• Functional foods
• Gastrointestinal passage
• Postbiotics
• Probiotics
• Stress conditions

• Probiotics/metabolism
• Humans
• Functional Food/microbiology
• Functional Food/analysis
• Stress, Physiological
• Gastrointestinal Tract/microbiology
• Fermentation

• University of Peloponnese

• drying
• food applications
• gastrointestinal digestion
• storage
• viability

• Food Storage
• Food Handling
• Bacteria
• Probiotics
• Digestion

• University of Tennessee Institute of Agriculture
• USDA National Institute of Food and Agriculture hatch project TEN00568

• Amino acids
• Cell volume
• Chemically defined medium
• Fed-batch culture
• Lactococcus lactis
• Osmotic pressure

• Natural Science Foundation of Inner Mongolia
• Industry-University-Research Cooperative Cultivation Fund of Inner Mongolia University of Science & Technology
• Fundamental Research Funds for Inner Mongolia University of Science & Technology

• Probiotication
• fruit juice
• vegetable juice

• compatible solutes
• cross-protection
• cryotolerance
• environmental stress
• freeze-drying
• lactic acid bacteria

• Bacterial strains
• Enteric infections
• Probiotics
• Regulation of gut barrier
• Therapeutic approach

Lactobacillus rhamnosus p75 protein with peptidoglycan hydrolase (PGH) activity is one of the key molecules exhibiting anti-apoptotic and cell-protective activity for human intestinal epithelial cells. In this study, with the goal of developing new probiotics, the p75 protein was displayed on the surface of Bacillus subtilis spores using spore coat protein CotG as an anchoring motif. The PGH activity, stability, and the antibacterial activity of the spore-displayed p75 (CotG-p75) protein were also investigated. The PGH activity of the CotG-p75 against peptidoglycan extracted from B. subtilis was confirmed by the ninhydrin test. Under various harsh conditions, compared to the control groups, the PGH activities of CotG-p75 were very stable in the range of pH 3–7 and maintained at 70% at 50 °C. In addition, the antibacterial activity of CotG-p75 against Listeria monocytogenes was evaluated by a time-kill assay. After 6 h incubation in phosphate-buffered saline, CotG-p75 reduced the number of viable cells of L. monocytogenes by up to 2.0 log. Scanning electron microscopy analysis showed that the cell wall of L. monocytogenes was partially damaged by the treatment with CotG-p75. Our preliminary results show that CotG-p75 could be a good candidate for further research to develop new genetically engineered probiotics.

• Antibacterial activity
• L. monocytogenes
• Spore surface display
• p75 protein

Propionibacterium freudenreichii is a beneficial bacterium widely used in food as a probiotic and as a cheese-ripening starter. In these different applications, it is produced, dried, and stored before being used. Both freeze-drying and spray-drying were considered for this purpose. Freeze-drying is a discontinuous process that is energy-consuming but that allows high cell survival. Spray-drying is a continuous process that is more energy-efficient but that can lead to massive bacterial death related to heat, osmotic, and oxidative stresses. We have shown that P. freudenreichii cultivated in hyperconcentrated rich media can be spray-dried with limited bacterial death. However, the general stress tolerance conferred by this hyperosmotic constraint remained a black box. In this study, we modulated P. freudenreichii growth conditions and monitored both osmoprotectant accumulation and stress tolerance acquisition. Changing the ratio between the carbohydrates provided and non-protein nitrogen during growth under osmotic constraint modulated osmoprotectant accumulation. This, in turn, was correlated with P. freudenreichii tolerance towards different stresses, on the one hand, and towards freeze-drying and spray-drying, on the other. Surprisingly, trehalose accumulation correlated with spray-drying survival and glycine betaine accumulation with freeze-drying. This first report showing the ability to modulate the trehalose/GB ratio in osmoprotectants accumulated by a probiotic bacterium opens new perspectives for the optimization of probiotics production.

• Cross-protection
• Osmoadaptation
• Propionibacteria
• Spray-drying
• Stress
• Viability

Elucidating the metabolite profiles during the growth of Streptococcus thermophilus is beneficial for understanding its growth characteristics. The changes in the intracellular and extracellular concentrations of carbohydrates, nucleotides, amino sugars, nucleoside sugars, fatty acids, and amino acids, as well as their metabolites over time, were investigated by metabolomics technology. Most metabolites of nucleotides were highly accumulated in the intracellular environment after the mid-exponential phase. Increases in the intracellular unsaturated fatty acids and N-acetyl-glucosamine and N-acetyl-muramoate recycling provided potential evidence that cell envelope remodeling occurred after the mid-exponential phase. At the later fermentation stages, potentially functional metabolite produced by glycine was highly accumulated in the intracellular environment. Additionally, potential toxic metabolites produced by phenylalanine and tyrosine could not be excreted into the extracellular environment in a timely basis. The accumulation of large amounts of these metabolites might be the primary cause of the overconsumption of amino acids and influence the growth of S. thermophilus.

• Streptococcus thermophilus
• extracellular metabolite
• intracellular metabolite
• metabolic pathway
• pH-controlled batch fermentations

• abiotic stresses
• evolutionary engineering
• improvement of microbial tolerance
• metabolic engineering
• process engineering

• Streptococcus thermophilus
• global changes
• proteomic
• transcriptomic

• adaptation
• drying
• osmo regulation
• probiotic
• stress

• Applied genomics
• Gut microbiota
• Next-generation therapeutic bacteria
• Probiotics

• Active dry probiotics
• Encapsulation
• Inactivation kinetics
• Probiotics
• Probiotics preservation
• Protectant
• Protective mechanism
• Single droplet drying
• Spray drying

• Global regulator
• High salt stress
• Osmoprotectants
• Seawater
• Succinic acid

• Escherichia coli
• Fermentation
• Glycerol
• Salt Tolerance
• Succinic Acid

• acidophile, bioleaching, biohydrometallurgy, biomining, halophile, metal, microorganism, resistance, tolerance, synthetic biology

• Antibiotic resistance
• Bioengineering
• Foodborne pathogens
• Probiotics

• University of Pretoria
• National Research Foundation

• biological containment
• biotherapeutics
• cancer
• probiotics
• synthetic biology
• vaccines

• Listeria
• betL*
• lux
• osmotolerance

Clostridium difficile is a major cause of morbidity and mortality worldwide, causing over 400,000 infections and approximately 29,000 deaths in the United States alone each year. C. difficile is the most common cause of nosocomial diarrhoea in the developed world, and, in recent years, the emergence of hyper-virulent (mainly ribotypes 027 and 078, sometimes characterised by increased toxin production), epidemic strains and an increase in the number of community-acquired infections has caused further concern. Antibiotic therapy with metronidazole, vancomycin or fidaxomicin is the primary treatment for C. difficile infection (CDI). However, CDI is unique, in that, antibiotic use is also a major risk factor for acquiring CDI or recurrent CDI due to disruption of the normal gut microbiota. Therefore, there is an urgent need for alternative, non-antibiotic therapeutics to treat or prevent CDI. Here, we review a number of such potential treatments which have emerged from advances in the field of microbiome research.

• Clostridium difficile
• antibiotic resistance
• bacteriocin
• faecal microbiota transplantation (FMT)
• genome sequencing
• gut microbiota
• human gut microbiome
• nanopore sequencing
• probiotics
• synthetic biology

• Listeria
• bile
• diagnostics
• gastrointestinal tract
• pathogens
• probiotics
• virulence

Given the increasing commercial and clinical relevance of probiotics, improving their stress tolerance profile and ability to overcome the physiochemical defences of the host is an important biological goal. Herein, I review the current state of the art in the design of engineered probiotic cultures, with a specific focus on their utility as therapeutics for the developing world; from the treatment of chronic and acute enteric infections, and their associated diarrhoeal complexes, to targeting HIV and application as novel mucosal vaccine delivery vehicles.

• Gastrointestinal tract
• Probiotics
• BetL
• Listeria monocytogenes
• Bifidobacterium
• Lactobacillus

• Fermented milks
• Microencapsulation
• Probiotic microorganisms
• Viability

• Animals
• Dairy Products/microbiology
• Fermentation/physiology
• Food Microbiology/methods
• Humans
• Lactobacillus/metabolism
• Lactobacillus/physiology
• Probiotics/metabolism

• bioengineered probiotics
• biotherapeutics
• functional metagenomics
• gut microbiome
• metabiotechnology
• metagenomics
• microbiota
• novel gene discovery

• Biological Products/isolation & purification
• Biological Products/therapeutic use
• Drug Discovery/methods
• Environmental Microbiology
• Genetic Association Studies/methods
• Humans
• Metagenome
• Metagenomics/methods

• bioengineered probiotics
• enteric infections
• foodborne diseases
• lactic acid bacteria
• probiotics
• recombinant probiotics

• Animals
• Anti-Infective Agents/administration & dosage
• Anti-Infective Agents/pharmacology
• Bioengineering
• Biotechnology
• Food Technology/methods
• Foodborne Diseases/prevention & control
• Humans
• Models, Animal
• Probiotics/administration & dosage
• Probiotics/pharmacology
• Stress, Physiological

• evolution
• symbiont
• hologenome
• holobiont
• probiotics

Betaine uptake in Listeria monocytogenes is mediated by three independent transport systems, the simplest of which in genetic terms is the secondary transporter BetL. Using a random mutagenesis approach, based on the E. coli XL1 Red mutator strain, we identified a single point mutation in a putative promoter region upstream of the BetL coding region which leads to a significant increase in betL transcript levels under osmo- and chill-stress conditions and a concomitant increase in stress tolerance. Furthermore, the mutation appears to counter the heretofore unreported “twisted” cell morphology observed for L. monocytogenes grown at elevated osmolarities in tryptone soy broth.

• Listeria
• chill-tolerance
• osmotolerance
• salt stress
• twisted cells

• Listeria
• Pseudomonas
• antigen delivery
• attenuation
• bacteria
• immunotherapy

Manufacture of probiotic products involves industrial processes that reduce the viability of the strains. This lost of viability constitutes an economic burden for manufacturers, compromising the efficacy of the product and preventing the inclusion of probiotics in many product categories. Different strategies have been used to improve probiotic stability during industrial processes. These include technological approaches, such as the modification of production parameters or the reformulation of products, as well as microbiological approaches focused on the strain intrinsic resistance. Among the later, both selection of natural strains with the desired properties and stress-adaptation of strains have been widely used.

During recent years, the knowledge acquired on the molecular basis of stress-tolerance of probiotics has increased our understanding on their responses to industrial stresses. This knowledge on stress-response may nowadays be used for the selection of the best strains and industrial conditions in terms of probiotic stability in the final product.

• Bifidobacterium
• Lactobacillus
• probiotics
• stability
• viability

Before a probiotic bacterium can even begin to fulfill its biological role, it must survive a battery of environmental stresses imposed during food processing and passage through the gastrointestinal tract (GIT). Food processing stresses include extremes in temperature, as well as osmotic, oxidative and food matrix stresses. Passage through the GIT is a hazardous journey for any bacteria with deleterious lows in pH encountered in the stomach to the detergent-like properties of bile in the duodenum. However, bacteria are equipped with an array of defense mechanisms to counteract intracellular damage or to enhance the robustness of the cell to withstand lethal external environments. Understanding these mechanisms in probiotic bacteria and indeed other bacterial groups has resulted in the development of a molecular toolbox to augment the technological and gastrointestinal performance of probiotics. This has been greatly aided by studies which examine the global cellular responses to stress highlighting distinct regulatory networks and which also identify novel mechanisms used by cells to cope with hazardous environments. This review highlights the latest studies which have exploited the bacterial stress response with a view to producing next-generation probiotic cultures and highlights the significance of studies which view the global bacterial stress response from an integrative systems biology perspective.

• salmonella
• foam drying
• freeze drying
• oral vaccine
• live bacterial vaccine
• temperature-stability

• Administration, Oral
• Animals
• Bacterial Vaccines/immunology
• Drug Carriers
• Drug Stability
• Genetic Vectors
• Humans
• Mice
• Microbial Viability/radiation effects
• Salmonella typhi/genetics
• Salmonella typhi/physiology
• Salmonella typhi/radiation effects
• Temperature
• Vaccines, Attenuated/immunology
• Vaccines, Synthetic/immunology

• R43 AI063829 NIAID NIH HHS