Non-pathogenic Bacteria Research Articles

The benefits of Lactiplantibacillus plantarum: From immunomodulator to vaccine vector.

Probiotics have been increasingly recognized for positively influencing many aspects of human health. Lactiplantibacillus plantarum (L. plantarum), a non-pathogenic bacterium, previously known as Lactobacillus plantarum, is one of the lactic acid bacteria commonly used in fermentation. The probiotic properties of L. plantarum have highlighted its health benefits to humans when consumed in adequate amounts. L. plantarum strains primarily enter the body orally and alter intestinal microflora and modulate the immune responses in their host; thereby benefiting human health. Furthermore, the use of L. plantarum as vaccine vectors delivering mucosal antigens has been shown to be a promising strategy. These aspects, from Immunomodulation to vaccine delivery by L. plantarum in preclinical settings, are highlighted in this review. Along these lines, construction of a recombinant L. plantarum strain expressing a B cell multi-peptide, as a future vaccine to modulate immunity and confer anti-tumor effect by targeting Her-2/neu-overexpressing cancers in local and distal sites, is also presented and discussed.

A single-plasmid-based, easily curable CRISPR/Cas9 system for rapid, iterative genome editing in Pseudomonas putida KT2440

BackgroundPseudomonas putida KT2440, a non-pathogenic soil bacterium, is a key platform strain in synthetic biology and industrial applications due to its robustness and metabolic versatility. Various systems have been developed for genome editing in P. putida, including transposon modules, integrative plasmids, recombineering systems, and CRISPR/Cas systems. However, rapid iterative genome editing is limited by complex and lengthy processes.ResultsWe discovered that the pBBR1MCS2 plasmid carrying the CRISPR/Cas9 module could be easily cured in P. putida KT2440 at 30 oC. We then developed an all-in-one CRISPR/Cas9 system for yqhD and ech-vdh-fcs deletions, respectively, and further optimized the editing efficiency by varying homology arm lengths and target sites. Sequential gene deletions of vdh and vanAB were carried out rapidly using single-round processing and easy plasmid curing. This system’s user-friendliness was validated by 3 researchers from two labs for 9 deletions, 3 substitutions, and 2 insertions. Finally, iterative genome editing was used to engineer P. putida for valencene biosynthesis, achieving a 10-fold increase in yield.ConclusionsWe developed and applied a rapid all-in-one plasmid CRISPR/Cas9 system for genome editing in P. putida. This system requires less than 1.5 days for one edit due to simplified plasmid construction, electroporation and curing processes, thus accelerating the cycle of genome editing. To our knowledge, this is the fastest iterative genome editing system for P. putida. Using this system, we rapidly engineered P. putida for valencene biosynthesis for the first time, showcasing the system’s potential for expanding biotechnological applications.

Urbanization enhances consumer protist-driven ARGs dissemination in riverine ecosystems.

Despite the emergence of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARBs), how biological inter-trophic interactions, modulated by watershed urbanization, shape the resistome remains unexplored. We collected water samples from the highly urbanized (western: 65% built land, sewage-affected) and lesser-urbanized (northern: 25% built land, drinking water source) downstream tributaries of the Jiulong River in southeast China over dry and wet seasons. We utilized metagenomic and amplicon (16S and 18S rDNA) sequencing to investigate the relationships among microeukaryotic algae, consumer protists, bacterial communities, and the resistome. Metagenomic results showed that ARG-MGE-carrying contigs (mobile ARGs), rather than ARG-carrying contigs (non-mobile ARGs), exhibited more pronounced discrepancies between tributaries. A higher total abundance of ARGs and a greater number of co-shared ARGs between pathogen and non-pathogen bacteria were observed in the more urbanized western tributary. Structural equation modeling revealed that consumer protist-bacteria and algae-bacteria cohesions predominantly influenced the resistome in the western and northern tributaries, respectively. Additionally, consumer protists had more significant associations (511 out of 634) with bacteria carrying mobile ARGs in western tributary, while algae had more significant associations (73 out of 105) in northern tributary. These results highlight the distinct inter-trophic driving factors of the resistome modulated by watershed urbanization.

Microfluidic Chip-based Enrichment and Nucleic Acid Extraction for Quantitative Detection of Mycobacterium Smegmatis in Aerosols.

Tuberculosis (TB) is ranked as the third most prevalent infectious disease globally. Early detection and treatment are crucial for effective management. Conventional diagnostic methods primarily rely on sputum samples, which present challenges in accessibility and have limited accuracy in certain populations such as children, individuals with HIV, and those with extrapulmonary TB. To address the need for point-of-care diagnostics, this study introduces a rapid diagnostic approach for TB using exhaled breath aerosol as a more easily obtainable specimen. Mycobacterium smegmatis, a non-pathogenic bacterium genetically similar to Mycobacterium tuberculosis, is used as a surrogate organism. The method involves the use of microfluidic chips for concentrating and electrolyzing mycobacteria in the aerosol, followed by extracting and quantifying nucleic acids using real-time fluorescence quantitative PCR. Notably, successful enrichment and quantification of bacterial content were achieved even at a minimal bacterial aerosol concentration of 104 CFU/mL. The developed chips are characterized by their cost-effectiveness, ease of use, high bacterial enrichment, efficient nucleic acid extraction, and low detection threshold (4.4 × 10-18 mol/L). This innovative approach offers a promising method for early TB screening and opens avenues for the rapid identification of other aerosol-transmitted diseases.

Differential substrate preferences IN ACTINOBACTERIAL protein O-MANNOSYLTRANSFERASES and alteration of protein-O-MANNOSYLATION by choice of secretion pathway.

Protein-O-mannosylation (POM) is a form of O-glycosylation that is ubiquitous and has been studied extensively throughout in fungi and animals. The key glycosyltransferase, protein O-mannosyltransferase (PMT), a member of family GT-39, is also found in over 3,800 bacterial genomes but has only been minimally examined from prokaryotes. In prokaryotes POM has only been investigated in terms of pathogenicity (in Mycobacterium tuberculosis) even though there are far more non-pathogenic bacteria that appear to carry out POM. To date, there is no consensus on what benefit POM imparts to the non-pathogenic bacteria that can perform it. Through the generation of a POM deficient mutant of Corynebacterium glutamicum - a widely utilized and known protein O-mannosylating actinobacteria - this work shows that even closely related actinobacterial GT-39s (the enzymes responsible for the initiation of POM) can have different substrate specificities for targets of POM. Moreover, presented here is evidence that POM does not only occur in a SEC-dependent manner; POM also occurs with TAT and non-SEC secreted substrates in a specific and likely tightly regulated manner. Together these results highlight the need for further biochemical characterization of POM in these and other bacterial species to help elucidate the true nature of its biological functions.

An update on recombinant vaccines against leishmaniasis.

Leishmaniasis is a parasitic disease caused by various species of the Leishmania parasite, manifesting in visceral (VL), cutaneous (CL), and mucocutaneous (MCL) forms. To combat this debilitating disease, various vaccines candidates including proteins, DNA, vectors, adjuvants, and recombinant whole parasites have been developed and tested experimentally and preclinically against several Leishmania species. Some vaccines have already entered human clinical trials. These vaccines aim to induce protective immunity using specific antigens. This review examines all efforts to develop recombinant vaccines against the parasite, analyzing successes including commercially available canine vaccines and the overall challenges faced in the quest to eradicate the disease. Additionally, recent advances in vaccine delivery systems, such as viral vectors and non-pathogenic bacteria, offer promising avenues to enhance immunogenicity and improve the targeted delivery of antigens, potentially leading to more effective and long-lasting immune responses. By understanding past and current efforts, future strategies can be refined to create more effective vaccines and ultimately control or eradicate this parasitic disease.

Prevalence, virulence potential, antibiotic resistance profile, heavy metal resistance genes of Listeria innocua: A first study in consumed foods for assessment of human health risk in Northern Turkey.

Listeria (L.) innocua is typically considered a non-pathogenic bacterium that can sometimes act as an opportunistic pathogen in severely immunocompromised patients. However, it plays an important role in food safety because it acts as an indicator organism for potential contamination and the effectiveness of sanitation methods. The aim of this study was to determine the prevalence, virulence genes, antibiotic resistance profiles, heavy metal and disinfectant resistance genes of L. innocua isolates from animal-derived foods. In this study, we isolated and characterized 39 L. innocua strains recovered from commonly 400 consumed beef meat, fresh fish meat, raw cow milk, and traditional cheese samples collected in Giresun, Turkey. The occurrence of virulence-associated genes was detected, such as plcA (97.4%), iap (35.8%), and hlyA (15.3%). A high incidence of resistance was recorded for fusidic acid (100%), followed by oxacillin (97.4%), clindamycin (82%), trimethoprim/sulfamethoxazole (69.2%), benzylpenicillin (41%), nitrofurantoin (35.8%), and fosfomycin (35.8%). Overall, 100% (39/39) of the isolates were resistant to at least one antibiotic, while 92.3% (36/39) of the isolate strains were multidrug resistant in the antimicrobial susceptibility tested. Among the L. innocua isolates (n = 39), 51.2%, 38.4%, 20.5%, 7.6%, 5.1%, 2.5%, and 2.5% were positive for qacH, cadA1, qacE, qacEΔ1-sul, qacJ, qacF, and qacG heavy metal and disinfectant resistance genes, respectively. The results highlight the need for more comprehensive studies to understand the monitoring and surveillance of L. innocua and their potential hazards to both humans and animals.

Identification and characterization of a surfactin from Pseudomonas gessardii: A symbiotic bacterium with potent anticancer activity

Prasiola japonica, traditionally used as food and folk medicine in South Korea, exerts pharmacological properties, including antioxidant, anti-inflammatory, antidiabetic, and anticancer effects. In this study, we explored symbiotic microbes associated with P. japonica and identified Pseudomonas gessardii as a nonpathogenic symbiotic bacterium through 16 S rDNA sequencing. Bioactivity-guided fractionation of P. gessardii ethanol extracts, utilizing a series of non-polar to polar solvents, led to the isolation of a single bioactive compound (SF10) from the ethyl acetate fraction. Structural analysis using LC-MS and NMR spectroscopy identified SF10 as surfactin C15, a lipopeptide consisting of 7 amino acids and a β-hydroxy fatty acid chain containing 15 carbon atoms. This represents the first discovery of surfactin production in P. gessardii, expanding known surfactin-producing genera beyond Bacillus. In HT-29 colorectal cancer cells, surfactin C15 demonstrated significant anticancer activity through multiple mechanisms: inhibition of cancer stem cell marker CD133 expression, upregulation of pro-apoptotic factors (CHOP, PUMA, DR5), and modulation of cell cycle regulators (CDKN1A,CCNE1, CDK5). Furthermore, surfactin C15 induced necrotic cell death, confirmed by increased lactate dehydrogenase release and flow cytometry analysis showing dose-dependent increases in necrotic cell populations. This study reveals a novel source of surfactin with unique cancer cell-targeting properties, particularly through its ability to induce necrosis in colorectal cancer cells, suggesting potential therapeutic applications in cancer treatment.

A conserved two-component system senses intracellular iron levels and regulates redox balance in Mycobacterium spp.

For bacteria, an intricate coordination between sensing and regulating iron levels and managing oxidative stress is required as their levels are tightly interlinked. While various oxidative stress and heme-based redox sensors have been reported for both pathogenic and non-pathogenic bacteria, the mechanisms governing the modulation of intracellular iron levels in response to changes in redox status remain unclear. In this study, a gene-inactivated strain of mycobacterial sensor kinase PdtaS showed dysregulated expression of genes associated with iron metabolism, including Fe-S clusters, NADH dehydrogenases, and iron uptake. The strain showed poor growth in nutrient-limiting conditions, a defect rescuable by heme but not by Fe3+ supplementation. This observation was associated with the PAS domain of the PdtaS sensor kinase. Biochemical and biophysical experiments established heme-binding to the PAS domain and its inhibitory effect on PdtaS auto-kinase activity, suggesting that the absence of heme induces activation of this sensor kinase. Interestingly, despite having an endogenous heme biosynthetic pathway or even external heme supplementation, the ∆pdtaS mutant exhibited persistent low intracellular iron levels concomitant with elevated oxidative stress. Antioxidant supplementation mitigated growth defects, emphasizing the link between oxidative stress, intracellular iron levels, and PdtaS activity. RNA-IP identified key targets associated with redox homeostasis and iron metabolism as targets of the PdtaR response regulator. The study proposes a novel role for the PdtaS-PdtaR TCS in sensing heme, regulation of intracellular iron levels, and redox balance.IMPORTANCEThe research article investigates the intricate interplay between bacteria's ability to take and utilize iron without inducing excess iron's toxic effects, including oxidative stress. The study shows that bacteria achieve this by sensing intracellular iron available as heme through a sensory protein PdtaS, which turns off when heme is in excess and prevents iron uptake and iron efflux. The process shields bacteria from generating Fe-dependent free radicals and allows it to maintain viability. The absence of sensor kinase abrogates all these processes, increasing bacteria susceptibility to ROS and thereby slowing growth. This feature of the sensor kinase PdtaS makes it an attractive co-therapeutic target for tuberculosis therapy, where its inhibition will prevent iron uptake, even in the presence of low iron, thereby halting bacterial proliferation.

Degradation mechanism of difructose dianhydride III in Blautia species.

Di-fructofuranose 1,2':2,3' dianhydride (DFA-III) is a cyclic fructo-disaccharide, which is produced by the condensation of two fructose molecules via the caramelization or enzymatic reaction of inulin fructotransferase. A strain of Blautia producta was known to utilize DFA-III as a carbohydrate source; however, the mechanisms remain unclear. In this study, we characterized the glycoside hydrolase (GH) family 91 DFA-III hydrolase (DFA-IIIase) from B. parvula NBRC 113351. Recombinant BpDFA-IIIase catalyzed the reversible conversion of DFA-III to inulobiose, which is further degraded to fructose by the cooperative action of DFA-IIIase and GH32 β-D-fructofuranosidase. DFA-III was utilized in several Blautia species with a gene cluster for DFA-III degradation (e.g., B. parvula NBRC 113351, B. hydrogenotrophica JCM 14656, and B. wexlerae JCM 35486), but not by B. wexlerae JCM 31267, which does not possess the gene cluster. Furthermore, B. hansenii JCM 14655, which cannot metabolize fructose, could not utilize DFA-III; however, it could degrade DFA-III to fructose in the presence of DFA-III-degrading enzymes. Fecal fermentation tests showed that Blautia species are important gut microbe for degrading DFA-III. KEY POINTS: • BpDFA-IIIase is the first characterized DFA-IIIase in intestinal non-pathogenic bacteria. • DFA-IIIase is widely conserved in Blautia species. • DFA-III is degraded to d-fructose through inulobiose by the cooperative action of DFA-IIIase and β-d-fructofuranosidase.

Effect of Probiotic Supplementation in Diet on Egg Production, Egg Quality, Intestinal Morphology and Bacterial Population in Caecum of Laying Hens

The objective of this study was to study the effect of probiotic supplementation in diet on egg production, egg quality, intestinal morphology, and bacterial population in caecum of laying hens. A total of 768 Lohmann Brown-Classic laying hens, aged 42 - 54 weeks, were used. The laying hens were divided into 3 groups, each with 8 subgroups of 32 birds each. The experiment was planned to use a completely randomized design method. The 3 experimental groups were classified based on their dietary treatment as follows: 1) Basal diet (without probiotic supplementation), 2) Basal diet with probiotic 0.01 and 0.02 % in 3, respectively. Data was collected for 12 weeks. Adding probiotic in the diet was no significant difference on egg production, egg quality, and bacterial population in caecum. However, probiotic supplementation in the diet increased villi height of the duodenum significantly improved (p < 0.02), villi height per depth crypt of the duodenum significantly improved (p < 0.05), villi height per depth crypt of the jejunum significantly improved (p < 0.01), and villi height per depth crypt of the ileum significantly improved (p < 0.02). Therefore, studies have shown that dietary probiotic supplementation can improved small intestinal morphology are the most important indexes for measuring the digestive and absorption function of the small intestine are more efficient. HIGHLIGHTS Probiotic (Bacillus subtilis) is a gram-positive, non-pathogenic bacterium that can inhibit digestive enzymes such as protease, amylase, and lipase. These enzymes help increase the efficiency of digestion and absorption of nutrients. As a result of the working mechanism of Bacillus subtilis, it helps strengthen the intestinal wall, eliminates pathogenic microorganisms, reduces damaged intestinal mucosal cells, and improves intestinal absorption, resulting in increased production. Effect of probiotic (Bacillus subtilis) supplementation in laying hen diets on total bacterial load in appendix. No difference was found in the load of total bacteria and Escherichia coli (P > 0.05). Its beneficial properties stimulate the growth of beneficial bacteria in the intestines, such as Bifidobacteria sp. and Lactobacillus sp., causing the production of lactic acid, which makes the colon more acidic, resulting in inhibition of the growth of pathogenic microorganisms. GRAPHICAL ABSTRACT

BglaTNB6, a tailocin produced by a plant-associated nonpathogenic bacterium, prevents rice seed-borne bacterial diseases.

Rice seed-borne diseases caused by the bacterial pathogens Burkholderia glumae and B. plantarii pose a major threat to rice production worldwide. To manage these diseases in a sustainable manner, a biocontrol strategy is crucial. In this study, we showed that B. gladioli NB6 (NB6), a nonpathogenic bacterium, strongly protects rice from infection caused by the above-mentioned pathogens. NB6 was isolated from the indica rice cultivar Nona Bokra seedlings, which possesses genetic resistance to B. glumae. We discovered that cell suspensions of NB6 and its culture filtrate suppressed the disease symptoms caused by B. glumae and B. plantarii in rice seedlings, which indicated that NB6 secretes a plant-protective substance extracellularly. Through purification and mass spectrometry analysis of the culture filtrate, combined with transmission electron microscopy and mutant analysis, the substance was identified as a tailocin and named BglaTNB6. Tailocins are bacteriotoxic multiprotein structures morphologically similar to headless phage tails. BglaTNB6 exhibited antibacterial activity against several Burkholderia species, including B. glumae, B. plantarii, and B. gladioli, suggesting it can prevent pathogen infection. Interestingly, BglaTNB6 greatly contributed only to the biocontrol activity of NB6 cell suspensions against B. plantarii, and not against B. glumae. BglaTNB6 was shown to be encoded by a prophage locus lacking genes for phage head proteins, and a B. gladioli strain with the coded BglaTNB6-like locus equipped with phage head proteins failed to prevent rice seedlings from being infected with B. plantarii. These results suggested that BglaTNB6 may enhance the competitiveness of NB6 against a specific range of bacteria. Our study also highlights the potential of tailocin-producing endophytes for managing crop bacterial diseases.

Microbiome-derived metabolite effects on intestinal barrier integrity and immune cell response to infection.

The gut microbiota exerts a significant influence on human health and disease. While compositional changes in the gut microbiota in specific diseases can easily be determined, we lack a detailed mechanistic understanding of how these changes exert effects at the cellular level. However, the putative local and systemic effects on human physiology that are attributed to the gut microbiota are clearly being mediated through molecular communication. Here, we determined the effects of gut microbiome-derived metabolites l-tryptophan, butyrate, trimethylamine (TMA), 3-methyl-4-(trimethylammonio)butanoate (3,4-TMAB), 4-(trimethylammonio)pentanoate (4-TMAP), ursodeoxycholic acid (UDCA), glycocholic acid (GCA) and benzoate on the first line of defence in the gut. Using in vitro models of intestinal barrier integrity and studying the interaction of macrophages with pathogenic and non-pathogenic bacteria, we could ascertain the influence of these metabolites at the cellular level at physiologically relevant concentrations. Nearly all metabolites exerted positive effects on barrier function, but butyrate prevented a reduction in transepithelial resistance in the presence of the pathogen Escherichia coli, despite inducing increased apoptosis and exerting increased cytotoxicity. Induction of IL-8 was unaffected by all metabolites, but GCA stimulated increased intra-macrophage growth of E. coli and tumour necrosis-alpha (TNF-α) release. Butyrate, 3,4-TMAB and benzoate all increased TNF-α release independent of bacterial replication. These findings reiterate the complexity of understanding microbiome effects on host physiology and underline that microbiome metabolites are crucial mediators of barrier function and the innate response to infection. Understanding these metabolites at the cellular level will allow us to move towards a better mechanistic understanding of microbiome influence over host physiology, a crucial step in advancing microbiome research.

B-095 The level of procalcitonin is a biomarker for differentiation between pathogenic and non-pathogenic bacteria

Abstract Background Sepsis is caused by bacteria infected in the bloodstream and the body’s inability to control inflammation. Procalcitonin (PCT) is a biomarker of infection in patients with sepsis, the severity of the infection, and whether the patient is responding to therapy. Thus, diagnostics and early treatment are very important for doctors and patients. In a hospital concerned with sepsis in patients, a doctor ordered a PCT level and hemoculture before treating an antibiotic on a patient whose doctor suspects sepsis. The objective of this study is to compare the PCT level in the blood and hemoculture results in patients. Methods In this study, we evaluated the patients who suspected sepsis disease and were admitted to the Uttaradit Hospital, Thailand, between October 2022 and October 2023. The patients were divided into two groups: those with positive hemoculture results (sepsis group) and those with negative hemoculture results (non-sepsis group). The PCT levels in the blood were measured on Alinity ci analyzers and compared between the two groups to determine if there was a significant difference. Additionally, clinical data such as age and gender were collected to assess their potential impact on PCT levels and hemoculture results. Results The results of the study showed that the sepsis group had significantly higher PCT levels compared to the non-sepsis group. And the difference in PCT levels between the sepsis and non-sepsis groups was considerably more marked for patients older than 60. Furthermore, there was no significant difference in PCT levels based on gender in either group. Conclusions This finding suggests that measuring PCT levels could potentially serve as a diagnostic tool for identifying sepsis in patients. A patient age may be a contributing factor to the severity of sepsis and could potentially be used as a marker for early detection and intervention in older patients. Further research is needed to validate these results and explore the clinical implications of using PCT as a biomarker for sepsis diagnosis.

EvoraPlus Oral Probiotic Tablet: New paradigm for Caries Prevention in Children.

According to the World Health Organization, probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit to the host. The use of oral probiotics in children to improve oral health may lead to nonpathogenic bacteria replacing cariogenic bacteria. The Evora Plus oral probiotics tablet is the first such oral probiotics tablet containing a proprietary blend of three select species of naturally occurring oral bacteria, each with a specific function for maintaining a healthy oral environment. These strains include Streptococcus oralis KJ3sm, Streptococcus uberis KJ2sm, and Streptococcus rattus JH145. To compare the levels of salivary total bacterial count, salivary pH levels, and salivary S. mutans count before and after consumption of the Evora Plus oral probiotic tablet. Around 40 caries-free schoolchildren from Daksh International School, Gadarwara, Madhya Pradesh, India, aged 12-14 years, were selected and divided equally into two groups-group A, in which total salivary bacterial count and pH were evaluated, and group B, in which salivary S. mutans count and pH were evaluated. These groups were further subdivided into group A1 and group B1, which served as the control groups not receiving the Evora Plus oral probiotic tablet, and group A2 and group B2, which were the test groups consuming the Evora Plus oral probiotic tablet for 30 days. Assessment of salivary samples for total bacterial count was done at baseline and after 30 days for groups A1 and B1. Salivary pH estimation was done at baseline and after 30 days for the entire group, and salivary S. mutans count was done at baseline and after 30 days for groups A2 and B2. Salivary pH level was checked using a digital pH meter; nutrient agar was used for salivary total bacterial count, while Mitis salivarius bacitracin agar was used for salivary S. mutans count. The number of colonies was counted and subjected to statistical analysis using unpaired and paired Student's t-test. The study showed a significant reduction in salivary total bacterial count and salivary S. mutans counts, as well as a significant increase in salivary pH after 30 days in the Evora Plus oral probiotic group compared with the group not receiving the Evora Plus oral probiotic tablet. Cariogenic microorganisms could be reduced by an oral probiotic formulation. Thus, the use of the Evora Plus oral probiotic tablet could be recommended for the prevention of enamel demineralization. Mishra A, Saurabh S. EvoraPlus Oral Probiotic Tablet: New paradigm for Caries Prevention in Children. Int J Clin Pediatr Dent 2024;17(9):1044-1048.

Microbial growth on temporary pacemaker leads post-TAVR: pathogen spectrum and clinical implications.

Transcatheter aortic valve replacement (TAVR) is an established treatment option for patients with symptomatic severe aortic stenosis across all stages of surgical risk. Rapid pacing during the procedure and the risk for the occurrence of conduction disturbances after TAVR requires the pre-interventional insertion of a temporary pacemaker (TP). However, this approach poses risks, including the risk of infection. For this reason, the following study aimed to investigate microbial growth on temporary pacemaker leads and its association with outcome post-TAVR and to identify associated pathogens and related risk factors. A prospective study was conducted including 344 patients undergoing TAVR at the Heart Centre Bonn. Of these, 97 patients did not require TP leads as they already had permanent pacemakers; this group was considered as comparison group. The TP leads of the remaining 247 patients were removed, sonicated, and cultured to investigate bacterial growth over a period of 14days. Finally, we compared patients without microbial growth (n = 184) and patients with microbial growth (n = 63). The primary endpoint of the study was 30-day all-cause mortality, secondary endpoints were periprocedural infections, the length of the postprocedural hospital stay, 30-day major vascular complications and the 30-day stroke rate. The majority of cases (74.5%) showed no bacterial growth. In the remaining cases (25.5%), diverse microorganisms were identified, mostly non-pathogenic bacteria. The statistical analysis revealed no significant differences between groups according to microbial growth in terms of 30-day mortality (p = 0.446), postprocedural hospital stay (p = 0.401), periprocedural infections (p = 0.434), 30-day major vascular complications (p = 1.0), and 30-day stroke rate (p = 1.0). Notably, the timing of sheath insertion was significantly associated with microbial growth; sheath placement more than 2days prior to the procedure was associated with a significantly higher risk of microbial growth (OR: 2.1; 95% CI 1.1-4.3) (p = 0.030). The presence of temporary leads does not significantly impact clinical outcomes, irrespective of bacterial growth on the lead. However, the timing and duration of sheath placement plays a crucial role in contamination incidence. Thus, temporary leads/sheaths should be placed shortly before the procedure and removed promptly to reduce the risk of contamination/infection.

Immunogenicity and protective efficacy of a recombinant lactococcus lactis vaccine against HSV-1 infection

BackgroundHerpes simplex virus type 1 (HSV-1) is a major cause of viral encephalitis, genital mucosal infections, and neonatal infections. Lactococcus lactis (L. lactis) has been proven to be an effective vehicle for delivering protein antigens and stimulating both mucosal and systemic immune responses. In this study, we constructed a recombinant L. lactis system expressing the protective antigen glycoprotein D (gD) of HSV-1.ResultsTo improve the stability and persistence of antigen stimulation of the local mucosa, we inserted the immunologic adjuvant interleukin (IL)-2 and the Fc fragment of IgG into the expression system, and a recombinant L. lactis named NZ3900-gD-IL-2-Fc was constructed. By utilizing this recombinant L. lactis strain to elicit an immune response and evaluate the protective effect in mice, the recombinant L. lactis vaccine induced a significant increase in specific neutralizing antibodies, IgG, IgA, interferon-γ, and IL-4 levels in the serum of mice. Furthermore, in comparison to the mice in the control group, the vaccine also enhanced the proliferation levels of lymphocytes in response to gD. Moreover, recombinant L. lactis expressing gD significantly boosted nonspecific immune reactions in mice through the activation of immune-related genes. Furthermore, following the HSV-1 challenge of the murine lung mucosa, mice inoculated with the experimental vaccine exhibited less lung damage than control mice.ConclusionOur study presents a novel method for constructing a recombinant vaccine using the food-grade, non-pathogenic, and non-commercial bacterium L. lactis. The findings indicate that this recombinant vaccine shows promise in preventing HSV-1 infection in mice.

Virulent Effector Hasp155 of Puccinia striiformis f. sp. tritici Suppresses Plant Immunity and Promotes Fungus Infection.

As a kind of obligate biotrophic fungus, Puccinia striiformis f. sp. tritici (Pst) secretes vast effectors via haustoria to host cells during the infection to inhibit host defense responses and promote fungal invasion. In this study, based on the completion of genome sequencing and haustorial transcriptome sequencing of Pst, we identified a Pst effector (Hasp155) that is significantly induced in the early stage of Pst infection to wheat. The 18 N-terminal amino acids of Hasp155 encoded a signal peptide with a secretory function. Transient expression of Hasp155 in Nicotiana benthamiana inhibited Bax-induced cell death as well as chitin-triggered callose deposition and defense-related gene expression. Moreover, delivery of the Hasp155 protein into wheat cells via type three secretion systems (TTSS) led to reduced plant immunity to nonpathogenic bacteria and to the avirulent Pst race with decreased H2O2 accumulation and promoted Pst development. Furthermore, transgenic overexpression of Hasp155 significantly renders wheat resistance susceptible, resulting in a decreased defense response and increased Pst pathogenicity. Overall, these results indicate that Hasp155 is an important effector of Pst pathogenicity by suppressing plant immunity.

The Genetic Architecture of Arabidopsis thaliana in Response to Native Non-Pathogenic Bacterial Species Revealed by Genome-Wide Association Mapping in Field Conditions

Non-pathogenic bacteria can substantially contribute to plant health by mobilizing and supplying nutrients, providing protection against pathogens, and alleviating abiotic stresses. However, the number of genome-wide association studies reporting the genetic architecture of the response to individual members of the beneficial microbiota remains limited. In this study, we established a genome-wide association study under field conditions to estimate the level of genetic variation and the underlying genetic architecture among 162 accessions of Arabidopsis thaliana originating from 54 natural populations in the southwest of France in response to 13 strains of seven of the most abundant and prevalent non-pathogenic bacterial species isolated from the leaf compartment of A. thaliana in the same geographical region. Using a high-throughput phenotyping methodology to score vegetative growth-related traits, extensive genetic variation was detected among A. thaliana accessions in response to these leaf bacteria, at both the species and strain levels. The presence of crossing reaction norms between each strain and the mock treatment indicates that declaring a strain as a plant growth-promoting bacterium is highly dependent on the host genotype tested. In line with the strong genotype-by-genotype interactions, we detected a complex and highly flexible genetic architecture between the 13 strains. Finally, the candidate genes underlying the quantitative trait loci revealed significant enrichment in several biological pathways, including cell, secondary metabolism, signaling, and transport. Altogether, plant innate immunity appears as a significant source of natural genetic variation in plant–microbiota interactions and opens new avenues for better understanding the ecologically relevant molecular dialog during plant–microbiota interactions. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Evaluation of scarless wound healing through nanohydrogel infused with selected plant extracts

In this study, a CMC-based hydrogel nanocomposite was prepared and loaded with bioactive components along with silver nanoparticles. For aesthetic reasons, an alternative was found that can result in scar-free wound healing. To accelerate scar-free wound healing, bioactive phytoproducts such as aloe vera, curcumin, and peel of plantain were blended along with the nanocomposite hydrogel that contained silver nanoparticles (CMC + Ag + P). The prepared hydrogels proved to have good antibacterial activity against both Gram-positive (S.aureus) and Gram-negative (E.coli) non-pathogenic bacteria. The prepared hydrogel had an excellent wound-healing ability which was studied using in vitro scratch assay against A375 cell line. The biocompatibility of the hydrogels was proved using an MTT assay. The scar free wound healing was established in Wistar rat model where burn wounds were healed using CMC + Ag + P. The wound healed were compared with only silver (CMC + Ag) and saline treated animals and the histopathological studies, VEGF and PDGF analysis confirmed that the wound healing was scar free after CMC + Ag + P treatment. We could conclude that the presence of plantain peel extract which is a source of ascorbic acid and is rich in vitamin C can aid in scar-free wound healing.