Antiviral potential of lactic acid bacteria and their bacteriocins

Enterocin DD14 can inhibit the infection of eukaryotic cells with enveloped viruses

Bacteriocins are ribosomally synthesized bacterial peptides endowed with antibacterial, antiprotozoal, anticancer and antiviral activities. In the present study, we evaluated the antiviral activities of two bacteriocins, enterocin DD14 (EntDD14) and lacticaseicin 30, against herpes simplex virus type 1 (HSV-1), human coronavirus 229E (HCoV-229E) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Vero, Huh7 and Vero E6 cells, respectively. In addition, the interactions of these bacteriocins with the envelope glycoprotein D of HSV-1 and the receptor binding domains of HCoV-229E and SARS-CoV-2 have been computationally evaluated using protein-protein docking and molecular dynamics simulations. HSV-1 replication in Vero cells was inhibited by EntDD14 and, to a lesser extent, by lacticaseicin 30 added to cells after virus inoculation. EntDD14 and lacticaseicin 30 had no apparent antiviral activity against HCoV-229E; however, EntDD14 was able to inhibit SARS-CoV-2 in Vero E6 cells. Further studies are needed to elucidate the antiviral mechanism of these bacteriocins.

The high-throughput solid-phase extraction of cis-cyclo(L-Leu-L-Pro) and cis-cyclo(L-Phe-L-Pro) from Lactobacillus plantarum demonstrates efficacy against multidrug-resistant bacteria and influenza A (H3N2) virus

Introduction: 2,5-diketopiperazines are the simplest forms of cyclic dipeptides (CDPs) and have diverse frameworks with chiral side chains that are useful for drug development. Previous research has investigated the antimicrobial properties of proline-linked CDPs and their combinations in the culture filtrate (CF) of Lactobacillus plantarum LBP-K10 using anion exchange chromatography (AEC). However, the quantity of CDPs showcasing notable anti-influenza virus activity derived from AECs was generally lower than those originating from Lactobacillus CF. Methods: To address this issue, the study aims to propose a more efficient method for isolating CDPs and to introduce the antiviral combinations of CDPs obtained using a new method. The study employed a novel technique entailing high-throughput C18-based solid-phase extraction with a methanol gradient (MeSPE). The MeSPE method involved increasing the methanol concentration from 5% to 50% in 5% increments. Results: The methanol SPE fractions (MeSPEfs) eluted with methanol concentrations between 35% and 45% evinced substantial efficacy in inhibiting the influenza A/H3N2 virus via plaque-forming assay. MeSPEf-45, the 45% MeSPEf, exhibited exceptional efficacy in preventing viral infections in Madin-Darby kidney cells, surpassing both individual CDPs and the entire set of MeSPEfs. To identify the specific antiviral components of MeSPEf-45, all MeSPEfs were further fractionated through preparative high-performance liquid chromatography (prep-HPLC). MeSPEf-45 fractions S8 and S11 presented the highest activity against multidrug-resistant bacteria and influenza A/H3N2 virus among all MeSPEfs, with 11 common fractions. Antiviral fractions S8 and S11 were identified as proline-based CDPs, specifically cis-cyclo(L-Leu-L-Pro) and cis-cyclo(L-Phe-L-Pro), using gas chromatography-mass spectrometry. The combination of MeSPEf-45 fractions S8 and S11 displayed superior antibacterial and anti-influenza virus effects compared to the individual fractions S8 and S11. Discussion: High-throughput MeSPE-derived MeSPEfs and subsequent HPLC-fractionated fractions presents an innovative approach to selectively purify large amounts of potent antimicrobial CDPs from bacterial CF. The findings also show the effectiveness of physiologically bioactive combinations that utilize fractions not containing CDP. This study provides the initial evidence demonstrating the antimicrobial properties of CDPs acquired through high-throughput SPE techniques.

Antiparasitic Activity of Enterocin M and Durancin-like from Beneficial Enterococci in Mice Experimentally Infected with Trichinella spiralis

Beneficial/probiotic strains protect the host from pathogens by competitive displacement and production of antibacterial substances, i.e., bacteriocins. The antiparasitic potential of bacteriocins/enterocins and their producing strains in experimental murine trichinellosis were tested as a new therapeutic strategy. Enterocin M and Durancin-like and their producers Enterococcus faecium CCM8558 and Enterococcus durans ED26E/7 were administered daily to mice that were challenged with Trichinella spiralis. Our study confirmed the antiparasitic effect of enterocins/enterococci, which reduced the number of adults in the intestine (Enterocin M-43.8%, E. faecium CCM8558-54.5%, Durancin-like-16.4%, E. durans ED26E/7-35.7%), suppressed the Trichinella reproductive capacity ex vivo (Enterocin M-61%, E. faecium CCM8558-74%, Durancin-like-38%, E. durans ED26E/7-66%), and reduced the number of muscle larvae (Enterocin M-39.6%, E. faecium CCM8558-55.7%, Durancin-like-15%, E. durans ED26E/7-36.3%). The direct effect of enterocins on Trichinella fecundity was documented by an in vitro test in which Durancin-like showed a comparable reducing effect to Enterocin M (40-60%) in contrast to the ex vivo test. The reducing activity of T.spiralis infection induced by Enterocin M was comparable to its strain E. faecium CCM8558; Durancin-like showed lower antiparasitic activity than its producer E. durans ED26E/7.

The Influence of Probiotic Lactobacilli on COVID-19 and the Microbiota

This comprehensive review explores the potential of using lactobacilli as a probiotic in the management of COVID-19. Our findings suggest that lactobacilli show promise in reducing the risk of death, gastrointestinal and overall symptoms, and respiratory failure, as well as in lowering cytokines and inflammatory markers associated with the disease. The molecular mechanisms by which lactobacilli protect against COVID-19 and other viral infections may be related to the reduction in inflammation, modulation of the immune response, and direct interaction with viruses to produce antiviral substances. However, the selected studies demonstrate the presence of mixed findings for various clinical, biochemical, hematological, and immunological parameters, which may be attributed to methodological differences among studies. We highlight the importance of clearly describing randomization processes to minimize bias and caution against small sample sizes and inappropriate statistical tests that could lead to errors. This review offers valuable insights into the therapeutic potential of lactobacilli in the context of COVID-19 and identifies avenues for further research and applications. These findings hold promise for the development of novel approaches to managing COVID-19 and warrant further investigation into the potential benefits of lactobacilli in combating the disease.

Microbial Community and Metabolome Analysis of the Porcine Intestinal Damage Model Induced by the IPEC-J2 Cell Culture-Adapted Porcine Deltacoronavirus (PDCoV) Infection

This study was conducted to elucidate the intestinal damage induced by the IPEC-J2 cell culture-passaged PDCoV. The results showed that PDCoV disrupted the intestinal structure and increased intestinal permeability, causing abnormalities in mucosal pathology. Additionally, PDCoV induced an imbalance in the intestinal flora and disturbed its stability. Microbial community profiling revealed bacterial enrichment (e.g., Proteobacteria) and reduction (e.g., Firmicutes and Bacteroidetes) in the PDCoV-inoculated piglet model. In addition, metabolomics analysis indicated that 82 named differential metabolites were successfully quantified, including 37 up-regulated and 45 down-regulated metabolites. Chenodeoxycholic acid, sphingosine, and oleanolic aldehyde levels were reduced in PDCoV-inoculated piglets, while phenylacetylglycine and geranylgeranyl-PP levels were elevated. Correlation analysis indicated a negative correlation between Escherichia-Shigella and choline, succinic acid, creatine, phenyllactate, and hippuric acid. Meanwhile, Escherichia-Shigella was positively correlated with acetylcholine, L-Glutamicacid, and N-Acetylmuramate. Roseburia, Lachnospiraceae_UCG-010, Blautia, and Limosilactobacillus were negatively and positively correlated with sphingosine, respectively. These data suggested PDCoV-inoculated piglets exhibited significant taxonomic perturbations in the gut microbiome, which may result in a significantly altered metabolomic profile.

Bacteriocins: potentials and prospects in health and agrifood systems

Bacteriocins are highly diverse, abundant, and heterogeneous antimicrobial peptides that are ribosomally synthesized by bacteria and archaea. Since their discovery about a century ago, there has been a growing interest in bacteriocin research and applications. This is mainly due to their high antimicrobial properties, narrow or broad spectrum of activity, specificity, low cytotoxicity, and stability. Though initially used to improve food quality and safety, bacteriocins are now globally exploited for innovative applications in human, animal, and food systems as sustainable alternatives to antibiotics. Bacteriocins have the potential to beneficially modulate microbiota, providing viable microbiome-based solutions for the treatment, management, and non-invasive bio-diagnosis of infectious and non-infectious diseases. The use of bacteriocins holds great promise in the modulation of food microbiomes, antimicrobial food packaging, bio-sanitizers and antibiofilm, pre/post-harvest biocontrol, functional food, growth promotion, and sustainable aquaculture. This can undoubtedly improve food security, safety, and quality globally. This review highlights the current trends in bacteriocin research, especially the increasing research outputs and funding, which we believe may proportionate the soaring global interest in bacteriocins. The use of cutting-edge technologies, such as bioengineering, can further enhance the exploitation of bacteriocins for innovative applications in human, animal, and food systems.

Evaluation of the Differential Postbiotic Potential of Shewanella putrefaciens Pdp11 Cultured in Several Growing Conditions

The increased knowledge of functional foods has led to the development of a new generation of health products, including those containing probiotics and products derived from them. Shewanella putrefaciens Pdp11 (SpPdp11) is a strain described as a probiotic that exerts important beneficial effects on several farmed fish. However, the use of live probiotic cells in aquaculture has limitations such as uncertain survival and shelf life, which can limit their efficacy. In addition, its efficacy can vary across species and hosts. When probiotics are administered orally, their activity can be affected by the environment present in the host and by interactions with the intestinal microbiota. Furthermore, live cells can also produce undesired substances that may negatively impact the host as well as the risk of potential virulence reversion acquired such as antibiotic resistance. Therefore, new alternatives emerged such as postbiotics. Currently, there is no knowledge about the postbiotic potential of SpPdp11 in the aquaculture industry. Postbiotic refers to the use of bacterial metabolites, including extracellular products (ECPs), to improve host physiology. However, the production of postbiotic metabolites can be affected by various factors such as cultivation conditions, which can affect bacterial metabolism. Thus, the objective of this study was to evaluate the postbiotic potential of ECPs from SpPdp11 under different cultivation conditions, including culture media, temperature, growth phase, and salinity. We analyzed their hydrolytic, antibacterial, antiviral, and cytotoxic capacity on several fish cell lines. The results obtained have demonstrated how each ECP condition can exert a different hydrolytic profile, reduce the biofilm formation by bacterial pathogens relevant to fish, lower the titer of nervous necrosis virus (NNV), and exert a cytotoxic effect on different fish cell lines. In conclusion, the ECPs obtained from SpPdp11 have different capacities depending on the cultivation conditions used. These conditions must be considered in order to recover the maximum number of beneficial capacities or to choose the appropriate conditions for specific activities.

Lactobacilli in COVID-19: A Systematic Review Based on Next-Generation Sequencing Studies

The global pandemic was caused by the SARS-CoV-2 virus, known as COVID-19, which primarily affects the respiratory and intestinal systems and impacts the microbial communities of patients. This systematic review involved a comprehensive search across the major literature databases to explore the relationship between lactobacilli and COVID-19. Our emphasis was on investigations employing NGS technologies to explore this connection. Our analysis of nine selected studies revealed that lactobacilli have a reduced abundance in the disease and an association with disease severity. The protective mechanisms of lactobacilli in COVID-19 and other viral infections are likely to be multifaceted, involving complex interactions between the microbiota, the host immune system, and the virus itself. Moreover, upon closely examining the NGS methodologies and associated statistical analyses in each research study, we have noted concerns regarding the approach used to delineate the varying abundance of lactobacilli, which involves potential biases and the exclusion of pertinent data elements. These findings provide new insight into the relationship between COVID-19 and lactobacilli, highlighting the potential for microbiota modulation in COVID-19 treatment.

The Role of Probiotics in Improving Food Safety: Inactivation of Pathogens and Biological Toxins

Currently, many advances have been made in avoiding food contamination by numerous pathogenic and toxigenic microorganisms. Many studies have shown that different probiotics, in addition to having beneficial effects on the host's health, have a very good ability to eliminate and neutralize pathogens and their toxins in foods which leads to enhanced food safety. The present review purposes to comprehensively discuss the role of probiotics in improving food safety by inactivating pathogens (bacterial, fungal, viral, and parasite agents) and neutralizing their toxins in food products. Some recent examples in terms of the anti-microbial activities of probiotics in the body after consuming contaminated food have also been mentioned. This review shows that different probiotics have the potential to inactivate pathogens and neutralize and detoxify various biological agents in foods, as well as in the host body after consumption.

Ribosomally synthesized bacteriocins of lactic acid bacteria: Simplicity yet having wide potentials - A review

Bacteriocins are ribosomally made bacterial peptides that have outstanding contributions in the field of food industry, as biopreservatives, and promising potentials in the medical field for improving human and animal health. Bacteriocins have many advantages over antibiotics such as being primary metabolites with relatively simpler biosynthetic mechanisms, which made their bioengineering for activity or specificity improving purposes much easier. Also, bacteriocins are degraded by proteolytic enzymes and do not stay in environment, which reduce chances of developing resistance. Bacteriocins can improve activity of some antibiotics, and some bacteriocins show potency against multidrug-resistant bacteria. Moreover, some potent bacteriocins have antiviral, antifungal, and antiprotozoal (antileishmanial) activities. On the other hand, bacteriocins have been introduced into the treatment of some ulcers and types of cancer. These potentials make bacteriocins attract extra attention as promising biotechnological tool. Hence, the history, characteristics, and classification of bacteriocins are described in this review. Furthermore, the main difference between bacteriocins and other antimicrobial peptides is clarified. Also, bacteriocins biosynthesis and identified modes of action are elucidated. Additionally, current and potential applications of bacteriocins in food and medical fields are highlighted. Finally, future perspectives concerning studying bacteriocins and their applications are discussed.

The Respiratory Microbiome in Paediatric Chronic Wet Cough: What Is Known and Future Directions

Chronic wet cough for longer than 4 weeks is a hallmark of chronic suppurative lung diseases (CSLD), including protracted bacterial bronchitis (PBB), and bronchiectasis in children. Severe lower respiratory infection early in life is a major risk factor of PBB and paediatric bronchiectasis. In these conditions, failure to clear an underlying endobronchial infection is hypothesised to drive ongoing inflammation and progressive tissue damage that culminates in irreversible bronchiectasis. Historically, the microbiology of paediatric chronic wet cough has been defined by culture-based studies focused on the detection and eradication of specific bacterial pathogens. Various 'omics technologies now allow for a more nuanced investigation of respiratory pathobiology and are enabling development of endotype-based models of care. Recent years have seen substantial advances in defining respiratory endotypes among adults with CSLD; however, less is understood about diseases affecting children. In this review, we explore the current understanding of the airway microbiome among children with chronic wet cough related to the PBB-bronchiectasis diagnostic continuum. We explore concepts emerging from the gut-lung axis and multi-omic studies that are expected to influence PBB and bronchiectasis endotyping efforts. We also consider how our evolving understanding of the airway microbiome is translating to new approaches in chronic wet cough diagnostics and treatments.

Implications and Mechanisms of Antiviral Effects of Lactic Acid Bacteria: A Systematic Review

Background

Lactic acid bacteria (LAB) are among the most important strains of probiotics. Some are normal flora of human mucous membranes in the gastrointestinal system, skin, urinary tract, and genitalia. There is evidence suggesting that LAB has an antiviral effect on viral infections. However, these studies are still controversial; a systematic review was conducted to evaluate the antiviral effects of LAB on viral infections.

Methods

The systematic search was conducted until the end of December 17, 2022, using international databases such as Scopus, Web of Science, and Medline (via PubMed). The keywords of our search were lactic acid bacteria, Lactobacillales, Lactobacillus (as well as its species), probiotics, antiviral, inhibitory effect, and virus.

Results

Of 15.408 potentially relevant articles obtained, 45 eligible in-vivo human studies were selected for inclusion in the study from databases, registers, and citation searching. We conducted a systematic review of the antiviral effects of the LAB based on the included articles. The most commonly investigated lactobacillus specie were Lactobacillus rhamnosus GG and Lactobacillus casei.

Conclusion

Our study indicates that 40 of the selected 45 of the included articles support the positive effect of LAB on viral infections, although some studies showed no significant positive effect of LABs on some viral infections.

Functional and genomic characterization of a novel probiotic Lactobacillus johnsonii KD1 against shrimp WSSV infection

White Spot syndrome virus (WSSV) causes rapid shrimp mortality and production loss worldwide. This study demonstrates potential use of Lactobacillus johnsonii KD1 as an anti-WSSV agent for post larva shrimp cultivation and explores some potential mechanisms behind the anti-WSSV properties. Treatment of Penaeus vannamei shrimps with L. johnsonii KD1 prior to oral challenge with WSSV-infected tissues showed a significantly reduced mortality. In addition, WSSV copy numbers were not detected and shrimp immune genes were upregulated. Genomic analysis of L. johnsonii KD1 based on Illumina and Nanopore platforms revealed a 1.87 Mb chromosome and one 15.4 Kb plasmid. Only one antimicrobial resistance gene (ermB) in the chromosome was identified. Phylogenetic analysis comparing L. johnsonii KD1 to other L. johnsonii isolates revealed that L. johnsonii KD1 is closely related to L. johnsonii GHZ10a isolated from wild pigs. Interestingly, L. johnsonii KD1 contains isolate-specific genes such as genes involved in a type I restriction-modification system and CAZymes belonging to the GT8 family. Furthermore, genes coding for probiotic survival and potential antimicrobial/anti-viral metabolites such as a homolog of the bacteriocin helveticin-J were found. Protein-protein docking modelling suggests the helveticin-J homolog may be able to block VP28-PmRab7 interactions and interrupt WSSV infection.

Utilisation of probiotics for disease management in giant freshwater prawn (Macrobrachium rosenbergii): Administration methods, antagonistic effects and immune response

The giant freshwater prawn (Macrobrachium rosenbergii) is a high-yielding prawn variety well-received worldwide due to its ability to adapt to freshwater culture systems. Macrobrachium rosenbergii is an alternative to shrimp typically obtained from marine and brackish aquaculture systems. However, the use of intensive culture systems can lead to disease outbreaks, particularly in larval and post-larval stages, caused by pathogenic agents such as viruses, bacteria, fungi, yeasts and protozoans. White tail disease (viral), white spot syndrome (viral) and bacterial necrosis are examples of economically significant diseases. Given the increasing antibiotic resistance of disease-causing microorganisms, probiotics have emerged as promising alternatives for disease control. Probiotics are live active microbes that are introduced into a target host in an adequate number or dose to promote its health. In the present paper, we first discuss the diseases that occur in M. rosenbergii production, followed by an in-depth discussion on probiotics. We elaborate on the common methods of probiotics administration and explain the beneficial health effects of probiotics as immunity enhancers. Moreover, we discuss the antagonistic effects of probiotics on pathogenic microorganisms. Altogether, this paper provides a comprehensive overview of disease control in M. rosenbergii aquaculture through the use of probiotics, which could enhance the sustainability of prawn culture.

The novel immunobiotic Clostridium butyricum S-45-5 displays broad-spectrum antiviral activity in vitro and in vivo by inducing immune modulation

Clostridium butyricum is known as a probiotic butyric acid bacterium that can improve the intestinal environment. In this study, we isolated a new strain of C. butyricum from infant feces and evaluated its physiological characteristics and antiviral efficacy by modulating the innate immune responses in vitro and in vivo. The isolated C. butyricum S-45-5 showed typical characteristics of C. butyricum including bile acid resistance, antibacterial ability, and growth promotion of various lactic acid bacteria. As an antiviral effect, C. butyricum S-45-5 markedly reduced the replication of influenza A virus (PR8), Newcastle Disease Virus (NDV), and Herpes Simplex Virus (HSV) in RAW264.7 cells in vitro. This suppression can be explained by the induction of antiviral state in cells by the induction of antiviral, IFN-related genes and secretion of IFNs and pro-inflammatory cytokines. In vivo, oral administration of C. butyricum S-45-5 exhibited prophylactic effects on BALB/c mice against fatal doses of highly pathogenic mouse-adapted influenza A subtypes (H1N1, H3N2, and H9N2). Before challenge with influenza virus, C. butyricum S-45-5-treated BALB/c mice showed increased levels of IFN-β, IFN-γ, IL-6, and IL-12 in serum, the small intestine, and bronchoalveolar lavage fluid (BALF), which correlated with observed prophylactic effects. Interestingly, after challenge with influenza virus, C. butyricum S-45-5-treated BALB/c mice showed reduced levels of pro-inflammatory cytokines and relatively higher levels of anti-inflammatory cytokines at day 7 post-infection. Taken together, these findings suggest that C. butyricum S-45-5 plays an antiviral role in vitro and in vivo by inducing an antiviral state and affects immune modulation to alleviate local and systemic inflammatory responses caused by influenza virus infection. Our study provides the beneficial effects of the new C. butyricum S-45-5 with antiviral effects as a probiotic.

Modulatory Effect of Beneficial Enterococci and Their Enterocins on the Blood Phagocytes in Murine Experimental Trichinellosis

Bacteriocins (enterocins) represent a new therapeutic strategy in various intestinal and non-intestinal infections. In antiparasitic defence, an oxidative inflammation of phagocytes is effective in destroying new-born Trichinella spiralis larvae. The strains Enterococcus faecium CCM8558 and E. durans ED26E/7 and their enterocins, enterocin M and a durancin-like enterocin, respectively, were administered daily, and mice were then infected with T. spiralis larvae on the seventh day of treatment. Phagotest and Bursttest kits were used to detect the phagocytosis and respiratory burst in blood leukocytes. T. spiralis infection inhibited phagocytosis from day 11 post-infection (dpi) during the migration of new-born larvae into the muscles. E. faecium CCM8558, E. durans ED26E/7, and the durancin-like enterocin increased phagocytic activity from day 11 dpi. Both strains and their enterocins (enterocin M and durancin-like) stimulated the ingestion capability of phagocytes from 18 to 32 dpi. Enterococci/enterocins therapy prevented a reduction in cells with respiratory burst caused by T. spiralis infection from 11 dpi. The enzymatic activity of phagocytes was stimulated on 18 and 25 dpi, particularly by E. faecium CCM8558 and enterocin M. Enterocin M and the durancin-like enterocin were as effective in stimulating phagocytosis as the bacterial strains that produce them. The stimulation of phagocytosis could contribute to decreased larval migration and reduced parasite burden in the host.

The Impacts of Acidophilic Lactic Acid Bacteria on Food and Human Health: A Review of the Current Knowledge

The need to improve the safety/quality of food and the health of the hosts has resulted in increasing worldwide interest in acidophilic lactic acid bacteria (LAB) for the food, livestock as well as health industries. In addition to the use of acidophilic LAB with probiotic potential for food fermentation and preservation, their application in the natural disposal of acidic wastes polluting the environment is also being investigated. Considering this new benefit that has been assigned to probiotic microorganisms in recent years, the acceleration in efforts to identify new, efficient, promising probiotic acidophilic LAB is not surprising. One of these effots is to determine both the beneficial and harmful compounds synthesized by acidophilic LAB. Moreover, microorganisms are of concern due to their possible hemolytic, DNase, gelatinase and mucinolytic activities, and the presence of virulence/antibiotic genes. Hence, it is argued that acidophilic LAB should be evaluated for these parameters before their use in the health/food/livestock industry. However, this issue has not yet been fully discussed in the literature. Thus, this review pays attention to the less-known aspects of acidophilic LAB and the compounds they release, clarifying critical unanswered questions, and discussing their health benefits and safety.

Targeted Application of Functional Foods as Immune Fitness Boosters in the Defense against Viral Infection

In recent times, the emergence of viral infections, including the SARS-CoV-2 virus, the monkeypox virus, and, most recently, the Langya virus, has highlighted the devastating effects of viral infection on human life. There has been significant progress in the development of efficacious vaccines for the prevention and control of viruses; however, the high rates of viral mutation and transmission necessitate the need for novel methods of control, management, and prevention. In recent years, there has been a shift in public awareness on health and wellbeing, with consumers making significant dietary changes to improve their immunity and overall health. This rising health awareness is driving a global increase in the consumption of functional foods. This review delves into the benefits of functional foods as potential natural means to modulate the host immune system to enhance defense against viral infections. We provide an overview of the functional food market in Europe and discuss the benefits of enhancing immune fitness in high-risk groups, including the elderly, those with obesity, and people with underlying chronic conditions. We also discuss the immunomodulatory mechanisms of key functional foods, including dairy proteins and hydrolysates, plant-based functional foods, fermentates, and foods enriched with vitamin D, zinc, and selenium. Our findings reveal four key immunity boosting mechanisms by functional foods, including inhibition of viral proliferation and binding to host cells, modulation of the innate immune response in macrophages and dendritic cells, enhancement of specific immune responses in T cells and B cells, and promotion of the intestinal barrier function. Overall, this review demonstrates that diet-derived nutrients and functional foods show immense potential to boost viral immunity in high-risk individuals and can be an important approach to improving overall immune health.

Sustainable production of bioemulsifiers, a critical overview from microorganisms to promising applications

Microbial bioemulsifiers are molecules of amphiphilic nature and high molecular weight that are efficient in emulsifying two immiscible phases such as water and oil. These molecules are less effective in reducing surface tension and are synthesized by bacteria, yeast and filamentous fungi. Unlike synthetic emulsifiers, microbial bioemulsifiers have unique advantages such as biocompatibility, non-toxicity, biodegradability, efficiency at low concentrations and high selectivity under different conditions of pH, temperature and salinity. The adoption of microbial bioemulsifiers as alternatives to their synthetic counterparts has been growing in ongoing research. This article analyzes the production of microbial-based emulsifiers, the raw materials and fermentation processes used, as well as the scale-up and commercial applications of some of these biomolecules. The current trend of incorporating natural compounds into industrial formulations indicates that the search for new bioemulsifiers will continue to increase, with emphasis on performance improvement and economically viable processes.

Probiotic therapy, African fermented foods and food-derived bioactive peptides in the management of SARS-CoV-2 cases and other viral infections

The current paper focuses on the impact of probiotics, African fermented foods and bioactive peptides on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection severity and related viral infections. Using probiotics or bioactive peptides as therapeutic adjuncts appears superior to standard care alone. Probiotics play critical roles in innate and adaptive immune modulation by balancing the gut microbiota to combat viral infections, secondary bacterial infections and microbial dysbiosis. African fermented foods contain abundant potential probiotic microorganisms such as the lactic acid bacteria (LAB), Saccharomyces, and Bacillus. More so, fermented food-derived bioactive peptides play vital roles in preventing cardiovascular diseases, hypertension, lung injury, diabetes, and other COVID-19 comorbidities. Regularly incorporating potential probiotics and bioactive peptides into diets should enable a build-up of the benefits in the body system that may result in a better prognosis, especially in COVID-19 patients with underlying complexities. Despite the reported therapeutic potentials of probiotics and fermented foods, numerous setbacks exist regarding their application in disease management. These shortfalls underscore an evident need for more studies to evaluate the specific potentials of probiotics and traditional fermented foods in ameliorating SARS-CoV-2 and other viral infections.

Protective and Therapeutic Capacities of Lactic Acid Bacteria Postmetabolites against Koi Herpesvirus Infection In Vitro

Background: The accumulation of data on beneficial biological effects of probiotics and their metabolic products favors their potential use in the prevention and treatment of various malaises. Methods: Nine postmetabolites from Lactic acid bacteria (LAB) of human or dairy origin and their antiviral activity were studied using the cytopathic effect inhibition test. The virucidal capacity, their influence on the adsorption stage of Koi herpes virus (KHV) and their preventive role against subsequent viral challenge on intact Common carp brain (CCB) cells were also determined by titration assay. Residual viral infectivity in postmetabolites-treated samples was compared to mock-treated controls and Δlgs were calculated. Results: When administered during KHV replication, the microbial products isolated from Lactiplantibacillus plantarum showed remarkable activity with a selectivity index (SI) between 26.5 and 221.4, as those effects were dependent on the sample-virus incubation time. Postmetabolites from Lactobacillus gasseri and Lactiplantibacillus plantarum also demonstrated significant inhibition of KHV replication with SI of 24 and 16, respectively. The bioactive metabolites isolated from Limosilactobacillus fermentum had a minor effect on the viral replicative cycle. Compounds, produced during the fermentation by lactobacilli, grown on different nutritive media and collected at different time points, significantly inhibited extracellular KHV virions. All investigated postmetabolites remarkably blocked KHV attachment to the host cell (CCB), leading to a drop in viral titers by Δlg = 4.25–5.25, and exerted protective effects on CCB cells before they were subjected to viral infection. Conclusions: Our results open new horizons and promote LAB and their postbiotic products to be used in the prophylaxis and therapy of viral infections.

Microbiome Structure and Mucosal Morphology of Jejunum Appendix and Colon of Rats in Health and Dysbiosis

Gut microbiota contributes to human health. Plenty of studies demonstrate that antibiotics can disrupt gut ecosystem leading to dysbiosis. Little is known about the microbial variation of appendix and its up/downstream intestine after antibiotic treatment. This study aimed to investigate the microbiome and mucosal morphology of jejunum, appendix, and colon of rats in health and dysbiosis. A rodent model of antibiotic-induced dysbiosis was employed. Microscopy was used to observe mucosal morphological changes. 16S rRNA sequencing was performed for identifying bacterial taxa and microbiome structure. The appendices of dysbiosis were found enlarged and inflated with loose contents. Microscopy revealed the impairment of intestinal epithelial cells. High-throughput sequencing showed the Operational Taxonomic Units changed from 361 ± 33, 634 ± 18, 639 ± 19 in the normal jejunum, appendix, colon to 748 ± 98, 230 ± 11, 253 ± 16 in the disordered segments, respectively. In dysbiosis, Bacteroidetes translocated inversely from the colon and appendix (0.26%, 0.23%) to the jejunum (13.87% ± 0.11%); the relative abundance of all intestinal Enterococcaceae increased, while Lactobacillaceae decreased. Several bacterial clusters were found correlated to the normal appendix, whereas nonspecific clusters correlated to the disordered appendix. In conclusion, species richness and evenness reduced in the disordered appendix and colon; similar microbiome patterns were shared between the appendix and colon regardless of dysbiosis; site-specific bacteria were missing in the disordered appendix. Appendix is likely a transit region involving in upper and lower intestinal microflora modulation. The limitation of this study is all the data were derived from rats. We must be cautious about translating the microbiome results from rats to humans.

In Vitro Screening of Antiviral Activity of Lactic Acid Bacteria Isolated from Traditional Fermented Foods

Studies of newly isolated strains of lactic acid bacteria (LAB) are a good basis for expanding the potential for their applications in functional foods, probiotic food supplements, and other probiotic products. They exhibit various functional properties, including such with antiviral activity. Probiotic strains can manifest their antiviral effects by various mechanisms, including direct interaction with viruses, production of antiviral compounds, or immune system modulation. Ten newly isolated LAB strains from traditional fermented food products have been tested for the determination of their antiviral activity. This study was performed to evaluate the effect of cell-free supernatants (CFSs) from the studied strains for the effect on viral replication of Human alphaherpesvirus—HHV-1 and HHV-2 as well as for direct virucidal activity. The CFSs of the LAB strains were used in non-toxic concentrations of 25%, 6.25%, and 1.6%. No direct virucidal activity was observed in tested CFSs, but five of the strains observed a well-defined effect of viral replication inhibition with the selective index (SI) from 4.40 to >54. For two of these five strains, Lactobacillus delbrueckii subsp. bulgaricus KZM 2-11-3 and Lactiplantibacillus plantarum KC 5-12 strong activity against HHV-2 with a selective index (SI) over 45 was detected, which is a good basis for further research.

Analysis of Industrial Bacillus Species as Potential Probiotics for Dietary Supplements

So far, Bacillus species bacteria are being used as bacteria concentrates, supplementing cleaning preparations in order to reduce odor and expel pathogenic bacteria. Here, we discuss the potential of Bacillus species as 'natural' probiotics and evaluate their microbiological characteristics. An industrial microbiological concentrate CS-4 of mixed Bacillus species cultures was tested, which may be a promising bacteria source for food probiotic preparation for supplementary diet. In this study, antagonistic activities and probiotic potential of Bacillus species, derived from an industrial microbiological concentrate, were demonstrated. The cell free supernatants (CFS) from Bacillus licheniformis mostly inhibited the growth of foodborne pathogenic bacteria, such as Escherichia coli O157:H7 ATCC 35150, Salmonella Enteritidis KCCM 12021, and Staphylococcus aureus KCCM 11335, while some of Bacillus strains showed synergistic effect with foodborne pathogenic bacteria. Moreover, Bacillus strains identified by the MALDI TOF-MS method were found sensitive to chloramphenicol, kanamycin, and rifampicin. B. licheniformis and B. cereus displayed the least sensitivity to the other tested antibiotics, such as ampicillin, ampicillin and sulfbactam, streptomycin, and oxacillin and bacitracin. Furthermore, some of the bacterial species detected extended their growth range from the mesophilic to moderately thermophilic range, up to 54 °C. Thus, their potential sensitivity to thermophilic TP-84 bacteriophage, infecting thermophilic Bacilli, was tested for the purpose of isolation a new bacterial host for engineered bionanoparticles construction. We reason that the natural environmental microflora of non-pathogenic Bacillus species, especially B. licheniformis, can become a present probiotic remedy for many contemporary issues related to gastrointestinal tract health, especially for individuals under metabolic strain or for the increasingly growing group of lactose-intolerant people.

The Fight against the Carcinogenic Epstein-Barr Virus: Gut Microbiota, Natural Medicines, and Beyond

Despite recent advances in oncology, cancer has remained an enormous global health burden, accounting for about 10 million deaths in 2020. A third of the cancer cases in developing counties are caused by microbial infections such as human papillomavirus (HPV), Epstein-Barr Virus (EBV), and hepatitis B and C viruses. EBV, a member of the human gamma herpesvirus family, is a double-stranded DNA virus and the primary cause of infectious mononucleosis. Most EBV infections cause no long-term complications. However, it was reported that EBV infection is responsible for around 200,000 malignancies worldwide every year. Currently, there are no vaccines or antiviral drugs for the prophylaxis or treatment of EBV infection. Recently, the gut microbiota has been investigated for its pivotal roles in pathogen protection and regulating metabolic, endocrine, and immune functions. Several studies have investigated the efficacy of antiviral agents, gut microbial metabolites, and natural products against EBV infection. In this review, we aim to summarise and analyse the reported molecular mechanistic and clinical studies on the activities of gut microbial metabolites and natural medicines against carcinogenic viruses, with a particular emphasis on EBV. Gut microbial metabolites such as short-chain fatty acids were reported to activate the EBV lytic cycle, while bacteriocins, produced by Enterococcus durans strains, have shown antiviral properties. Furthermore, several natural products and dietary bioactive compounds, such as curcumin, epigallocatechin gallate, resveratrol, moronic acid, and andrographolide, have shown antiviral activity against EBV. In this review, we proposed several exciting future directions for research on carcinogenic viruses.

Bacterial Exopolysaccharides as Emerging Bioactive Macromolecules: From Fundamentals to Applications

Microbial exopolysaccharides (EPS) are extracellular carbohydrate polymers forming capsules or slimy coating around the cells. EPS can be secreted by various bacterial genera that can help bacterial cells in attachment, environmental adaptation, stress tolerance and are an integral part of microbial biofilms. Several gut commensals (e.g., Lactobacillus, Bifidobacterium) produce EPS that possess diverse bioactivities. Bacterial EPS also has extensive commercial applications in the pharmaceutical and food industries. Owing to the structural and functional diversity, genetic and metabolic engineering strategies are currently employed to increase EPS production. Therefore, the current review provides a comprehensive overview of the fundamentals of bacterial exopolysaccharides, including their classification, source, biosynthetic pathways, and functions in the microbial community. The review also provides an overview of the diverse bioactivities of microbial EPS, including immunomodulatory, anti-diabetic, anti-obesity, and anti-cancer properties. Since several gut microbes are EPS producers and gut microbiota helps maintain a functional gut barrier, emphasis has been given to the intestinal-level bioactivities of the gut microbial EPS. Collectively, the review provides a comprehensive overview of microbial bioactive exopolysaccharides.

Alterations of the gut microbiota in coronavirus disease 2019 and its therapeutic potential

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a serious threat to global health. SARS-CoV-2 infects host cells primarily by binding to angiotensin-converting enzyme 2, which is coexpressed in alveolar type 2 cells and gut epithelial cells. It is known that COVID-19 often presents with gastrointestinal symptoms and gut dysbiosis, mainly characterized by an increase in opportunistic pathogens and a decrease in beneficial commensal bacteria. In recent years, multiple studies have comprehensively explored gut microbiota alterations in COVID-19 and highlighted the clinical correlation between dysbiosis and COVID-19. SARS-CoV-2 causes gastrointestinal infections and dysbiosis mainly through fecal-oral transmission and the circulatory and immune pathways. Studies have shown that the gut microbiota and its metabolites can regulate the immune response and modulate antiviral effects. In addition, the gut microbiota is closely related to gastrointestinal symptoms, such as diarrhea, a common gastrointestinal symptom among COVID-19. Therefore, the contribution of the gut microbiota in COVID-19 should not be overlooked. Strategies targeting the gut microbiota via probiotics, prebiotics and fecal microbiota transplantation should be considered to treat this patient population in the future. However, the specific alterations and mechanisms as well as the contributions of gut microbiota in COVID-19 should be urgently further explored.

Evaluation of Bioactive Attributes and Emulsification Potential of Exopolysaccharide Produced by a Brown-rot Fungus Fomitopsis meliae AGDP-2

Mushrooms possess wide array of biologically active secondary metabolites and have been traditionally used for their medicinal properties. Exopolysaccharide (EPS) is one of such bioactive metabolites. The bioactive attributes and emulsification capabilities of the exopolysaccharides produced by a novel brown-rot fungus Fomitopsis meliae AGDP-2 under submerged fermentation has been thoroughly investigated in the present study. Exopolysaccharide displayed anti-oxidant activities in dose dependent manner with the maximum scavenging of ABTS radicals (42.45%), DPPH radicals (75.34%), Hydroxyl radicals (63.64%), Superoxide anion radical (76.54%) and Ferric Reducing Antioxidant Power with IC₅₀ value of 231 µg/mL. Additionally, evaluation of anti-proliferative properties revealed that EPS significantly inhibited the proliferation of HepG2 and HT-29 cancer cells followed by moderate inhibition of HeLa and MCF-7 cancer cell lines and quite less inhibition of L-132 and KB cell lines. The IC₅₀ values of EPS for the abovementioned cell lines are 9.465 µg/mL, 11.25 µg/mL, 38.98 µg/mL, 87.78 µg/mL, 2061 µg/mL and 2361 µg/mL respectively. Moreover EPS also possess good anti-microbial as well as anti-biofilm properties. The studies on emulsification potential described that EPS is good emulsifier of different vegetable oils and the emulsion formed was quite stable up to 144 h.

Antiviral Potential of Natural Resources against Influenza Virus Infections

Influenza is a severe contagious disease caused by influenza A and B viruses. The WHO estimates that annual outbreaks lead to 3-5 million severe infections of which approximately 10% lead to the death of the patient. While vaccination is the cornerstone of prevention, antiviral drugs represent the most important treatment option of acute infections. Only two classes of drugs are currently approved for the treatment of influenza in numerous countries: M2 channel blockers and neuraminidase inhibitors. In some countries, additional compounds such as the recently developed cap-dependent endonuclease inhibitor baloxavir marboxil or the polymerase inhibitor favipiravir are available. However, many of these compounds suffer from poor efficacy, if not applied early after infection. Furthermore, many influenza strains have developed resistances and lost susceptibility to these compounds. As a result, there is an urgent need to develop new anti-influenza drugs against a broad spectrum of subtypes. Natural products have made an important contribution to the development of new lead structures, particularly in the field of infectious diseases. Therefore, this article aims to review the research on the identification of novel lead structures isolated from natural resources suitable to treat influenza infections.

Lactic Acid Bacteria as Mucosal Immunity Enhancers and Antivirals through Oral Delivery

Mucosal vaccination offer an advantage over systemic inoculation from the immunological viewpoint. The development of an efficient vaccine is now a priority for emerging diseases such as COVID-19, that was declared a pandemic in 2020 and caused millions of deaths globally. Lactic acid bacteria (LAB) especially Lactobacillus are the vital microbiota of the gut, which is observed as having valuable effects on animals’ and human health. LAB produce lactic acid as the major by-product of carbohydrate degradation and play a significant role in innate immunity enhancement. LAB have significant characteristics to mimic pathogen infections and intrinsically possess adjuvant properties to enhance mucosal immunity. Increasing demand and deliberations are being substantially focused on probiotic organisms that can enhance mucosal immunity against viral diseases. LAB can also strengthen their host’s antiviral defense system by producing antiviral peptides, and releasing metabolites that prevent viral infections and adhesion to mucosal surfaces. From the perspectives of “one health” and the use of probiotics, conventional belief has opened up a new horizon on the use of LAB as antivirals. The major interest of this review is to depict the beneficial use of LAB as antivirals and mucosal immunity enhancers against viral diseases.

The bacteriocin Angicin interferes with bacterial membrane integrity through interaction with the mannose phosphotransferase system

In a natural environment, bacteria are members of multispecies communities. To compete with rival species, bacteria produce antimicrobial peptides (AMPs), called bacteriocins. Bacteriocins are small, cationic, ribosomally synthesized peptides, which normally inhibit closely related species of the producing organism. Bacteriocin production is best studied in lactic bacteria (LAB). Streptococcus anginosus, belonging to LAB, produces the potent bacteriocin Angicin, which shows inhibitory activity against other streptococci, Listeria monocytogenes and vancomycin resistant Enterococcus faecium (VRE). Furthermore, Angicin shows a high resistance toward pH changes and heat, rendering it an interesting candidate for food preservation or clinical applications. The inhibitory activity of Angicin depends on the presence of a mannose phosphotransferase system (Man-PTS) in target cells, since L. monocytogenes harboring a deletion in an extracellular loop of this system is no longer sensitive to Angicin. Furthermore, we demonstrated by liposome leakage and pHluorin assays that Angicin destroys membrane integrity but shows only low cytotoxicity against human cell lines. In conclusion, we show that Angicin has a detrimental effect on the membrane of target organisms by using the Man-PTS as a receptor.

Pharmacological Efficacy of Probiotics in Respiratory Viral Infections: A Comprehensive Review

Mortality and morbidity from influenza and other respiratory viruses are significant causes of concern worldwide. Infections in the respiratory tract are often underappreciated because they tend to be mild and incapacitated. On the other hand, these infections are regarded as a common concern in clinical practice. Antibiotics are used to treat bacterial infections, albeit this is becoming more challenging since many of the more prevalent infection causes have acquired a wide range of antimicrobial resistance. Resistance to frontline treatment medications is constantly rising, necessitating the development of new antiviral agents. Probiotics are one of several medications explored to treat respiratory viral infection (RVI). As a result, certain probiotics effectively prevent gastrointestinal dysbiosis and decrease the likelihood of secondary infections. Various probiotic bacterias and their metabolites have shown immunomodulating and antiviral properties. Unfortunately, the mechanisms by which probiotics are effective in the fight against viral infections are sometimes unclear. This comprehensive review has addressed probiotic strains, dosage regimens, production procedures, delivery systems, and pre-clinical and clinical research. In particular, novel probiotics’ fight against RVIs is the impetus for this study. Finally, this review may explore the potential of probiotic bacterias and their metabolites to treat RVIs. It is expected that probiotic-based antiviral research would be benefitted from this review’s findings.

Potential probiotics for regulation of the gut-lung axis to prevent or alleviate influenza in vulnerable populations

Influenza, also known as "flu", is an infectious disease caused by influenza viruses. Three types of influenza virus, A, B, and C, are able to infect humans. In most people, influenza causes mild symptoms, but it can also induce severe complications and death. Annual influenza vaccines are currently the main intervention used to minimize mortality and morbidity. However, vaccination frequently fails to provide adequate protection, especially in the elderly. Traditional flu vaccine targets hemagglutinin to prevent virus infection, but the constant mutation of hemagglutinin means that it is a challenge to develop vaccines quickly enough to keep up with mutations. Thus, other methods of curbing influenza incidence would be welcomed, especially for vulnerable populations. Although influenza viruses primarily infect the respiratory tract, influenza virus infection also induces intestinal dysbiosis. Through gut microbiota-derived secreted products and the circulating immune cells, gut microbiota can affect pulmonary immunity. The crosstalk between the respiratory tract and gut microbiota, termed the "gut-lung axis", is observed in the regulation of immune responses against influenza virus infection or inflammation-induced lung damage, indicating the possibility of using probiotics to prevent influenza virus infection or alleviate respiratory symptoms. In this review, we summarize the current findings on the antiviral functions of particular probiotics and/or combinations and discuss the antiviral mechanisms and immunomodulatory activities of probiotics in vitro, in mice, and in humans. Clinical studies show probiotic supplements can provide health benefits, not only to the elderly or children with compromised immune systems, but also to young- and middle-aged adults.

Purification, amino acid sequence, and characterization of bacteriocin GA15, a novel class IIa bacteriocin secreted by Lactiplantibacillus plantarum GCNRC_GA15

The bacteriocins produced by lactic acid bacteria (LAB) are attracting attention due to their promising applications in food and pharmaceuticals fields. Hence, a LAB strain, GCNRC_GA15, was isolated from Egyptian goat cheese, and molecularly identified as Lactiplantibacillus plantarum. This strain showed a wide antimicrobial spectrum, which was found to be of proteineous nature, suggesting that L. plantarum GCNRC_GA15 is a bacteriocin-producer. This bacteriocin (bacteriocin GA15) was partially purified using cation exchange, and hydrophobic interaction chromatography. Tricine SDS-PAGE analysis for the fraction showing bacteriocin activity has estimated the molecular mass to be 4369 Da. Furthermore, amino acid sequencing of this peptide has detected 34 amino acids, and comparing its amino acid sequence with those of some pediocin-like bacteriocins revealed that bacteriocin GA15 has the conserved sequence (YYGNGV/L) in its N-terminal region which identified bacteriocin GA15 as a pediocin-like bacteriocin. Bacteriocin GA15 showed good heat and pH stabilities, and its activity was enhanced after treatment with Tween 80 or Triton X-100. Bacteriocin production medium was statistically optimized using the Plackett-Burman and Central Composite designs. As a result, bacteriocin production increased from 800 to 12,800 AU/ml using the optimized medium in comparison with result recorded for the un-optimized medium.

Probiotic-Based Bacteriocin: Immunity Supplementation Against Viruses. An Updated Review

Viral infections are a major cause of severe, fatal diseases worldwide. Recently, these infections have increased due to demanding contextual circumstances, such as environmental changes, increased migration of people and product distribution, rapid demographic changes, and outbreaks of novel viruses, including the COVID-19 outbreak. Internal variables that influence viral immunity have received attention along with these external causes to avert such novel viral outbreaks. The gastrointestinal microbiome (GIM), particularly the present probiotics, plays a vital role in the host immune system by mediating host protective immunity and acting as an immune regulator. Bacteriocins possess numerous health benefits and exhibit antagonistic activity against enteric pathogens and immunobiotics, thereby inhibiting viral infections. Moreover, disrupting the homeostasis of the GIM/host immune system negatively affects viral immunity. The interactions between bacteriocins and infectious viruses, particularly in COVID-19, through improved host immunity and physiology are complex and have not yet been studied, although several studies have proven that bacteriocins influence the outcomes of viral infections. However, the complex transmission to the affected sites and siRNA defense against nuclease digestion lead to challenging clinical trials. Additionally, bacteriocins are well known for their biofunctional properties and underlying mechanisms in the treatment of bacterial and fungal infections. However, few studies have shown the role of probiotics-derived bacteriocin against viral infections. Thus, based on the results of the previous studies, this review lays out a road map for future studies on bacteriocins for treating viral infections.

In vitro evaluation of antiviral activity of Shouchella clausii probiotic strain and bacterial supernatant against herpes simplex virus type 1

Herpes simplex virus-1 (HSV-1) is an important human neurotropic virus infecting 70% of the world population. Due to the emergence of viral resistance via mutations in HSV-1 genes and some of the adverse effects of antiviral compounds, there is a growing need for safe, novel, and effective therapeutic and preventive strategies. The aim of the present study was to investigate for the first time the potential antiviral activity of Shouchella clausii probiotic strain and bacterial supernatant against HSV-1. The MTT assay was used to determine the possible cytotoxicity of the S. clausii and bacterial supernatant. Vero cells were treated by S. clausii, bacterial supernatant, and HSV-1 under pre-treatment (incubation of Vero cells with S. clausii then HSV-1 inoculation), pre-incubation (mixture of co-incubated HSV-1/S. clausii added to Vero cell), competition (adding HSV-1 and S. clausii into Vero cells simultaneously) and post-treatment (Vero cells inoculated with HSV-1 then incubated with S. clausii) assays. Viral titer reduction (TCID₅₀) and viral DNA relative quantification by real-time PCR were measured in each experimental condition. The results indicated that S. clausii and its supernatant had the greatest inhibitory activity toward HSV-1 in pre-treatment assay. The HSV-1 titer treated with S. clausii, and bacterial supernatant was 3.6 and 2.2 Log₁₀TCID₅₀/mL lower compared to the control (7.66 Log₁₀TCID₅₀/mL). Results showed an antiviral effect of S. clausii and its supernatant. S. clausii could be considered as a novel inhibitor for HSV-1 infection.

Recent advances in antiviral effects of probiotics: potential mechanism study in prevention and treatment of SARS-CoV-2

SARS-CoV-2 is responsible for coronavirus disease 2019 (COVID-19), progressively extended worldwide countries on an epidemic scale. Along with all the drug treatments suggested to date, currently, there are no approved management protocols and treatment regimens for SARS-CoV-2. The unavailability of optimal medication and effective vaccines against SARS-CoV-2 indicates the requirement for alternative therapies. Probiotics are living organisms that deliberate beneficial effects on the host when used sufficiently and in adequate amounts, and fermented food is their rich source. Probiotics affect viruses by antiviral mechanisms and reduce diarrhea and respiratory tract infection. At this point, we comprehensively evaluated the antiviral effects of probiotics and their mechanism with a particular focus on SARS-CoV-2. In this review, we suggested the conceptual and potential mechanisms of probiotics by which they could exhibit antiviral properties against SARS-CoV-2, according to the previous evidence concerning the mechanism of antiviral effects of probiotics. This study reviewed recent studies that speculate about the role of probiotics in the prevention of the SARS-CoV-2-induced cytokine storm through the mechanisms such as induction of anti-inflammatory cytokines (IL-10), downregulation of pro-inflammatory cytokines (TNF-α, IL-2, IL-6), inhibition of JAK signaling pathway, and act as HDAC inhibitor. Also, the recent clinical trials and their outcome have been reviewed.

Impact of Probiotics on Dairy Production Efficiency

There has been growing interest on probiotics to enhance weight gain and disease resistance in young calves and to improve the milk yield in lactating animals by reducing the negative energy balance during the peak lactation period. While it has been well established that probiotics modulate the microbial community composition in the gastrointestinal tract, and a probiotic-mediated homeostasis in the rumen could improve feed conversation competence, volatile fatty acid production and nitrogen flow that enhances the milk composition as well as milk production, detailed changes on the molecular and metabolic level prompted by probiotic feed additives are still not understood. Moreover, as living biotherapeutic agents, probiotics have the potential to directly change the gene expression profile of animals by activating the signalling cascade in the host cells. Various direct and indirect components of probiotic approaches to improve the productivity of dairy animals are discussed in this review.

Bacterially mediated drug delivery and therapeutics: Strategies and advancements

It was already clinically apparent 150 years ago that bacterial therapy could alleviate diseases. Recently, a burgeoning number of researchers have been using bacterial regimens filled with microbial therapeutic leads to diagnose and treat a wide range of disorders and diseases, including cancers, inflammatory diseases, metabolic disorders and viral infections. Some bacteria that were designed to have low toxicity and high efficiency in drug delivery have been used to treat diseases successfully, especially in tumor therapy in animal models or clinical trials, thanks to the progress of genetic engineering and synthetic bioengineering. Therefore, genetically engineered bacteria can serve as efficient drug delivery vehicles, carrying nucleic acids or genetic circuits that encode and regulate therapeutic payloads. In this review, we summarize the development and applications of this approach. Strategies for genetically modifying strains are described in detail, along with their objectives. We also describe some controlled strategies for drug delivery and release using these modified strains as carriers. Furthermore, we discuss treatment methods for various types of diseases using engineered bacteria. Tumors are discussed as the most representative example, and other diseases are also briefly described. Finally, we discuss the challenges and prospects of drug delivery systems based on these bacteria.

Bacteriocin-Producing Probiotic Lactic Acid Bacteria in Controlling Dysbiosis of the Gut Microbiota

Several strains of lactic acid bacteria are potent probiotics and can cure a variety of diseases using different modes of actions. These bacteria produce antimicrobial peptides, bacteriocins, which inhibit or kill generally closely related bacterial strains and other pathogenic bacteria such as Listeria, Clostridium, and Salmonella. Bacteriocins are cationic peptides that kill the target cells by pore formation and the dissipation of cytosolic contents, leading to cell death. Bacteriocins are also known to modulate native microbiota and host immunity, affecting several health-promoting functions of the host. In this review, we have discussed the ability of bacteriocin-producing probiotic lactic acid bacteria in the modulation of gut microbiota correcting dysbiosis and treatment/maintenance of a few important human disorders such as chronic infections, inflammatory bowel diseases, obesity, and cancer.

In Vitro Inactivation of Respiratory Viruses and Rotavirus by the Oral Probiotic Strain Weissella cibaria CMS1

Weissella cibaria CMS1 (oraCMS1) has been commercially used in Korea as an oral care probiotic for several years. Human respiratory syncytial virus (RSV) and the influenza A virus (H1N1) are representative viruses that cause infantile lower respiratory tract infections. Rotavirus A (RVA) is the most common cause of diarrhea in infants and young children. Here, we aimed to evaluate the efficacy of the cell-free supernatant (CFS) of oraCMS1 in inactivating RSV, H1N1, and RVA in suspension as per ASTM (American Society for Testing and Materials) E1052-20. The mixture of oraCMS1 and these viruses was evaluated at contact times of 1, 2, and 4 h. Virucidal activity was measured using a 50% tissue culture infective dose assay (log₁₀TCID₅₀) after infecting the host cells with the viruses. The CFS of oraCMS1 inactivated RSV by up to 99.0% after 1 h and 99.9% after 2 and 4 h, and H1N1 and RVA were inactivated by up to 99.9% and 99.0% at 2 h, respectively. Although these in vitro results cannot be directly interpreted as implying clinical efficacy, our findings suggest that oraCMS1 provides a protective barrier against RSV, H1N1, and RVA, and therefore, it can help decrease the risk of respiratory tract and intestinal infections.

Biological Functions of Exopolysaccharides from Lactic Acid Bacteria and Their Potential Benefits for Humans and Farmed Animals

Lactic acid bacteria (LAB) synthesize exopolysaccharides (EPS), which are structurally diverse biopolymers with a broad range of technological properties and bioactivities. There is scientific evidence that these polymers have health-promoting properties. Most commercialized probiotic microorganisms for consumption by humans and farmed animals are LAB and some of them are EPS-producers indicating that some of their beneficial properties could be due to these polymers. Probiotic LAB are currently used to improve human health and for the prevention and treatment of specific pathologic conditions. They are also used in food-producing animal husbandry, mainly due to their abilities to promote growth and inhibit pathogens via different mechanisms, among which the production of EPS could be involved. Thus, the aim of this review is to discuss the current knowledge of the characteristics, usage and biological role of EPS from LAB, as well as their postbiotic action in humans and animals, and to predict the future contribution that they could have on the diet of food animals to improve productivity, animal health status and impact on public health.

Staphylococcus epidermidis Controls Opportunistic Pathogens in the Nose, Could It Help to Regulate SARS-CoV-2 (COVID-19) Infection?

Staphylococcus epidermidis is more abundant in the anterior nares than internal parts of the nose, but its relative abundance changes along with age; it is more abundant in adolescents than in children and adults. Various studies have shown that S. epidermidis is the guardian of the nasal cavity because it prevents the colonization and infection of respiratory pathogens (bacteria and viruses) through the secretion of antimicrobial molecules and inhibitors of biofilm formation, occupying the space of the membrane mucosa and through the stimulation of the host’s innate and adaptive immunity. There is a strong relationship between the low number of S. epidermidis in the nasal cavity and the increased risk of serious respiratory infections. The direct application of S. epidermidis into the nasal cavity could be an effective therapeutic strategy to prevent respiratory infections and to restore nasal cavity homeostasis. This review shows the mechanisms that S. epidermidis uses to eliminate respiratory pathogens from the nasal cavity, also S. epidermidis is proposed to be used as a probiotic to prevent the development of COVID-19 because S. epidermidis induces the production of interferon type I and III and decreases the expression of the entry receptors of SARS-CoV-2 (ACE2 and TMPRSS2) in the nasal epithelial cells.

Correction of intestinal microbial composition disturbances as a potential link in complex therapy of patients with COVID-19

The article reflects the potential for correcting intestinal microbiota disorders in the complex therapy of patients with COVID-19. It has been noted that the inclusion of dietary fiber in the diet contributes to protection against disruption of the integrity of the intestinal barrier and may limit bacterial translocation into the systemic circulation. The possibility of using psyllium (Mucofalk) is reflected, the action of which is realized both through its sorption, cytoprotective and anti-inflammatory properties in viral lesions of the gastrointestinal tract, and through stimulation of the own beneficial intestinal microbiota. The paper presents studies of the prospects for the use of probiotics, synbiotics in the complex therapy of patients with COVID-19. Detailed data are provided on the mechanisms of the positive effect of short-chain fatty acid preparations on reducing the severity of the disease in patients with COVID-19. It was noted that taking the drug Zacofalk leads to a significant increase in its own butyrate-producing microbiota (Faecalibacterium prausnitzii) and suppression of the growth of opportunistic flora with pro-inflammatory activity. The results of a recent study are presented showing that in patients with a mild course of COVID infection with respiratory and intestinal symptoms, the administration of Zakofalk for 30 days (3 tablets per day) led to significantly faster stool normalization (by day 7), persistent normalization of the frequency and consistency of stools by the 21st day and a significantly more pronounced regression of bloating and abdominal pain, as well as a decrease in the risk of developing post-infectious irritable bowel syndrome.

Gastrointestinal Microbiota Dysbiosis Associated with SARS-CoV-2 Infection in Colorectal Cancer: The Implication of Probiotics

The complexity of coronavirus disease 2019 (COVID-19)’s pathophysiology is such that microbial dysbiosis in the lung and gastrointestinal (GI) microbiota may be involved in its pathogenic process. GI microbiota dysbiosis has been associated with respiratory disorders, including COVID-19, as well as sporadic colorectal cancer (CRC) through imbalanced microbiota and compromised immune response. It is pertinent to understand the possible role of probiotics in stabilizing the microbial environment and maintaining the integrity of the respiratory and GI tracts in SARS-CoV-2 induced dysbiosis and colorectal carcinogenesis. The long-term implication of SARS-CoV-2 in GI dysbiosis via microbiota-gut-lung cross-talk could increase the risk of new CRC diagnosis or worsen the condition of previously diagnosed individuals. Recent knowledge shows that the immune-modulatory response to probiotics is shifting the beneficial use of probiotics towards the treatment of various diseases. In this review, we highlight the potential impact of probiotics on SARS-CoV-2 infection associated with CRC through microbiota imbalance in COVID-19 patients.

Probiotics Regulating Inflammation via NLRP3 Inflammasome Modulation: A Potential Therapeutic Approach for COVID-19

Inflammasomes are cytoplasmic multiprotein complexes formed by the host's immune system as a response to microbial infection and cellular damage. Many studies have revealed various regulators of NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome activation, while it has been recently shown that NLRP3 is implicated in COVID-19 pathogenesis. At the same time, probiotics counteract the inflammatory process and modulate cytokine release, thus influencing both innate and adaptive immune systems. Herein, we review the immunomodulatory potential of probiotics on the assembly of NLRP3 inflammasome, as well as the pathophysiological mechanisms supporting the use of probiotic bacteria for SARS-CoV-2 infection management, presenting evidence from preclinical studies of the last decade: in vivo, ex vivo, and mixed trials. Data show that probiotics intake is related to NLRP3 inflammasome attenuation and lower levels of inflammation markers, highlighting the beneficial effects of probiotics on inflammatory conditions. Currently, none of the ongoing clinical trials evaluating the effectiveness of probiotics intake in humans with COVID-19 has been completed. However, evidence from preclinical studies indicates that probiotics may block virus invasion and replication through their metabolites, bacteriocins, and their ability to block Angiotensin-Converting Enzyme 2 (ACE2), and by stimulating the immune response through NLRP3 inflammasome regulation. In this review, the beneficial effects of probiotics in the inflammatory process through NLRP3 inflammasome attenuation are presented. Furthermore, probiotics may target SARS-CoV-2 both by blocking virus invasion and replication and by stimulating the immune response through NLRP3 inflammasome regulation. Heterogeneity of the results-due to, among others, different bacterial strains and their metabolites, forms, dosage, and experimental designs-indicates the need for more extensive research.

Bacteriocin producing microbes with bactericidal activity against multidrug resistant pathogens

BACKGROUND

Bacteriocins are proteins or peptides synthesized by bacteria that show inhibitory or killing activities against various bacteria. Bacteriocins are mainly considered for effective alternatives to different commercial antibiotics, preservatives in the food and pharmaceutical industries.

OBJECTIVES

To screen and analyze novel bacteriocin-producing bacteria from the fermented food shidal for antibacterial activity against food pathogens and their molecular interactions studied through computationally.

METHODS

In this study, a strain Lactobacillus plantarum LA21 was isolated from the fermented food shidal identified based on morphological, biochemical, and 16S rDNA gene sequencing. The potent bacterium was subjected to improve bacteriocins production and characterized. Antimicrobial activity against drug-resistant bacteria and minimum inhibitory concentration (MIC) were determined. The bacteriocin was treated with proteolytic enzymes, and the mechanism of action on food pathogens was analyzed. Molecular docking studies were carried out as GLIDE module in the maestro tool of Schrodinger Software.

RESULTS

Bacteriocin was effective against pathogens such as Bacillus pumilus, Bacillus amyloliquefaciens, Staphylococcus aureus, and Listeria monocytogenes, with the most negligible MIC value was detected in L. monocytogenes. Furthermore, the depleted viability of bacterial cells indicated bacteriocin-induced cell lysis in L. monocytogenes via bactericidal activity. In addition, proteolytic enzyme digested bacteriocins revealed bacteriocin-like substances. Finally, molecular docking was performed to study the interactions between the targets and bacteriocins, results in relative intense contact with minimally 3 Å distance.

CONCLUSIONS

The characteristic features of these bacteriocin-like molecules revealed that L. plantarum LA21 is a novel bacteriocin-producing bacterial strain to prepare novel antimicrobial drugs, feed additives or preservatives for future use in livestock and food industries.

Effects of Different Fermented Feeds on Production Performance, Cecal Microorganisms, and Intestinal Immunity of Laying Hens

Simple Summary

Fermented feed exerts beneficial effects on intestinal microorganisms, host health, and production performance. However, the effect of fermented feed on laying hens is uncertain due to the different types of inoculated probiotics, fermentation substrates, and fermentation technology. Hence, this experiment was conducted to investigate the effects of fermented feed with different compound strains on the performance and intestinal health of laying hens. Supplement fermented feed reduced the feed conversion ratio and promoted egg quality. Both dietary treatment (fermented feed A produced Bacillus subtilis, Lactobacillus, and Yeast and fermented feed B produced by C. butyricum and L. salivarius) influenced intestinal immunity and regulated cecal microbial structure. This may be because the metabolites of microorganisms in fermented feed and the reduced pH value inhibited the colonization of harmful bacteria, improved the intestinal morphology, and then had a positive impact on the production performance and albumen quality of laying hens.

Abstract

This experiment was conducted to investigate the effects of different compound probiotics on the performance, cecal microflora, and intestinal immunity of laying hens. A total of 270 Jing Fen No.6 (22-week-old) were randomly divided into 3 groups: basal diet (CON); basal diet supplemented with 6% fermented feed A by Bacillussubtilis,Lactobacillus, and Yeast (FA); and with 6% fermented feed B by C. butyricum and L. salivarius (FB). Phytic acid, trypsin inhibitor, β-glucan concentrations, and pH value in fermented feed were lower than the CON group (p < 0.05). The feed conversion ratio (FCR) in the experimental groups was decreased, while albumen height and Haugh unit were increased, compared with the CON group (p < 0.05). Fermented feed could upregulate the expression of the signal pathway (TLR4/MyD88/NF-κB) to inhibit mRNA expression of pro-inflammatory cytokines (p < 0.05). Fermented feed promoted the level of Romboutsia (in the FA group) Butyricicoccus (in the FB group), and other beneficial bacteria, and reduced opportunistic pathogens, such as Enterocooccus (p < 0.05). Spearman’s correlations showed that the above bacteria were closely related to albumen height and intestinal immunity. In summary, fermented feed can decrease the feed conversion ratio, and improve the performance and intestinal immunity of laying hens, which may be related to the improvement of the cecal microflora structure.