Visceral pain: role of the microbiome-gut-brain axis

A growing body of preclinical and clinical evidence supports a relationship between the complexity and diversity of the microorganisms that inhabit our gut (human gastrointestinal microbiome) and health status. These microbes can influence centrally regulated emotional behaviour through mechanisms including microbially derived bioactive molecules, mucosal immune and enteroendocrine cell activation, as well as vagal nerve stimulation. Changes to the microbial environment, as a consequence of illness, stress or injury can lead to a broad spectrum of local physiological and behavioural effects including a decrease in gut barrier integrity, altered gut motility, inflammatory mediator release, as well as nociceptive and distension receptor sensitization. Impacts at a central level include alterations in the hypothalamic-pituitary-adrenal axis, neuroinflammatory events and concomitant changes to neurotransmitter systems. Thus, both central and peripheral pathways associated with pain manifestation and perception are altered as a consequence of the microbiome-gut-brain axis imbalance. The dogmatic approach of antibiotic treatment in the latter century, for the treatment of many diseases and conditions, has undergone a radical change. We are 90% microbe, and pragmatism suggests that we manipulate this ecosystem for the treatment of various ailments, stress dysfunction and affective disorders, including the alleviation of visceral pain

Genetic, enzymatic and metabolite profiling of the Lactobacillus casei group reveals strain biodiversity and potential applications for flavour diversification

Aims: The Lactobacillus casei group represents a widely explored group of lactic acid bacteria, characterized by a high level of biodiversity. In this study, the genetic and phenotypic diversity of a collection of more than 300 isolates of the Lact. casei group and their potential to produce volatile metabolites important for flavour development in dairy products, was examined. Methods and Results: Following confirmation of species by 16S rRNA PCR, the diversity of the isolates was determined by pulsed-field gel electrophoresis. The activities of enzymes involved in the proteolytic cascade were assessed and significant differences among the strains were observed. Ten strains were chosen based on the results of their enzymes activities and they were analysed for their ability to produce volatiles in media with increased concentrations of a representative aromatic, branched chain and sulphur amino acid. Volatiles were assessed using gas chromatography coupled with mass spectrometry. Strain-dependent differences in the range and type of volatiles produced were evident. Conclusions: Strains of the Lact. casei group are characterized by genetic and metabolic diversity which supports variability in volatile production. Significance and Impact of the Study: This study provides a screening approach for the knowledge-based selection of strains potentially enabling flavour diversification in fermented dairy products

Evaluation of the Potential of Lactobacillus paracasei Adjuncts for Flavor Compounds Development and Diversification in Short-Aged Cheddar Cheese

peer-reviewedThe non-starter microbiota of Cheddar cheese mostly comprises mesophilic lactobacilli, such as Lactobacillus casei, Lactobacillus paracasei, Lactobacillus rhamnosus, and Lactobacillus plantarum. These bacteria are recognized for their potential to improve Cheddar cheese flavor when used as adjunct cultures. In this study, three strains of L. paracasei (DPC2071, DPC4206, and DPC4536) were evaluated for their contribution to the enhancement and diversification of flavor in short-aged Cheddar cheese. The strains were selected based on their previously determined genomic diversity, variability in proteolytic enzyme activities and metabolic capability in cheese model systems. The addition of adjunct cultures did not affect the gross composition or levels of lipolysis of the cheeses. The levels of free amino acids (FAA) in cheeses showed a significant increase after 28 days of ripening. However, the concentrations of individual amino acids in the cheeses did not significantly differ except for some amino acids (aspartic acid, threonine, serine, and tryptophan) at Day 14. Volatile profile analysis revealed that the main compounds that differentiated the cheeses were of lipid origin, such as long chain aldehydes, acids, ketones, and lactones. This study demonstrated that the adjunct L. paracasei strains contributed to the development and diversification of compounds related to flavor in short-aged Cheddar cheeses

Genome Sequence of Staphylococcus saprophyticus DPC5671, a Strain Isolated from Cheddar Cheese

peer-reviewedThe draft genome sequence of Staphylococcus saprophyticus DPC5671, isolated from cheddar cheese, was determined. S. saprophyticus is a common Gram-positive bacterium detected on the surface of smear-ripened cheese and other fermented foods

High and Mighty? Cannabinoids and the microbiome in pain

Within the human gut, we each harbour a unique ecosystem represented by trillions of microbes that contribute to our health and wellbeing. These gut microbiota form part of a complex network termed the microbiota-gut-brain axis along with the enteric nervous system, sympathetic and parasympathetic divisions of the autonomic nervous system, and neuroendocrine and neuroimmune components of the central nervous system. Through endocrine, immune and neuropeptide/neurotransmitter systems, the microbiota can relay information about health status of the gut. This in turn can profoundly impact neuronal signalling not only in the periphery, but also in the brain itself and thus impact on emotional systems and behavioural responses. This may be true for pain, as the top-down facilitation or inhibition of pain processing occurs at a central level, while ascending afferent nociceptive information from the viscera and systemic areas travel through the periphery and spinal cord to the brain. The endogenous cannabinoid receptors are ubiquitously expressed throughout the gut, periphery and in brain regions associated with pain responding, and represent targets for endogenous and exogenous manipulation. In this review, we will focus on the potential role of the endogenous cannabinoids in modulating microbiota-driven changes in peripheral and central pain processing. We also focus on the overlap in mechanisms whereby commensal gut microbiota and endocannabinoid ligands can regulate inflammation and further aim to exploit our understanding of their role in microbiota-gut-brain axis communication in pain processing

Pain bugs: Gut microbiota and pain disorders

The microbiota-gut–brain axis is a complex and dynamic multi-directional ‘communication superhighway’ within the body including the central nervous system, the autonomic nervous system, the neuroendocrine and neuroimmune systems, the lymphatic system, the enteric nervous system and the gastrointestinal microbiota. The mechanisms of communication are slowly being unravelled and involve the main systems mentioned along with the by-products produced such as neuropeptides, neurotransmitter, hormones and immune modulators. Over the last decade increasing evidence points to an essential role of this axis in many fundamental neural processes and brain disorders. However, the limited clinical and preclinical studies do not clearly delineate a role for gut microbiota in the pathophysiology of pain state. The most researched area is in irritable bowel syndrome and in visceral pain studies in animal models. However, one cannot overlook the involvement of the microbiota in symptoms that are comorbid with chronic pain especially affective disorders. In this review we synthesise the available information highlighting the gut microbiota in visceral, inflammatory, and neuropathic pain states, including fibromyalgia, migraine, cancer and chemotherapy-associated pain. Given its part in many effector systems, there is a clear need for more focused investigations on the mechanism of action of the microbiota in human pain states, as current treatment strategies are often ineffective or provide limited relief

Strains of the Lactobacillus casei group show diverse abilities for the production of flavor compounds in 2 model systems

peer-reviewedCheese flavor development is directly connected to the metabolic activity of microorganisms used during its manufacture, and the selection of metabolically diverse strains represents a potential tool for the production of cheese with novel and distinct flavor characteristics. Strains of Lactobacillus have been proven to promote the development of important cheese flavor compounds. As cheese production and ripening are long-lasting and expensive, model systems have been developed with the purpose of rapidly screening lactic acid bacteria for their flavor potential. The biodiversity of 10 strains of the Lactobacillus casei group was evaluated in 2 model systems and their volatile profiles were determined by gas chromatography-mass spectrometry. In model system 1, which represented a mixture of free AA, inoculated cells did not grow. In total, 66 compounds considered as flavor contributors were successfully identified, most of which were aldehydes, acids, and alcohols produced via AA metabolism by selected strains. Three strains (DPC2071, DPC3990, and DPC4206) had the most diverse metabolic capacities in model system 1. In model system 2, which was based on processed cheese curd, inoculated cells increased in numbers over incubation time. A total of 47 compounds were identified, and they originated not only from proteolysis, but also from glycolytic and lipolytic processes. Tested strains produced ketones, acids, and esters. Although strains produced different abundances of volatiles, diversity was less evident in model system 2, and only one strain (DPC4206) was distinguished from the others. Strains identified as the most dissimilar in both of the model systems could be more useful for cheese flavor diversification

Use of smear bacteria and yeasts to modify flavour and appearance of Cheddar cheese

The strains Staphylococcus saprophyticus DPC5671 and Corynebacterium casei DPC5298 were applied in combination with Debaryomyces hansenii DPC6258 to the surface of young Cheddar cheese curd to obtain two different smear-ripened cheeses. A surface microbiota developed over the incubation period, comprising of both yeast and bacteria; pulsed field gel electrophoresis confirmed that the inoculated strains of S. saprophyticus DPC5671 or C. casei DPC5298 were the dominant bacterial strains on the surface of the cheese at the end of the ripening period. The smear cultures changed the appearance and aroma, which were significantly different from the control cheese. The approach presented in this study represents a method for the development of new cheese varieties with novel aromas within a short ripening time