First reported isolation of hemin-requiring Proteus vulgaris small-colony variant from urine culture.

A hemin-requiring Proteus vulgaris small-colony variant (SCV) was isolated from a urine culture. This isolate was grown on 5% sheep blood agar but not on modified Drigalski agar. The single nucleotide substitution was found in the SCV of the hemC gene (c.55C > T), and this substitution caused a nonsense mutation (p.Gln19Ter). Porphyrin test results showed that the biosynthesis of δ-aminolevulinic acid stopped up to porphobilinogen and not pre-uroporphyrinogen due to a mutation in the hemC gene. To our knowledge, this is the first report of hemin-requiring P. vulgaris.

Genomic and biological characterization of vB_PvuS_Pm34, a novel lytic bacteriophage that infects Proteus vulgaris.

Proteus phage vB_PvuS_Pm34 (Pm34) isolated from the sewage, is a novel virus specific to Proteus vulgaris. Pm34 belonged to the family Siphovirodae with an icosahedron capsid head and a non-contractile tail. Its genome was 39,558 bp in length with a G + C content of 41.4%. Similarity analysis showed that Pm34 shared low identities of 27.6%-38.4% with any other Proteus phages, but had the 96% high identity with Proteus mirabilis AOUC-001. In the genome of Pm34, 70 open reading frames was deduced and 32 had putative functions including integrase and host lysis proteins. No tRNAs, antibiotic resistance and virulence genes were detected. Pm 34 presented a broad pH (4-8) and good temperature tolerance (<40 °C). This is the first report of the bacteriophage specific to P. vulgaris, which can enrich the knowledge of bacteriophages of Prouteus bacteria and provide the possibility for the alternative treatment of P. vulgaris infection.

Identification of iron-responsive genes in Proteus vulgaris.

Iron is essential for almost all bacteria, and iron homeostasis is precisely controlled by the ferric uptake regulator (Fur). The Fur regulons have been well characterized in some model bacteria, yet little is known in the common opportunistic pathogen Proteus vulgaris. In this study, Fur regulon and iron-responsive genes in P. vulgaris were mainly defined by in silico and proteomic analyses. The results showed that about 250 potential Fur-regulated operons including 14 transcriptional factors were predicted, while 559 proteins exhibited differential expression in response to iron deficiency, not all being directly regulated by Fur, such as transcriptional factors lexA, recA, narL, and arcA. Collectively, these results demonstrated that Fur functioned as a global regulatory protein to repress or activate expression of a large repertoire of genes in P. vulgaris; besides, not all the iron-responsive genes were directly regulated by Fur, whereas indirectly regulated through other mechanisms such as additional transcriptional regulatory proteins.

Antibacterial activity of colloidal copper nanoparticles against Gram-negative (Escherichia coli and Proteus vulgaris) bacteria.

Antibacterial activities of as-synthesized nanoparticles have gained attention in past few years due to rapid phylogenesis of pathogens developing multi-drug resistance (MDR). Antibacterial activity of copper nanoparticles (CuNPs) on surrogate pathogenic Gram-negative bacteria Escherichia coli (MTCC no. 739) and Proteus vulgaris (MTCC no. 426) was evaluated under culture conditions. Three sets of colloidal CuNPs were synthesized by chemical reduction method with per batch yield of 0·2, 0·3 and 0·4 g. As-synthesized CuNPs possess identical plasmonic properties and have similar hydrodynamic particle sizes (11-14 nm). Antibacterial activities of CuNPs were evaluated by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests, cytoplasmic leakage and reactive oxygen species (ROS) assays. MIC and MBC tests revealed dose dependence bactericidal action. Growth curves of E. coli show faster growth inhibition along with higher cytoplasmic leakage than that of P. vulgaris. This might be because of increased membrane permeability of E. coli. CuNP-microorganism interaction induces oxidative stress generated by ROS. Leakage of cytoplasmic components, loss of membrane permeability and ROS generation are the primary causes of CuNP-induced bacterial cell death. As-synthesized CuNPs exhibiting promising antibacterial activities and could be a promising candidate for novel antibacterial agents.

Aspergillus flavus originated pure compound as a potential antibacterial.

PROBLEM BACKGROUND: Penicillin was the first and most famous fungal secondary metabolite used as broad spectrum antibiotic that revolutionarised pharmaceutical research and also saved millions of lives. The over optimistic belief in 1967 that sufficient antibiotics had been discovered to defeat infectious diseases was quickly crashed with the appearance of multidrug resistant (MDR) bacteria in 1990s. This has posed a serious threat to mankind. Although scientists are making efforts to synthesize and discover new antibiotics there are not enough new drugs in pharmaceutical pipeline to beat the pace at which MDR bacteria are emerging. In view of this there is an urgent and serious medical need for new bioactive compounds to be discovered to treat infections caused by MDR pathogens. The present study is aimed to investigate the antibacterial potential of Aspergillus flavus originated compounds that may act as drug leads to treat future infections. METHODOLOGY: Among the 6 isolated fungal strains from the rhizosphere of Mentha piperetta, one was processed for isolation of secondary metabolites on the basis of preliminary antibacterial testing. Observation of morphological and microscopic features helped in identification of the fungal strain as Aspergillus flavus. Potato Dextrose Agar (PDA) medium was used for fungal growth while Czapec Yeast Broth (CYB) medium was used for production of fungal metabolites. Column chromatography technique was utilized for purification of compound from crude fungal extract and the mass of the compound was determined using Liquid Chromatography Mass Spectrometry (LCMS) method. Structure elucidation of the pure compound was performed using 500 Varian Nuclear Magnetic Resonance (NMR) machine. Docking was performed using Glide SP algorithm. Agar well diffusion method was used to determine the invitro antibacterial potential of the compound against two MDR bacterial strains i.e. Staphylococcus aureus and Proteus vulgaris. For this a total of 4 dose concentrations i.e. (100, 250, 500, 1000 µg mL- 1) of the compound were prepared and applied to bacterial strains on Mueller Hinton agar using tetracycline as control. RESULTS: The chemical name of the purified compound from A. flavus was determined as (2E)-3-[(3S, 4R)-8-hydroxy-3, 4-dimethyl-1-oxo-3, 4-dihydro-1H-2- benzopyran-7-yl] prop-2-enoic acid with the formula C14H14O5 and exact mass of 262.08. The in-Silico analysis showed that this compound has the potential to inhibit the binding pocket of S. aureus TyrRS (1JII) with docking score of - 8.67 Kcal mole- 1. The results obtained from invitro experiments were encouraging as at 1000 µg mL- 1 the compound showed 58.8% inhibition against S. aureus and 28% inhibition against P. vulgaris. CONCLUSIONS: The pure compound with formula C14H14O5 and exact mass of 262 exhibited antibacterial potential both insilico and invitro against both Gram negative and Gram positive bacteria. The compound was more active against S. aureus in comparison to P. vulgaris. From the obtained results it is concluded that this compound can be used as potent antibacterial candidate but further studies will be needed prior to its use as antibiotic.

The antibacterial and antihemolytic activities assessment of zinc oxide nanoparticles synthesized using plant extracts and gamma irradiation against the uro-pathogenic multidrug resistant Proteus vulgaris.

In the case of Proteus vulgaris infection, the increased occurrence of multidrug-resistance strains has become a critical challenge in the treatment of urinary tract diseases. Therefore, using plant extracts as eco-friendly antibacterial provides an attractive solution to battle bacterial infection. The current study investigates the antibacterial and antihemolytic activity of nine medicinal plant extracts against P. vulgaris. Citrus limon extract at 150 µg/ml exhibited the highest antimicrobial action against P. vulgaris (the inhibition zone diameter; 22.7 mm). Zinc oxide nanoparticles (ZnO NPs) are synthesized using the plant extracts of C. limon, Allium sativum, Sonchus bulbosus, Allium cepa, and Asparagus racemosus. The antibacterial activity of ZnO NPs synthesized using C. limon extract at 150 µg/ml is significantly increased (33.8 mm). ZnO NPs synthesized using A. cepa, A. racemosus, and C. limon plant extracts are effectively protective for human red blood cells. The ZnO NPs synthesized using C. limon extract are characterized using UV-Visible spectroscopy, FTIR, XRD, and TEM. FTIR revealed that the plant extracts may serve as reducing and capping agents of ZnO NPs. XRD spectra confirmed the crystallinity of ZnO NPs. TEM image demonstrated the formation of spherical shapes of ZnO NPs with an average size of 37.05 nm. SEM of P. vulgaris cells treated with ZnO NPs showed cellular morphological damage compared to the untreated cells. ZnO NPs are synthesized by gamma irradiation as a clean and novel method. This study recommended the promising uses of the biosynthesized ZnO NPs using plant extracts as a natural, unique approach, to control the pathogenicity of P. vulgaris.

New pyrimidine and pyrazole-based compounds as potential EGFR inhibitors: Synthesis, anticancer, antimicrobial evaluation and computational studies.

This study was focused on the synthesis of new pyrimidines 4a,b, 5a,b and pyrazoles 6a, b as ATP mimicking tyrosine kinase inhibitors of the epidermal growth factor receptor (EGFR). The new compounds were assessed as cytotoxic candidates against human breast cancer cells (MCF-7) and hepatocellular carcinoma cells (HepG-2). All the new compounds appeared as more potent cytotoxic agents than erlotinib, while only compound 4a exhibited more potency than 5-flourouracil and 4b analogue was equipotent to it. Accordingly, the kinase suppression effect of 4a and 4b was further evaluated against EGFRWT, EGFRL858R and EGFRT790M. Both pyrimidine analogues 4a and 4b displayed outstanding inhibitory activity against EGFRWT and its two mutated isoforms EGFRL858R and EGFRT790M in comparing to erlotinib and osimertinib as reference drugs. Additionally, all the new analogues were subjected to antimicrobial assay. Interestingly, both 4a and 4b represented the most promising activity of wide spectrum antimicrobial effect against the examined microbes in comparison to gentamycin and ketoconazole as standard drugs. Moreover, docking results proved the good binding interactions of the compounds 4a and 4b with EGFRWT and EGFRT790M which were in accordance with the results of the in vitro enzyme assay. Additional in silico ADMET studies were performed for the new derivatives which represented their good oral absorption, good drug-likeness properties and low toxicity risks in human.

A Novel Non-Coding RNA CsiR Regulates the Ciprofloxacin Resistance in Proteus vulgaris by Interacting with emrB mRNA.

Bacterial non-coding RNAs (ncRNAs) play important regulatory roles in various physiological metabolic pathways. In this study, a novel ncRNA CsiR (ciprofloxacin stress-induced ncRNA) involved in the regulation of ciprofloxacin resistance in the foodborne multidrug-resistant Proteus vulgaris (P. vulgaris) strain P3M was identified. The survival rate of the CsiR-deficient strain was higher than that of the wild-type strain P3M under the ciprofloxacin treatment condition, indicating that CsiR played a negative regulatory role, and its target gene emrB was identified through further target prediction, quantitative real-time PCR (qRT-PCR), and microscale thermophoresis (MST). Further studies showed that the interaction between CsiR and emrB mRNA affected the stability of the latter at the post-transcriptional level to a large degree, and ultimately affected the ciprofloxacin resistance of P3M. Notably, the base-pairing sites between CsiR and emrB mRNAs were highly conserved in other sequenced P. vulgaris strains, suggesting that this regulatory mechanism may be ubiquitous in this species. To the best of our knowledge, this is the first identification of a novel ncRNA involved in the regulation of ciprofloxacin resistance in P. vulgaris species, which lays a solid foundation for comprehensively expounding the antibiotic resistance mechanism of P. vulgaris.

New Mononuclear and Binuclear Cu(II), Co(II), Ni(II), and Zn(II) Thiosemicarbazone Complexes with Potential Biological Activity: Antimicrobial and Molecular Docking Study.

Herein, we report the synthesis of eight new mononuclear and binuclear Co2+, Ni2+, Cu2+, and Zn2+ methoxy thiosemicarbazone (MTSC) complexes aiming at obtaining thiosemicarbazone complex with potent biological activity. The structure of the MTSC ligand and its metal complexes was fully characterized by elemental analysis, spectroscopic techniques (NMR, FTIR, UV-Vis), molar conductivity, thermogravimetric analysis (TG), and thermal differential analysis (DrTGA). The spectral and analytical data revealed that the obtained thiosemicarbazone-metal complexes have octahedral geometry around the metal center, except for the Zn2+-thiosemicarbazone complexes, which showed a tetrahedral geometry. The antibacterial and antifungal activities of the MTSC ligand and its (Co2+, Ni2+, Cu2+, and Zn2+) metal complexes were also investigated. Interestingly, the antibacterial activity of MTSC- metal complexes against examined bacteria was higher than that of the MTSC alone, which indicates that metal complexation improved the antibacterial activity of the parent ligand. Among different metal complexes, the MTSC- mono- and binuclear Cu2+ complexes showed significant antibacterial activity against Bacillus subtilis and Proteus vulgaris, better than that of the standard gentamycin drug. The in silico molecular docking study has revealed that the MTSC ligand could be a potential inhibitor for the oxidoreductase protein.

Establishment and elicitation of transgenic root culture of Plantago lanceolata and evaluation of its anti-bacterial and cytotoxicity activity.

Hairy root induction in Plantago lanceolata was optimized to take advantage of transformed root cultures. The highest frequency of transformation was achieved using leaf explant, A4 strain, pre-cultivation of explant, 150 µM Acetosyringone, 5 min inoculation, half-strength Murashige and Skoog basal medium as co-cultivation, and half-strength Gamborg's basal medium as a selective medium with 3% sucrose. Among the studied compound encompassing gallic acid, catalpol and apigenin, only the production of gallic acid in hairy roots was affected by 20 mg L-1 AgNO3 and 100 mg L-1 chitosan at 24 hr which yielded 7.63, 4.76-fold increase in its content, respectively. The methanolic extracts of hairy roots elicited by 20 mg L-1 AgNO3 exhibited anti-bacterial activity (MIC and MBC = 25 mg mL-1) against Klebsiella pneumoniae, Proteus vulgaris and Salmonella typhi and anti-bacterial potential of non-elicited hairy roots of P. lanceolata (MIC = 25 mg mL-1 and MBC = 35 mg mL-1) were more active against Klebsiella pneumoniae and P. vulgaris than other bacteria. The methanolic extracts of the P. lanceolata hairy roots demonstrated significant cytotoxic activity on colorectal carcinoma cell line (SW-480) with IC50 = 250.65 ± 6.8 µg mL-1 in comparison to human embryonic kidney (HEK-293) with IC50 = 5263.65 ± 4.6 µg mL-1. Plantago lanceolata hairy roots showed important biological activity explaining its role in traditional medicine.

Phytochemical Profile, Antimicrobial, Cytotoxic, and Antioxidant Activities of Fresh and Air-Dried Satureja nabateorum Essential Oils.

Satureja nabateorum (Danin and Hedge) Bräuchler is a perennial herb in the Lamiaceae family that was discovered and classified in 1998. This green herb is restricted to the mountains overlooking the Dead Sea, specifically in Jordan's southwest, the Edom mountains, and the Tubas mountains in Palestine. Gas chromatography-mass spectrometry (GC-MS) analysis of essential oil (EO) of air-dried and fresh S. nabateorum resulted in the identification of 30 and 42 phytochemicals accounting for 99.56 and 98.64% of the EO, respectively. Thymol (46.07 ± 1.1 and 40.64 ± 1.21%) was the major compound, followed by its biosynthetic precursors γ-terpinene (21.15 ± 1.05% and 20.65 ± 1.12%), and p-cymene (15.02 ± 1.02% and 11.51 ± 0.97%), respectively. Microdilution assay was used to evaluate the antimicrobial property of EOs against Staphylococcus aureus (ATCC 25923), clinical isolate Methicillin-Resistant Staphylococcus aureus (MRSA), Enterococcus faecium (ATCC 700221) Klebsiella pneumoniae (ATCC 13883), Proteus vulgaris (ATCC 700221), Escherichia coli (ATCC 25922) and Pseudomonas aeruginosa (ATCC 27853) and Candida albicans (ATCC-90028). With a MIC of 0.135 µg/mL, the EOs has the most potent antibacterial action against K. pneumonia. Both EOs display good antifungal efficacy against C. albicans, with a MIC value of 0.75 µg/mL, which was better than that of Fluconazole's (positive control, MIC = 1.56 µg/mL). The antioxidant capacity of EOs extracted from air-dried and fresh S. nabateorum was determined using the DPPH assay, with IC50 values of 4.78 ± 0.41 and 5.37 ± 0.40 µg/mL, respectively. The tested EOs showed significant cytotoxicity against Hela, HepG2, and COLO-205 cells, with IC50 values ranging from 82 ± 0.98 to 256 ± 1.95 µg/mL. The current work shows there is a possibility to use the S. nabateorum EOs for various applications.

Comparing Bacterial Leakage of Three Intraorifice Barrier Sealing Materials against Enterococcus faecalis and Proteus vulgaris.

AIM: The purpose of this in vitro study was to evaluate the intraorifice sealing ability of light-cured glass-ionomer cement (LC-GIC), Tetric N-Flow, and ProRoot mineral trioxide aggregate (MTA) against Enterococcus faecalis and Proteus vulgaris. MATERIALS AND METHODS: Crowns of the eighty human mandibular teeth were decapitated. Working length determination was performed, after which cleaning and shaping were carried out. A uniform orifice diameter of 1.3 mm, at its widest point, was made. Once instrumentation was completed, the canals were irrigated and then obturated. A heat carrier was used to remove gutta-percha to the depth of 3.5 mm. Samples were then divided into a control group (Group 1) with no barrier, and three groups, namely, Group 2, Group 3, and Group 4, were restored with the LC-GIC, Tetric N-Flow, and ProRoot MTA, respectively. The groups were further subdivided into Subgroup A for checking bacterial leakage against E. faecalis and Subgroup B, against P. vulgaris. All samples were subjected to the bacterial leakage test and observed daily for the appearance of turbidity after which statistical analysis was performed. RESULTS: Group 1 showed leakage in, as early as, 3 days. The longest time for the turbidity to appear was shown by Group 4 with an average of 31 days. The mean number of days for turbidity to appear in Group 2 and Group 3 was 23 and 24 days, respectively. Group 4 showed the best intraorifice sealing ability with a significant difference. CONCLUSION: The teeth with an intraorifice coronal seal had better protection against microbial leakage. Among all materials used, the ProRoot MTA showed the best intraorifice sealing ability. CLINICAL SIGNIFICANCE: Use of the ProRoot MTA promises long-term results in the endodontically treated teeth as compared with other materials.

Antimicrobial and antioxidant activities of silver nanoparticles synthesized by novel biogenic method using mixed reductants.

A novel method, for the synthesis of silver nanoparticles that are eco-friendly by means of mixed reductants method, has been developed. The combined extract of Mentha viridis plant and Prunus domestica gum were used as reducing agents for the synthesis of silver nanoparticles of the size less than 40 nm in diameter. The effect of time and concentration on the formation of silver nanoparticles were also monitored. The silver nanoparticles formed were verified by surface Plasmon spectra using single and double beam UV-Vis spectrophotometer. The XRD technique and scanning electron microscopy were performed to analyze the crystalline structure, crystallite size and morphology. The synthesized silver nanoparticles were tested against different bacterial and fungus strains. The silver nanoparticles showed good inhibition in antimicrobial study and low MIC for bacterial strains. The antioxidant assay was performed to check the scavenging activity. In DPPH, the silver nanoparticles showed good scavenging activity and were found close to that of ascorbic acid.

Structural basis of transcriptional regulation by the HigA antitoxin.

Bacterial toxin-antitoxin systems are important factors implicated in growth inhibition and plasmid maintenance. Type II toxin-antitoxin pairs are regulated at the transcriptional level by the antitoxin itself. Here, we examined how the HigA antitoxin regulates the expression of the Proteus vulgaris higBA toxin-antitoxin operon from the Rts1 plasmid. The HigBA complex adopts a unique architecture suggesting differences in its regulation as compared to classical type II toxin-antitoxin systems. We find that the C-terminus of the HigA antitoxin is required for dimerization and transcriptional repression. Further, the HigA structure reveals that the C terminus is ordered and does not transition between disorder-to-order states upon toxin binding. HigA residue Arg40 recognizes a TpG dinucleotide in higO2, an evolutionary conserved mode of recognition among prokaryotic and eukaryotic transcription factors. Comparison of the HigBA and HigA-higO2 structures reveals the distance between helix-turn-helix motifs of each HigA monomer increases by ~4 Å in order to bind to higO2. Consistent with these data, HigBA binding to each operator is twofold less tight than HigA alone. Together, these data show the HigB toxin does not act as a co-repressor suggesting potential novel regulation in this toxin-antitoxin system.

Integration of the blaNDM-1 carbapenemase gene into a novel SXT/R391 integrative and conjugative element in Proteus vulgaris.

OBJECTIVES: To characterize the genetic environment of the carbapenem resistance determinant in Proteus vulgaris of swine origin. METHODS: The carbapenem-resistant P. vulgaris strain BC22 was isolated from a faecal swab from a diseased pig with diarrhoea in Sichuan Province of China in 2018. The presence of carbapenemase genes was screened by PCR. WGS and bioinformatics analysis were performed to analyse the genetic environment of the carbapenem resistance determinant. RESULTS: P. vulgaris strain BC22 was found to harbour the carbapenemase gene blaNDM-1. WGS data revealed that blaNDM-1 was located in a truncated ISAba125 composite transposon. The carbapenem resistance gene blaNDM-1 and 20 other resistance genes, including the multiresistance gene cfr and the bifunctional aminoglycoside/quinolone resistance gene aac(6')-lb-cr, were located in a novel SXT/R391 integrative and conjugative element (ICE). This new SXT/R391 ICE of 148.7 kb was chromosomally located, and could be transferred to Escherichia coli. CONCLUSIONS: Here, we report a carbapenemase gene, blaNDM-1, integrated into an SXT/R391 ICE. Our study highlights that this SXT/R391 ICE may facilitate the dissemination of clinically important resistance genes such as blaNDM-1, cfr and aac(6')-lb-cr.

Taxonomic identification and bioactive compounds characterization of Psilocybe cubensis DPT1 to probe its antibacterial and mosquito larvicidal competency.

Mushrooms have an important role in sustainability since they have long been used as valuable food source and traditional medicine around the world. Regrettably, they are among the most rigorously affected populations, along with several plants and animals, due to the destructive activities of mankind. Thus the authentication and conservation of mushroom species are constantly needed to exploit the remarkable potential in them. In this perspective, an attempt has been made to identify and assess the biological attributes of psychedelic mushrooms collected from Kodaikanal, Tamil Nadu, India. The macromorphological features of the psychedelic mushroom DPT1 helped its presumptive identification and the molecular characters depicted by DNA marker revealed its close relationship with the genus Psilocybe. Accordingly, the psychedelic mushroom was identified as Psilocybe cubensis DPT1 and its crude ethyl acetate extract on analysis revealed the occurrence of phytoconstituents like alkaloids, flavonoids, tannins, saponins and carbohydrates. Moreover, it exhibited 80% larvicidal activity against Culex quinquefasciatus mosquito at 800 ppm concentration and an array of antibacterial effects with utmost susceptibility of Proteus vulgaris, and the identification of bioactive compounds by different analytical techniques substantiate that the bioactivities might be due to the presence of phytochemicals. The results of the study indicated that the extract of P. cubensis DPT1 having notable antibacterial and mosquito larvicidal efficacies which could be probed further for the isolation of medicinally important as well as bio-control compounds.

Novel thiobarbiturates as potent urease inhibitors with potential antibacterial activity: Design, synthesis, radiolabeling and biodistribution study.

Urease enzyme is a virulence factor that helps in colonization and maintenance of highly pathogenic bacteria in human. Hence, the inhibition of urease enzymes is well-established to be a promising approach for preventing deleterious effects of ureolytic bacterial infections. In this work, novel thiobarbiturate derivatives were synthesized and evaluated for their urease inhibitory activity. All tested compounds effectively inhibited the activity of urease enzyme. Compounds 1, 2a, 2b, 4 and 9 displayed remarkable anti-urease activity (IC50 = 8.21-16.95 µM) superior to that of thiourea reference standard (IC50 = 20.04 µM). Moreover, compounds 3a, 3g, 5 and 8 were equipotent to thiourea. Among the tested compounds, morpholine derivative 4 (IC50 = 8.21 µM) was the most potent one, showing 2.5 folds the activity of thiourea. In addition, the antibacterial activity of the synthesized compounds was estimated against both standard strains and clinical isolates of urease producing bacteria. Compound 4 explored the highest potency exceeding that of cephalexin reference drug. Moreover, biodistribution study using radiolabeling approach revealed a remarked uptake of 99mTc-compound 4 into infection induced in mice. Furthermore, a molecular docking analysis revealed proper orientation of title compounds into the urease active site rationalizing their potent anti-urease activity.

Comparing the Bacteriostatic Effects of Different Metal Nanoparticles Against Proteus vulgaris.

For many years, researchers were looking for new antibacterial substances to deal with hospital infections and especially resistant infections. Nanoparticles attracted much attentions because of their very small size that increases the surface to capacity ratio and consequently increase chemical activity. In this study, the antibacterial effects of silver, copper oxide, nickel oxide, and titanium dioxide nanoparticles were studied on Proteus vulgaris, as a bacterium involved in the resistant hospital infections. The capability of nanoparticles to inhibit the growth of bacteria was assessed via 9 different methods including cylinder, disk, and well-diffusion, spot test, MBC, MIC, liquid inhibitory action test, diffusion, and assessing the effects of nanoparticles on a 24-h culture. Based on the results, copper oxide and silver nanoparticles had high antibacterial effects on P. vulgaris in both liquid and solid cultures, respectively. However, nickel oxide and titanium dioxide nanoparticles only had a weak effect on the inhibition of bacterial growth in the liquid culture. CuO and Ag NPs could release ions and consequently produce free radicals, disturb the equilibrium of electrons between electron donor groups and inactivate enzymes and DNA of the organisms. Moreover, they triggered holes in the bacterial membrane to disturb cellular ion equilibrium. So, they can be used to inhibit the growth of pathogens. Besides, further studies have shown that they could be used as a supplementary treatment and/or in combination with other drugs to cure infections caused by P. vulgaris.

Biochemical characterization of a surfactant-stable keratinase purified from Proteus vulgaris EMB-14 grown on low-cost feather meal.

OBJECTIVES: The bioaccumulation of keratinous wastes from poultry and dairy industries poses a danger of instability to the biosphere due to resistance to common proteolysis and as such, microbial- and enzyme-mediated biodegradation are discussed. RESULTS: In submerged fermentation medium, Proteus vulgaris EMB-14 utilized and efficiently degraded feather, fur and scales by secreting exogenous keratinase. The keratinase was purified 14-fold as a monomeric 49 kDa by DEAE-Sephadex A-50 anion exchange and Sephadex G-100 size-exclusion chromatography. It exhibited optimum activity at pH 9.0 and 60 °C and was alkaline thermostable (pH 7.0-11.0), retaining 87% of initial activity after 1 h pre-incubation at 60 °C. The Km and Vmax of the keratinase with keratin azure were respectively 0.283 mg/mL and 0.241 U/mL/min. Activity of P. vulgaris keratinase was stimulated by Ca2+, Mg2+, Zn2+, Na+ and maintained in the presence of some denaturing agents, except ß-mercaptoethanol while Cu2+ and Pb2+ showed competitive and non-competitive inhibition with Ki 6.5 mM and 17.5 mM, respectively. CONCLUSION: This purified P. vulgaris keratinase could be surveyed for the biotechnological transformation of bioorganic keratinous wastes into valuable products such as soluble peptides, cosmetics and biodegradable thermoplastics.

Negative-Ion Mode Capillary Isoelectric Focusing Mass Spectrometry for Charge-Based Separation of Acidic Oligosaccharides.

Glycosaminoglycans (GAGs) are biologically and pharmacologically important linear, anionic polysaccharides containing various repeating disaccharides sequences. The analysis of these polysaccharides generally relies on their chemical or enzymatic breakdown to disaccharide units that are separated, by chromatography or electrophoresis, and detected, by UV, fluorescence, or mass spectrometry (MS). Isoelectric focusing (IEF) is an important analytical technique with high resolving power for the separation of analytes exhibiting differences in isoelectric points. One format of IEF, the capillary isoelectric focusing (cIEF), is an attractive approach in that it can be coupled with mass spectrometry (cIEF-MS) to provide online focusing and detection of complex mixtures. In the past three decades, numerous studies have applied cIEF-MS methods to the analysis of protein and peptide mixtures by positive-ion mode mass spectrometry. However, polysaccharide chemists largely rely on negative-ion mode mass spectrometry for the analysis of highly sulfated GAGs. The current study reports a negative-ion mode cIEF-MS method using an electrokinetically pumped sheath liquid nanospray capillary electrophoresis-mass spectrometry (CE-MS) coupling technology. The feasibility of this negative-ion cIEF-MS method and its potential applications are demonstrated using chondroitin sulfate and heparan sulfate oligosaccharides mixtures.