Live Bacteria Research Articles

Wash-Free Bacterial Gram-Typing and Photodynamic Inactivation with Long-Chain-Tailed BODIPY Derivatives.

The rapid identification of bacterial Gram types and their viability, as well as efficient bacterial elimination are crucial for managing bacterial infections yet present important challenges. In this research, we utilized long-chain-tailed BODIPY derivatives to address these hurdles. Our data indicated that these derivatives can distinguish bacteria types and their viability in aqueous solutions through a concise turn-on fluorescent response. Among them, B-8 stained both live and dead bacteria, and B-14 offered a wash-free staining. B-18 demonstrated the highest affinity to selectively fluorescent label viable gram-positive bacteria with a 53.2-fold fluorescent enhancement. Confocal imaging confirmed that B-18 can serve as an effective membrane-specific probe for facilitating the typing between gram-negative and gram-positive bacteria in a wash-free manner. Additionally, B-18 displayed selective photodynamic inactivation at 1 μM toward gram-positive bacteria. Invivo studies variformed the ideal photodynamic therapeutic efficacy of B-18 against methicillin-resistant Staphylococcus aureus in mice wound infections.

КОНТРОЛЬ ВЫЖИВАЕМОСТИ БИФИДОБАКТЕРИЙ В НОВЫХ ВИДАХ ПРОБИОТИЧЕСКИХ ПИЩЕВЫХ ПРОДУКТОВ НА ФЕРМЕНТИРОВАННОЙ РАСТИТЕЛЬНОЙ ОСНОВЕ

This study aimed to determine the survival rate of bifidobacteria in new types of plant-based probiotic food products over their shelf life and to identify the identified cultures using polymerase chain reaction (PCR). A variety of new plant-based probiotic food products, including yogurt alternatives made from soy, almond, and coconut, and fermented plant-based beverages, were selected for the study. Microbiological indicators of product safety, such as total viable count, coliforms, and pathogens, were analyzed according to standard methods. The survival of bifidobacteria was evaluated throughout the shelf life of the products, as declared by the manufacturer, by plating on selective media and counting viable bifidobacteria colonies. Additionally, PCR analysis was performed to confirm the presence and identify the specific strains of bifidobacteria present in the samples. The microbiological analysis of the plant-based probiotic food products confirmed that they met the safety criteria, with no coliforms or pathogens detected. The survival of bifidobacteria was found to be variable among different products, but overall, bifidobacteria were able to maintain their viability throughout the entire shelf life stated by the manufacturer. PCR analysis confirmed the presence of live bifidobacteria in all samples and identified the specific strains present, including Bifidobacterium animalis subsp. lactis, Bifidobacterium bifidum, and Bifidobacterium longum. The results of this study demonstrate that new types of plant-based probiotic food products containing bifidobacteria are safe to consume and can provide a source of live beneficial bacteria throughout their shelf life.

Human breast milk isolated lactic acid bacteria: antimicrobial and immunomodulatory activity on the Galleria mellonella burn wound model.

Managing burn injuries is a challenge in healthcare. Due to the alarming increase in antibiotic resistance, new prophylactic and therapeutic strategies are being sought. This study aimed to evaluate the potential of live Lactic Acid Bacteria for managing burn infections, using Galleria mellonella larvae as an alternative preclinical animal model and comparing the outcomes with a common antibiotic. The antimicrobial activity of LAB isolated from human breast milk was assessed in vitro against Pseudomonas aeruginosa ATCC 27853. Additionally, the immunomodulatory effects of LAB were evaluated in vivo using the G. mellonella burn wound infection model. In vitro results demonstrated the antimicrobial activity of Lactic Acid Bacteria against P. aeruginosa. In vivo results show that their prophylactic treatment improves, statistically significant, larval survival and modulates the expression of immunity-related genes, Gallerimycin and Relish/NF-κB, strain-dependently. These findings lay the foundation and suggest a promising alternative for burn wound prevention and management, reducing the risk of antibiotic resistance, enhancing immune modulation, and validating the potential G. mellonella as a skin burn wound model.

Supramolecular pyrrole radical cations for bacterial theranostics.

Bacterial infections with emerging resistance to antibiotics require urgent development of antibacterial agents with new core skeletons. Recently, a series of antibacterial agents have been reported based on positively charged organic groups, such as ammonium, guanidine, and phosphonium groups, which can selectively bind and destroy negatively charged bacterial membranes. To achieve imaging-guided precise antibacterial therapy, these positively charged organic groups usually require further decoration with imaging modalities, such as fluorescence. However, most fluorophores with electron-closed shell structures usually suffer from tedious synthetic procedures for preparation. We herein prepare a series of positively charged and deep-red fluorescent supramolecular pyrrole radical cations (P˙+-CB[7]) based on the simple mixing of pyrroles and CB[7] in water under air. The readily available deep-red fluorescent P˙+-CB[7] can not only be used for selective imaging and killing of live Gram-positive bacteria with excellent biocompatibility, but also for imaging of dead Gram-negative bacteria killed by drugs and in vivo monitoring of phagocytosis of bacteria by innate immune cells in zebrafish. It is believed that the deep-red fluorescent pyrrole radical cations as a new core skeleton are promising in bacterial theranostics.

A promising strategy to improve the stability and immunogenicity of killed but metabolically active vaccines: low-temperature preparation and coating of nanoparticles.

Bacteria are becoming an increasingly serious threat to human health. The emergence of super bacteria makes clinical treatment more difficult. Vaccines are one of the most effective means of preventing and treating bacterial infections. As a new class of vaccines, killed but metabolically active (KBMA) vaccines provide the immunogenicity of live vaccines and the safety of inactivated vaccines. Herein, a promising strategy is proposed to improve the stability and immunogenicity of KBMA vaccines. KBMA vaccines were produced at low temperature (4 °C), and the bacterial surface was engineered using mesoporous silica nanoparticle (MSN) coating. Compared to vaccines prepared at room temperature, the metabolic activity of KBMA vaccines prepared at 4 °C remarkably improved. Benefiting from the induction of MSNs, the stability of KBMA vaccines was increased and the preservation time was prolonged at 4 °C. Meanwhile, metabolomics analysis showed that the metabolite spectrum of live bacteria changed after photochemical treatment and MSN coating, which interfered with organic acid metabolism pathways, lipid metabolism and biosynthesis of secondary metabolites. Furthermore, the immune response in the mice treated with KBMA/MSN vaccines was similar to that in those treated with live vaccines and stronger than that in those treated with inactivated vaccines. In comparison with the control group, bacteria tissue burdens of KBMA/MSN group were significantly reduced. CD4+ T cells dominated immune responses for the protection of mice. Thus, the current work promotes the application of KBMA vaccines, providing an alternative choice for treating bacterial infections.

Cytosolic sorting platform complexes shuttle type III secretion system effectors to the injectisome in Yersinia enterocolitica

Bacteria use type III secretion injectisomes to inject effector proteins into eukaryotic target cells. Recruitment of effectors to the machinery and the resulting export hierarchy involve the sorting platform. These conserved proteins form pod structures at the cytosolic interface of the injectisome but are also mobile in the cytosol. Photoactivated localization microscopy in Yersinia enterocolitica revealed a direct interaction of the sorting platform proteins SctQ and SctL with effectors in the cytosol of live bacteria. These proteins form larger cytosolic protein complexes involving the ATPase SctN and the membrane connector SctK. The mobility and composition of these mobile pod structures are modulated in the presence of effectors and their chaperones, and upon initiation of secretion, which also increases the number of injectisomes from ~5 to ~18 per bacterium. Our quantitative data support an effector shuttling mechanism, in which sorting platform proteins bind to effectors in the cytosol and deliver the cargo to the export gate at the membrane-bound injectisome.

Метабиотики и комплексный подход в профилактике дисбиотических нарушений

Aim. To conduct a systematic analysis of modern data on the role of metabiotics in the correction of functional disorders of organs and systems that arise as a result of dysbiotic disorders of the intestinal microflora. Key points. With the development of research on the human microbiome, more and more scientific evidence supports the key role of the gut microbiota in the pathogenesis of various diseases. Maintaining normal functional activity of the microbiome is an integral physiological task of any living organism. Dysbiotic disorders of the intestinal flora are associated with the phenomenon of bacterial translocation - the process of movement of microorganisms that colonize the mucous membrane of the gastrointestinal tract to other parts of the body, including the pelvic organs. Metabiotics are new generation drugs that can have a positive regulatory effect on the relationship between the host and its microflora, without entering into an antagonistic relationship with it. It is assumed that they inhibit the growth of pathogenic and opportunistic microflora. Offering the same health benefit profile as probiotics, metabiotics are free of the risks and uncertain reactions associated with introducing live bacteria into the body. Conclusion. Since the relationship between dysbiotic disorders of the intestinal flora and the development of a number of inflammatory diseases of the female reproductive system cannot be excluded, the use of metabiotics as a preventive or concomitant therapy can help improve the effectiveness of treatment. Key words: probiotics, metabiotics, dysbiosis, bacterial vaginosis, microbiota.

Encapsulation of Lactobacillus rhamnosus GG in chymosin treated milk protein-alginate microgel

Encapsulation of probiotic bacteria helps to protect its viability in food and enhances bioavailability in the human body. Alginate, a widely used gellant, singly cannot offer adequate protection to the encapsulated probiotics because the porosity of its micro-particles limits its stability in acidic conditions. Milk protein concentrate (MPC) is known to enhance gel strength. This study attempts to use chymosin treated MPC (1.0% solids w/w) as a co-gelling agent with sodium alginate (1.0%, 1.5% and 2.0% solids w/w) to enhance encapsulation of Lactobacillus rhamnosus GG (LGG) by adopting a continuous impinging aerosol technique using CaCl2. The moisture content of microgel paste of test formulations ranged from 88.1% to 90.4% (w/w) (P>0.05). Amongst the alginate MPC composite formulations, microparticles comprising of 1.0% alginate and 1.0% MPC solids exhibited highest (P<0.05) probiotic count (7.27 log CFU/g solids) and lowest viability reduction (P<0.05). Confocal image of its microparticle illustrate the presence of live bacteria, which appear as green, rod-shaped entities, entrapped within dark gel matrix. Under simulated gastric condition of pH 2 at 37oC, its microgel particle exhibited detectable viability upto 15 minutes. In case of 1.0% alginate control microgel, comparatively higher viability was noted in the 5th minute, which was undetectable by the 10th minute. With a progressive increase in alginate concentration among test formulations, cell count decreased, suggesting milk protein positively impacted viability. Microgel of 1.0% MPC control exhibited lowest loss of viable cells (0.93 log CFU/g solids). Optical image of its microparticles appeared as large flocculate rather than spherical microgel, as observed with alginate control microparticles, suggesting MPC alone is unable to produce microgels. While this study infers better viability of microparticles comprising of 1.0 % alginate and 1.0 % MPC, it opens avenues for further research for strengthening co-gelation for probiotic survival in low pH.

Postbiotics: Functional Food Materials and Therapeutic Agents for Cancer, Diabetes, and Inflammatory Diseases.

Postbiotics are (i) "soluble factors secreted by live bacteria, or released after bacterial lysis, such as enzymes, peptides, teichoic acids, peptidoglycan-derived muropeptides, polysaccharides, cell-surface proteins and organic acids"; (ii) "non-viable metabolites produced by microorganisms that exert biological effects on the hosts"; and (iii) "compounds produced by microorganisms, released from food components or microbial constituents, including non-viable cells that, when administered in adequate amounts, promote health and wellbeing". A probiotic- and prebiotic-rich diet ensures an adequate supply of these vital nutrients. During the anaerobic fermentation of organic nutrients, such as prebiotics, postbiotics act as a benevolent bioactive molecule matrix. Postbiotics can be used as functional components in the food industry by offering a number of advantages, such as being added to foods that are harmful to probiotic survival. Postbiotic supplements have grown in popularity in the food, cosmetic, and healthcare industries because of their numerous health advantages. Their classification depends on various factors, including the type of microorganism, structural composition, and physiological functions. This review offers a succinct introduction to postbiotics while discussing their salient features and classification, production, purification, characterization, biological functions, and applications in the food industry. Furthermore, their therapeutic mechanisms as antibacterial, antiviral, antioxidant, anticancer, anti-diabetic, and anti-inflammatory agents are elucidated.

N-Heterocycle Modified Graphene Quantum Dots as Topoisomerase Targeted Nanoantibiotics for Combating Microbial Infections.

Developing next-generation antibiotics to eliminate multidrug-resistant (MDR) bacteria/fungi and stubborn biofilms is challenging, because of the excessive use of currently available antibiotics. Herein, the fabrication of anti-infection graphene quantum dots (GQDs) is reported, as a new class of topoisomerase (Topo) targeting nanoantibiotics, by modification of rich N-heterocycles (pyridinic N) at edge sites. The membrane-penetrating, nucleus-localizing, DNA-binding GQDs not only damage the cell walls/membranes of bacteria or fungi, but also inhibit DNA-binding proteins, such as Topo I, thereby affecting DNA replication, transcription, and recombination. The obtained GQDs exhibit excellent broad-spectrum antimicrobial activity against non-MDR bacteria, MDR bacteria, endospores, and fungi. Beyond combating planktonic microorganisms, GQDs inhibit the formation of biofilms and can kill live bacteria inside biofilms. RNA-seq further demonstrates the upregulation of riboflavin biosynthesis genes, DNA repair related genes, and transport proteins related genes in methicillin-resistant S. aureus (MRSA) in response to the stress induced by GQDs. In vivo animal experiments indicate that the biocompatible GQDs promote wound healing in MRSA or C. albicans-infected skin wound models. Thus, GQDs may be a promising antibacterial and antifungal candidate for clinical applications in treating infected wounds and eliminating already-formed biofilms.

Effects of dietary supplementation of a blend of Saccharomyces cerevisiae, multiple live probiotic bacteria, and their fermentation products on performance, health, and rumen bacterial community of newly weaned beef steers during a 56-d receiving period.

We examined the effects of a blend of Saccharomyces cerevisiae, multiple live probiotic bacteria, and their fermentation products on performance, health, and the ruminal bacterial community of newly weaned beef steers during a 56-d receiving period. Forty newly weaned Angus crossbred steers (221 ± 25.6kg BW; 180 ± 17 d of age) were stratified by body weight (BW) into four pens (10 steers per pen) such that each pen had a similar average BW at the beginning of the experiment. The pens were randomly assigned to receive a corn silage basal diet (CON; n = 20) or the basal diet supplemented with 9g/steer/d of PRO feed additive (PRO; n = 20). The PRO additive is a blend of S. cerevisiae and the fermentation products of Enterococcus faecium, Bacillus licheniformis, B. subtilis, Lactobacillus animalis, and Propionibacterium freudenreichii. The DMI and water consumed were monitored using the GrowSafe intake nodes and custom flow meters, respectively. BWs were recorded weekly to calculate average daily gain (ADG). Before morning feeding, 10mL of blood was taken from each steer on days 0-7, and thereafter weekly for analyses of immune cells, plasma glucose, and NEFAs. On day 56, rumen fluid samples (200mL each) were collected from all the steers for microbiome analysis. Over the 56-d receiving period, the supplemental PRO had no effects on DMI, water intake, or ADG. However, compared to CON, beef steers fed supplemental PRO tended to have greater ADG (P = 0.08) and BW (P = 0.07) during the first 14 d of the study. There was a treatment × day interaction (P ≤ 0.05) for WBC, neutrophils and monocytes over the 56 d such that beef steers fed supplemental PRO had lower blood concentrations on certain days during the first 7 d after weaning, indicating reduced inflammation or stress response. The results of the rumen microbiome analysis revealed that the relative abundance of complex fiber degrading or obligate proton-reducing bacterial genera such as Bacteroides, Ruminococcus gauvreauii group, Desulfovibrio, Syntrophococcus, and Acetitomaculum were greater (P ≤ 0.05) in beef steers fed supplemental PRO compared to CON. This study demonstrated that dietary supplementation of PRO improved the growth performance, reduced stress or inflammatory response during the initial days after weaning, and altered the ruminal bacterial community toward increased relative abundance of bacterial genera associated with improved rumen function.

Metagenomic Insights into the Taxonomic and Functional Features of Traditional Fermented Milk Products from Russia.

Fermented milk products (FMPs) contain probiotics that are live bacteria considered to be beneficial to human health due to the production of various bioactive molecules. In this study, nine artisanal FMPs (kefir, ayran, khurunga, shubat, two cottage cheeses, bryndza, khuruud and suluguni-like cheese) from different regions of Russia were characterized using metagenomics. A metagenomic sequencing of ayran, khurunga, shubat, khuruud and suluguni-like cheese was performed for the first time. The taxonomic profiling of metagenomic reads revealed that Lactococcus species, such as Lc. lactis and Lc. cremoris prevailed in khuruud, bryndza, one sample of cottage cheese and khurunga. The latter one together with suluguni-like cheese microbiome was dominated by bacteria, affiliated to Lactobacillus helveticus (32-35%). In addition, a high proportion of sequences belonging to the genera Lactobacillus, Lactococcus and Streptococcus but not classified at the species level were found in the suluguni-like cheese. Lactobacillus delbrueckii, as well as Streptococcus thermophilus constituted the majority in another cottage cheese, kefir and ayran metagenomes. The microbiome of shubat, produced from camel's milk, was significantly distinctive, and Lentilactobacillus kefiri, Lactobacillus kefiranofaciens and Bifidobacterium mongoliense represented the dominant components (42, 7.4 and 5.6%, respectively). In total, 78 metagenome-assembled genomes with a completeness ≥ 50.2% and a contamination ≤ 8.5% were recovered: 61 genomes were assigned to the Enterococcaceae, Lactobacillaceae and Streptococcaceae families (the Lactobacillales order within Firmicutes), 4 to Bifidobacteriaceae (the Actinobacteriota phylum) and 2 to Acetobacteraceae (the Proteobacteria phylum). A metagenomic analysis revealed numerous genes, from 161 to 1301 in different products, encoding glycoside hydrolases and glycosyltransferases predicted to participate in lactose, alpha-glucans and peptidoglycan hydrolysis as well as exopolysaccharides synthesis. A large number of secondary metabolite biosynthetic gene clusters, such as lanthipeptides, unclassified bacteriocins, nonribosomal peptides and polyketide synthases were also detected. Finally, the genes involved in the synthesis of bioactive compounds like β-lactones, terpenes and furans, nontypical for fermented milk products, were also found. The metagenomes of kefir, ayran and shubat was shown to contain either no or a very low count of antibiotic resistance genes. Altogether, our results show that traditional indigenous fermented products are a promising source of novel probiotic bacteria with beneficial properties for medical and food industries.

MICROBIOME MODULATORS IN THE PREVENTION AND MITIGATION OF CANCER TREATMENT-INDUCED ACCELERATED AGING BIOLOGY

Abstract Advancements in oncology research have led to increased survivorship in patients with cancer. However, cancer treatments like chemotherapy cause debilitating side effects including multi-organ dysfunction and increased risk for chronic diseases, which mimic accelerated aging. Abnormalities in the gut microbiome composition (dysbiosis) increase inflammation, resulting in accelerated cognitive impairment with aging and a poor quality of life (QOL), which are all exacerbated by cancer treatments. We have screened, evaluated, and optimized our previously isolated human-origin live bacteria (probiotics) as well as pasteurized probiotics (postbiotics) for their anti-aging potential using Caenorhabditis (C.) elegans and mouse models. Probiotics improved the healthspan in C. elegans when given live and when fermented. Interestingly, PFM and LpD3.5 significantly protected from body weight loss, microbiome dysbiosis, and cognitive impairment in mice receiving 5-fluorouracil chemotherapy and protected from intestinal damage. We are planning a clinical trial where we will (1) cross-sectionally analyze the gut microbiome, leaky gut, and inflammation in cancer survivors with and without brain distress and (2) determine the safety, tolerance, and efficacy of PFM and LpD3.5 on microbiome diversity, inflammation, and cognitive health in cancer survivors with brain distress, using a 60-day open-label, randomized comparison study. These studies will improve our understanding of how cancer treatment-induced changes in the gut microbiome, inflammation, and gut permeability contribute to accelerated aging. Furthermore, they will establish the utilization of probiotics and postbiotics to improve QOL and mitigate cancer treatment-induced accelerated aging, which constitutes a debilitating public health concern among the increasing population of cancer survivors.

Prospects for using flow cytometry in the quality control of live plague vaccines

Scientific relevance. The number of live bacteria is a quality parameter controlled at all stages of live plague vaccine production. Currently, live microbial cell counting uses a bacteriological method. However, flow cytometry has the potential to increase analytical accuracy and reduce testing time.Aim. This study aimed at testing the applicability of flow cytometry to assessing the quality of live plague vaccines.Materials and methods. The study quantified live microbial cells in 5 experimental batches of live plague vaccine as part of their quality control using the bacteriological method according to the State Pharmacopoeia of the Russian Federation (FS.3.3.1.0022.15). Cytofluorometry of the samples used the SynaptoGreen fluorescent dye.Results. The study quantified live microbial cells in live plague vaccine samples using the bacteriological method and flow cytometry. The results obtained by the bacteriological method ranged from 27.8±2.2 to 56.5±3.1% with an average of 39.8±5.4%. The results obtained by flow cytometry ranged from 29.2±1.2 to 59.1±2.1% with an average of 41.7±5.5%. The statistical analysis showed no significant difference between the results of vaccine quality control by both methods, as well as a high coefficient of determination.Conclusions. The results show that flow cytometry is an appropriate method for the quantification of live microbial cells as part of the quality control of plague vaccines. Being quick, easy, and highly informative, flow cytometry is preferable to traditional methods.

Staphylococcus aureus functional amyloids catalyze degradation of β-lactam antibiotics

Antibiotic resistance of bacteria is considered one of the most alarming developments in modern medicine. While varied pathways for bacteria acquiring antibiotic resistance have been identified, there still are open questions concerning the mechanisms underlying resistance. Here, we show that alpha phenol-soluble modulins (PSMαs), functional bacterial amyloids secreted by Staphylococcus aureus, catalyze hydrolysis of β-lactams, a prominent class of antibiotic compounds. Specifically, we show that PSMα2 and, particularly, PSMα3 catalyze hydrolysis of the amide-like bond of the four membered β-lactam ring of nitrocefin, an antibiotic β-lactam surrogate. Examination of the catalytic activities of several PSMα3 variants allowed mapping of the active sites on the amyloid fibrils’ surface, specifically underscoring the key roles of the cross-α fibril organization, and the combined electrostatic and nucleophilic functions of the lysine arrays. Molecular dynamics simulations further illuminate the structural features of β-lactam association upon the fibril surface. Complementary experimental data underscore the generality of the functional amyloid-mediated catalytic phenomenon, demonstrating hydrolysis of clinically employed β-lactams by PSMα3 fibrils, and illustrating antibiotic degradation in actual S. aureus biofilms and live bacteria environments. Overall, this study unveils functional amyloids as catalytic agents inducing degradation of β-lactam antibiotics, underlying possible antibiotic resistance mechanisms associated with bacterial biofilms.

Characterization of Lactococcus lactis 11/19-B1 Isolated from Kiwi Fruit as a Potential Probiotic and Paraprobiotic.

Probiotics are live bacteria used as food additives that are beneficial to human health. Lactococcus lactis 11/19-B1 strain isolated from kiwi fruit stimulates innate immunity in silkworms. Intake of yogurt containing the living 11/19-B1 strain significantly decreases the level of low-density lipoproteins (LDLs) in high-LDL volunteers and improves atopic dermatitis in humans. In this study, the probiotic properties of the 11/19-B1 strain, such as sensitivity to antimicrobial compounds, biogenic amine production, some virulence genes for human health, antimicrobial activity, tolerance to gastric acid and bile acids, and ability to adhere to the intestinal mucosa, were evaluated. The 11/19-B1 strain did not show resistance to the tested antimicrobial compounds except cefoxitin and fosfomycin. In addition, no production of amines that can harm humans, the antimicrobial activity required for probiotics, and the absence of adhesion to Caco-2 cells suggest that it is unlikely to attach to the intestinal epithelium. The 11/19-B1 strain grew in 0.3% but not in 1% bile salt. In the presence of 2% skim milk, the survival rate of the 11/19-B1 strain under simulated gastrointestinal tract conditions was 67% even after 4 h. These results indicate that the 11/19-B1 strain may function as a probiotic or paraprobiotic to be utilized in the food industry.

Screening of anti-allergic Lactiplantibacillus species by splenocyte sensitization model and evaluate their probiotic and postbiotic characteristics

Lactiplantibacillus species has garnered considerable attention due to its multifaceted probiotic properties, particularly its potential in alleviating food allergies. Despite numerous reports supporting this claim, scant research exists concerning the methodology for screening anti-allergic probiotics. Thus study sought to establish an in vitro splenocyte sensitization model for the purpose of screening potential anti-allergic Lactiplantibacillus strains. Through the splenocyte model, different Lactiplantibacillus strains were assessed for their ability to modulate the Th1/Th2 balance in sensitized splenocytes. The results showed that compared with the of positive control (IFN-γ/IL-4 value was 1.12) and LGG (IFN-γ/IL-4 value was 15.88), Lactiplantibacillus XJ 002, TLF 1-2 and TLF 5-3-2 had the greatest effect on improving IFN-γ/IL-4 value, which were 9.89, 15.81 and 9.72 respectively. The further results showed that the IL-10 levels of Lactiplantibacillus XJ 002, TLF 1-2 and TLF 5-3-2 reached 125.23, 147.44 and 113.16 ng/L, which were significantly higher than the positive control (84.95 ng/L, p < 0.05). Moreover, the IgE reduction rates of Lactiplantibacillus XJ 002, TLF 1-2 and TLF 5-3-2 were 82%, 72% and 40% respectively, which indicated that Lactiplantibacillus XJ 002 and TLF 1-2 showed the best regulatory ability. Subsequently, Lactiplantibacillus XJ 002 and TLF 1-2 were considered promising probiotic candidates following rigorous probiotic evaluation. Remarkably, the inactivated forms of these strains, functioning as postbiotics, exhibited similar anti-allergic effects to those of the live bacteria. Consequently, this study not only offers valuable insights into the screening of anti-allergic probiotics but also explores the potential applications of postbiotics.

PH-dependent pressure-sensitive colonic capsules for the delivery of aqueous bacterial suspensions

Microbiome-based therapies hold great promise for treating various diseases, but the efficient delivery of live bacteria to the colon remains a challenge. Furthermore, current oral formulations, such as lyophilized bacterial capsules or tablets, are produced using processes that can decrease bacterial viability. Consequently, high dosages are required to achieve efficacy. Herein, we report the design of pressure-sensitive colonic capsules for the encapsulation and delivery of aqueous suspensions of live bacteria. The capsules consisted of 2 functional thin-films (hydrophobic and enteric) of ethyl cellulose and Eudragit S100 dip-coated onto hydroxypropyl methylcellulose molds. The capsules could be loaded with aqueous media and provide protection against acidic fluids and, to some extent, oxygen diffusion, suggesting their potential suitability for delivering anaerobic bacterial strains. Disintegration and mechanical studies indicated that the capsules could withstand transit through the stomach and upper/proximal small intestinal segments and rupture in the ileum/colon. In vitro studies showed that bacterial cells (anaerobic and aerobic commensals) remained highly viable (74–98%) after encapsulation and exposure to the simulated GI tract conditions. In vivo studies with a beagle dog model revealed that 67% of the capsules opened after 3.5 h, indicating content release in the distal gastrointestinal tract. These data demonstrate that live aqueous bacterial suspensions comprised of both aerobic and anaerobic commensals can be encapsulated and in the future might be efficiently delivered to the distal gastrointestinal tract, suggesting the practical applications of these capsules in microbiome-based therapies.

Rapid screening of electrochemically active bacteria based on a biocathode-functional bipolar electrode-electrochemiluminescence platform.

A functional bipolar electrode-electrochemiluminescence (BPE-ECL) platform based on biocathode reducing oxygen was constructed for detecting electrochemically active bacteria (EAB) in this paper. Firstly, thiolated trimethylated chitosan quaternary ammonium salt (TMC-SH) layer was assembled on the gold-plated cathode of BPE. TMC-SH contains quaternary ammonium salt branch chain, which can inhibit the growth of microorganisms on the surface or in the surrounding environment while absorbing bacteria. Then, the peristaltic pump was used to flow all of the samples through the cathode, and the EAB was electrostatically adsorbed on the electrode surface. Finally, applying a constant potential to the BPE, bacteria can catalyze electrochemical reduction of O2, and decrease the overpotential of O2 reduction at the cathode, which in turn generates an ECL reporting intensity change at the anode. In this way, live and dead bacteria can be distinguished, and the influence of complex food substrates on detection can be greatly reduced.

Moisture evaporation effect on pore structure and microbial distribution during sludge biodrying

Biodrying of dewatered sludge is an eco-friendly and efficient technology to decrease the sludge moisture content (MC) by metabolic heat generated from sludge organic matter degradation. By analyzing the water states and visualizing the sludge pore structure during the biodrying process, it was found that the bound water accounted for 96.5–97.9% of the sludge water and interstitial water was only 2.0–3.5%. The microscopic and dispersed sludge pores were transformed into larger and linked ones by the transformation of bound water into interstitial water and the subsequent evaporation. As a result, the depth of live bacteria distribution thickened, reaching 0–180 µm, 0–330 µm, and 0–350 µm during the temperature ramp-up to 45.6 °C, the peak temperature of 70.7 °C, and the cool-down to 45.6 °C, respectively. Briefly, as moisture evaporated, the pore structure of the sludge expanded and the microbial distribution deepened. Moreover, the phylum of anaerobic bacteria was drastically decreased.