Chitosan and its derivatives regulate lactic acid synthesis during milk fermentation.

Introduction: The influence of chitosan's physicochemical characteristics on the functionality of lactic acid bacteria and the production of lactic acid remains very obscure and contradictory to date. While some studies have shown a stimulatory effect of oligochitosans on the growth of Lactobacillus spp, other studies declare a bactericidal effect of chitosan. The lack and contradiction of knowledge prompted us to study the effect of chitosan on the growth and productivity of L. bulgaricus in the presence of chitosan and its derivatives. Methods: We used high molecular weight chitosan (350 kDa) and oligochitosans (25.4 and 45.3 kDa). The experiment was carried out with commercial strain of L. bulgaricus and the low fat skim cow milk powder reconstituted with sterile distilled water. After fermentation, dynamic viscosity, titratable acidity, pH, content of lactic acid, colony forming units, chitosan and oligochitosans radii were measured in the samples. Fermented dairy products were also examined using sodium dodecyl sulfate electrophoretic analysis, gas chromatography-mass spectrometry and light microscopy. Results and discussion: The results of the study showed that when L. bulgaricus was cultured in the presence of 25.4 kDa oligochitosans at concentrations of 0.0025%, 0.005%, 0.0075% and 0.01%, the average rate of LA synthesis over 24 hours was 11.0 × 10-3 mol/L/h, 8.7 × 10-3 mol/L/h, 6.8 × 10-3 mol/L/h, 5.8 × 10-3 mol/L/h, respectively. The 45.3 kDa oligochitosans had a similar effect, while the average rate of lactic acid synthesis in the control sample was only 3.5 × 10-3 mol/L/h. Notably, 350 kDa chitosan did not affect the rate of lactic acid synthesis compared with the control sample. Interestingly, interaction of chitosan with L. bulgaricus led to a slowdown in the synthesis of propanol, an increase in the content of unsaturated and saturated fatty acids, and a change in the composition and content of other secondary metabolites. The quantity of L. bulgaricus in a sample with 0.01% chitosan exceeded their content in the control sample by more than 1,700 times. At the same chitosan concentration, the fermentation process was slowed down, increasing the shelf life of the fermented milk product from 5 to 17 days while maintaining a high content of L. bulgaricus (6.34 × 106 CFU/g).

Identification and Characterization of Human Breast Milk and Infant Fecal Cultivable Lactobacilli Isolated in Bulgaria: A Pilot Study.

During the last few decades, the main focus of numerous studies has been on the human breast milk microbiota and its influence on the infant intestinal microbiota and overall health. The presence of lactic acid bacteria in breast milk affects both the quantitative and qualitative composition of the infant gut microbiota. The aim of this study was to assess the most frequently detected cultivable rod-shaped lactobacilli, specific for breast milk of healthy Bulgarian women and fecal samples of their infants over the first month of life, in 14 mother-infant tandem pairs. Additionally, we evaluated the strain diversity among the most common isolated species. A total of 68 Gram-positive and catalase-negative strains were subjected to identification using the MALDI-TOF technique. Predominant cultivable populations belonging to the rod-shaped lactic acid bacteria have been identified as Lacticaseibacillus rhamnosus, Limosilactobacillus fermentum, Lacticaseibacillus paracasei, and Limosilactobacillus reuteri. Also, we confirmed the presence of Lactiplantibacillus plantarum and Lactobacillus gasseri. Up to 26 isolates were selected as representatives and analyzed by 16S rRNA sequencing for strain identity confirmation and a phylogenetic tree based on 16S rRNA gene sequence was constructed. Comparative analysis by four RAPD primers revealed genetic differences between newly isolated predominant L. rhamnosus strains. This pilot study provides data for the current first report concerning the investigation of the characteristic cultivable lactobacilli isolated from human breast milk and infant feces in Bulgaria.

Lingonberry (Vaccinium vitis-idaea L.) Fruit Phenolic Bioactivities-A Review of In Vitro and In Vivo Human Studies.

This review is focused on the effects of lingonberry (Vaccinium vitis-idaea L.) fruit phenolic compounds in human in vitro cells and in vivo clinical studies. Studies with lingonberries, lingonberry juice/lingonberry nectar/fermented lingonberry juice, and phenolic fractions with active molecules are reviewed. Lingonberry's bioactive substances have a diverse range of antimicrobial, anti-inflammatory, antiproteolytic, anticancer, and antioxidant properties. Fermentation of lingonberries and modulation of the dysbiotic microbiome to a more symbiotic composition by favoring the growth of lactobacilli and inhibiting the growth of human opportunistic pathogens are discussed. Research results suggest that more studies on humans are needed.

Candidate-Probiotic Lactobacilli and Their Postbiotics as Health-Benefit Promoters.

Lactobacillus species are widely recognized for their probiotic potential, focusing on their mechanisms of health benefits and protection. Here we conducted an in vitro investigation of the probiotic potential with a role in microbiome homeostasis of four strains: Lactiplantibacillus plantarum L6 and F53, Ligilactobacillus salivarius 1, and Lactobacillus helveticus 611. A broad spectrum of antibacterial and antifungal activity was determined. The strain-specific inhibition of Staphylococcus aureus, Streptococcus mutans, Escherichia coli, Pseudomonas aeruginosa, and saprophytic/toxigenic fungi makes them promising as protective cultures. DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic) acid) measurements showed that tested samples had strain-specific capacity for scavenging of radicals. The molecular base for the antioxidant potential of two lyophilized forms of active strains was investigated by electron paramagnetic resonance spectroscopy. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, with fractions of the most active postbiotics obtained by SEC-FPLC (fast protein liquid chromatography) analysis, showed a wide variety of effects on the growth of a K562 myeloid leukemia cell line. The IC50 (half-maximal inhibitory concentration) of L. salivarius 1 was determined to be 46.15 mg/mL. The proven in vitro functionality of the selected lactobacilli make them suitable for development of target probiotics with specific beneficial effects expected in vivo. Further investigations on produced postbiotics and safety have to be completed before they can be considered as scientifically proven probiotic strains.

Impact of postsurgical vaginal microbiome on high-risk HPV infection and recurrence risk in patients with cervical cancer and intraepithelial neoplasia: A retrospective study.

Purpose: This study aimed to determine the effect of postsurgical vaginal microbiome (VM) on high-risk human papillomavirus (hrHPV) infection and the risk of disease recurrence in patients surgically treated for cervical cancer (CC) or intraepithelial neoplasia (CIN). Methods: 207 women who underwent surgical treatment for CC or CIN at the Department of Gynecologic Oncology of the First Affiliated Hospital of University of Science and Technology of China from November 2016 to October 2023 were included. The patients' clinical data, including age, surgical modality, and diagnosis at time of index surgery, were collected retrospectively and analyzed. Associations between postsurgical VM indices, hrHPV infection, cervical cytology, and recurrence were also evaluated. Results: Patient age, surgical modality (whether complete excision of the cervix was performed), and diagnosis at time of index surgery (cervical dysplasia vs. cervical carcinoma) showed no significant association with postsurgical hrHPV infection, cervical cytology, or disease recurrence. However, postsurgical VM imbalance was significantly associated with hrHPV infection status (OR = 4.640, 95 % CI = 2.085-10.460, P < 0.001), abnormal cervical cytology (OR = 3.994, 95 % CI = 1.154-13.826, P = 0.020), and disease recurrence (OR = 3.789, 95 % CI = 1.091-13.154, P = 0.026). Among the specific VM indices, a vaginal pH above 4.5 (OR = 4.570, 95 % CI = 1.640-12.690, P = 0.002), a lactobacilli proportion below 50 % (OR = 3.938, 95 % CI = 1.299-11.934, P = 0.010), and the presence of aerobic vaginitis (AV, OR = 2.425, 95 % CI = 0.996-5.901, P = 0.046) were risk factors for postsurgical recurrence. Conclusion: Postsurgical VM imbalance, especially abnormal indices, such as a pH above 4.5, a lactobacilli proportion below 50 %, and the presence of AV, was associated with an increased risk of postsurgical recurrence in patients who underwent surgical treatment for CIN and CC. Monitoring and potentially intervening in the VM may improve the prognosis of these patients.

Dental plaque caries related microorganism in relation to demographic factors among a group of Iraqi children.

INTRODUCTION: Streptococcusmutans and lactobacilli are most important bacteria in the pathogenesis of dental caries. Cariogenic microflora has been associated to the primary caregiver transmission and sugary diets.

Synbiotics in patients at risk for spontaneous preterm birth: protocol for a multi-centre, double-blind, randomised placebo-controlled trial (PRIORI).

BACKGROUND: Prematurity remains one of the main causes of neonatal morbidity and mortality. Approximately two thirds of preterm births are spontaneous, i.e. secondary to preterm labour, preterm prelabour rupture of membranes (PPROM) or cervical insufficiency. Etiologically, the vaginal microbiome plays an important role in spontaneous preterm birth (sPTB). Vaginal dysbiosis and bacterial vaginosis are well-known risk factors for ascending lower genital tract infections and sPTB, while a Lactobacillus crispatus-dominated vaginal microbiome is associated with term deliveries. Synbiotics may help to achieve and/or maintain a normal, Lactobacillus-dominated vaginal microbiome. METHODS: We will perform a multi-centre, double-blind, randomised, placebo-controlled trial. Women aged 18 years or older with a singleton pregnancy are eligible for inclusion at 80/7-106/7 weeks gestational age if they have one or more of the following risk factors for sPTB: previous sPTB at 240/7-356/7 weeks, prior PPROM before 360/7 weeks, or spontaneous pregnancy loss at 140/7-236/7 weeks of gestation. Exclusion criteria are multiple gestation, cervix conisation, inflammatory bowel disease, uterine anomaly, and the use of pro-/pre-/synbiotics. Patients will be randomised to oral synbiotics or placebo, starting before 11 weeks of gestation until delivery. The oral synbiotic consists of eight Lactobacillus species (including L. crispatus) and prebiotics. The primary outcome is the gestational age at delivery. Vaginal microbiome analysis once per trimester (at approximately 9, 20, and 30 weeks) and delivery will be performed using metataxonomic sequencing (16S rRNA gene) and microbial culture. Secondary outcomes include PPROM, the use of antibiotics, antenatal admission information, and neonatal outcomes. DISCUSSION: This study will evaluate the effect of oral synbiotics on the vaginal microbiome during pregnancy in a high-risk population and correlate the microbial changes with the gestational age at delivery and relevant pregnancy outcomes. TRIAL REGISTRATION: ClinicalTrials.gov, NCT05966649. Registered on April 5, 2024.

Lactobacilli Cell-Free Supernatants Modulate Inflammation and Oxidative Stress in Human Microglia via NRF2-SOD1 Signaling.

Microglia are macrophage cells residing in the brain, where they exert a key role in neuronal protection. Through the gut-brain axis, metabolites produced by gut commensal microbes can influence brain functions, including microglial activity. The nuclear factor erythroid 2-related factor 2 (NRF2) is a key regulator of the oxidative stress response in microglia, controlling the expression of cytoprotective genes. Lactobacilli-derived cell-free supernatants (CFSs) are postbiotics that have shown antioxidant and immunomodulatory effects in several in vitro and in vivo studies. This study aimed to explore the effects of lactobacilli CFSs on modulating microglial responses against oxidative stress and inflammation. HMC3 microglia were exposed to lipopolysaccaride (LPS), as an inflammatory trigger, before and after administration of CFSs from three human gut probiotic species. The NRF2 nuclear protein activation and the expression of NRF2-controlled antioxidant genes were investigated by immunoassay and quantitative RT-PCR, respectively. Furthermore, the level of pro- and anti-inflammatory cytokines was evaluated by immunoassay. All CFSs induced a significant increase of NRF2 nuclear activity in basal conditions and upon inflammation. The transcription of antioxidant genes, namely heme oxygenase 1, superoxide dismutase (SOD), glutathione-S transferase, glutathione peroxidase, and catalase also increased, especially after inflammatory stimulus. Besides, higher SOD1 activity was detected relative to inflamed microglia. In addition, CFSs pre-treatment of microglia attenuated pro-inflammatory TNF-α levels while increasing anti-inflammatory IL-10 levels. These findings confirmed that gut microorganisms' metabolites can play a relevant role in adjuvating the microglia cellular response against neuroinflammation and oxidative stress, which are known to cause neurodegenerative diseases.

Protective Mechanisms of Vaginal Lactobacilli against Sexually Transmitted Viral Infections.

The healthy cervicovaginal microbiota is dominated by various Lactobacillus species, which support a condition of eubiosis. Among their many functions, vaginal lactobacilli contribute to the maintenance of an acidic pH, produce antimicrobial compounds, and modulate the host immune response to protect against vaginal bacterial and fungal infections. Increasing evidence suggests that these beneficial bacteria may also confer protection against sexually transmitted infections (STIs) caused by viruses such as human papillomavirus (HPV), human immunodeficiency virus (HIV) and herpes simplex virus (HSV). Viral STIs pose a substantial public health burden globally, causing a range of infectious diseases with potentially severe consequences. Understanding the molecular mechanisms by which lactobacilli exert their protective effects against viral STIs is paramount for the development of novel preventive and therapeutic strategies. This review aims to provide more recent insights into the intricate interactions between lactobacilli and viral STIs, exploring their impact on the vaginal microenvironment, host immune response, viral infectivity and pathogenesis, and highlighting their potential implications for public health interventions and clinical management strategies.

Exploring Oral and Vaginal Probiotic Solutions for Women's Health from Puberty to Menopause: A Narrative Review.

The vaginal microbiota (VMB) plays a crucial role in women's health from puberty to menopause. Traditional studies have focused on the microorganisms present within the vaginal environment and their roles in disease onset. However, the dynamic relationship between the VMB and its host remains underexplored. Common narratives emphasize the presence of Lactobacilli spp. as an indicator of vaginal health, yet this does not fully explain the occurrence of asymptomatic yet significant dysbiosis. Moreover, a wide array of bacterial types can inhabit the vaginal environment, suggesting that probiotic Lactobacilli could offer a natural, safe solution for balancing vaginal microbiota. This review examines the current literature on VMB, key factors affecting its composition, and the changes it undergoes during different life stages. Given the health-promoting potential of probiotics, we also examine their role in maintaining a healthy VMB and overall women's health throughout life.

Effectiveness of Combination of Tibolone and Lactobacilli Plus Lactoferrin in Postmenopausal Women with Vulvar Vestibular Pain: A Preliminary Report.

BACKGROUND: Postmenopausal dyspareunia and vulvar pain are common complaints, affecting about 60% of women within a few years after hormone levels begin to decline (such as estrogen and androgen). Atrophic changes mainly located in the vulvar vestibule and vulnerability to vulvovaginal infections in postmenopause could be predisposing factors to the development of vulvar burning/pain and introital dyspareunia (vestibulodynia secondary to atrophy). Tibolone is the most effective and safe alternative for treating menopausal symptoms. The role of Lactobacilli and lactoferrin shows its effectiveness in the treatment of vaginal microbiota dysbiosis. The aim of the present study was to assess the efficacy of the combination of tibolone and an oral-specific Lactobacilli mixture in combination with bovine lactoferrin as synergistic therapy for the treatment of vestibulodynia related to atrophy. METHODS: In this study, we included 35 postmenopausal women with at least 1 year of amenorrhea, affected by vulvar burning/pain and introital dyspareunia. All participants received treatment with open-label, oral Tibolone 2.5 mg and Lactobacilli mixture (5 × 109 CFU per capsule) in combination with bovine lactoferrin (Respecta®). Each product was taken once daily for 90 days. RESULTS: After 90 d of therapy with TIB+ Respecta®, in 30 women that completed the treatment, there was a statistically significant decrease from the baseline in the mean of the Visual Analog Scale for vulvar burning/pain and a reduction in scores in the pain evaluation test. CONCLUSIONS: This study provides evidence that the combination of TIB+ Respecta® was effective in reducing symptoms related to vestibular pain and hypersensitivity in a postmenopausal setting.

Mangosteen extracts: Effects on intestinal bacteria, and application to functional fermented milk products.

Mangosteen (Garcinia mangostana L.) is a tasty, polyphenol-rich tropical fruit. The edible part is highly appreciated by its aroma, taste and texture. The non-edible part, rich in polyphenols, has been traditionally used in Thai medicine. In this work, flavonoids and phenolic acid/derivatives were identified in mangosteen extracts (ME) from edible and non-edible portions. We first studied the effects of MEs on the growth, metabolism, antioxidant capacity, biofilm formation and antimicrobial capacity of eight bifidobacteria and lactobacilli strains from intestinal origin and two commercial probiotic strains (BB536 and GG). ME concentrations higher than 10-20 % were inhibitory for all strains. However, ME concentrations of 5 % significantly (P < 0.01) increased all strains antioxidant capacity, reduced biofilm-formation, and enhanced inhibition against Gram-positive pathogens. To apply these knowledge, bifunctional fermented milk products were elaborated with 5 % ME and individual strains, which were selected taking into account their growth with ME, and the widest range of values on antioxidant capacity, biofilm formation and antimicrobial activity (bifidobacteria INIA P2 and INIA P467, lactobacilli INIA P459 and INIA P708, and reference strain GG). Most strains survived well manufacture, refrigerated storage and an in vitro simulation of major conditions encountered in the gastrointestinal tract. As expected, products supplemented with ME showed higher polyphenol content and antioxidant capacity levels than control. After sensory evaluation, products containing strains INIA P2, INIA P708 and GG outstood as best.

Tween 80™-induced changes in fatty acid profile of selected mesophilic lactobacilli.

Fatty acid profiles are crucial for the functionality and viability of lactobacilli used in food applications. Tween 80™, a common culture media additive, is known to influence bacterial growth and composition. This study investigated how Tween 80™ supplementation impacts the fatty acid profiles of six mesophilic lactobacilli strains (Lacticaseibacillus spp., Limosilactobacillus spp., Lactiplantibacillus plantarum). Analysis of eleven strains revealed 29 distinct fatty acids. Tween 80™ supplementation significantly altered their fatty acid composition. Notably, there was a shift towards saturated fatty acids and changes within the unsaturated fatty acid profile. While some unsaturated fatty acids decreased, there was a concurrent rise in cyclic derivatives like lactobacillic acid (derived from vaccenic acid) and dihydrosterculic acid (derived from oleic acid). This suggests that despite the presence of Tween 80™ as an oleic acid source, lactobacilli prioritize the synthesis of these cyclic derivatives from precursor unsaturated fatty acids. Myristic acid and dihydrosterculic acid levels varied across strains. Interestingly, palmitic acid content increased, potentially reflecting enhanced incorporation of oleic acid from Tween 80™ into membranes. Conversely, cis-vaccenic acid levels consistently decreased across all strains. The observed fatty acid profiles differed from previous studies, likely due to a combination of factors including strain-specific variations and growth condition differences (media type, temperature, harvesting point). However, this study highlights the consistent impact of Tween 80™ on the fatty acid composition of lactobacilli, regardless of these variations. In conclusion, Tween 80™ significantly alters fatty acid profiles, influencing saturation levels and specific fatty acid proportions. This work reveals key factors, including stimulated synthesis of lactobacillic acid, competition for oleic acid incorporation, and strain-specific responses to myristic and dihydrosterculic acids. The consistent reduction in cis-vaccenic acid and the presence of cyclic derivatives warrant further investigation to elucidate their roles in response to Tween 80™ supplementation.

Complete genome sequence of the probiotic Lacticaseibacillus paracasei LPC100 strain from the NORDBIOTIC collection isolated from a human fecal sample.

We report the genome sequence of the human fecal isolate Lacticaseibacillus paracasei LPC100 from the NORDBIOTIC collection, comprising a 3.075 Mb chromosome and three plasmids (61 kb, 12 kb, and 7 kb). Genetic content reveals the strain's beneficial features-complete lactose metabolic pathway, potential production of bacteriocins, and short-chain fatty acids.

Liquorilactobacillus: A Context of the Evolutionary History and Metabolic Adaptation of a Bacterial Genus from Fermentation Liquid Environments.

In the present work, we carried out a comparative genomic analysis to trace the evolutionary trajectory of the bacterial species that make up the Liquorilactobacillus genus, from the identification of genes and speciation/adaptation mechanisms in their unique characteristics to the identification of the pattern grouping these species. We present phylogenetic relationships between Liquorilactobacillus and related taxa such as Bacillus, basal lactobacilli and Ligilactobacillus, highlighting evolutionary divergences and lifestyle transitions across different taxa. The species of this genus share a core genome of 1023 genes, distributed in all COGs, which made it possible to characterize it as Liquorilactobacillus sensu lato: few amino acid auxotrophy, low genes number for resistance to antibiotics and general and specific cellular reprogramming mechanisms for environmental responses. These species were divided into four clades, with diversity being enhanced mainly by the diversity of genes involved in sugar metabolism. Clade 1 presented lower (< 70%) average amino acid identity with the other clades, with exclusive or absent genes, and greater distance in the genome compared to clades 2, 3 and 4. The data pointed to an ancestor of clades 2, 3 and 4 as being the origin of the genus Ligilactobacillus, while the species of clade 1 being closer to the ancestral Bacillus. All these traits indicated that the species of clade 1 could be soon separated in a distinct genus.

Comprehensive characterization of γ-aminobutyric acid (GABA) production by Levilactobacillus brevis CRL 2013: insights from physiology, genomics, and proteomics.

Introduction: Levilactobacillus brevis CRL 2013, a plant-derived lactic acid bacterium (LAB) with immunomodulatory properties, has emerged as an efficient producer of γ-aminobutyric acid (GABA). Notably, not all LAB possess the ability to produce GABA, highlighting the importance of specific genetic and environmental conditions for GABA synthesis. This study aimed to elucidate the intriguing GABA-producing machinery of L. brevis CRL 2013 and support its potential for safe application through comprehensive genome analysis. Methods: A comprehensive genome analysis of L. brevis CRL 2013 was performed to identify the presence of antibiotic resistance genes, virulence markers, and genes associated with the glutamate decarboxylase system, which is essential for GABA biosynthesis. Then, an optimized chemically defined culture medium (CDM) was supplemented with monosodium glutamate (MSG) and yeast extract (YE) to analyze their influence on GABA production. Proteomic and transcriptional analyses were conducted to assess changes in protein and gene expression related to GABA production. Results: The absence of antibiotic resistance genes and virulence markers in the genome of L. brevis CRL 2013 supports its safety for potential probiotic applications. Genes encoding the glutamate decarboxylase system, including two gad genes (gadA and gadB) and the glutamate antiporter gene (gadC), were identified. The gadB gene is located adjacent to gadC, while gadA resides separately on the chromosome. The transcriptional regulator gadR was found upstream of gadC, with transcriptional analyses demonstrating cotranscription of gadR with gadC. Although MSG supplementation alone did not activate GABA synthesis, the addition of YE significantly enhanced GABA production in the optimized CDM containing glutamate. Proteomic analysis revealed minimal differences between MSG-supplemented and non-supplemented CDM cultures, whereas YE supplementation resulted in significant proteomic changes, including upregulation of GadB. Transcriptional analysis confirmed increased expression of gadB and gadR upon YE supplementation, supporting its role in activating GABA production. Conclusion: These findings provide valuable insights into the influence of nutrient composition on GABA production. Furthermore, they unveil the potential of L. brevis CRL 2013 as a safe, nonpathogenic strain with valuable biotechnological traits which can be further leveraged for its probiotic potential in the food industry.

New Aspects in the Study of Lactobacillus iners.

A cultural microbiological study of the vaginal microbiota of patients of reproductive age was carried out to isolate the species Lactobacillus iners with subsequent study of phenotypic features. The presence of two phenotypically different species variants was found in patients with bacterial vaginosis.

Anti-Persisters Activity of Lacticaseibacillus rhamnosus Culture Filtrates against Pseudomonas aeruginosa in Artificial Sputum Medium.

Persisters are antibiotic-tolerant bacteria, playing a role in the recalcitrance and relapse of many bacterial infections, including P. aeruginosa pulmonary infections in Cystic Fibrosis (CF) patients. Among novel antimicrobial strategies, the use of probiotics and their products is emerging as a particularly promising approach. The aim of this study was to evaluate the anti-persisters activity of culture filtrate supernatants of Lacticaseibacillus rhamnosus (LRM-CFS) against P. aeruginosa in artificial sputum medium (ASM), which resembles the CF lung environment. Planktonic persisters of two clinical strains of P. aeruginosa (PaCF1 and PaCF4) were obtained following two different procedures: (i) exposing stationary-phase cultures to cyanide m-chlorophenylhydrazone (CCCP) in LB medium; (ii) incubating stationary-phase cultures with high doses of tobramycin (128-fold MIC) in ASM. In addition, persisters from biofilm were obtained by exposing 48 h old biofilm of P. aeruginosa to 128 x MIC of ciprofloxacin. LRM-CFS at dilutions of 1:6 and 1:4 resulted in being bactericidal in ASM against both PaCF1 and PaCF4 persisters obtained after CCCP or tobramycin treatment. Moreover, LRM-CFS at dilution 1:4 caused a reduction of antibiotic-tolerant bacteria in the biofilm of both P. aeruginosa strains. Overall, LRM-CFS represents a promising adjuvant therapeutic strategy against P. aeruginosa recalcitrant infections in CF patients.

Mapping a sustainable approach: biosynthesis of lactobacilli-silver nanocomposites using whey-based medium for antimicrobial and bioactivity applications.

This study explores a sustainable approach for synthesizing silver nanocomposites (AgNCs) with enhanced antimicrobial and bioactivity using safe Lactobacillus strains and a whey-based medium (WBM). WBM effectively supported the growth of Lactobacillus delbrueckii and Lactobacillus acidophilus, triggering a stress response that led to AgNCs formation. The synthesized AgNCs were characterized using advanced spectroscopic and imaging techniques such as UV‒visible, Fourier transform infrared (FT-IR) spectroscopy, transmission electron (TEM), and scanning electron microscopy with energy dispersive X-ray analysis (SEM-Edx). Lb acidophilus-synthesized AgNCs in WBM (had DLS size average 817.2-974.3 ± PDI = 0.441 nm with an average of metal core size 13.32 ± 3.55 nm) exhibited significant antimicrobial activity against a broad spectrum of pathogens, including bacteria such as Escherichia coli (16.47 ± 2.19 nm), Bacillus cereus (15.31 ± 0.43 nm), Clostridium perfringens (25.95 ± 0.03 mm), Enterococcus faecalis (32.34 ± 0.07 mm), Listeria monocytogenes (23.33 ± 0.05 mm), methicillin-resistant Staphylococcus aureus (MRSA) (13.20 ± 1.76 mm), and filamentous fungi such as Aspergillus brasiliensis (33.46 ± 0.01 mm). In addition, Lb acidophilus-synthesized AgNCs in WBM exhibit remarkable free radical scavenging abilities, suggesting their potential as bioavailable antioxidants. These findings highlight the dual functionality of these biogenic AgNCs, making them promising candidates for applications in both medicine and nutrition.

Postbiotic lactobacilli induce cutaneous antimicrobial response and restore the barrier to inhibit the intracellular invasion of Staphylococcus aureus in vitro and ex vivo.

Intracellular pathogens including Staphylococcus aureus contribute to the non-healing phenotype of chronic wounds. Lactobacilli, well known as beneficial bacteria, are also reported to modulate the immune system, yet their role in cutaneous immunity remains largely unknown. We explored the therapeutic potential of bacteria-free postbiotics, bioactive lysates of lactobacilli, to reduce intracellular S. aureus colonization and promote healing. Fourteen postbiotics derived from various lactobacilli species were screened, and Latilactobacillus curvatus BGMK2-41 was selected for further analysis based on the most efficient ability to reduce intracellular infection by S. aureus diabetic foot ulcer clinical isolate and S. aureus USA300. Treatment of both infected keratinocytes in vitro and infected human skin ex vivo with BGMK2-41 postbiotic cleared S. aureus. Keratinocytes treated in vitro with BGMK2-41 upregulated expression of antimicrobial response genes, of which DEFB4, ANG, and RNASE7 were also found upregulated in treated ex vivo human skin together with CAMP exclusively upregulated ex vivo. Furthermore, BGMK2-41 postbiotic treatment has a multifaceted impact on the wound healing process. Treatment of keratinocytes stimulated cell migration and the expression of tight junction proteins, while in ex vivo human skin BGMK2-41 increased expression of anti-inflammatory cytokine IL-10, promoted re-epithelialization, and restored the epidermal barrier via upregulation of tight junction proteins. Together, this provides a potential therapeutic approach for persistent intracellular S. aureus infections.