Bacteriocidal Activity Research Articles

Biomimetic green synthesis of ZnO nanoflowers using α-amylase: from antimicrobial to toxicological evaluation

Biologically mediated synthesis of nanomaterials has emerged as an ecologically benign and biocompatible approach. Our study explores enzymatic synthesis, utilizing α-amylase to synthesize ZnO nanoflowers (ZnO-NFs). X-ray diffraction and energy-dispersive X-ray spectroscopy revealed crystal structure and elemental composition. Dynamic light scattering analysis indicates that ZnO-NFs possess a size of 101 nm. Transmission electron microscopy showed a star-shaped morphology of ZnO-NFs with petal-like structures. ZnO-NFs exhibit potent photocatalytic properties, degrading 90% eosin, 87% methylene blue, and 81% reactive red dyes under UV light, with kinetics fitting the Langmuir–Hinshelwood pseudo-first-order rate law. The impact of pH and interfering substances on dye degradation was explored. ZnO-NFs display efficient bacteriocidal activity against different Gram-positive and negative strains, antibiofilm potential (especially with P. aeruginosa), and hemocompatibility up to 600 ppm, suggesting versatile potential in healthcare and environmental remediation applications.

Antimicrobial and anti-biofilm activity of a thiazolidinone derivative against Staphylococcus aureus in vitro and in vivo.

Staphylococcus aureus (S. aureus) causes many infections with significant morbidity and mortality. S. aureus can form biofilms, which can cause biofilm-associated diseases and increase resistance to many conventional antibiotics, resulting in chronic infection. It is critical to develop novel antibiotics against staphylococcal infections, particularly those that can kill cells embedded in biofilms. This study aimed to investigate the bacteriocidal and anti-biofilm activities of thiazolidinone derivative (TD-H2-A) against S. aureus. A total of 40 non-duplicate strains were collected, and the minimum inhibitory concentrations (MICs) of TD-H2-A were determined. The effect of TD-H2-A on established S. aureus mature biofilms was examined using a confocal laser scanning microscope (CLSM). The antibacterial effects of the compound on planktonic bacteria and bacteria in mature biofilms were investigated. Other characteristics, such as cytotoxicity and hemolytic activity, were researched. A mouse skin infection model was used, and a routine hematoxylin and eosin (H&E) staining was used for histological examination. The MIC values of TD-H2-A against the different S. aureus strains were 6.3-25.0 µg/mL. The 5 × MIC TD-H2-A killed almost all planktonic S. aureus USA300. The derivative was found to have strong bacteriocidal activity against cells in mature biofilms meanwhile having low cytotoxicity and hemolytic activity against Vero cells and human erythrocytes. TD-H2-A had a good bacteriocidal effect on S. aureus SA113-infected mice. In conclusion, TD-H2-A demonstrated good bacteriocidal and anti-biofilm activities against S. aureus, paving the way for the development of novel agents to combat biofilm infections and multidrug-resistant staphylococcal infections.IMPORTANCEStaphylococcus aureus, a notorious pathogen, can form a stubborn biofilm and develop drug resistance. It is crucial to develop new anti-infective therapies against biofilm-associated infections. The manuscript describes the new antibiotic to effectively combat multidrug-resistant and biofilm-associated diseases.

Self-controllable proteinic antibacterial coating with bacteria-triggered antibiotic release for prevention of periprosthetic infection

Periprosthetic infection is a devastating postimplantation complication in which a biofilm layer harboring invasive microorganisms forms around orthopedic implants, leading to severe implant failure and patient morbidity. Despite the development of several infection-triggered antibiotic release approaches, most current antibacterial coatings are susceptible to undesired antibiotic leakage or mechanical disintegration during prosthesis installation. Herein, we propose a self-controllable proteinic antibacterial coating capable of both long-lasting adherence onto titanium implant substrates over the implant fixation period and instantaneous bacterial eradication. Importantly, the pH-dependent reversible metal coordination of mussel adhesive protein (MAP) enabled bacterial concentration-dependent antibiotic delivery in response to infection-induced acidification. In addition, the MAP coating exhibited superior self-healable adhesive properties and scratch resistance, which enabled to avert issues associated with mechanical damages, including peeling and cracking, often occurring in conventional implant coating systems. The gentamicin-loaded MAP coating exhibited complete inhibition of bacterial growth in vivo against Staphylococcus aureus penetrations during implantation surgery (immediate infection) and even 4 weeks after implantation (delayed infection). Thus, our antibiotic-loaded MAP hydrogel coating can open new avenues for self-defensive antibiotic prophylaxis to achieve instant and sustainable bacteriocidal activity in orthopedic prostheses.© 2017 Elsevier Inc. All rights reserved.

One-Year Water-Stable and Porous Bi(III) Halide Semiconductor with Broad-Spectrum Antibacterial Performance.

Hybrid metal halide semiconductors are a unique family of materials with immense potential for numerous applications. For this to materialize, environmental stability and toxicity deficiencies must be simultaneously addressed. We report here a porous, visible light semiconductor, namely, (DHS)Bi2I8 (DHS = [2.2.2] cryptand), which consists of nontoxic, earth-abundant elements, and is water-stable for more than a year. Gas- and vapor-sorption studies revealed that it can selectively and reversibly adsorb H2O and D2O at room temperature (RT) while remaining impervious to N2 and CO2. Solid-state NMR measurements and density functional theory (DFT) calculations verified the incorporation of H2O and D2O in the molecular cages, validating the porous nature. In addition to porosity, the material exhibits broad band-edge light emission centered at 600 nm with a full width at half-maximum (fwhm) of 99 nm, which is maintained after 6 months of immersion in H2O. Moreover, (DHS)Bi2I8 exhibits bacteriocidal action against three Gram-positive and three Gram-negative bacteria, including antibiotic-resistant strains. This performance, coupled with the recorded water stability and porous nature, renders it suitable for a plethora of applications, from solid-state batteries to water purification and disinfection.

Characterization of novel bacteriocin PB2 and comprehensive detection of the pediocin gene ped-A1 from Pediococcus pentosaceus PB2 strain isolated from a sorghum-based fermented beverage in Nigeria

Lactic acid bacteria (LAB) have been known to possess bacteriocidal activity resulting from ribosomally synthesized antimicrobial peptides called bacteriocin. This study focused on the characterization of the bactericidal activity of bacteriocin PB2 and comprehensive detection of the pediocin ped-A1 from Pediococcus pentosaceus obtained from fermented sorghum beverage, Pito, in Nigeria against Escherichia coli ATCC 25922 and Listeria monocytogenes ATCC 15313. Bacteriocin PB2 was purified in a 2-step purification using 80% NH4 (SO4)2, and Carboxymethyl-Sephadex G-50 column chromatography to achieve a 12.62% purification fold. The physicochemical properties of purified bacteriocin were characterized being treated at different temperatures (20 – 120 °C), pH (2.0 – 10.0), with different detergents and enzymes (sodium dodecyl sulphate (SDS) urea, ox-gall, and proteinase K and RNase A), organic solvents (ethanol, phenol, acetone, chloroform and isoamyl alcohol), and exposure to ultraviolet (UV) radiation (2–12 h) respectively. The molecular weight of the bacteriocin PB2 was determined to be 4.87 kDa. The antibacterial activity of bacteriocin PB2 was optimum at 40 °C and pH 5.0. The bacteriocin PB2 lost its activity on treatment with proteinase K and exposure to UV radiation (after 6 h) but was observed to have stable activity in the presence of organic solvents. Also, P. pentosaceus PB2 harbored two plasmids, 0.9 and 1.2 kb which when cured resulted in the loss of the antimicrobial activity. The mRNA transcript for pedA was detected in P. pentosaceus PB2, but not in the cured derivative, confirming the expression of the plasmid ped-A1 gene in PB2. This study validates our previous study that the PB2 strain of Pediococcus pentosaceus isolated from fermented sorghum, Pito, may be used as a probiotic toward clinically important enteropathogenic bacteria. This peptide is a potential agent for use as an alternative antibacterial agent for the treatment of drug-resistant strains of bacterial infection.

Evaluation of antibacterial oxygen/ozone mixture in vitro activity on bacteria isolated from cervico-vaginal mucus of cows with acute metritis

Ozone is an oxidating gas showing a strong microbicidal activity on bacteria, fungi, viruses and protozoa. The aim of this study was to test the in vitro bacteriocidal action of an Ozone/Oxygen gas mixture on bacteria isolated from the cervico-vaginal mucus of cows affected by acute metritis. A pilot study was initially carried out on reference strains (Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923 and Mycoplasma bovigenitalium ATCC 19852) that were tested with three different treatments: a control positive baseline group (B-group) was incubated without gas treatment, a control positive oxygen group (O2-group) was treated with pure oxygen 100%, and the treated group (T-group) was exposed to a gaseous constant flow of an Ozone/Oxygen mixture, at 50, 35, 20 μg Ozone/ml and for 5, 3 and 1 min for every different Ozone concentration. In both positive control groups, the number of colony forming units (CFU) per ml was higher than 300 CFU/ml (E. coli and S. aureus) and higher than 30 CFU/ml for M. bovigenitalium, after incubation. The T-groups showed a minimal bacterial growth equal to or lower than 1 CFU/ml per plate.Based on the results of the pilot study, a second phase was performed on bacteria isolated from the cervico-vaginal mucus (Klebsiella pneumoniae, Enterobacter agglomerans, E. coli, Proteus mirabilis and M. bovigenitalium) using the lower concentration of 20 μg/ml of Ozone for the minimum exposure time of 1 min. The E. coli and S. aureus reference strains and the clinical isolates (K. pneumoniae, E. agglomerans, E. coli, P. mirabilis) were incubated at 37 °C for 48 h and the colonies were manually counted at 24 h and 48 h following inoculation. The cultures of M. bovigenitalium (both ATCC and clinical isolate) were incubated in a jar with modified atmosphere conditions with 5% CO2 at 37 °C for 4–7 days and colony counting was performed. The second phase showed a low number of CFUs (equal to or less than 7 CFU/ml) for the clinical isolates K. pneumoniae, E. agglomerans, E. coli and P. mirabilis, and, of note, for M. bovigenitalium, both ATCC and clinical isolate, the growth was completely inhibited. Ozone was demonstrated to have a bacteriocidal activity. This study encourages further research of in vivo application of low doses of gaseous Ozone for the treatment of metritis in cows by using minimal exposure times.

Applications of Hydrophobins in Medical Biotechnolog

Class I and class II Hydrophobins are small, low molecular weight cysteine-rich protein produced by filamentous fungi, of approximately 100 amino acids, whose size ranges between 5-20 kDa. Research over the last 10 years gave an improved insight into the applications of hydrophobins in the medical and pharmaceutical fields. The study of hydrophobins, self-assembly between hydrophobic and hydrophilic interfaces led to a better understanding of physical properties and their applications. Different coatings which use anti-fouling agents like hydrophobins are used for fabricating medical devices to provide bacteriocidal and antiplatelet activity for instance by fusion of SC3-NO-releasing medical-grade polymer; formation of antibacterial surfaces. Hydrophobins have been used for making Nano suspensions of water-insoluble drugs to increase their efficiency/effectiveness and for better oral administration.In addition to it, Hydrophobins are used for immobilization of molecules and cells, Detection of antigen-antibody interaction. This review highlights the study of a significant wide range of applications by various methods, also showcasing the need for developing new product strategies to improve the low yields for their broader use. Hydrophobins being a promising protein gives widespread opportunities for their application in medical and therapeutics.

A novel ML protein functions as a pattern recognition protein in antibacterial responses in Eriocheir sinensis

The myeloid differentiation factor 2 (MD-2)-related lipid recognition (ML) domain is present in MD-2, MD-1, GM2-activator protein (GM2A) and Niemann-Pick disease type C2 (NPC2). ML proteins function in antibacterial signal transduction and lipid metabolism in vertebrates, but the mechanism in invertebrates is unknown. In this study, we found that ML proteins were involved in bacterial resistance in Chinese mitten crab (Eriocheir sinensis). One member, EsML3, a soluble, bacterial-induced pattern recognition protein was upregulated in hemocytes following bacterial challenge. Recombinant EsML3 bound to Gram-negative bacteria (Vibrio parahaemolyticus) and Gram-positive bacteria (Staphylococcus aureus) by interaction with peptidoglycan, lipopolysaccharide. EsML3 showed no direct bacteriostatic or bacteriocidal activity. Pre-incubating bacteria with rEsML3 significantly promoted in vivo bacterial clearance. EsML3 also promoted phagocytic activity and plays a role against bacterial infection. In summary, EsML3 mediates cellular immune responses by recognising invasive microorganisms, promoting bacterial clearance and phagocytosis against bacterial infection in crab.

Experimental investigations of application of the water-steam оzone-containing gaseous mixture for prophylaxis and treatment of respiratory infectious diseases

Objective. Determination of the virus-cidal and bacterio-cidal action of the ozone-containing steam-water mixture, which was obtained, using apparatus POS-1, simulated on viral models of transmissive gastroenteritis of pigs of the coronaviruses family and polyresistant clinical strains of bacterial cultures, as well as adjustment of optimal parameters of ozone in the gaseous mixture content, which do not cause pathological changes in the organism’s organs and systems.
 Materials and methods. Apparatus POS-1, created by collective of Scientific-Methodical Centre «Medical Innovation Technologies»», was applied for production of the ozone-containing gaseous mixture. Virusological investigations were conducted on the base of the Institute of Epidemiology and Infectious Diseases named after L. V, Gromashevskiy. As a working material the models of virus of the pigs transmissive gastroenteritis of the coronaviruses family were applied. The series of bacteriological and experimental investigations were conducted on the base of Shalimov National Institute of Surgery and Transplantology NAMS of Ukraine. Polyresistant cultures in concentration of 108 colony-creating units per 1 ml were applied for bacteriological investigations. The experiment was conducted on white rats to study the gaseous ozone-containing mixture affection on living biological tissues.
 Results. Virusological investigations have shown, that in the 20 minutes exposition and a contact with extracellular virus the infection titer have lowered in 100 000 times, and in a 30 minutes exposition - a complete deactivation of virus have had occurred. Bacteriological investigations have revealed the complete absence of the cultures development after their processing with the ozone-containing mixture during 20 min. The results of swimming tests and behavioral reactions in white rats of control and experimental groups did not differ. Histological investigations of the respiratory organs tissues as well as of spleen, thyroid gland, kidneys and suprarenal glands did not reveal pathological effects of the ozone-containing mixture.
 Conclusion. Parameters of the ozone generation and delivery in the gaseous mixture content were studied and optimally selected. Investigations of the ozone-containing mixture affection on a viral strain of the coronaviruses family, as well as bacteriological investigations on polyresistant bacterial cultures have had confirmed its pronounced virus-cidal and bactericidal properties. Application of the ozone-containing mixture do not cause any pathological changes in the living organism organs and systems. This gaseous mixture may be used for prevention and treatment of respiratory infectious diseases of viral and bacterial genesis.

Mycobacterium tuberculosis Cells Surviving in the Continued Presence of Bactericidal Concentrations of Rifampicin in vitro Develop Negatively Charged Thickened Capsular Outer Layer That Restricts Permeability to the Antibiotic.

Majority of the cells in the bacterial populations exposed to lethal concentrations of antibiotics for prolonged duration succumbs to the antibiotics’ sterilizing activity. The remaining cells survive by diverse mechanisms that include reduced permeability of the antibiotics. However, in the cells surviving in the continued presence of lethal concentrations of antibiotics, it is not known whether any cell surface alterations occur that in turn may reduce permeability of the antibiotics. Here we report the presence of a highly negatively charged, hydrophilic, thickened capsular outer layer (TCOL) on a small proportion of the rifampicin surviving population (RSP) of Mycobacterium tuberculosis (Mtb) cells upon prolonged continuous exposure to bactericidal concentrations of rifampicin in vitro. The TCOL reduced the intracellular entry of 5-carboxyfluorescein-rifampicin (5-FAM-rifampicin), a fluorochrome-conjugated rifampicin permeability probe of negligible bacteriocidal activity but comparable properties. Gentle mechanical removal of the TCOL enabled significant increase in the 5-FAM-rifampicin permeability. Zeta potential measurements of the cells’ surface charge and hexadecane assay for cell surface hydrophobicity showed that the TCOL imparted high negative charge and polar nature to the cells’ surface. Flow cytometry using the MLP and RSP cells, stained with calcofluor white, which specifically binds glucose/mannose units in β (1 → 4) or β (1 → 3) linkages, revealed the presence of lower content of polysaccharides containing such residues in the TCOL. GC-MS analyses of the TCOL and the normal capsular outer layer (NCOL) of MLP cells showed elevated levels of α-D-glucopyranoside, mannose, arabinose, galactose, and their derivatives in the TCOL, indicating the presence of high content of polysaccharides with these residues. We hypothesize that the significantly high thickness and the elevated negative charge of the TCOL might have functioned as a physical barrier restricting the permeability of the relatively non-polar rifampicin. This might have reduced intracellular rifampicin concentration enabling the cells’ survival in the continued presence of high doses of rifampicin. In the context of our earlier report on the de novo emergence of rifampicin-resistant genetic mutants of Mtb from the population surviving under lethal doses of the antibiotic, the present findings attain clinical significance if a subpopulation of the tubercle bacilli in tuberculosis patients possesses TCOL.

English

Dried seeds of Monodora myristica were obtained from Oba market in Edo State, ground into fine powder and stored in an air tight plastic container at room temperature until when used. Essential oils were extracted using steam distillation and characterised using the gas chromatography-mass spectroscopy (GC-MS) technique. Microbial isolates obtained from smoke dried fish samples purchased from Oba Market, Benin City, Edo State. Fish samples were put in perforated polythene bags kept in plastic baskets and stored for four (4) weeks. Identification and characterisation of isolates were carried out following standard microbiological procedures. The antimicrobial activity was determined using agar well diffusion method. Data obtained were subjected to a one-way analysis of variance. Significant means were separated using Duncan Multiple Range Test at 95% confidence level. The result showed that M. myristica oil contained twenty-five components which were mainly monoterpene hydrocarbons constituents consisting of limonene (17.6%), α-phellandrene (16.3%), α-pinene (12.2%), β-myrcene (11.2%), 3-Thujene and β-Linalool (7.3%). The oil showed bacteriocidal activity at minimum ihhibitory concentration/minimum bactericidal concentration (MIC/MBC) of 150 mg/mL against Staphylococcus epidermidis PM221, Micrococcus luteus NCTC 2665, Bacillus subtilis 6051-HGW and Pseudomonas aeruginosa AAU2 and fungicidal activity at MIC/minimum fungicidal concentration (MFC) of 300 mg/mL against Aspergillus flavus and Rhizopus species. In view of the aforementioned, the expressed antimicrobial activity is a demonstration of the efficacy of the oil against fish spoilage organism and use in the fishery industry. Key words: Chemical compositions essential oils, antimicrobial activity, Monodora myristica, agar well diffusion method, Clarias gariepinus.

IMPROVING SOME PARAMETERS OF ANTIBODY RESPONSE IN HORSES BY PROBIOTIC AGENTS AGAINST BACKGROUND USE OF MACROCYCLIC LACTONE ANTHELMINTIC

Multiple researches demonstrate that both invasive diseases and use of anthelmintcs adversely affect horse immunity harming the gut flora. Macrocyclic lactone anthelmintics are proved to be highly effective agents but there is insufficient knowledge of their effect on the horse antibody immunity. The issue of immune system correction by the probiotic agents is also underreported. The paper demonstrates the results of the effect made by parascaridosis and strongylidosis invasion and deworming using the macrocyclic lactone drug on some parameters of antibody response in horses. Data on effect of probiotic Bioxymin horse on blood serum bacteriocidal and lysozyme activity were reported for the first time. The research was performed from December 2018 to January 2019. The results demonstrated that helminthic invasion and anthelmintic drug Univerm make depressive effect on some parameters of antibody response in horses. It also has an impact on the extensive efficacy of the anthelmintic agent. Probiotic Bioxymin horse makes a stimulating effect on the antibody response in horses.

Bactericidal and cytotoxic effects of acid-electrolyzed functional water.

Sodium hypochlorite (NaOCl) is widely used as an antimicrobial irrigant; however, it has cytotoxic and neurotoxic effects. For these reasons, development of new, safe irrigants other than NaOCl is long overdue. In the present study, the antimicrobial and noxious effects of acid-electrolyzed functional water (FW) were evaluated and compared with those of NaOCl. Enterococcus faecalis, Streptococcus mutans, Porphyromonas gingivalis, or Candida albicans were mixed with each tested solution for 30 s. The mixtures were then plated on brain-heart infusion agar plates, after which colony numbers were counted. Serially diluted acid FW was used to determine the actual chloride concentration (ACC) required for a bactericidal effect. Noxious effects were evaluated by measuring lactate dehydrogenase released from HeLa cells. Acid FW and NaOCl had similar bactericidal effects against all bacterial species but not against C. albicans. An ACC of at least 10 ppm was required in order to ensure effective bacteriocidal activity and induce significant lactate dehydrogenase release. Acid FW-treated HeLa cells exhibited healthy growth, with slight retardation as compared with non-treated cells. Because of its efficient bactericidal, and less noxious, effects on human cells, acid FW may be a useful irrigant for effective root canal treatment.

Cation-dependent mannose-6-phosphate receptor functions as a pattern recognition receptor in anti-bacterial immunity of Marsupenaeus japonicus

The cation-dependent mannose-6-phosphate receptor (CD-MPR) is a member of the P-type lectin family. As a type I transmembrane glycoprotein, it functions in the delivery of newly synthesized acid hydrolases from the trans-Golgi network to endosomes for their subsequent transfer to the lysosome by binding the mannose-6-phosphate receptor-recognition moieties in the hydrolases. However, the functions of CD-MPR in immune responses are seldom reported. In the present study, we identified a CD-MPR-like molecule in Marsupenaeus japonicus and designed it as MjCD-MPR. It was significantly upregulated after challenge with Vibrio anguillarum at the mRNA and protein levels. Knockdown of MjCD-MPR resulted in a significant increase in the amount of V. anguillarum in the hemolymph of shrimp, which suggested that MjCD-MPR plays a role in shrimp antibacterial defense. The recombinant extracytoplasmic region of MjCD-MPR could bind gram-positive and gram-negative bacteria by interaction with peptidoglycan, lipopolysaccharide, and lipoteichoic acid. MjCD-MPR showed no direct bacteriostatic or bacteriocidal activity. Knockdown of MjCD-MPR decreased the expression levels of several antimicrobial peptides (Alf-C1, Alf-E1, Crustin I-2, and Crustin I-3), suggesting that MjCD-MPR promotes the expression of antimicrobial peptides in shrimp. In summary, working as a pattern recognition receptor, MjCD-MPR recognizes invading bacteria and triggers the expression of AMPs against bacterial infection in shrimp.

ANTI-MRSA OF THE ETHYL ACETATE CRUDE EXTRACT FROM LASIODIPLODIA PSEUDOTHEOBROMAE IBRL OS-64, AN ENDOPHYTIC FUNGUS ISOLATED FROM LEAF OF OCIMUM SANCTUM LINN

Objective: To investigate the effects of ethyl acetate crude extract of an endophytic fungus, L. pseudotheobromae IBRL OS-64 which was isolated from leaf of Ocimum sanctum against the growth of methicillin-resistant Staphylococcus aureus (MRSA)., a common pathogenic bacteria to human.Methods: Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were determined. Time-kill assay was used to examine the effect of the extract on the MRSA growth profile. The effects of the extract on the ultrastructure of MRSA cells were analyzed by scanning electron microscopic (SEM) study.Results: The results obtained from this study showed the fungal ethyl acetate crude extract exhibited a strong bactericidal effect on MRSA where the ratio of MBC/MIC was 2 and less than 4. The MIC and MBC values were 125.0 and 250.0 µg/ml, respectively. The time-kill study revealed that the bacteriocidal activity of the extract was both concentration and time-dependent. After 12 h treatment, the interaction of extract with MRSA cells resulted in the formation of dents, cavity or small dimples on the cell surface, indicating disintegration of the cell wall and cell membrane that resulting in leakage of their cytoplasmic contents, and ultimately cell death.Conclusion: The ethyl acetate crude extract of L. pseudotheobromae IBRL OS-64 showed a significant anti-MRSA activity and principally affected the cell wall and the cell membrane of the growing MRSA cells. This is the first report on L. pseudotheobromae, an endophytic fungus isolated from medicinal herb, Ocimum sanctum Linn.

MazE Antitoxin of Toxin Antitoxin System and fbpA as Reliable Targets to Eradication of Neisseria meningitidis.

Neisseria meningitidis is considered as a dangerous pathogen threatening human health. Nowadays, the new drug target is focused. Toxin antitoxin (TA) system is recently identified as an antimicrobial drug target. Also, in N. meningitidis, iron-uptake system could be an interesting target for drug discovery. In this study, fbpA and mazE genes were chosen as new antimicrobial targets and treated with antisense peptide nucleic acid (PNA). Firstly, they were evaluated by bioinformatics and then analyzed by experimental procedures. Secondly, the functionality was evaluated by stress conditions. Our results interestingly demonstrated that when fbpA and mazE loci of N. meningitidis were targeted by antisense PNA, 8 µM concentration of fbpA-PNA as well as 30 µM concentration of mazE-PNA inhibited the growth of N. meningitides and were found to be bacteriostatic, whereas 10 μM concentration of fbpA-PNA showed bacteriocidal activity. Our findings demonstrated the bactriocidal activity of fbpA-PNA and bacteriostatic activity of mazEPNA. Therefore, mazE and fbpA genes should be potent antimicrobial targets but further analysis including in vivo analysis should be performed.

Production optimization of broad spectrum bacteriocin of three strains of Lactococcus lactis isolated from homemade buttermilk

Abstract Three potent strains of lactic acid bacteria (LAB) with bacteriocin producing abilities have been isolated from homemade buttermilk. They can produce proteinaceous bacteriocins in the medium which are resistant to heat (121 °C for 15 min) and can tolerate range of pH from 3.0 to 11.0. They were found to be Gram positive, non-motile, non-endospore forming, coccoid structures. The strains LABW1 and LABW3 were present in chains while LABW4 were present singly or in pairs. By considering the 16S rDNA sequence homologies and phylogenetic analysis LABW1 and LABW3 were identified as Lactococcus lactis subsp. hordniae where as LABW4 was identified as Lactococcus lactis subsp. lactis. Maximum extracellular bacteriocin production by the isolates takes place in MRS medium (pH 5.0–7.0) at 28 °C and it showed strong correlation with bacterial growth. They started producing bacteriocin at early exponential phase (400 AU/ml) and reached its peak at the early stationary phase (12800 AU/ml for LABW1 and LABW3 and 25600 AU/ml for LABW4) which remain unchanged up to late stationary phase. The bacteriocin of the isolates had an antibacterial spectrum both against Gram positive as well as Gram negative pathogenic bacterial strains. The inhibition of Gram negative bacteria by bacteriocin of LAB is an unusual phenomenon. It exhibits bacteriocidal action on Staphylococcus aureus MTCC96 and Pseudomonas aeruginosa MTCC741. Prominent morphological aberrations, cell shrinkages and pore formations on cell wall of pathogenic bacterial cells upon bacteriocin treatment as evidenced from scanning electron microscope (SEM).

Synthesis , Characterization and Biological activity of new derivatives of Chromen-2-one

We report the organic syntheses of new derivatives from Chromen-2-one and their antibacterial activity. Compounds 4-[Acetyl-(2-oxo-2H-chromen-4-yl)-amino]-
 benzenesulfonyl chloride 1a, 4-[Acetyl-(2-oxo-3-phenylsulfamoyl-2H-chromen-4-yl)-amino]-benzenesulfonyl chloride 2a , 2-{4-[Acetyl-(4-chlorosulfonyl-phenyl)-amino]-2-oxo-3-phenylsulfamoyl-2H-chromen-7-ylamino}-benzoic acid 3a. 
 All Structures have been synthesized and characterized using melting points , IR spectra , 1H-NMR, 13C-NMR spectra , and elemental analyses . The purified synthesized compounds (1a,2a,3a), at contcentrations 2,3,5 mg/ml was tested for their antibacterial activity against three bacterial cultures ;Staphylococcus aureus, Escherchia coli and Bacillus cereus. The antibacterial activity of synthesized compounds are compared with antibacterial activity of standard antibiotics cephalexine and streptomycine. 
 The compounds (1a,2a,3a) shows different bacteriostatic and bacteriocidal activity.

Nitrates and Nitrites in meat products

Nitrates and nitrites have been traditionally used as curing agents in the production of cured meat products. Beneficial effects of the addition of nitrates and nitrites to meat products are the improvement of quality characteristics as well as the microbiological safety. The nitrates and nitrites are mainly responsible for the development of the distinct flavor, the stability of the red color, as well as the protection against lipid oxidation in cured meat products. The nitrites show important bacteriostatic and bacteriocidal activity against several spoilage bacteria as well as foodborne pathogens found in meat products. The nitrites prevent the growth and toxin production by Clostridium botulinum. According to Commission Regulation (EU) No. 1129/2011, nitrates (sodium nitrate, E251; potassium nitrate, E252) and nitrites (potassium nitrite, E249; sodium nitrite, E250) are listed as permitted food additives. Nitrates are relatively non-toxic, but nitrites, and nitrites metabolic compounds such as nitric oxide and N-nitroso compounds, have raised concern over potential adverse health effects. Recently, the International Agency for Research on Cancer (IARC) concluded that ingested nitrates or nitrites are probable carcinogen to humans under conditions favoring the endogenous nitrosation. Legal limits for the addition of nitrates and nitrites have been set by several countries and EU [Commission Regulation (EU) No. 601/2014]. Several data from recent reviews conducted in several countries on the levels of nitrates and nitrites in cured meat products were summarized. In recent reviews, the residual levels of nitrites in cured meat samples have been constantly reduced and are in accordance with the legal limits set by most countries.

Solution and Solid-State Nuclear Magnetic Resonance Structural Investigations of the Antimicrobial Designer Peptide GL13K in Membranes.

The antimicrobial peptide GL13K encompasses 13 amino acid residues and has been designed and optimized from the salivary protein BPIFA2 to exhibit potent bacteriocidal and anti-biofilm activity against Gram-negative and Gram-positive bacteria as well as anti-lipopolysaccharide activity in vitro and in vivo. Here, the peptide was analyzed in a variety of membrane environments by circular dichroism spectroscopy and by high-resolution multidimensional solution nuclear magnetic resonance (NMR) spectroscopy. Whereas in the absence of membranes a random coil conformation predominates, the peptide adopts a helical structure from residue 5 to 11 in the presence of dodecylphosphocholine micelles. In contrast, a predominantly β-sheet structure was observed in the presence of lipid bilayers carrying negatively charged phospholipids. Whereas 15N solid-state NMR spectra are indicative of a partial alignment of the peptide 15N-1H vector along the membrane surface, 2H and 31P solid-state NMR spectra indicate that in this configuration the peptide exhibits pronounced disordering activities on the phospholipid membrane, which is possibly related to antimicrobial action. GL13K, thus, undergoes a number of conformational transitions, including a random coil state in solution, a helical structure upon dilution at the surface of zwitterionic membranes, and β-sheet conformations at high peptide:lipid ratios.