Effects Of Antimicrobial Peptides Research Articles

Antimicrobial effects of peptides from fenugreek and ginger proteins using Fe3O4@PDA-MWCNT conjugated trypsin by improving enzyme stability & applications

Trypsin was immobilized onto a newly formulated nanocomposite (NC) comprising magnetic (Fe3O4) multiwalled carbon nanotubes (MWCNTs) anchored with polydopamine (PDA). The fabricated NC and the NC-bound trypsin were subjected to comprehensive characterization using various biophysical techniques including Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and fluorescence spectroscopy. The NC-bound trypsin exhibited significantly enhanced thermostability and increased tolerance to various organic solvents and denaturants. The enzymatic activity of trypsin was notably augmented through its coupling with the nano support, yielding an effectiveness factor (η) of 2.65. Fenugreek and ginger protein hydrolysates, prepared using both native and NC-bound enzyme, were evaluated for their antimicrobial activities. The analysis revealed that peptides generated by NC-bound trypsin showed higher antimicrobial activity (~ 10) in most cases compared to peptides obtained by using native trypsin. This strategy presents an innovative methodology for the production of potential biopeptides, with the prospect of their incorporation into pharmaceutical and therapeutic sectors through the utilization of NC-bound trypsin in protein hydrolysis.

A Comprehensive Review of Recent Research into the Effects of Antimicrobial Peptides on Biofilms-January 2020 to September 2023.

Microbial biofilm formation creates a persistent and resistant environment in which microorganisms can survive, contributing to antibiotic resistance and chronic inflammatory diseases. Increasingly, biofilms are caused by multi-drug resistant microorganisms, which, coupled with a diminishing supply of effective antibiotics, is driving the search for new antibiotic therapies. In this respect, antimicrobial peptides (AMPs) are short, hydrophobic, and amphipathic peptides that show activity against multidrug-resistant bacteria and biofilm formation. They also possess broad-spectrum activity and diverse mechanisms of action. In this comprehensive review, 150 publications (from January 2020 to September 2023) were collected and categorized using the search terms 'polypeptide antibiotic agent', 'antimicrobial peptide', and 'biofilm'. During this period, a wide range of natural and synthetic AMPs were studied, of which LL-37, polymyxin B, GH12, and Nisin were the most frequently cited. Furthermore, although many microbes were studied, Staphylococcus aureus and Pseudomonas aeruginosa were the most popular. Publications also considered AMP combinations and the potential role of AMP delivery systems in increasing the efficacy of AMPs, including nanoparticle delivery. Relatively few publications focused on AMP resistance. This comprehensive review informs and guides researchers about the latest developments in AMP research, presenting promising evidence of the role of AMPs as effective antimicrobial agents.

The Effect of Antimicrobial Peptide (PA-13) on Escherichia coli Carrying Antibiotic-Resistant Genes Isolated from Boar Semen.

A major global public health concern is antimicrobial resistance (AMR). Antimicrobial peptides (AMPs) are a potentially appropriate replacement for conventional antibiotics. The purpose of this research was to investigate the potential of the antimicrobial peptide PA-13, a synthetic AMP with 13 amino acids, to inhibit E. coli isolated from boar semen expressing antibiotic-resistant genes, as well as to determine the mechanism of action of this antimicrobial peptide on the bacterial membrane. The effectiveness of the bacterial inhibitory activity of PA-13 was tested at different concentrations by two fold serial dilutions in the range 0.488-500 µg/mL using the MIC and MBC methods. The impact of PA-13 on the bacterial membrane was examined at different concentrations of 0×, 0.5×, 1×, 2× and 4× of MIC using DNA leakage assay and electron microscopy. The PA-13 antibacterial activity result exhibited the same MIC and MBC values at a concentration of 15.625 µg/mL. When comparing DNA leakage at different MIC values, the results revealed that the maximum amount of DNA concentration was found two and three hours after incubation. For the results of SEM and TEM, the bacterial membrane disruption of this E. coli was found in the PA-13-treated group when compared with the negative control. In conclusion, synthetic PA-13 with its antibacterial properties is an alternative antimicrobial peptide to antibiotics in the pig industry.

Antimicrobial peptides as new-generation antibiotics against Mycobacterium

Abstract More than 10 million cases of tuberculosis (TB) in 2019 have made TB a global health problem. The increase in infection has caused an increase in the use of antibiotics for treatment, but with the spread of antibiotic use and the emergence of antibiotic resistance, the treatment has become difficult. This issue highlights the need to find a suitable alternative more than in the past. This matter emphasizes the urgency of discovering a viable substitute more than ever before. These obstacles underscore the necessity of developing innovative approaches that are not only cost-effective and efficient but also possess reduced levels of toxicity. Antimicrobial peptides (AMPs) possess a wide range of characteristics, which positions them as highly promising alternatives for a future era that follows the use of antibiotics. Here, we will focus on investigating AMPs from different sources, such as animal, nonanimal, and synthetic, with their inhibitory activity against TB as a therapeutic strategy. The aim of this study was to investigate different aspects of using AMPs to deal with Mycobacterium tuberculosis as a new strategy in its treatment. For this purpose, we studied more than 50 articles with the keywords peptide, AMP, and M. tuberculosis and investigated the importance of AMP against TB by searching valuable data sources such as PubMed, Scopus, Google Scholar, and Web of Science. In this study, the effect of antimicrobial peptides (AMPs) against mycobacteria was investigated. With the review done and considering all the advantages and challenges of AMPs, we concluded that this class of new antibiotics can be used as a long-term strategy to fight TB. As a result, we suggest research priorities to discover and optimize the challenges of these peptides as TB treatment and diagnostic methods in different countries.

Effects of antimicrobial peptides on membrane dynamics: A comparison of fluorescence and NMR experiments

Antimicrobial peptides (AMPs) represent a promising class of compounds to fight resistant infections. They are commonly thought to kill bacteria by perturbing the permeability of their cell membranes. However, bacterial killing requires a high coverage of the cell surface by bound peptides, at least in the case of cationic and amphipathic AMPs. Therefore, it is conceivable that peptide accumulation on the bacterial membranes might interfere with vital cellular functions also by perturbing bilayer dynamics, a hypothesis that has been termed “sand in the gearbox”. Here we performed a systematic study of such possible effects, for two representative peptides (the cationic cathelicidin PMAP-23 and the peptaibol alamethicin), employing fluorescence and NMR spectroscopies. These approaches are commonly applied to characterize lipid order and dynamics, but sample different time-scales and could thus report on different membrane properties. In our case, fluorescence anisotropy measurements on liposomes labelled with probes localized at different depths in the bilayer showed that both peptides perturb membrane fluidity and order. Pyrene excimer-formation experiments showed a peptide-induced reduction in lipid lateral mobility. Finally, laurdan fluorescence indicated that peptide binding reduces water penetration below the headgroups region. Comparable effects were observed also in fluorescence experiments performed directly on live bacterial cells. By contrast, the fatty acyl chain order parameters detected by deuterium NMR spectroscopy remained virtually unaffected by addition of the peptides. The apparent discrepancy between the two techniques confirms previous sporadic observations and is discussed in terms of the different characteristic times of the two approaches. The perturbation of membrane dynamics in the ns timescale, indicated by the multiple fluorescence approaches reported here, could contribute to the antimicrobial activity of AMPs, by affecting the function of membrane proteins, which is strongly dependent on the physicochemical properties of the bilayer.

Эффекты антимикробного пептида из лактоферрина в сыворотке крови и моче пациентов с почечной коликой при уролитиазе и пиелонефрите

Эффекты антимикробного пептида из лактоферрина в сыворотке крови и моче пациентов с почечной коликой при уролитиазе и пиелонефрите

Functionality of dietary antimicrobial peptides in aquatic animal health: Multiple meta-analyses.

Effects of antimicrobial peptides (AMP) added to diets on aquatic animal health and body function are influenced by multiple factors such as animal species, initial body weight, the dosage of AMP and feeding duration. However, there is limited knowledge on the relationship between these factors and the body function of aquatic animals. Here, we aimed to perform multiple meta-analyses to investigate the effects of dietary AMP on growth performance (feed conversion ratio [FCR], specific growth rate [SGR]), enzyme activity (superoxide dismutase activity [SOD], lysozyme activity [LSA]), disease resistance (cumulative survival rate [CSR], the expression of immune-related genes [GENE]) and the abundance of gut microbiota (MICRO) from a pool of empirical studies. Additionally, the dose-effect model was applied to determine the optimal AMP dose, initial body weight and feeding duration to maximize body function. To conduct the meta-analyses, we included 34 publications that estimated 705 effect sizes across 21 fish, 2 shrimp and 2 shellfish species. The results confirmed that the inclusion of AMP in the diet can significantly improve SGR, SOD, LSA, CSR and GENE and decrease FCR for aquatic animals. Interestingly, our findings implied a slight positive effect of AMP on MICRO albeit with a limited number of studies available on fish gut microbial communities. Although no significant linear or quadratic relationship was predicted by meta-regression, the dose-effect indicated that the optimal AMP doses for FCR, SGR, SOD and LSA were 707.5, 750.0, 1,050.0 and 937.5mg/kg, respectively. Taken together, fish with an initial body weight of 30g could be fed with a dose of 600 to 800mg/kg for 2mo when AMP-supplemented diets were applied in aquaculture, which can effectively improve body function and health while lowering aquafeed costs. In addition, more studies should address fish gut microbiota to delimitate the influence of dietary AMP on MICRO in the future.

Cholesterol Stiffening of Lipid Membranes.

Biomembrane order, dynamics, and other essential physicochemical parameters are controlled by cholesterol, a major component of mammalian cell membranes. Although cholesterol is well known to exhibit a condensing effect on fluid lipid membranes, the extent of stiffening that occurs with different degrees of lipid acyl chain unsaturation remains an enigma. In this review, we show that cholesterol locally increases the bending rigidity of both unsaturated and saturated lipid membranes, suggesting there may be a length-scale dependence of the bending modulus. We review our published data that address the origin of the mechanical effects of cholesterol on unsaturated and polyunsaturated lipid membranes and their role in biomembrane functions. Through a combination of solid-state deuterium NMR spectroscopy and neutron spin-echo spectroscopy, we show that changes in molecular packing cause the universal effects of cholesterol on the membrane bending rigidity. Our findings have broad implications for the role of cholesterol in lipid–protein interactions as well as raft-like mixtures, drug delivery applications, and the effects of antimicrobial peptides on lipid membranes.Graphical

Beta-lactam resistance and the effectiveness of antimicrobial peptides against KPC-producing bacteria.

Bacterial resistance is a problem that is giving serious cause for concern because bacterial strains such as Acinetobacter baumannii and Pseudomonas aeruginosa are difficult to treat and highly opportunistic. These bacteria easily acquire resistance genes even from other species, which confers greater persistence and tolerance towards conventional antibiotics. These bacteria have the highest death rate in hospitalized intensive care patients, so strong measures must be taken. In this review, we focus on the use of antimicrobial peptides (AMPs) as an alternative to traditional drugs, due to their rapid action and lower risk of generating resistance by microorganisms. We also present an overview of beta-lactams and explicitly explain the activity of AMPs against carbapenemase-producing bacteria as potential alternative agents for infection control.

The Role of Methyl-(Z)-11-tetradecenoate Acid from the Bacterial Membrane Lipid Composition in Escherichia coli Antibiotic Resistance.

Background The bacterial membrane plays a critical role in the survival of bacteria and the effectiveness of antimicrobial peptides in protecting the host. The lipid constituents of the bacterial membrane are not evenly distributed, and they could be affected by clustering anionic lipids with cationic peptides with multiple positive charges. That could be harmful to bacteria because it prevents lipids from interacting with other molecular components of the cell membrane, disrupts existing natural domains, or creates phase boundary defects between the clustered lipids and the bulk of the membrane. This preliminary quantitative study is aimed at assembling a correlation between antibiotic resistance and bacterial lipid composition in E. coli, based on the function and arrangement of the bilipid coating of the bacterial cell, intimately associated with the path of antimicrobials through membranes. Methods Fifteen multiresistant E. coli samples are collected from swine with enterocolitis tested for resistance levels using the disc diffusimetric method (Kirby-Bauer disc diffusion). Pathogen identification completed using the API 20E multitest system revealed the E. coli presence in 11 samples. In these samples, bacterial membrane detection of fatty acid methyl esters (FAME) operating a 240 MS Ion Trap (Varian) GC/MS (Agilent Technologies, Santa Clara, CA, USA) was performed, using the MIDI Sherlock recognition software model. Results Interpreting the descriptive statistical method, the correlation matrix, and regression curves and after ANOVA analysis, we ascertained that the studied E. coli population statistically confirmed different degrees of resistance in most of the samples analyzed in this test. Conclusions In one case, the methyl-(Z)-11-tetradecenoate acid was observed to have a relationship with the susceptibility evaluation by using the disc diffusimetric method, which has revealed the lowest rate of antimicrobial resistance, so it has importance in further resistance evaluation studies.

Antibacterial and Anti-Inflammatory Properties of a Novel Antimicrobial Peptide Derived from LL-37.

Peri-implantitis is a pathological condition involving tissues around dental implants that are characterized by inflammation of the peri-implant mucosa and progressive loss of supporting bone. We found that the antimicrobial peptide KR-12-3 (KRIVKWIKKFLR) derived from LL-37 had antibacterial properties against Streptococcus gordonii. The purpose of this study was to evaluate its antibacterial and anti-inflammatory activities and its underlying mechanisms. We evaluated the antibacterial activities of antimicrobial peptides in planktonic and biofilm states by measuring their minimum inhibitory concentration, minimum bactericidal concentration, and biofilm susceptibility. The effects of antimicrobial peptides on the production of IL-6 and IL-8 in LPS-stimulated RAW264.7 cells were detected by enzyme-linked immunosorbent assay and other experiments, and their toxicity to MC3T3-E1 cells was also studied. While maintaining low cytotoxicity, KR-12-3 exhibited growth inhibitory effects on S. gordonii in planktonic and biofilm states. Lower concentrations of KR-12-3 treatment reduced the production of inflammatory cytokines in LPS-stimulated RAW264.8 cells. The mechanisms underlying the inhibition of biofilm formation and anti-inflammatory effects have been associated with the low expression of related genes. KR-12-3 may be used to develop an antibacterial, anti-infective, and anti-inflammatory drugs for peri-implantitis.

C-terminal mini-PEGylation of a marine peptide N6 had potent antibacterial and anti-inflammatory properties against Escherichia coli and Salmonella strains in vitro and in vivo

BackgroundEnteropathogenic Escherichia coli and Salmonella pullorum are two important groups of zoonotic pathogens. At present, the treatment of intestinal pathogenic bacteria infection mainly relies on antibiotics, which directly inhibit or kill the pathogenic bacteria. However, due to long-term irrational, excessive use or abuse, bacteria have developed different degrees of drug resistance. N6, an arenicin-3 derivative isolated from the lugworm, has potent antibacterial activity and is poorly resistant to enzymatic hydrolysis and distribution in vivo. Polyethylene glycol (PEG) is an extensively studied polymer and commonly used in protein or peptide drugs to improve their therapeutic potential. Here, we modified the N-/C-terminal or Cys residue of N6 with liner PEGn of different lengths (n = 2, 6,12, and 24), and the effects of PEGylation of N6 on the stability, toxicity, bactericidal mechanism, distribution and efficacy were investigated in vitro and in vivo.ResultsThe antimicrobial activity of the peptide showed that PEGylated N6 at the C-terminus (n = 2, N6-COOH-miniPEG) had potent activity against Gram-negative bacteria; PEGylated N6 at the N-terminus and Cys residues showed low or no activity with increasing lengths of PEG. N6-COOH-miniPEG has higher stability in trypsin than the parent peptide-N6. N6-COOH-miniPEG significantly regulated cytokine expression in lipopolysaccharides (LPS)-induced RAW 264.7 cells, and the levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-1β were reduced by 31.21%, 65.62% and 44.12%, respectively, lower than those of N6 (-0.06%, -12.36% and -12.73%); N6-COOH-miniPEG increased the level of IL-10 (37.83%), higher than N6 (-10.21%). The data indicated that N6-COOH-miniPEG has more potent anti-inflammatory and immune-regulatory effect than N6 in LPS-stimulated RAW 264.7 cells. N6-COOH-miniPEG exhibited a much wider biodistribution in mice and prolonged in vivo half-time. FITC-labeled N6-COOH-miniPEG was distributed throughout the body of mice in the range of 0.75 – 2 h after injection, while FITC-labeled N6 only concentrated in the abdominal cavity of mice after injection, and the distribution range was narrow. N6-COOH-miniPEG improved the survival rates of mice challenged with E. coli or S. pullorum, downregulated the levels of TNF-α, IL-6, IL-1β and IL-10 in the serum of LPS-infected mice, and alleviated multiple-organ injuries (the liver, spleen, kidney, and lung), superior to antibiotics, but slightly inferior to N6.ConclusionsThe antibacterial activity, bactericidal mechanism and cytotoxicity of N6-COOH-miniPEG and N6 were similar. N6-COOH-miniPEG has a higher resistance to trysin than N6. The distribution of N6-COOH-miniPEG in mice was superior to that of N6. In exploring the modulatory effects of antimicrobial peptides on cytokines, N6-COOH-miniPEG had stronger anti-inflammatory and immunomodulatory effects than N6. The results suggested that C-terminal PEGylated N6 may provide an opportunity for the development of effective anti-inflammatory and antibacterial peptides.

Novel non-cytotoxic antimicrobial peptides WSKK11 and WSRR11 with potent activity against Cutibacterium acnes.

Cutibacterium acnes is one of the common multifactorial causes that play an important role in the pathophysiology of acne vulgaris. We aimed to develop novel antimicrobial peptides for reduction of the hypercolonization. Six cationic peptides were derived by de novo designation. The antimicrobial and cytotoxic activities of peptides were investigated. The peptide conformation was determined by circular dichroism spectrometry. The antimicrobial effects of peptides were evaluated using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and DNA-binding ability assay. Among designed peptides, WSKK11 and WSRR11 were effective antimicrobials against C. acnes at MICs of 128 and 64 mg/L, respectively. The MICs of WSKK11 against Staphylococcus epidermidis, Staphylococcus aureus and Candida albicans were 8, 8 and 32 mg/L, while those of WSRR11 were 64, 32 and 32 mg/L, respectively. WSKK11 and WSRR11 were less toxic to human erythrocytes (<2%) and not toxic to macrophages, keratinocytes and fibroblasts up to 512 mg/L. WSKK11 and WSRR11 mostly revealed the conformation of the undefined or random coil structures under mimicked environmental conditions. The peptides affected cell surfaces and cell membranes of C. acnes as well as possibly translocating through the cell membrane, observed by a combination of SEM and TEM, respectively. WSKK11 and WSRR11 had the ability to bind bacterial DNA. The two novel antimicrobial peptides WSKK11 and WSRR11 are members of a new class of antimicrobial agents that could deal with acne problems. Therefore, the antimicrobial peptides may be promising novel active agents for dermatological, beauty and cosmeceutical applications.

Eff ect of Antimicrobial Peptides from Fly Maggots on Immunity of Yellow-feathered Broilers

Eff ect of Antimicrobial Peptides from Fly Maggots on Immunity of Yellow-feathered Broilers

Effect of Antimicrobial peptides and chemicals produced by animals on Streptococcus pyogenes

There are about 700 million infections occur annually by Streptococcus pyogenes species around the world. Although the mortality rate of these infections does not exceed 0.1%. Among over 650 thousands cases which are invasive and severe, their mortality rate is 25%. Certainly early diagnosis and early treatment play an important role in severity prevention; failure of right diagnosis can lead to sepsis and death. Streptococcus pyogenes species infect the throat, genitalia, rectum and even skin. Among healthy individual, there are 1% to 5% carrier of Streptococcus pyogenes infection in skin, rectum and vaginal without appearance of any signs or symptoms. Among children, about 17% are carriers of these bacteria. There are four methods of transmission of Streptococcus pyogenes species infection which are inhalation of droplets, contact with contaminated objects like surfaces or dust, skin contact and rarely contaminated food. These bacteria can cause deleterious diseases like pharyngitis rheumatic heart disease and scarlet fever which caused by streptococcal infections. Although pharyngitis is caused mainly by viral infection, about 15% to 30% of pharyngitis infections are streptococcal in origin. The rate of pharyngitis infection in adult is less than children infection due to children exposure in nurseries, schools, playgrounds as well as the low host immunity. Infection rate increases during winter time every year. Metabolic type 1 clone is associated with Streptococcus pyogenes species infection. Mortality rate of Streptococcus pyogenes was high in developed country especially before the penicillin era, but the rate decreased after penicillin availability. So, the environmental factors play a vital role in streptococcal infection. Streptococcal infections are more frequently in men rather than women. With patient with risk factors like rheumatic heart disease, cancer, viral infections like covid-19 and flu and surgical incision, streptococcal infection occurs to 17% to 25% of those cases. Among children; chicken pox represents an important risk factor to increase possibility of streptococcal infection. However, 30% of people can be infected with Streptococcus pyogenes species without any previous risk factors. Rheumatic heart disease and scarlet fever occur after throat infection. In this manuscript, some antimicrobial chemicals extracted from animals will be shown and their activity against Streptococcus pyogenes species using optical density analysis technique then their minimum inhibitory concentrations (MIC) will be determined as well as ICs 50 to measure the potency to inhibit a biological function using programmes like Gene5, graph pad prism as well as testing antimicrobial activity of some chemicals which are found in animal secretions.

Effect of antimicrobial peptide (AMP)–tethered stainless steel surfaces on the bacterial membrane

Bacterial colonization leading to biofilm formation on surfaces induces industry-related as well as health care–associated infections worldwide. Emerging antibiotic-resistant microbes and related persistent infections due to adherent biofilm formation on surfaces have urged the need of effective alternative solutions to eradicate prevailing problems. Antimicrobial peptides are considered as potential candidates with distinguished characteristics, namely, broad-spectrum antimicrobial activity, low propensity toward pathogen resistance, and low immune response. In this study, we immobilize an in-house–designed peptide, KLLLRLRKLLRR (KLR), using a 2-step functionalization strategy onto stainless steel (SS) surfaces. SS is amino-silanized using (3-aminopropyl) triethoxysilane followed by tethering of KLR on it via formation of the amide bond. KLR-coated SS surfaces show nearly 95–100% reduction in bacterial colonization in vitro as obtained from antibacterial susceptibility testing while being non-toxic to mammalian cells. The coating strategy does not affect the microstructure of the SS surfaces. These findings demonstrate that this tethering process is able to produce excellent antibacterial surfaces.

Effect of Antimicrobial Peptides on the Growth and Immunity of Swamp Eels

This study aimed to investigate the effect of different levels of antimicrobial peptides (AMPs) supplementation in the diet feed on growth performance, survival rate, biochemical parameters in swamp eels. Healthy fishes were randomly assigned to five groups feeding with different supplementation of AMPs (0, 200, 400, 600, or 800 mg/kg) in diets for 68 days. Results showed that relative weight gain, feed coefficient and survival rate were significantly (p&lt;0.05) increased by supplementation of AMPs in feed. Level of protein (TP), triglyceride TG, alanine transaminase (ALT), alkaline phosphate (ALP), acid phosphate (ACP), superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) in the serum were significantly (p&lt;0.05) improved in all AMPs treatments, while no significant difference was found between the control and AMPs 200 mg/kg. AMPs supplementation significantly enhanced (p&lt;0.05) the survival rate and immune protection in swamp eels after challenged with Aeromonas hydrophila compared to the control group and eels fed with AMPs 800 mg/kg had the highest survival rate and immune protection (32.50 and 85.71%, respectively). The diets containing AMPs enhanced the survival rate, immune ability, and antioxidant capacity in swamp eels, indicate that an appropriate dosage of AMPs can be used as a potential alternative to antibiotics in swamp eels.

Effect of Antimicrobial Peptides and Chemicals Produced by Animals on Liver Microsomal Enzymes CYP450

The problem of multidrug-resistant pathogens as bacteria, fungi and yeast in addition to the restriction of using antibiotics as growth promoting substances in feed has attracted attention for looking for alternative sources instead of conventional antibiotics like natural products which have antimicrobial activity. Much interest and researches have been focused on using natural antimicrobial peptides and chemicals extracted from animal secretions and some insect’s venoms as they exhibit antimicrobial activity against pathogens with lower resistance and higher synergistic effects if they were given in combination with blends of them. In this paper, some antibacterial peptides extracted from honeybees venom and expression with yeast Saccharomyces cerevisiae will be discussed as well as antimicrobial chemicals extracted from giraffes in addition to their inhibitory effects on liver microsomal enzymes CYP450 will be discussed also with its activity against microorganisms which are Agrobacterium rhizogenes, Aspergillus niger, Candida albicans and E. coli using optical density analysis technique then their minimum inhibitory concentrations (MIC) will be determined as well as ICs 50 to measure the potency to inhibit a biological function using programmes like Gene5, graph pad prism and clone manager as well as testing antimicrobial activity of some chemicals which are provided in animal secretions.

Effect of antimicrobial peptides and monoterpenes on control of fire blight

Aim of study: Antimicrobial peptides and monoterpenes are safe compounds that have been used for control of many plant diseases. Herein, the effects of two recombinant antibacterial peptides (AMPs) were compared with two monoterpenes for control of Erwinia amylovora directly or via induction of plant defense enzyme guaiacol peroxidase (GPOD).Area of study: The experiments were performed at the Ferdowsi University of Mashhad (Iran).Material and methods: The central composite design (CCD) method was used to study the effect of mixing the compounds and copper compound (Nordox) in controlling the pathogen. The resistance level was studied on shoots of tolerant (‘Dargazi’) and semi-susceptible (‘Spadona’) pear cultivars treated with the antibacterial compounds.Main results: Thanatin and 1,8-cineole showed the highest and lowest antibacterial effects. All treatments reduced E. amylovora pathogenicity on blossom. The CCD analysis revealed that the best reduction in colony number obtained by mixing Lfc, thanatin, thymol, 1,8-cineole and Nordox at concentrations of 32, 16, 24, 250 and 250 μg/mL. Thymol and 1,8-cineole at 500 μg/mL decreased disease severity significantly compared to that of AMPs. The level of GPOD enzyme in ‘Dargazi’ was higher than in ‘Spadona’. All treatments increased the GPOD levels in both cultivars. Furthermore, resistance level and GPOD ratio were negatively correlated.Research highlights: Antimicrobial peptides showed better effect on growth inhibition of E. amylovora than monoterpenes. Mixing of these peptides and monoterpens at special dosage enhanced their antimicrobial efficacy against E. amylovora; that could represent a new method in control of fire blight disease.

Protective properties of native milk components

A review of the antimicrobial properties of native dairy components was done based on local and international sources. The contribution of biologically active whey proteins (immunoglobulins, lactoferrin, lactoperoxidase, nuclease) to maintaining homeostasis of the body is determined. The mechanism of pathogens suppression by immunoglobulins is described. Two ways of lactoferrin antimicrobial activity are shown: one by absorbing iron in the intestine, and the second by direct interaction of lactoferrin with the bacterial cell. The principle of lactoperoxidase inhibition of various cellular functions of microorganisms is disclosed. The destruction pattern of bacterial cell membranes under the lysozyme treatment is described. The role of xanthine oxidase in the antimicrobial activity of milk is shown. The effect of antimicrobial peptides produced by lactic acid bacteria is considered. The protective components of milk play an important physiological role in the body and have significant technological value. Antimicrobial substances fulfill an important function during passive immunization of a newborn in the initial period of a newborn’s life, when its own immunity has not yet been formed. The components of passive immunity protect the infant from pathogenic microflora. The protective substances maximum level is observed in the first days after calving. The protective components of milk are involved in correcting digestive system homeostasis disorders at adults organisms. The antimicrobial components of milk determine the bactericidal phase of milk, which has a certain technological value. The described biologically active substances complex with antimicrobial properties is highly valued and innovative methods of heat and physical required to maximize its native properties preservation.