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The present investigation reports an in-vitro study using combination of laccase and an enhancer capable of inhibiting the growth of pathogenic microorganisms, preventing biofilm formation, and whitening teeth. Laccase-cinnamic acid system remarkably inhibited the growth of Aggregatibacter actinomycetemcomitans, Candida albicans, S. aureus, and Streptococcus mutans whilst showed no significant effects on Gram-negative bacteria. Data presented that cinnamic acid (10 mM) with laccase (0.125 U ml−1) led to a maximum decrease of about 90%, in S. mutans biofilm formation. The confocal laser scanning microscopy showed considerable detachment of S. mutans cells from glass substratum. The combined laccase-cinnamic acid system could remove teeth discoloration caused by coffee. SEM of the teeth surface exhibited no damages such as surface cracking or fracture. Liquid chromatography-tandem mass spectrometry (LC-MS) and cyclic voltammetry (CV) studies showed that laccase can catalyze the one-electron oxidation of cinnamic acid to the respective radical. This radical can then undergo several fates, including recombination with another radical to form a dimeric species, dismutation of the radical back to cinnamic acid or decarboxylation to give various reduced oxygen species. Therefore, the redox potential values of phenolic monomers/oligomers are related with their biological activities.

The Lactococcus lactis is known as a probiotic bacterium and also as a producer of nisin. Nisin has been approved by related legal agencies to be used as an antimicrobial peptide in food preservation. In fact, the L. lactis is present in different food products along with other micro-organisms especially pathogenic bacteria. So, it is important to predict the behavior of nisin-producer strain in contact with other pathogens. In this regard, nisin gene expression and the level of secreted biologically active form of nisin by L. lactis subsp. lactis in modified MRS broth and whey solution in co-culture with Listeria monocytogenes or Salmonella enterica were studied. The nisin concentration was determined by microbiological assay method and the transcription level of nisin gene was assayed through quantitative reverse transcription PCR (RT-qPCR). According to our results, the highest concentration of nisin and its gene transcription level were detected in mono- and co-cultures after 16 h of incubation, concurrent with the end of L. lactis exponential phase of growth. The nisin mRNA copies in co-cultures were higher than mono-cultures only at 16 h of incubation. But, differences between nisin concentrations in mono- and co-cultures were significant at 16, 24 h and at 12, 16, 24 h of incubation in the modified MRS medium and whey solution, respectively. This incompatibility could be related to the low availability of components required for nisin precursor modification, transportation and processing in mono-cultures. Overall, the L. lactis produced more mature and active nisin when it was in contact with pathogenic bacteria.

Polyhexamethylene biguanide (PHMB) has been used increasingly in various applications because of antibacterial properties; however, its cytotoxicity hampers application. On the other hand, there is a high affinity between the cell membrane complexes (CMCs) in wool structure and phospholipids of cationic nanoliposomes, leading to the transmission of cationic nanoliposomes into the wool. In this research, a novel method for PHMB controlled release is introduced by combining these facts. Firstly, PHMB was encapsulated into cationic liposome and then permeated into the wool to establish a highly controlled release then characterized through diverse methods. SEM images revealed successful transmission of cationic-liposome-encapsulated PHMB into the wool. The prepared wound dressings demonstrated highly sustained release for days and subsequently, long-term perfect antibacterial activity and biocompatibility.

Laccase is a blue enzyme with a remarkable ability to eliminate environmental pollutants. The use of the eco-friendly enzyme for removing ecological contaminants is extensive. In addition, there are some restrictions like its deactivation in various environmental conditions. Researchers have applied many strategies to improve the Laccase stability in different conditions, but those ways are expensive or demanding. Herein, we used betaine, a co-solvent, to increase the enzyme stability in various temperatures and pHs as an appropriate alternative strategy to improve the Laccase stability. The experimental results showed that the enzyme's stability would increase in the presence of betaine at high temperatures. Although no significant changes were detected for the enzyme secondary structure contents, betaine at high temperatures exhibited a protective effect on the enzyme's alpha-helical contents. The simulation results indicated that betaine and ion molecules could be excluded from the enzyme surface and help Laccase maintain its stability and activity. Increasing the betaine concentration up to 0.5 M increased the Tm value of laccase. The molecular dynamics (MD) simulation results also demonstrated that the enzyme's polar amino acids play essential roles in making hydrogen bonds with betaine molecules. Lys377 was also recognized as the most critical residue for electrostatic interactions with the osmolyte at low and high temperatures. At the same time, the higher temperatures could not considerably affect the electrostatic interactions between the carboxyl group of betaine and the basic residues. The results indicated that the negatively charged amino acids could strengthen electrostatic interactions with betaine at high temperatures. The computational analyses also demonstrated that the hydrated state of betaine would not change even at high temperatures. This study's outcomes could be valuable to researchers who seek to use a more affordable approach to increase Laccase activity in severe environmental conditions.

The presence of recalcitrant synthetic dyes in environment is a major concern due to their possible threat on living organisms and aquatic ecosystems. To investigate the potential of combined thermal and enzymatic decolorization, betaine was applied to protect the secondary and tertiary structures as well as the enzymatic activity of laccase under thermal stress. At 60 °C, betaine 1 M significantly enhanced the stability of laccase in addition to keeping its catalytic efficiency (p T m of laccase in the presence of betaine. Once incubated at 60 °C, betaine exhibited superior protein-stabilizing properties than at 25 °C. Furthermore, fluorescence spectroscopy supported this concept that the overall folded structure of laccase became more rigid in the presence of betaine at 60 °C. Betaine-stabilized laccase was used for combined thermal and enzymatic decolorization of some recalcitrant organic dyes. This osmolyte could improve the enzymatic removal of most dyes at 60 °C. A detoxification study with respect to the inhibition of bacterial growth showed a decrease in microtoxicity of the laccase-treated dye solution in the presence of betaine at 60 °C.

Herein we reported the structure and several properties of a new biosurfactants produced by Corynebacterium xerosis strain NS5. This strain was capable of producing a novel lipopeptide biosurfactant that we have named coryxin. The biosurfactant structure was characterized by using Fourier transform infrared spectroscopy (FTIR), Nuclear magnetic resonance spectroscopy (NMR), and Liquid chromatography-mass spectrometry (LC-MS). It contained a hydrophobic moiety of 3-hydroxydecanoic acid and a peptide part predicted as a sequence of seven amino acids including Asn-Arg-Asn-Gln-Pro-Asn-Ser. Coryxin lowered the surface tension of water to 31.4 mN/m, with a critical micelle concentration of 25mg/l. It was a strong emulsifier with an emulsification index of 61% against n-hexane. Coryxin showed antibacterial activity against test organisms belonging to Gram-positive and Gram-negative bacteria and disrupted preformed biofilms of Staphylococcus aureus (82.5%), Streptococcus mutans (80%), Escherichia coli (66%) and Pseudomonas aeruginosa (30%). In conclusion, microbial surfactant from C. xerosis exhibited inhibitory and disruptive activities against biofilm formation that could be of use in biofilm-related menace.

Novel Mannich bases of 7-piperazinylquinolones with kojic acid and chlorokojic acid were designed as new quinolone antibacterials. All compounds showed significant in vitro antibacterial activity against both Gram-positive and Gram-negative bacteria. Particularly, chlorokojic derivative 2b was the most potent compound against Staphylococcus aureus and Pseudomonas aeruginosa (MIC values ≤0.19 μg/mL). Its activity was 4–8 times more than that of standard drug norfloxacin. The molecular docking study of compound 2b further supported the molecular basis of the designed compounds.

A series of novel 3-(1,2,4-triazol-1-yl)flavanones were synthesized based on the N-phenethylazole pharmacophore of azole antifungals. The results of antifungal assay revealed that 4′-fluoroflavanone derivative 4c exhibited the best profile of activity against Candida and Saccharomyces strains. Compound 4c was 4–16 times more potent than reference drug fluconazole against Candida albicans and Saccharomyces cerevisiae. The molecular docking study with lanosterol 14α-demethylase, in silico toxicity risks and drug-likeness predictions were used to better define of title compounds as antifungal agents. The favorable drug-like property of compound 4c makes 3-(1,2,4-triazol-1-yl)flavanone prototype as a promising lead for the future development of azole antifungal agents.

Efficacy of commercial detergent and disinfectants to eliminate microorganisms associated with fresh vegetables eaten raw in Iran, including radish, parsley, basil, coriander (cilantro), Allium porrum (leek), and peppermint were studied. The raw vegetables were subjected to a triple wash treatment of washing in tap water for mud removal, washing in water containing a detergent (dishwashing liquid) or disinfectant individually, and rinsing in tap water. The population of total mesophilic microbes on the surface of untreated vegetables ranged from 10(5) to 10(6) CFU/g. Washing in tap water or treatment with detergent (333 ppm for 10 min) or benzalkonium chloride (92 ppm for 15 min) reduced the total microbial count, most probable number (MPN) of coliforms, MPN of fecal coliforms, and MPN of fecal streptococci by about 1.2 to 2.3 log. No significant differences in microbial populations were found on vegetables after decontamination with tap water, detergent, or benzalkonium chloride (P > 0.05). Treatments with peracetic acid (100 ppm for 15 min) and hydrogen peroxide (133 ppm for 30 min) reduced the total mesophilic microbial counts by about 2.8 log. The microbial reductions with calcium hypochlorite (300 ppm for 15 min) and combined hydrogen peroxide and silver ion (133 ppm for 30 min) were significantly higher than those obtained after rinsing in tap water or after detergent or benzalkonium chloride wash (P < 0.05). Pretreatment with detergent slightly enhanced the efficacy of all decontamination treatments, but results were not significantly different from those obtained after individual application of disinfectants.

Some foods are prone to contamination with aflatoxins, with detrimental effect on human health. Lactic acid bacteria have been reported to bind aflatoxins and remove them from foods and feeds. Reduction of aflatoxin B1 (AFB1) from the liquid media by the autochthonous lactic acid bacteria (Lactobacillus casei, Lactobacillus plantarum, and Lactobacillus fermentum) isolated from traditional Iranian sourdough and dairy products is reported in the current study. The effect of incubation time on the binding capacity of the strains to AFB1 was also investigated. Duplicates of individual bacteria with population equivalent to 2 X 10(10) CFU/ml were incubated in the presence of AFB1 at 37 degrees C for a period of 72 h, and the amounts of unbound AFB1 were quantitated by reverse-phase high-performance liquid chromatography. All the strains were capable of removal of AFB1, and the reduction of AFB1 ranged from 25 to 61% throughout the incubation period. Removal of AFB1 was a rapid process, with approximately 61 and 56% of the toxin taken instantly by L. fermentum and L. plantarum, respectively. Binding was of a reversible nature, and some of the bound AFB1 was released into the media by the repeated centrifugation and resuspension of the cell pellets. The stability of the bacteria-toxin complex was strain dependent, and L. casei was a stronger binder of AFB1 compared with the other bacteria. No toxin release was observed after 24 h. These findings tend to suggest that certain novel probiotic bacteria with high aflatoxin binding capacity could be selected for detoxification of foods.

A new series of (Z)-2-(1-methyl-5-nitroimidazole-2-ylmethylene)-3( 2 H )-benzofuranones (11a–p) and (Z)-2-(1-methyl-4-nitroimidazole-5-ylmethylene)-3( 2 H )-benzofuranones (12a–m) were synthesized and assayed for their antibacterial activity against Gram-positive and Gram-negative bacteria. Most of the 5-nitroimidazole analogues (11a–p) showed a remarkable inhibition of a wide spectrum of Gram-positive bacteria (Staphylococcus aureus, Streptococcus epidermidis, MRSA, and Bacillus subtilis) and Gram-negative Klebsiella pneumoniae, whereas 4-nitroimidazole analogues (12a–m) were not effective against selected bacteria. The quantitative structure–activity relationship investigations were applied to find out the correlation between the experimentally evaluated activities with various parameters of the compounds studied. The QSAR models built in this work had reasonable predictive power and could be explained by the observed trends in activities.

Food poisoning originating from contaminated foods by both Gram-positive and Gram-negative bacteria causes concern to society and to the industry. Spices have been used safely since ancient times as food flavoring agents and also as herbal medicines and are now mainly considered “generally regarded as safe” (GRAS). Antimicrobial effects of two spices used in Iranian traditional medicine were investigated against some pathogenic food-borne bacteria. Hydroalcoholic extracts of Rhus coriaria L. (sumac) and Zataria multiflora Boiss. (avishan-e shirazi or zaatar) obtained from Tehran botanicals market were prepared by cool percolation method using 80% (v/v) aqueous alcohol. Antimicrobial activities of the extracts were tested against several Gram-positive and Gram-negative bacteria including Staphylococcus aureus , Bacillus cereus , Escherichia coli , Salmonella typhi , Proteus vulgaris , and Shigella flexneri. All the extracts were primarily screened for their possible antimicrobial effects using disc and well diffusion methods. Both R . coriaria L. and Z . multiflora Boiss. showed considerable antibacterial effects. The potential antibacterial activities of the two herbal extracts were further investigated at concentrations of 0.05%, 0.1%, 0.2%, 0.4%, 0.8% and 1.6% (w/v) and minimum inhibitory concentration (MICs) as well as minimum bactericidal concentrations (MBCs) of the extracts were elucidated. Sumac showed better activity against the tested bacteria compared to avishan-e shirazi inhibiting Bacillus cereus and Staphylococcus aureus at concentrations of 0.05% and 0.1%, respectively while Gram-negative bacteria were affected by higher concentrations of sumac ranging 0.1–2%. The MICs of avishan-e shirazi against the tested bacteria ranged from 0.4% to 0.8%. Salmonella typhi was found to be the most resistant showing the MICs of 0.2% and 0.8% with sumac and avishan-e shirazi, respectively. Both popular Iranian spices which are traditionally used as astringent agents have promising inhibitory effects on food-borne bacteria and could be considered as natural food preservatives.

Propolis is a resinous natural hive product derived from plant exudates collected by honeybees. Due to biological and pharmacological activities, it has been extensively used in folk medicine. The present study was designed to investigate the chemical composition, subchronic toxicity, antimicrobial activity of Iranian propolis ethanolic extract, which has not been studied previously. One hundred and nine compounds were identified by gas chromatography–mass spectrometry analysis. Forty-five days subchronic toxicity of oral propolis extract was investigated in male rats. During the study no significant behavioral and clinical toxicity has been seen in animals however, hematologic, blood biochemistry and histopathologic data studies exhibited some significant differences between the groups. The ethanolic extract of propolis inhibited the growth of all examined microorganisms including bacteria and fungi with the highest antimicrobial activity against Gram-positive bacteria such as Staphylococcus aureus and Staphylococcus epidermidis.

The essential oil of Oliveria decumbens was investigated for its components and antimicrobial activity against six bacteria and two fungal strains. The essential oil was characterized by a high amount of oxygenated monoterpene components of which thymol (47.06%) and carvacrol (23.31%) were the major components. The oil exhibited high antimicrobial activity against all tested Gram(+) and Gram() bacteria and fungal strains. D 2005 Elsevier B.V. All rights reserved.

Background: Although a number of investigation have been carried out to find alternative adjuvants to aluminum salts in vaccine formulations, they are still extensively used due to their good track record of safety, low cost and proper adjuvanticity with a variety of antigens. Adsorption of antigens onto aluminum compounds depends heavily on electrostatic forces between adjuvant and antigen. Commercial recombinant protein hepatitis B vaccines containing aluminum hydroxide as adjuvant is facing low induction of immunity in some sections of the vaccinated population. To follow the current global efforts in finding more potent hepatitis B vaccine formulation, adjuvanticity of aluminum phosphate has been compared to aluminum hydroxide. Materials and methods: The adjuvant properties of aluminum hydroxide and aluminum phosphate in a vaccine formulation containing a locally manufactured hepatitis B (HBs) surface antigen was evaluated in Balb/C mice. The formulations were administered intra peritoneally (i.p.) and the titers of antibody which was induced after 28 days were determined using ELISA technique. The geometric mean of antibody titer (GMT), seroconversion and seroprotection rates, ED50 and relative potency of different formulations were determined. Results: All the adjuvanicity markers obtained in aluminum phosphate formulation were significantly higher than aluminum hydroxide. The geometric mean of antibody titer of aluminum phosphate was approximately three folds more than aluminum hydroxide. Conclusion: Aluminum phosphate showed more adjuvanticity than aluminum hydroxide in hepatitis B vaccine. Therefore the use of aluminum phosphate as adjuvant in this vaccine may lead to higher immunity with longer duration of effects in vaccinated groups.