Bacteriocin-Nanoconjugates (Bac10307-AgNPs) Biosynthesized from Lactobacillus acidophilus-Derived Bacteriocins Exhibit Enhanced and Promising Biological Activities

Natural, safety immunomodulatory derivatives of lactobacillus biofilms promote diabetic wound healing by metabolically regulating macrophage phenotype and alleviating local inflammation

INTRODUCTION

Long-term inflammatory microenvironment further impairs the healing process of diabetic wounds. Many studies have shown that Lactobacillus can regulate immune function and promote injured tissue repair. However, the immunomodulatory function and safety of Lactobacillus biofilm (LB) on wounds need further investigation.

OBJECTIVES

In this present research, we proposed a "bacteria-free biofilm derivative therapy" and successfully extracted Lactobacillus biofilm derivatives (LBDs) by ultrasonic separation and filtration technology for the natural and safe treatment of diabetic wounds.

METHODS

The study first cultured Lactobacillus anaerobically and extracted LBDs using ultrasound separation combined with filtration technology. LBDs were characterized via scanning electron microscopy, Concanavalin A fluorescence staining, and protein gel electrophoresis. In vivo diabetic wound model, wound closure rates were dynamically monitored, and tissue sections were analyzed using hematoxylin-eosin and immunofluorescence staining to evaluate LBDs' healing effects. An in vitro macrophage inflammation model was established, employing immunofluorescence, flow cytometry, and Western blotting techniques to explore the molecular mechanisms underlying LBDs' effects on macrophage phenotypes. Furthermore, whole-genome sequencing and proteomics of LBDs-treated macrophages were performed to further elucidate the intrinsic molecular mechanisms through which LBDs regulate macrophage phenotypes.

RESULTS

LBDs were effectively extracted utilizing ultrasonic separation coupled with filtration technology. Studies revealed that LBDs modulate the systemic metabolic reprogramming in wound-site macrophages, suppress JAK-STAT1 signaling pathway, alleviate the local inflammatory microenvironment, promote neovascularization and ultimately accelerate wound healing.

CONCLUSION

The LBDs retains most bioactive components of the LB. As a natural, safe and immunomodulatory agent, LBDs promote diabetic wound healing by metabolically reprogramming macrophage phenotypes and improving the local immune microenvironment, offering promising potential for regenerative applications in diabetic wound management.

Biogenic-Synthesized Silver Nanoparticles Using the Ligilactobacillus salivarius KC27L Postbiotic: Antimicrobial, Anti-Biofilm, and Antioxidant Activity and Cytotoxic Effects

This study aimed to synthesize silver nanoparticles (AgNPs) using the postbiotic of the Ligilactobacillus salivarius KC27L strain and evaluate their multifunctional biological properties. The use of L. salivarius, a probiotic bacterium known for its ability to produce a wide range of metabolites, plays a crucial role in this process by acting as a natural, eco-friendly reducing, and stabilizing agent during AgNP synthesis. This approach not only eliminates the need for hazardous chemicals typically used in nanoparticle synthesis but also enhances the biocompatibility and biological efficacy of the resulting nanoparticles. Synthesized AgNPs were analyzed by Fourier transform infrared spectroscopy, FTIR (metabolites of postbiotic); UV-vis (peak of 435 nm); scanning electron microscope, SEM; transmission electron microscopy, TEM (spherical shapes, sizes < 50 nm), energy-dispersive spectrometry, EDS (peak at 3 keV); and zeta potential (- 18.6 mV). These nanoparticles (0.156-40 mg/mL) were evaluated for the antimicrobial and anti-biofilm activities against Escherichia coli ATCC 11229, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923, Staphylococcus epidermidis ATCC 35984, and Streptococcus mutans ATCC 25175, and antioxidant activities using four different methods (2,2-diphenyl-1-picrylhydrazyl free radical scavenging, metal ion chelating, hydroxyl radical scavenging, and superoxide anion scavenging activities). Also, the cytotoxic activity was investigated against a normal cell line (L929) for 24, 48, and 72 h. At a concentration of 40 mg/mL, the AgNPs demonstrated the highest antimicrobial efficacy, with inhibition zones measured as 14.9 mm for P. aeruginosa, 9.5 mm for E. coli, 15.7 mm for S. epidermidis, and 12.9 mm for S. mutans. The AgNPs exhibited anti-biofilm activities against all Gram-positive and Gram-negative bacteria strains studied. According to the DPPH method, the highest antioxidant activity was determined at 40 mg/mL AgNP concentration (80.93%). AgNPs were found to have no toxic effect at low concentrations (0.39-25 µg/mL). Biogenic synthesized AgNPs could be used in biotechnological applications (biomaterials, health, environmental, etc.) with antibacterial, anti-biofilm, antioxidant, and nontoxic properties. However, further research is needed to understand the mechanisms of action of the particles fully.

Distinct phenotypes of salivaricin-producing Ligilactobacillus salivarius isolated from the gastrointestinal tract of broiler chickens and laying hens

Ligilactobacillus salivarius harbors bacteriocin genes in its repA-type megaplasmid, specifically salivaricin P (salP), a class IIb bacteriocin. This study aimed to differentiate 25 salP-positive Lig. salivarius strains isolated from the gastrointestinal tract (GIT) of broilers and laying hens. Results showed that 12 isolates were classified as Type A, with active bacteriocins, while the rest were Type B, with no active bacteriocins. In vitro and in silico characterization of salP bacteriocins revealed narrow-spectrum antibacterial activity against Listeria monocytogenes and Enterococcus faecalis. SalP bacteriocins were predicted as positively charged, hydrophobic, small molecular weight (α, 4.097 kDa; ß, 4.285 kDa) bacteriocins with characteristic GXXXG motif. Investigation of the salP gene cluster based on genomic data revealed that Type B strains lacked the lanT and hlyD genes that encode export proteins dedicated to the modification and extracellular transport of mature salP peptides. However, two Type B strains (B4311 and B5258) showed inhibitory activity against L. monocytogenes ATCC19114. Multiplex PCR analysis and synteny mapping analysis revealed that B4311 and B5258 strains harbored the lanT gene, highlighting the importance of LanT protein in the cleavage of leader peptide and excretion of mature peptides. Further analysis revealed that the resistance of Type B strains to salP was attributable to the presence of a dedicated immunity protein, blurring the evolutionary significance of producing active bacteriocins for competitive advantage. Additionally, the loss of export proteins occurred in a polyphyletic manner, consistent with the genetic plasticity of the repA-type megaplasmid. This suggests that the loss of lanT and hlyD is likely in the presence of limited nutritional competitors. In conclusion, the observed differences in salivaricin production of Lig. salivarius exist independent of isolation host and that Type A and Type B strains can coexist in the same environment. Finally, the functional characterization of active salP allows for a better understanding of its potential to control specific bacteria in human food and animal production.

Harnessing Nanoparticles to Overcome Antimicrobial Resistance: Promises and Challenges

The rise of antimicrobial resistance (AMR) has become a serious global health issue that kills millions of people each year globally. AMR developed in bacteria is difficult to treat and poses a challenge to clinicians. Bacteria develop resistance through a variety of processes, including biofilm growth, targeted area alterations, and therapeutic drug alteration, prolonging the period they remain within cells, where antibiotics are useless at therapeutic levels. This rise in resistance is linked to increased illness and death, highlighting the urgent need for effective solutions to combat this growing challenge. Nanoparticles (NPs) offer unique solutions for fighting AMR bacteria. Being smaller in size with a high surface area, enhancing interaction with bacteria makes the NPs strong antibacterial agents against various infections. In this review, we have discussed the epidemiology and mechanism of AMR development. Furthermore, the role of nanoparticles as antibacterial agents, and their role in drug delivery has been addressed. Additionally, the potential, challenges, toxicity, and future prospects of nanoparticles as antibacterial agents against AMR pathogens have been discussed. The research work discussed in this review links with Sustainable Development Goal 3 (SDG-3), which aims to ensure disease-free lives and promote well-being for all ages.

Synthesis, Characterization, and Biomedical Applications of Bacteriocin-Selenium Nanoconjugates

The antibiotic overuse in hospitals, the food industry, and animal feed over past times has led to a significant rise in the incidence of antibiotic-resistant bacteria. To address these potentially life-threatening antibiotic-resistant illnesses, a quick identification and development of novel antimicrobials are necessary. The aim of this study was to synthesize a novel bacteriocin-nanoconjugates by combining selenium nanoparticles with purified bacteriocin from the Enterococcus faecium SMAA23 and investigate some of its biomedical activities. The nanoconjugates were characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray desorption (EDX), and zeta potential analytical techniques. There is investigation of the antibacterial, antifungal, and anticancer properties of nanoconjugates. Purified bacteriocin has a known molecular weight of approximately 43,000 Daltons. The characterization of nanoparticles and nanoconjugates was performed. The crystallite size of nanoconjugate was determined via X-ray diffraction (XRD) to be 15.29 nm. Transmission electron microscopy (TEM) detected particles of irregular form of nanoconjugate, measuring between 11 and 24 nm in diameter. Energy dispersive X-ray spectroscopy (EDX) confirmed the presence of selenium and protein. The measured zeta potential was - 12.1 + 0.12 mV. The results revealed potent antibacterial activity against Acinetobacter baumannii, with a growth inhibition zone of 23 mm ± SD. A minimum inhibitory concentration (MIC) of nanoconjugate was 15.625 µg/mL, while a minimum bactericidal concentration (MBC) was 31.25 µg/mL. The application of scanning electron microscopy (SEM) enhanced the rupture of the bacterial cell wall. The antifungal activity against C. albicans and C. tropicalis resulted in growth inhibition zones of 14 mm and 16 mm (± SD), respectively. Various concentrations of the nanoconjugate strongly inhibited MDA-MB-231 cells in the MTT experiment. The novel synthesized bacteriocin-nanoconjugates exhibited substantial antibacterial, antifungal, and anticancer properties.

Nanomaterials for intelligent CRISPR-Cas tools: improving environment sustainability

Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) is a desirable gene modification tool covering a wide area in various sectors of medicine, agriculture, and microbial biotechnology. The role of this incredible genetic engineering technology has been extensively investigated; however, it remains formidable with cargo choices, nonspecific delivery, and insertional mutagenesis. Various nanomaterials including lipid, polymeric, and inorganic are being used to deliver the CRISPR-Cas system. Progress in nanomaterials could potentially address these challenges by accelerating precision targeting, cost-effectiveness, and one-step delivery. In this review, we highlighted the advances in nanotechnology and nanomaterials as smart delivery systems for CRISPR-Cas so as to ameliorate applications for environmental remediation including biomedical research and healthcare, strategies for mitigating antimicrobial resistance, and to be used as nanofertilizers for enhancing crop growth, and reducing the environmental impact of traditional fertilizers. The timely co-evolution of nanotechnology and CRISPR technologies has contributed to smart novel nanostructure hybrids for improving the onerous tasks of environmental remediation and biological sustainability.

Probiotic Lactobacillus salivarius mediated synthesis of silver nanoparticles (AgNPs-LS): A sustainable approach and multifaceted biomedical application

Biogenic synthesis of silver nanoparticles (AgNPs) has emerged as an eco-friendly and sustainable approach with diverse biological applications. This study presents synthesis of AgNPs-LS using a probiotic strain Lactobacillus salivarius (L. salivarius) and explores their multifaceted biological activities, including antibacterial, antibiofilm, anti-quorum sensing, antifungal, antioxidant, anticancer, anticoagulant and thrombolytic properties. The biosynthesis of AgNPs-LS was successfully achieved using L. salivarius cell free supernatants, resulting in well-characterized nanoparticles as confirmed by UV-Vis spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS) and zeta potential analysis. The AgNPs-LS demonstrated potent antibacterial activity against different pathogenic bacteria (C. violaceum, P. aeruginosa, S. aureus, E. coli and S. marcescens), emphasizing their potential in combating bacterial infections. Moreover, these AgNPs-LS were effective in inhibiting biofilm formation (>60 % at 1/2 MIC), a key mechanism of bacterial virulence, highlighting their utility in preventing biofilm-related infections. AgNPs-LS exhibited anti-quorum sensing activity, disrupting bacterial communication systems and potentially reducing virulence factor such as, violacein production in C. violaceum, pyocyanin production in P. aeruginosa and prodigiosin production in S. marcescens. Additionally, AgNPs-LS also exhibited notable antifungal activity towards a different pathogenic fungus (F. proliferatum, P. purpurogenum, A. niger and R. stolonifer). In terms of health applications, the AgNPs-LS displayed significant antioxidant activity, effectively scavenging DPPH• (IC50 = 42.65 μg/mL) and ABTS•+ (IC50 = 53.77 μg/mL) free radicals. Furthermore, AgNPs-LS showed cytotoxicity against breast cancer cells (MCF-7) (IC50 = 52.29 μg/mL), positioning them as promising candidates for cancer therapy. Moreover, AgNPs-LS were also shown promising anticoagulant and thrombolytic activities under practical conditions. Therefore, the biogenic synthesis of AgNPs-LS using L. salivarius offers a sustainable and cost-effective route for producing AgNPs with an array of biological activities. These AgNPs-LS have the potential to address various challenges in healthcare, ranging from antimicrobial, anticancer applications to biofilm inhibition, antioxidant therapy, anticoagulant and thrombolytic agents.

Emerging lactic acid bacteria bacteriocins as anti-cancer and anti-tumor agents for human health

Modern cancer diagnostics and treatment options have greatly improved survival rates; the illness remains a major cause of mortality worldwide. Current treatments for cancer, such as chemotherapy, are not cancer-specific and may cause harm to healthy cells; therefore, it is imperative that new drugs for cancer be developed that are both safe and effective. It has been found that lactic acid bacteria (LAB) have the potential to produce bacteriocins, which could potentially offer a promising alternative for cancer treatment. They have been shown in several studies to be effective against cancer cells while having no effect on healthy cells. More research is needed to fully understand the potential of LAB bacteriocins as anti-cancer medicines, to find the appropriate dose and delivery route, and to conduct clinical trials to evaluate the effectiveness and safety of the products in human patients, as is suggested by this work. Furthermore, LAB bacteriocins may evolve into a significant new class of anti-cancer drugs and food products. Patients with cancer may have a safe and effective alternative treatment option in the form of anti-cancer foods and drugs. Therefore, the aim of this study is to provide an in-depth analysis of the recent breakthroughs and potential future technical advancements of significant bacteriocins that are produced by LAB, how these bacteriocins function, and how these bacteriocins may be utilized as an anti-cancer agent. In addition, the current analysis emphasizes the significant constraints and boundaries that bacteriocins face when they are used as an anti-cancer factor.

Biosynthesis of bacteriocin BacZY05-silver nanoconjugates and evaluation of their antibacterial properties

Bacteriocins are antimicrobial peptides produced by bacteria to prevent the growth of pathogens. Combining bacteriocins with metal nanoparticles, like silver nanoparticles (AgNPs), has developed into a viable strategy to get over bacteriocin limitations. In this study, bacteriocin BacZY05 was extracted from Bacillus subtilis ZY05 and purified using various techniques. The resulting purified bacteriocin was then combined with silver nanoparticles to form bacteriocin silver nanoconjugates (BacZY05-AgNPs). The physicochemical properties of the BacZY05-AgNPs were characterized using various analytical techniques. The mean diameter of the synthesized AgNPs was approximately 20-60 nm with an oval or spherical shape. The antimicrobial activity of the BacZY05-AgNPs was evaluated against several indicator strains by their zone of inhibition (ZOI), using the agar well diffusion method. Compared to bacteriocin (ZOI- 13 to 20 mm) and AgNPs (ZOI- 10-22 mm) alone, the antibacterial activity data demonstrated a 1.3-1.5-fold increase in the activity of bacteriocin-nanoconjugates (ZOI- 22 to 26 mm). For Staphylococcus aureus MTCC3103 and Klebsiella pneumoniae MTCC109, BacZY05-capped AgNPs exhibited the lowest minimum inhibitory concentration (MIC), measuring 10.93 µg/mL. For Salmonella typhi NCIM2501, the MIC was 28.75 µg/mL. The highest MIC value was 57.5 µg/mL for Escherichia coli DH5α and Vibrio cholerae MTCC3909. With BacZY05-capped AgNPs, the lowest minimum bactericidal concentration (MBC) of 28.75 µg/mL was observed for Staphylococcus aureus MTCC31003. In the cases of Salmonella typhi NCIM2501 and Klebsiella pneumoniae MTCC109 concentration was 57.5 µg/mL. Vibrio cholerae MTCC3909 and Escherichia coli DH5α had the highest MBC values at 115 µg/mL.

Antagonistic Interactions of Lactic Acid Bacteria from Human Oral Microbiome against Streptococcus mutans and Candida albicans

Oral probiotic lactic acid bacteria can exhibit antagonistic activities against pathogens associated with diseases in the oral cavity. Therefore, twelve previously isolated oral strains were assessed for antagonistic evaluation against selected oral test microorganisms Streptococcus mutans and Candida albicans. Two separate co-culturing analyses were performed, where all tested strains showed the presence of antagonistic activity and four strains, Limosilactobacillus fermentum N 2, TC 3-11, and NA 2-2, and Weissella confusa NN 1, significantly inhibited Streptococcus mutans by 3-5 logs. The strains showed antagonistic activity against Candida albicans, and all exhibited pathogen inhibition by up to 2 logs. Co-aggregation capability was assessed, showing co-aggregative properties with the selected pathogens. Biofilm formation and antibiofilm activity of the tested strains against the oral pathogens were assayed, where the strains showed specificity in self-biofilm formation and well-expressed antibiofilm properties by most of them above 79% and 50% against Streptococcus mutans and Candida albicans, respectively. The tested LAB strains were assayed by a KMnO₄ antioxidant bioassay, where most of the native cell-free supernatants exhibited total antioxidant capacity. These results show that five tested strains are promising candidates to be included in new functional probiotic products for oral healthcare.