Simplified lipid II-binding antimicrobial peptides: Design, synthesis and antimicrobial activity of bioconjugates of nisin rings A and B with pore-forming peptides

Multiple potential strategies for the application of nisin and derivatives

Nisin is a naturally occurring bioactive small peptide produced by Lactococcus lactis subsp. lactis and belongs to the Type A (I) lantibiotics. Due to its potent antimicrobial activity, it has been broadly employed to preserve various food materials as well as to combat a variety of microbial pathogens. The present review discusses the antimicrobial properties of nisin and different types of their derivatives employed to treat microbial pathogens with a detailed underlying mechanism of action. Several alternative strategies such as combination, conjugation, and nanoformulations have been discussed in order to address several issues such as rapid degradation, instability, and reduced activity due to the various environmental factors that arise in the applications of nisin. Furthermore, the evolutionary relationship of many nisin genes from different nisin-producing bacterial species has been investigated. A detailed description of the natural and bioengineered nisin variants, as well as the underlying action mechanisms, has also been provided. The chemistry used to apply nisin in conjugation with natural or synthetic compounds as a synergetic mode of antimicrobial action has also been thoroughly discussed. The current review will be useful in learning about recent and past research that has been performed on nisin and its derivatives as antimicrobial agents.

Engineering of Nisin as a Means for Improvement of Its Pharmacological Properties: A Review

Lantibiotics are believed to have a conceivable potential to be used as therapeutics, especially against clinically resistant bacterial strains. However, their low solubility and poor stability under physiological conditions limit their availability for clinical studies and further pharmaceutical commercialization. Nisin is a readily available and cheap lanthipeptide and thus serves as a good model in the search for the tools to engineer lantibiotics with improved pharmacological properties. This review aims to address technologies that can be applied to alter and enhance the antimicrobial activity, antibacterial spectrum and physicochemical properties (solubility, solution stability and protease resistance) of nisin. There are basically two general means to obtain nisin analogs-protein engineering and chemical functionalization of this antibiotic. Although bioengineering techniques have been well developed and enable the creation of nisin mutants of variable structures and properties, they are lacking spectacular effects so far. Chemical modifications of nisin based on utilization of the reactivity of its free amino and carboxylic moieties, as well as reactivity of the double bonds of its dehydroamino acids, are in their infancy.

The effect of nisin on the biofilm production, antimicrobial susceptibility and biofilm formation of Staphylococcus aureus and Pseudomonas aeruginosa

Objectives

Staphylococcus aureus and Pseudomonas aeruginosa were the most common bacteria in nosocomial infections. Different bacteriocins are currently being studied as antibiotics or in conjunction with antibiotics as potential strategies to treat resistant infectious agents. The study aimed to determine nisin's effect on the biofilm production, antimicrobial susceptibility, and biofilm formation of S. aureus and P. aeruginosa.

Materials and methods

The experimental research tested two antibiotic-resistant isolates of S. aureus and P. aeruginosa strains. The experimental study tested two antibiotic-resistant isolates of S. aureus and P. aeruginosa strains. The MIC of bacteriocin nisin was determined using the micro broth dilution method, and crystal violet was used to assess the effect of bacteriocin on the biofilm. In addition, L929 cell culture was used to determine the effectiveness of bacteriocin on the isolate under similar cell conditions. Moreover, the MTT assay was used to and evaluate bacteriocin toxicity. In this study, the software Prism version 9 and Graph pad software were utilized.

Results

The results of this study reveal that the nisin has different activities at different doses and is considered dose-dependent. At various times and doses, nisin inhibits biofilm formation in S. aureus, and P. aeruginosa isolates. Nisin also showed a decreasing survival of the isolates. Antibiotic-resistant bacteria can be made more vulnerable by nisin. Furthermore, nisin treatment affected the production of virulence factors such as hemolysins in S. aureus and had little or a negative effect on P. aeruginosa virulence factors. This medication stops S. aureus and P. aeruginosa from growing and causes bacterial cell damage.

Conclusions

Antibacterial properties of nicin against S. aureus and P. aeruginosa were successfully studied. This bacteriocin stops S. aureus and P. aeruginosa from growing and causes bacterial cell damage or death. Damage to the membrane among the fundamental causes is reduced membrane potential and enzyme inactivation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40001-022-00804-x.

Nisin Mutant Prevention Concentration and the Role of Subinhibitory Concentrations on Resistance Development by Diabetic Foot Staphylococci

The most prevalent microorganism in diabetic foot infections (DFI) is Staphylococcus aureus, an important multidrug-resistant pathogen. The antimicrobial peptide nisin is a promising compound for DFI treatment, being effective against S. aureus. However, to avoid the selection of resistant mutants, correct drug therapeutic doses must be established, being also important to understand if nisin subinhibitory concentrations (subMIC) can potentiate resistant genes transfer between clinical isolates or mutations in genes associated with nisin resistance. The mutant selection window (MSW) of nisin was determined for 23 DFI S. aureus isolates; a protocol aiming to prompt vanA horizontal transfer between enterococci to clinical S. aureus was performed; and nisin subMIC effect on resistance evolution was assessed through whole-genome sequencing (WGS) applied to isolates subjected to a MEGA-plate assay. MSW ranged from 5–360 μg/mL for two isolates, from 5–540 μg/mL for three isolates, and from 5–720 μg/mL for one isolate. In the presence of nisin subMIC values, no transconjugants were obtained, indicating that nisin does not seem to promote vanA transfer. Finally, WGS analysis showed that incubation in the presence of nisin subMIC did not promote the occurrence of significant mutations in genes related to nisin resistance, supporting nisin application to DFI treatment.

Effects of dietary antimicrobial peptides on intestinal morphology, antioxidant status, immune responses, microbiota and pathogen disease resistance in grass carp Ctenopharyngodon idellus

This study aims to highlight the effects (8 weeks) of dietary antimicrobial peptides (AMPs, a compound of 6 kDa and 5 kDa from intestine) on intestinal morphological functions and health status in grass carp (Ctenopharyngodon idellus). Fish were supplemented with various gradient concentrations of AMPs, including M0 (0 mg/kg), M1 (100 mg/kg), M2 (200 mg/kg), M3 (400 mg/kg), M4 (800 mg/kg) and M5 (1600 mg/kg). Our results showed that amylase, lipase, chymotrypsin enzymatic levels, and total antioxidant capacity (T-AOC) were significantly increased (p < 0.05), while malondialdehyde (MDA) content was significantly decreased in the intestines of the AMP treated groups compared to the M0. Histological analysis revealed villus height and crypt depth of foregut and midgut in the M4 group were significantly different (p < 0.05) compared to the M0. In the M3 group, the gene expression levels of IL-1β were significantly up-regulated, while levels of IL10 and TGF-β were significantly down-regulated than other treated and control groups. The abundance of Firmicutes was significantly increased (p < 0.05), while the Planctomycetes abundance was decreased at phylum level in M1-M5 groups. Subsequent to the AMP treatment, fish were injected with Aeromonas. hydrophila to assess disease resistant potential. In A. hydrophila injected M3-group, the gene expressions of IL-1β, IL8, and TNF-α were significantly down-regulated while that of TGF-β was significantly up-regulated, and IL10 showed no significant difference compared to the control. Further, AMPs also increased the abundance of the Acidobacteria, Proteobacteria, and Patescibacteria, and decreased the abundance of the Fusobacteria and Firmicutes. Therefore, dietary AMPs (400-800 mg/kg) boosted intestinal health by promoting intestinal morphology, digestive and antioxidant capacities, immunity, and intestinal microbiota in C. idellus.

Ring-opening reactions for the solid-phase synthesis of nisin lipopeptide analogues

Strategy for the solid-phase synthesis of nisin lipopeptide analogues using orthogonally protected lanthionines synthesised by ring-opening chemistry, and on-resin formation of dehydroalanine and dehydrobutyrine residues.

Bromelain and Nisin: The Natural Antimicrobials with High Potential in Biomedicine

Infectious diseases along with various cancer types are among the most significant public health problems and the leading cause of death worldwide. The situation has become even more complex with the rapid development of multidrug-resistant microorganisms. New drugs are urgently needed to curb the increasing spread of diseases in humans and livestock. Promising candidates are natural antimicrobial peptides produced by bacteria, and therapeutic enzymes, extracted from medicinal plants. This review highlights the structure and properties of plant origin bromelain and antimicrobial peptide nisin, along with their mechanism of action, the immobilization strategies, and recent applications in the field of biomedicine. Future perspectives towards the commercialization of new biomedical products, including these important bioactive compounds, have been highlighted.

The multifaceted nature of antimicrobial peptides: current synthetic chemistry approaches and future directions

Bacterial infections caused by 'superbugs' are increasing globally, and conventional antibiotics are becoming less effective against these bacteria, such that we risk entering a post-antibiotic era. In recent years, antimicrobial peptides (AMPs) have gained significant attention for their clinical potential as a new class of antibiotics to combat antimicrobial resistance. In this review, we discuss several facets of AMPs including their diversity, physicochemical properties, mechanisms of action, and effects of environmental factors on these features. This review outlines various chemical synthetic strategies that have been applied to develop novel AMPs, including chemical modifications of existing peptides, semi-synthesis, and computer-aided design. We will also highlight novel AMP structures, including hybrids, antimicrobial dendrimers and polypeptides, peptidomimetics, and AMP-drug conjugates and consider recent developments in their chemical synthesis.

Effective adsorption of nisin on the surface of polystyrene using hydrophobin HGFI

Herein, a new method was demonstrated for effective immobilization of the antibacterial peptide nisin on Grifola frondosa hydrophobin (HGFI), without the need of any additional complex reaction. Hydrophobin can self-assemble as a monolayer to form continuous negative-charged surfaces with enhanced wettability and biocompatibility. Adding nisin solution to such hydrophobin surface created antibacterial surfaces. The quantification analysis revealed that more nisin could be adsorbed on the HGFI-coated than to control polystyrene surfaces at different pH values. This suggested that electronic attraction and wettability may play important roles in this process. The transmission electron microscopy, atomic force microscopy and fourier transform infrared (FTIR) analysis indicated the adsorption mode of nisin on the HGFI film, i.e., hydrophobins served as an adhesive layer for binding charged peptides to interfaces. The antibacterial activity of the treated surface was investigated via counting, a nucleic acid release test, scanning electron microscopy, and biofilm detection. These results indicated the excellent antibacterial activity of nisin adsorbed on the HGFI-coated surfaces. The activity retention of adsorbed nisin was demonstrated by immersing the modified substrates in a flowed liquid condition.

Effects of compound antimicrobial peptides on the growth performance, antioxidant and immune responses and disease resistance of grass carp (Ctenopharyngodon idellus)

In this study, the compound antimicrobial peptides was added to the basic diet to probe its effects on grass carp for 8 weeks. There were 6 groups in our study, including M0 (0 mg/kg) and 5 additional groups: M1 (100 mg/kg), M2 (200 mg/kg), M3 (400 mg/kg), M4 (800 mg/kg) and M5 (1600 mg/kg). The results are as follows: (1) The grass carp's FBW, WGR and SGR in M4 were significantly increased than M0 (p < 0.05). (2) In the hepatopancreas, the amylase activity of M2, M3 and M5 were significant up-regulation than other groups (p < 0.05). (3) The activity of T-AOC in the M3 and M4 was significantly higher compared to the other groups in grass carp hepatopancreas, while MDA was significantly reduced compared to the control group (p < 0.05). The activity of SOD in M5 was significantly increased than the other groups (p < 0.05). (4) The expression of MnSOD (except head kidney), IL8 and TNF-α and IL-1β (except hepatopancreas) were significantly increased (p < 0.05), while TGF-β and were significantly reduced in the hepatopancreas, spleen and head kidney at M3 (p < 0.05), and IL10 were significantly decreased in the hepatopancreas at M3 (p < 0.05). In addition, expression of IL8 and TNF-α were significant down-regulation, whereas TGF-β (expect head kidney) were significant up-regulation in hepatopancreas, spleen and head kidney in M3 after challenge with A. hydrophila. The expression of IL-1β in spleen and head kidney were also down-regulated, whereas IL10 were significantly up-regulated in the hepatopancreas at M3 after challenge with A. hydrophila (p < 0.05). The results of this study showed that grass carp fed a diet supplemented compound antimicrobial peptides was added with 400-800 mg/kg, which could improve the growth performance, antioxidant and digestive capabilities, and could also enhance the expression of immune-related genes and control to A. hydrophila.

A Chemical Biology Approach to Understanding Molecular Recognition of Lipid II by Nisin(1-12): Synthesis and NMR Ensemble Analysis of Nisin(1-12) and Analogues

Natural products that target lipid II, such as the lantibiotic nisin, are strategically important in the development of new antibacterial agents to combat the rise of antimicrobial resistance. Understanding the structural factors that govern the highly selective molecular recognition of lipid II by the N-terminal region of nisin, nisin(1-12), is a crucial step in exploiting the potential of such compounds. In order to elucidate the relationships between amino acid sequence and conformation of this bicyclic peptide fragment, we have used solid-phase peptide synthesis to prepare two novel analogues of nisin(1-12) in which the dehydro residues have been replaced. We have carried out an NMR ensemble analysis of one of these analogues and of the wild-type nisin(1-12) peptide in order to compare the conformations of these two bicyclic peptides. Our analysis has shown the effects of residue mutation on ring conformation. We have also demonstrated that the individual rings of nisin(1-12) are pre-organised to an extent for binding to the pyrophosphate group of lipid II, with a high degree of flexibility exhibited in the central amide bond joining the two rings.