in a high carbon footprint. We investigated if fertilizer type and medium constituents determine microbial nitrogen conversions in organic growing media and can be used as a next step towards a more sustainable horticulture. We demonstrated that growing media constituents showed differences in urea hydrolysis, ammonia and nitrite oxidation and in carbon dioxide respiration rate. Interestingly, mixing of the growing media constituents resulted in a stimulation of the function of the microorganisms. The use of organic fertilizer resulted in an increase in amoA gene copy number by factor 100 compared to inorganic fertilizers. Our results support our hypothesis that the activity of the functional microbial community with respect to nitrogen turnover in an organic growing medium can be improved by selecting and mixing the appropriate growing media components with each other. These findings contribute to the understanding of the functional microbial community in growing media and its potential role towards a more responsible horticulture

NONSTEROIDAL ANTI-INFLAMMATORY DRUGS AS THERAPEUTIC ALLIES OF THE GUT MICROBIOME ON CHRONIC INFLAMMATION

Our gut harbours around 1014 bacteria of more than 1000 species, accounting for approximately 2 kg of biomass. The gut microbiome plays several vital functions in processes such as the development of the immune system, food digestion and protection against pathogens. For these functions to be beneficial for both host and microbiome, interactions are tightly regulated. Gut and immune cells continuously interact to distinguish among commensal microbiota, harmless foodstuff, and pathogens. A fine balance between inflammatory and anti-inflammatory state is fundamental to protect intestinal homeostasis. Nonsteroidal anti-inflammatories (NSAIDs) are a class of drugs used for management of pain and inflammation. These compounds have heterologous structures but similar therapeutic activities. The target of all NSAIDs are the isoforms of cyclooxygenase enzymes (COX): the primarily constitutive form COX-1, and the inducible from COX-2. Both isoforms catalyse the conversion of arachidonic acid to PGH2, the immediate substrate for specific prostaglandin and thromboxane synthesis. The gut microbiota plays a role in drug metabolism,  resulting in altered bioavailability of these compounds. Additionally, complex host-microbiome interactions lead to modified xenobiotic metabolism and altered expression of genes involved in drug metabolism. These effects can be at gut tissue-level, or distant, including in the liver. Besides the gut microbiome influencing drug metabolism, drugs also impact the microbial communities in the gut. As different drugs exert selective pressures on the gut microbiome,  understanding this bidirectional relationship is crucial for developing effective therapies for managing chronic inflammation

Nonsteroidal anti-inflammatory drugs as therapeutic allies of the gut microbiome on chronic inflammation

Our gut harbours around 1014bacteria of more than 1000 species, accounting for approximately 2 kg of biomass. Thegut microbiome plays several vital functions in processes such as the development of the immune system, food digestion and protection against pathogens. For these functions to be beneficial for both host and microbiome, interactions are tightly regulated.Gut and immune cells continuously interact to distinguish among commensal microbiota, harmless foodstuff, and pathogens. A fine balance between inflammatory and anti-inflammatory state is fundamental to protect intestinal homeostasis. Nonsteroidal anti-inflammatories (NSAIDs) are a class of drugs used for management of pain and inflammation. These compounds have heterologous structures but similar therapeutic activities. The target of all NSAIDs are the isoforms of cyclooxygenase enzymes (COX): the primarily constitutive form COX-1, and the inducible from COX-2. Both isoforms catalyse the conversion of arachidonic acid to PGH2, the immediate substrate for specific prostaglandin and thromboxane synthesis. The gut microbiota plays a role in drug metabolism, resulting in altered bioavailability of these compounds. Additionally, complex host-microbiome interactions lead to modified xenobiotic metabolism and altered expression of genes involved in drug metabolism. These effects can be at gut tissue-level, or distant, including in the liver. Besides the gut microbiome influencing drug metabolism, drugs also impact the microbial communities in the gut. As different drugs exert selective pressures on the gut microbiome, understanding this bidirectional relationshipis crucial for developing effective therapies for managing chronic inflammation