Effect of Lacticaseibacillus paracasei Strain Shirota on Improvement in Depressive Symptoms, and Its Association with Abundance of Actinobacteria in Gut Microbiota

Effects of Heat-Treated Lactobacillus helveticus CP790-Fermented Milk on Gastrointestinal Health in Healthy Adults: A Randomized Double-Blind Placebo-Controlled Trial

Probiotic-fermented milk is commonly used to maintain intestinal health. However, the effects of heat-treated fermented milk, which does not contain live microorganisms, on intestinal function are not yet fully understood. This study aimed to investigate whether heat-treated Lactobacillus helveticus CP790-fermented milk affects fecal microbiota and gut health as a "postbiotic". A randomized, double-blind, placebo-controlled trial was conducted in healthy Japanese individuals aged 20-59 years with a tendency toward constipation. Participants consumed 100 mL of either the test beverage (n = 60) or placebo beverage (n = 60) for four weeks. The test beverages were prepared with heat-treated CP790-fermented milk, while the placebo beverages were prepared with nonfermented milk flavored with lactic acid. Fecal samples were analyzed using 16S rRNA gene sequencing. Constipation symptoms were assessed using defecation logs and the Patient Assessment of Constipation Symptoms (PAC-SYM) questionnaire. Mood state was also assessed using the Profile of Mood States 2 (POMS2) questionnaire to explore its potential as a "psychobiotic". Desulfobacterota were significantly decreased by CP790-fermented milk intake. PICRUSt2 analysis predicted a decrease in the proportion of genes involved in the sulfate reduction pathway following the consumption of CP790-fermented milk. The CP790-fermented milk intervention significantly improved stool consistency and straining during defecation. These improvements were correlated with a decrease in Desulfobacterota. After the intervention, overall mood, expressed as total mood disturbance, and depression-dejection were significantly better in the CP790 group than in the placebo group. These results suggest that the intake of CP790-fermented milk could be effective in modulating gut microbiota and improving constipation symptoms and mood states.

Psychobiotics and the Microbiota-Gut-Brain Axis: Where Do We Go from Here?

The bidirectional relationship between the gut microbiota and the nervous system is known as the microbiota-gut-brain axis (MGBA). The MGBA controls the complex interactions between the brain, the enteric nervous system, the gut-associated immune system, and the enteric neuroendocrine systems, regulating key physiological functions such as the immune response, sleep, emotions and mood, food intake, and intestinal functions. Psychobiotics are considered tools with the potential to modulate the MGBA through preventive, adjunctive, or curative approaches, but their specific mechanisms of action on many aspects of health are yet to be characterized. This narrative review and perspectives article highlights the key paradigms needing attention as the scope of potential probiotics applications in human health increases, with a growing body of evidence supporting their systemic beneficial effects. However, there are many limitations to overcome before establishing the extent to which we can incorporate probiotics in the management of neuropsychiatric disorders. Although this article uses the term probiotics in a general manner, it remains important to study probiotics at the strain level in most cases.

Probiotic, prebiotic, synbiotic and fermented food supplementation in psychiatric disorders: A systematic review of clinical trials

The use of probiotics, prebiotics, synbiotics or fermented foods can modulate the gut-brain axis and constitute a potentially therapeutic intervention in psychiatric disorders. This systematic review aims to identify current evidence regarding these interventions in the treatment of patients with DSM/ICD psychiatric diagnoses. Forty-seven articles from 42 studies met the inclusion criteria. Risk of bias was assessed in all included studies. Major depression was the most studied disorder (n = 19 studies). Studies frequently focused on schizophrenia (n = 11) and bipolar disorder (n = 5) and there were limited studies in anorexia nervosa (n = 4), ADHD (n = 3), Tourette (n = 1), insomnia (n = 1), PTSD (n = 1) and generalized anxiety disorder (n = 1). Except in MDD, current evidence does not clarify the role of probiotics and prebiotics in the treatment of mental illness. Several studies point to an improvement in the immune and inflammatory profile (e.g. CRP, IL6), which may be a relevant mechanism of action of the therapeutic response identified in these studies. Future research should consider lifestyle and dietary habits of patients as possible confounders that may influence inter-individual treatment response.

Microbiota-mediated metabolic perturbations in the gut and brain of mice after microplastic exposure

Microplastics (MPs), emerging environmental toxicants, have drawn attention because of their wide distribution in the environment. Exposure to MPs induces gut microbiota dysbiosis, intestinal barrier dysfunction, metabolic perturbations, and neurotoxicity in different rodents. However, the relationship between MPs, gut microbiota, and the metabolome of the gut and brain in mice remains unclear. In this study, female C57BL/6 mice were orally gavaged with vehicle, 200 nm MP, and 800 nm MP three times per week for four weeks. Cecal contents were collected for gut microbiota analysis using 16S rRNA gene sequencing. Intestinal and brain tissues from mice were used to determine metabolic profiles using liquid chromatography-mass spectrometry (LC-MS). The results showed that MP altered microbiota composition, accompanied by metabolic perturbations in the mouse gut and brain. Specifically, Firmicutes and Bacteroidetes were suggested to be important phyla for MP exposure, partially dominating further metabolite alterations. Simultaneously, MP-induced metabolic profiles were associated with energy homeostasis and bile acid, nucleotide, and carnitine metabolic pathways. The results of the mediation analysis further revealed an MP-microbiota-metabolite relationship. Our results indicate that MPs can induce gut dysbiosis and disturb metabolic dysfunction in the mouse brain and/or intestine. Integrative omics approaches have the potential to monitor MP-induced molecular responses in various organs and systematically elucidate the complex mechanisms of human health effects.

BDNF/CREB signaling pathway contribution in depression pathogenesis: A survey on the non-pharmacological therapeutic opportunities for gut microbiota dysbiosis

Emerging evidence supports the gut microbiota and the brain communication in general health. This axis may affect behavior through modulating neurotransmission, and thereby involve in the pathogenesis and/or progression of different neuropsychiatric disorders such as depression. Brain-derived neurotrophic factor and cAMP response element-binding protein known as CREB/BDNF pathway plays have critical functions in the pathogenesis of depression as the same of mechanisms related to antidepressants. However, the putative causal significance of the CREB/BDNF signaling cascade in the gut-brain axis in depression remains unknown. Also interventions such as probiotics supplementation and exercise can influence microbiome also improve bidirectional communication of gut and brain. In this review we aim to explain the BDNF/CREB signaling pathway and gut microbiota dysfunction and then evaluate the potential role of probiotics, prebiotics, and exercise as a therapeutic target in the gut microbiota dysfunction induced depression. The current narrative review will specifically focus on the impact of exercise and diet on the intestinal microbiota component, as well as the effect that these therapies may have on the microbiota to alleviate depressive symptoms. Finally, we look at how BDNF/CREB signaling pathway may exert distinct effects on depression and gut microbiota dysfunction.

Digestive characteristics of extracellular polysaccharide from Lactiplantibacillus plantarum T1 and its regulation of intestinal microbiota

This study assessed the potential prebiotic characteristics of the previously reported Lactiplantibacillus plantarum extracellular polysaccharide (EPS-T1) with immunological activity. EPS-T1 was a novel heteropolysaccharide composed of glucose and galactose (1.00:1.21), with a molecular weight of 1.41 × 106 Da. The monosaccharide composition, molecular weight, fourier transform infrared, and 1H NMR analysis showed that EPS-T1 was well tolerated in the simulated oral cavity, gastric fluid, and small intestinal fluid environments, and was not easily degraded. Meanwhile, EPS-T1 could effectively be used as a carbon source to promote the growth of beneficial Lactobacillus species (Lactobacillus delbrueckii ssp. Bulgaricus, Streptococcus thermophilus, Lacticaseibacillus rhamnose GG, Lactiplantibacillus plantarum, Lacticaseibacillus paracasei and Lactobacillus reuteri). After 24 h of fecal fermentation, EPS-T1(5 mg/mL) effectively reduced the relative abundance of harmful bacteria such as the Escherichia-Shigella, Citrobacter, Fusobacterium, Parasutterella, and Lachnoclostridium. While, the level content of beneficial flora (Bacteroides, Blautia, Phascolarctobacterium, Bifidobacterium, Parabacteroides, and Subdoligranulum) were significantly increased. In addition, EPS-T1 was able to significantly promote the enrichment of short-chain fatty acids such as acetic acid, propionic acid and butyric acid. These results provide some basis for the functional application of EPS-T1 as a potential prebiotic.

Effects of Lacticaseibacillus paracasei Strain Shirota on Daytime Performance in Healthy Office Workers: A Double-Blind, Randomized, Crossover, Placebo-Controlled Trial

Lacticaseibacillus paracasei strain Shirota (LcS) modulates psychological homeostasis via the gut-brain axis. To explore the possible efficacy of LcS for improving daytime performance, we conducted a double-blind, randomized, crossover, placebo-controlled study of 12 healthy office workers with sleep complaints. The participants received fermented milk containing viable LcS (daily intake of 1 × 1011 colony-forming units) and non-fermented placebo milk, each for a 4-week period. In the last week of each period, the participants underwent assessments of their subjective mood and measurements of physiological state indicators via an electroencephalogram (EEG) and heart rate variability in the morning and afternoon. The attention score in the afternoon as assessed by the visual analog scale was higher in the LcS intake period than in the placebo intake period (p = 0.041). Theta power on EEG measured at rest or during an auditory oddball task in the afternoon was significantly lower in the LcS period than in the placebo period (p = 0.025 and 0.009, respectively). The change rate of theta power was associated with the change in attention score. Treatment-associated changes were also observed in heart rate and the sympathetic nerve activity index. These results indicate that LcS has possible efficacy for improving daytime performance, supported by observations of the related physiological state indicators.

From-Toilet-to-Freezer: A Review on Requirements for an Automatic Protocol to Collect and Store Human Fecal Samples for Research Purposes

The composition, viability and metabolic functionality of intestinal microbiota play an important role in human health and disease. Studies on intestinal microbiota are often based on fecal samples, because these can be sampled in a non-invasive way, although procedures for sampling, processing and storage vary. This review presents factors to consider when developing an automated protocol for sampling, processing and storing fecal samples: donor inclusion criteria, urine-feces separation in smart toilets, homogenization, aliquoting, usage or type of buffer to dissolve and store fecal material, temperature and time for processing and storage and quality control. The lack of standardization and low-throughput of state-of-the-art fecal collection procedures promote a more automated protocol. Based on this review, an automated protocol is proposed. Fecal samples should be collected and immediately processed under anaerobic conditions at either room temperature (RT) for a maximum of 4 h or at 4 °C for no more than 24 h. Upon homogenization, preferably in the absence of added solvent to allow addition of a buffer of choice at a later stage, aliquots obtained should be stored at either -20 °C for up to a few months or -80 °C for a longer period-up to 2 years. Protocols for quality control should characterize microbial composition and viability as well as metabolic functionality.

Probiotics, Live Biotherapeutic Products (LBPs), and Gut-Brain Axis Related Psychological Conditions: Implications for Research and Dietetics

It is well-known that probiotics have key roles in the crosstalk between the gut and brain in terms of nutrition and health. However, when investigating their role in nutrition and health, it can be important to discriminate probiotics used as foods, food supplements, or drugs. For clarification of this terminology, the Food and Drug Administration (FDA) has established a new "live biotherapeutic products" (LBP) category, expressing pharmaceutical expectations and to reduce confusion in the literature. Growing evidence advises that the community of microorganisms found in the gut microbiota is associated with psychological conditions. Hence, it is thought that LBPs may positively affect depression, anxiety, bipolar disorder, and schizophrenia by reducing inflammation, improving gut microbiota, and balancing gut neurometabolites. This review focuses on the specific position of probiotics as LBPs in psychological conditions. Condition-specific potential pathways and mechanisms of LBPs and the prominent strains are discussed in the light of novel studies for future research, dietetic and pharmaceutical applications.

The role of probiotics and prebiotics in modulating of the gut-brain axis

Pro-and prebiotics have been indicated to modulate the gut-brain axis, which have supportive impacts on central nervous systems, and decrease or control the incidence of some mental disorders such as depression, anxiety, autism, Schizophrenia, and Alzheimer's. In this review, complex communications among microbiota, gut, and the brain, and also recent scientific findings of the impacts and possible action mechanisms of pro-and prebiotics on mental disorders have been discussed. The results have shown that pro-and prebiotics can improve the function of central nervous system and play an important role in the prevention and treatment of some brain disorders; however, in order to prove these effects conclusively and firmly and to use these compounds in a therapeutic and supportive way, more studies are needed, especially human studies/clinical trials.

Special Issue "An Update on Lactobacillus": Editorial

As indicated in the introduction to this Special Issue, as of 2020, the original genus Lactobacillus comprised over 260 recognized species, a figure which is probably much higher now [...].

The Brain-Gut-Microbiota Interplay in Depression: a key to design innovative therapeutic approaches

Depression is the most prevalent mental disorder in the world associated with huge socio-economic consequences. While depressive-related symptoms are well known, the molecular mechanisms underlying disease pathophysiology and progression remain largely unknown. The gut microbiota (GM) is emerging as a key regulator of the central nervous system homeostasis by exerting fundamental immune and metabolic functions. In turn, the brain influences the intestinal microbial composition through neuroendocrine signals, within the so-called gut microbiota-brain axis. The balance of this bidirectional crosstalk is important to ensure neurogenesis, preserve the integrity of the blood-brain barrier and avoid neuroinflammation. Conversely, dysbiosis and gut permeability negatively affect brain development, behavior, and cognition. Furthermore, although not fully defined yet, changes in the GM composition in depressed patients are reported to influence the pharmacokinetics of common antidepressants by affecting their absorption, metabolism, and activity. Similarly, neuropsychiatric drugs may shape in turn the GM with an impact on the efficacy and toxicity of the pharmacological intervention itself. Consequently, strategies aimed at re-establishing the correct homeostatic gut balance (i.e., prebiotics, probiotics, fecal microbiota transplantation, and dietary interventions) represent an innovative approach to improve the pharmacotherapy of depression. Among these, probiotics and the Mediterranean diet, alone or in combination with the standard of care, hold promise for clinical application. Therefore, the disclosure of the intricate network between GM and depression will give precious insights for innovative diagnostic and therapeutic approaches towards depression, with profound implications for drug development and clinical practice.

Probiotics for the treatment of depression and its comorbidities: A systemic review

Depression is one of the most common psychiatric conditions, characterized by significant and persistent depressed mood and diminished interest, and often coexists with various comorbidities. The underlying mechanism of depression remain elusive, evidenced by the lack of an appreciate therapy. Recent abundant clinical trials and animal studies support the new notion that the gut microbiota has emerged as a novel actor in the pathophysiology of depression, which partakes in bidirectional communication between the gut and the brain through the neuroendocrine, nervous, and immune signaling pathways, collectively known as the microbiota-gut-brain (MGB) axis. Alterations in the gut microbiota can trigger the changes in neurotransmitters, neuroinflammation, and behaviors. With the transition of human microbiome research from studying associations to investigating mechanistic causality, the MGB axis has emerged as a novel therapeutic target in depression and its comorbidities. These novel insights have fueled idea that targeting on the gut microbiota may open new windows for efficient treatment of depression and its comorbidities. Probiotics, live beneficial microorganisms, can be used to modulate gut dysbiosis into a new eubiosis and modify the occurrence and development of depression and its comorbidities. In present review, we summarize recent findings regarding the MGB axis in depression and discuss the potential therapeutic effects of probiotics on depression and its comorbidities.

The Survival of Psychobiotics in Fermented Food and the Gastrointestinal Tract: A Review

In recent years, scientists have been particularly interested in the gut-brain axis, as well as the impact of probiotics on the nervous system. This has led to the creation of the concept of psychobiotics. The present review describes the mechanisms of action of psychobiotics, their use in food products, and their viability and survival during gastrointestinal passage. Fermented foods have a high potential of delivering probiotic strains, including psychobiotic ones. However, it is important that the micro-organisms remain viable in concentrations ranging from about 10⁶ to 10⁹ CFU/mL during processing, storage, and digestion. Reports indicate that a wide variety of dairy and plant-based products can be effective carriers for psychobiotics. Nonetheless, bacterial viability is closely related to the type of food matrix and the micro-organism strain. Studies conducted in laboratory conditions have shown promising results in terms of the therapeutic properties and viability of probiotics. Because human research in this field is still limited, it is necessary to broaden our understanding of the survival of probiotic strains in the human digestive tract, their resistance to gastric and pancreatic enzymes, and their ability to colonize the microbiota.

The metabolites of lactic acid bacteria: classification, biosynthesis and modulation of gut microbiota

Lactic acid bacteria (LAB) are ubiquitous microorganisms that can colonize the intestine and participate in the physiological metabolism of the host. LAB can produce a variety of metabolites, including organic acids, bacteriocin, amino acids, exopolysaccharides and vitamins. These metabolites are the basis of LAB function and have a profound impact on host health. The intestine is colonized by a large number of gut microorganisms with high species diversity. Metabolites of LAB can keep the balance and stability of gut microbiota through aiding in the maintenance of the intestinal epithelial barrier, resisting to pathogens and regulating immune responses, which further influence the nutrition, metabolism and behavior of the host. In this review, we summarize the metabolites of LAB and their influence on the intestine. We also discuss the underlying regulatory mechanisms and emphasize the link between LAB and the human gut from the perspective of health promotion.

The Antimicrobial Effect of Various Single-Strain and Multi-Strain Probiotics, Dietary Supplements or Other Beneficial Microbes against Common Clinical Wound Pathogens

The skin is the largest organ in the human body and is colonized by a diverse microbiota that works in harmony to protect the skin. However, when skin damage occurs, the skin microbiota is also disrupted, and pathogens can invade the wound and cause infection. Probiotics or other beneficial microbes and their metabolites are one possible alternative treatment for combating skin pathogens via their antimicrobial effectiveness. The objective of our study was to evaluate the antimicrobial effect of seven multi-strain dietary supplements and eleven single-strain microbes that contain probiotics against 15 clinical wound pathogens using the agar spot assay, co-culturing assay, and agar well diffusion assay. We also conducted genera-specific and species-specific molecular methods to detect the DNA in the dietary supplements and single-strain beneficial microbes. We found that the multi-strain dietary supplements exhibited a statistically significant higher antagonistic effect against the challenge wound pathogens than the single-strain microbes and that lactobacilli-containing dietary supplements and single-strain microbes were significantly more efficient than the selected propionibacteria and bacilli. Differences in results between methods were also observed, possibly due to different mechanisms of action. Individual pathogens were susceptible to different dietary supplements or single-strain microbes. Perhaps an individual approach such as a 'probiogram' could be a possibility in the future as a method to find the most efficient targeted probiotic strains, cell-free supernatants, or neutralized cell-free supernatants that have the highest antagonistic effect against individual clinical wound pathogens.

Effects of dog ownership on the gut microbiota of elderly owners

Dog owners are usually in close contact with dogs. Whether dogs can affect the gut microbiota of elderly dog owners is worth studying. Data from 54 elderly (over 65 years of age) dog owners were screened from the American Gut Project. Owning a dog did not affect the α-diversity of the gut microbiota of the dog owner. Dog ownership significantly modulated the composition of the gut microbiota of the dog owner. The abundance of Actinobacteria was significantly increased. The abundances of Bifidobacteriaceae and Ruminococcaceae were significantly increased, while the abundance of Moracellaceae was significantly suppressed. In general, dog ownership can regulate the composition of gut microbiota and has a more significant effect on elderly males.

Bioprospecting for Novel Probiotic Strains from Human Milk and Infants: Molecular, Biochemical, and Ultrastructural Evidence

Simple Summary

Demographic, genetic factors, and maternal lifestyle could modify and alter the microbial diversity of human milk and infants’ gut. We screened human breast milk and infant stool samples from Egyptian sources for possible novel probiotic strains. Forty-one isolates were submitted to the gene bank database, classified, and identified through physiological and biochemical tests. All samples revealed antibiotic resistance, antibacterial activity, and high probiotic features. Six of the isolates revealed less than 95% Average Nucleotide Identity with deposited sequences in the database. Isolate Lactobacillus delbrueckii ASO 100 exhibited the lowest identity ratio with promising probiotic and antibacterial features, enlightening the high probability of being a new probiotic species.

Abstract

Human milk comprises a diverse array of microbial communities with health-promoting effects, including colonization and development of the infant’s gut. In this study, we characterized the bacterial communities in the Egyptian mother–infant pairs during the first year of life under normal breastfeeding conditions. Out of one hundred isolates, forty-one were chosen for their potential probiotic properties. The selected isolates were profiled in terms of morphological and biochemical properties. The taxonomic evidence of these isolates was investigated based on 16S rRNA gene sequence and phylogenetic trees between the isolates’ sequence and the nearest sequences in the database. The taxonomic and biochemical evidence displayed that the isolates were encompassed in three genera: Lactobacillus, Enterococcus, and Lactococcus. The Lactobacillus was the most common genus in human milk and feces samples with a high incidence of its different species (Lacticaseibacillus paracasei, Lactobacillus delbrueckii, Lactiplantibacillus plantarum, Lactobacillus gasseri, and Lacticaseibacillus casei). Interestingly, BlastN and Jalview alignment results evidenced a low identity ratio of six isolates (less than 95%) with database sequences. This divergence was supported by the unique physiological, biochemical, and probiotic features of these isolates. The isolate L. delbrueckii, ASO 100 exhibited the lowest identity ratio with brilliant probiotic and antibacterial features suggesting the high probability of being a new species. Nine isolates were chosen and subjected to probiotic tests and ultrastructural analysis; these isolates exhibited antibiotic resistance and antibacterial activity with high probiotic characteristics, and high potentiality to be used as prophylactic and therapeutic agents in controlling intestinal pathogens.

Impairment of the gut health in Danio rerio exposed to triclocarban

Triclocarban (TCC) is the principal component in personal and health care products because it is a highly effective, broad-spectrum, and safe antibacterial agent. TCC has recently been discovered in aquatic creatures and has been shown to constitute a health danger to aquatic animals. Although several studies have looked into the toxicological effects of TCC on a variety of aquatic animals from algae to fish, the possible gut-toxicity molecular pathway in zebrafish has never been thoroughly explored. We investigated the gut-toxic effects of TCC on zebrafish by exposing them to different TCC concentrations (100 and 1000 μg/L) for 21 days. We discovered for the first time that the MAPK and TLR signaling pathways related to gut diseases were significantly altered, and inflammation (up-regulation of TNF-α, IL-6, and IL-1β) caused by TCC was confirmed to be largely mediated by the aryl hydrocarbon receptor (AHR) and its related cytokines. This was found using the results of qPCR, a transcriptome analysis, and molecular docking (AHR, AHRR, CYP1A1 and CYP1B1). Furthermore, high-throughput 16S rDNA sequencing demonstrated that TCC exposure reduced the bacterial diversity and changed the gut microbial composition, with the primary phyla Fusobacteria and Proteobacteria, as well as the genera Cetobacterium and Rhodobacteraceae, being the most affected. TCC exposure also caused damage to the gut tissue, including an increase in the number of goblet cells and a reduction in the height of the columnar epithelium and the thickness of the muscular layer, as shown by hematoxylin and eosin staining. Our findings will aid in understanding of the mechanism TCC-induced aquatic toxicity in aquatic species.

The Role of Psychobiotics in Supporting the Treatment of Disturbances in the Functioning of the Nervous System-A Systematic Review

Stress and anxiety are common phenomena that contribute to many nervous system dysfunctions. More and more research has been focusing on the importance of the gut-brain axis in the course and treatment of many diseases, including nervous system disorders. This review aims to present current knowledge on the influence of psychobiotics on the gut-brain axis based on selected diseases, i.e., Alzheimer's disease, Parkinson's disease, depression, and autism spectrum disorders. Analyses of the available research results have shown that selected probiotic bacteria affect the gut-brain axis in healthy people and people with selected diseases. Furthermore, supplementation with probiotic bacteria can decrease depressive symptoms. There is no doubt that proper supplementation improves the well-being of patients. Therefore, it can be concluded that the intestinal microbiota play a relevant role in disorders of the nervous system. The microbiota-gut-brain axis may represent a new target in the prevention and treatment of neuropsychiatric disorders. However, this topic needs more research. Such research could help find effective treatments via the modulation of the intestinal microbiome.

Genomic Insight Into Lacticaseibacillus paracasei SP5, Reveals Genes and Gene Clusters of Probiotic Interest and Biotechnological Potential

The Lacticaseibacillus paracasei species is comprised by nomadic bacteria inhabiting a wide variety of ecological niches, from fermented foodstuffs to host-associated microenvironments. Lc. paracasei SP5 is a novel strain, originally isolated from kefir grains that presents desirable probiotic and biotechnological attributes. In this study, we applied genomic tools to further characterize the probiotic and biotechnological potential of the strain. Firstly, whole genome sequencing and assembly, were performed to construct the chromosome map of the strain and determine its genomic stability. Lc. paracasei SP5 carriers several insertion sequences, however, no plasmids or mobile elements were detected. Furthermore, phylogenomic and comparative genomic analyses were utilized to study the nomadic attributes of the strain, and more specifically, its metabolic capacity and ability to withstand environmental stresses imposed during food processing and passage through the gastrointestinal (GI) tract. More specifically, Kyoto Encyclopedia of Genes and Genomes (KEGG) and Carbohydrate-active enzyme (CAZymes) analyses provided evidence for the ability of the stain to utilize an array of carbohydrates as growth substrates. Consequently, genes for heat, cold, osmotic shock, acidic pH, and bile salt tolerance were annotated. Importantly bioinformatic analysis showed that the novel strain does not harbor acquired antimicrobial resistance genes nor virulence factors, in agreement with previous experimental data. Putative bacteriocin biosynthesis clusters were identified using BAGEL4, suggesting its potential antimicrobial activity. Concerning microbe-host interactions, adhesins, moonlighting proteins, exopolysaccharide (EPS) biosynthesis genes and pilins mediating the adhesive phenotype were, also, pinpointed in the genome of Lc. paracasei SP5. Validation of this phenotype was performed by employing a microbiological method and confocal microscopy. Conclusively, Lc. paracasei SP5 harbors genes necessary for the manifestation of the probiotic character and application in the food industry. Upcoming studies will focus on the mechanisms of action of the novel strain at multiple levels.

How to Improve Health with Biological Agents-Narrative Review

The proper functioning of the human organism is dependent on a number of factors. The health condition of the organism can be often enhanced through appropriate supplementation, as well as the application of certain biological agents. Probiotics, i.e., live microorganisms that exert a beneficial effect on the health of the host when administered in adequate amounts, are often used in commonly available dietary supplements or functional foods, such as yoghurts. Specific strains of microorganisms, administered in appropriate amounts, may find application in the treatment of conditions such as various types of diarrhoea (viral, antibiotic-related, caused by Clostridioides difficile), irritable bowel syndrome, ulcerative colitis, Crohn’s disease, or allergic disorders. In contrast, live microorganisms capable of exerting influence on the nervous system and mental health through interactions with the gut microbiome are referred to as psychobiotics. Live microbes are often used in combination with prebiotics to form synbiotics, which stimulate growth and/or activate the metabolism of the healthy gut microbiome. Prebiotics may serve as a substrate for the growth of probiotic strains or fermentation processes. Compared to prebiotic substances, probiotic microorganisms are more tolerant of environmental conditions, such as oxygenation, pH, or temperature in a given organism. It is also worth emphasizing that the health of the host may be influenced not only by live microorganisms, but also by their metabolites or cell components, which are referred to as postbiotics and paraprobiotics. This work presents the mechanisms of action employed by probiotics, prebiotics, synbiotics, postbiotics, paraprobiotics, and psychobiotics, together with the results of studies confirming their effectiveness and impact on consumer health.

Recent advances in understanding depressive disorder: Possible relevance to brain stimulation therapies

Recent research has provided novel insights into the major depressive disorder (MDD) and identified certain biomarkers of this disease. There are four main mechanisms playing a key role in the related pathophysiology, namely (1) monoamine systems dysfunction, (2) stress response, (3) neuroinflammation, and (4) neurotrophic factors alteration. Robust evidence on the decreased homovanillic acid in the cerebrospinal fluid (CSF) of patients with MDD supports a rationale for therapeutic stimulation of the medial forebrain bundle activating the dopamine reward system. Both activation and suppression of the hypothalamic-pituitary-adrenal (HPA) axis in MDD and related conditions indicate usefulness of its evaluation for the disease subtyping. Elevated proinflammatory cytokines (specifically, interleukin-6) in CSF imply the role of neuroinflammation resulting in activation of the tryptophan-kynurenine pathway. Finally, neuroplasticity and trophic effects of the brain-derived neurotrophic factor (BDNF) may be related to both structural abnormalities of the brain in MDD and the underlying mechanisms of various therapies. In addition, the gut-brain interaction is pivotal, since lack of beneficial microbes confer the risk of MDD through negative effects on the dopamine system, HPA axis, and vagal nerve. All these factors may be highly relevant to treatment of MDD with contemporary brain stimulation therapies.

How Microbes Affect Depression: Underlying Mechanisms via the Gut-Brain Axis and the Modulating Role of Probiotics

Accumulating evidence suggests that the gut microbiome influences the brain functions and psychological state of its host via the gut-brain axis, and gut dysbiosis has been linked to several mental illnesses, including major depressive disorder (MDD). Animal experiments have shown that a depletion of the gut microbiota leads to behavioral changes, and is associated with pathological changes, including abnormal stress response and impaired adult neurogenesis. Short-chain fatty acids such as butyrate are known to contribute to the up-regulation of brain-derived neurotrophic factor (BDNF), and gut dysbiosis causes decreased levels of BDNF, which could affect neuronal development and synaptic plasticity. Increased gut permeability causes an influx of gut microbial components such as lipopolysaccharides, and the resultant systemic inflammation may lead to neuroinflammation in the central nervous system. In light of the fact that gut microbial factors contribute to the initiation and exacerbation of depressive symptoms, this review summarizes the current understanding of the molecular mechanisms involved in MDD onset, and discusses the therapeutic potential of probiotics, including butyrate-producing bacteria, which can mediate the microbiota-gut-brain axis.

Characterization of Bacterial Microbiota of P.D.O. Feta Cheese by 16S Metagenomic Analysis

Background: The identification of bacterial species in fermented PDO (protected designation of origin) cheese is important since they contribute significantly to the final organoleptic properties, the ripening process, the shelf life, the safety and the overall quality of cheese. Methods: Ten commercial PDO feta cheeses from two geographic regions of Greece, Epirus and Thessaly, were analyzed by 16S metagenomic analysis. Results: The biodiversity of all the tested feta cheese samples consisted of five phyla, 17 families, 38 genera and 59 bacterial species. The dominant phylum identified was Firmicutes (49% of the species), followed by Proteobacteria (39% of the species), Bacteroidetes (7% of the species), Actinobacteria (4% of the species) and Tenericutes (1% of the species). Streptococcaceae and Lactobacillaceae were the most abundant families, in which starter cultures of lactic acid bacteria (LAB) belonged, but also 21 nonstarter lactic acid bacteria (NSLAB) were identified. Both geographical areas showed a distinctive microbiota fingerprint, which was ultimately overlapped by the application of starter cultures. In the rare biosphere of the feta cheese, Zobellella taiwanensis and Vibrio diazotrophicus, two Gram-negative bacteria which were not previously reported in dairy samples, were identified. Conclusions: The application of high-throughput DNA sequencing may provide a detailed microbial profile of commercial feta cheese produced with pasteurized milk.

Microbial Therapeutics in Neurocognitive and Psychiatric Disorders

Microbial therapeutics, which include gut biotics and fecal transplantation, are interventions designed to improve the gut microbiome. Gut biotics can be considered as the administration of direct microbial populations. The delivery of this can be done through live microbial flora, certain food like fiber, microbial products (metabolites and elements) obtained through the fermentation of food products, or as genetically engineered substances, that may have therapeutic benefit on different health disorders. Dietary intervention and pharmacological supplements with gut biotics aim at correcting disruption of the gut microbiota by repopulating with beneficial microorganism leading to decrease in gut permeability, inflammation, and alteration in metabolic activities, through a variety of mechanisms of action. Our understanding of the pharmacokinetics of microbial therapeutics has improved with in vitro models, sampling techniques in the gut, and tools for the reliable identification of gut biotics. Evidence from human studies points out that prebiotics, probiotics and synbiotics have the potential for treating and preventing mental health disorders, whereas with paraprobiotics, proteobiotics and postbiotics, the research is limited at this point. Some animal studies point out that gut biotics can be used with conventional treatments for a synergistic effect on mental health disorders. If future research shows that there is a possibility of synergistic effect of psychotropic medications with gut biotics, then a gut biotic or nutritional prescription can be given along with psychotropics. Even though the overall safety of gut biotics seems to be good, caution is needed to watch for any known and unknown side effects as well as the need for risk benefit analysis with certain vulnerable populations. Future research is needed before wide spread use of natural and genetically engineered gut biotics. Regulatory framework for gut biotics needs to be optimized. Holistic understanding of gut dysbiosis, along with life style factors, by health care providers is necessary for the better management of these conditions. In conclusion, microbial therapeutics are a new psychotherapeutic approach which offer some hope in certain conditions like dementia and depression. Future of microbial therapeutics will be driven by well-done randomized controlled trials and longitudinal research, as well as by replication studies in human subjects.

Gut Microbiota and Pathophysiology of Depressive Disorder

BACKGROUND

Accumulating evidence has suggested that the bi-directional communication pathway, the microbiota-gut-brain axis, plays an important role in the pathophysiology of many neuropsychiatric diseases including major depressive disorder (MDD). This review outlines current evidence and promising findings related to the pathophysiology and treatment of MDD.

SUMMARY

There are at least 4 key biological molecules/systems underlying the pathophysiology of MDD: central dopamine, stress responses by the hypothalamic-pituitary-adrenal axis and autonomic nervous system, inflammation, and brain-derived neurotrophic factor. Animal experiments in several depression models have clearly indicated that gut microbiota is closely related to these molecules/systems and administration of probiotics and prebitotics may have beneficial effects on them. Although the results of microbiota profile of MDD patients varied from a study to another, multiple studies reported that bacteria which produce short-chain fatty acids such as butyrate and those protective against metabolic diseases (e.g., Bacteroidetes) were reduced. Clinical trials of probiotics have emerged, and the majority of the studies have reported beneficial effects on depression symptoms and related biological markers. Key Messages: The accumulating evidence suggests that research on the microbiota-gut-brain axis in major depressive disorder (MDD) is promising to elucidate the pathophysiology and to develop novel treatment of MDD, although there is still a long distance yet to reach the goals.