Proteus Hauseri Research Articles

Isolation and identification of hyper-ammonia-producing bacteria from commercial fermented skates (Raja kenojei).

Ammonia-producing bacteria were isolated and identified from five commercial fermented skates (A1, A2, A3, A4, and A5). In addition, the pH, ammonia nitrogen, total volatile nitrogen (TVBN), trimethylamine nitrogen (TMAN), and amino nitrogen contents of skate samples were also determined. A total of 88 strains of ammonia-producing bacteria was isolated and seven hyper-ammonia-producing bacteria isolates (A2-2, A2-3, A2-12, A2-18, A2-20, A3-6 and A3-14) were selected based on ammonia nitrogen producing ability. Those isolates were identified as Proteus hauseri (three strains), Providencia rustigianii (three strains), and Kurthia gibsonii. The pH and ammonia nitrogen content in skate samples were ranged from 8.63 to 9.03, and 4.86 to 7.31g/kg, respectively. No significant difference of pH values was observed in skate samples A2, A3, A4 and A5. While, skate samples A3, A4 and A5 showed similar level of TVBN and TMAN content. Skate sample A2 showed the highest amino nitrogen content among all samples, which indicated the highest degree of protein degradation of skate muscle during fermentation. Bivariate cluster analysis showed that skate samples A3, A4, and A5 clustered together at a relatively high level, implying a similar microbial environment during fermentation. The cluster analysis allowed different commercial fermented skates to be clearly differentiated based on the characteristics determined in this study. This study can provide important information for investigating the mechanisms underlying ammonia flavor formation in skate muscle during fermentation.

Novel Kombucha Beverage from Lingzhi or Reishi Medicinal Mushroom, Ganoderma lucidum, with Antibacterial and Antioxidant Effects.

Kombucha is a nonalcoholic beverage traditionally made by fermenting black tea using a combination of yeast and acetic acid bacteria (AAB) cultures. Ganoderma lucidum hot water extract (HWE) was used-to our knowledge for the first time-to prepare a novel, health-promoting kombucha product. During the 11-day fermentation, pH, total acidity, and the numbers of yeasts and AAB were monitored. It was found that sweetened G. lucidum HWE was a good medium for yeast and AAB growth. The desired acidity for the beverage was reached on the second day (3 g/L) of the fermentation process; the maximum established acidity was 22.8 ± 0.42 g/L. Fourier transform infrared analysis revealed that the vacuum-dried beverage is a mixture of various compounds such as polysaccharides, phenols, proteins, and lipids. Total phenolic content of the liquid sample was 4.91 ± 0.2338 mg gallic acid equivalents/g, whereas the vacuum-dried sample had a smaller amount of phenolics (2.107 ± 0.228 mg gallic acid equivalents/g). Established half-maximal effective concentrations for DPPH scavenging activity and reducing power were 22.8 ± 0.17 and 10.61 ± 0.34 mg/mL, respectively. The antibacterial testing revealed that activity does not originate solely from synthesized acetic acid. The liquid G. lucidum beverage was the most effective against the tested bacteria, with the lowest minimum inhibitory concentration (0.04 mg/mL) against Staphylococcus epidermidis and Rhodococcus equi, and a minimum bactericidal concentration (0.16 mg/mL) against Bacillus spizizenii, B. cereus, and R. equi. The vacuum-dried sample was less effective, with the lowest minimum bactericidal concentration against the Gram-positive bacteria R. equi (1.875 mg/mL) and against the Gram-negative bacteria Proteus hauseri (30 mg/mL).

Cytotoxic and Antimicrobial Properties of Copper(II) Complexes of Pyridine and Benzimidazole Derivatives

The cytotoxic and antimicrobial activity of a series of six copper(II) complexes with phosphate and hydroxymethyl derivatives of pyridine and benzimidazole were investigated. The complexes and the corresponding free ligands were tested against Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 12228, Pseudomonas aeruginosa ATCC 15442, Escherichia coli ATCC 25922, Proteus hauseri ATCC 13315, and Candida albicans ATCC 10231. Among the tested copper(II) complexes, compounds 2 and 5 containing 1H‐benzimidazol‐2‐ylmethyl diethyl phosphate and 2‐(hydroxymethyl)benzimidazole as ligands, respectively, were most active and limited the growth of S. aureus, E. coli, and C. albicans by 30–60 % according to concentration and microorganism. The in vitro cytotoxic activity of the CuII complexes and free ligands towards cancerous B16 (murine melanoma) and non‐cancerous 10T1/2 (murine fibroblasts) cell lines was determined. The 10T1/2 cells were treated with the compounds at concentrations equal to IC50 values for B16 cells. In spite of the use of relatively high concentrations of the complexes, the viability of 10T1/2 cells was very high, ca. 80 % in some cases. Stability of the CuII complexes was evaluated in water solutions by UV/Vis spectroscopy. The copper(II) complex of 4‐(hydroxymethyl)pyridine was synthesized and identified.

Impact of pH regulation on multicopper oxidase production and swarming motility in the bacterium Proteus hauseri ZMd44.

Proteus hauseri ZMd44, a biodecolorizing bacterium, has been known to produce electricity and multicopper oxidase (Mco-laccase) under copper induction. However, optimization and regulation of production have not been explored. This study is the first attempt to evaluate several parameters on biomass and Mco-laccase production of P. hauseri ZMd44. Through orthogonal experiments with Taguchi's L9, it was found that P. hauseri ZMd44 was sensitive to pH value. The cells grew relatively quickly at pH 7, thus the biomass and Mco-laccase production reached 1.66 g/L and 1043.6 U/L, respectively. Higher pH values also influenced the swarming motility, which is an important characteristic of P. hauseri ZMd44 that affects urinary tract infection. The swarming circle and the diameter of the swarm, represented by the motility velocity, were found to be more controlled after 24 h of growth at pH 6. The swarming ability of P. hauseri was completely inhibited by the addition of 3mM copper or zinc ions. Therefore, the Mco-laccase and swarming motility could be controlled by regulating pH and ion content.

Psacalium paucicapitatum has in vitro antibacterial activity

In Mexico, in 2010, urinary tract infection (UTI) occupied third place in morbidity. Enterobacter aerogenes, Escherichia coli, Proteus hauseri, Proteus mirabilis, Proteus vulgaris, and Staphylococcus epidermidis are included among the bacteria that cause UTIs. Currently, there is an urgent need to develop new alternatives to control antibiotic-resistant bacteria. The secondary metabolites of plants have traditionally been used to remedy the illnesses caused by bacteria. Psacalium paucicapitatum [(B.L. Rob. & Greenm.) H. Rob. & Brettell] is an endemic plant that grows in the state of Oaxaca, Mexico, which is used to relieve diseases such as gastric ulcers, diabetes and hypertension, with excellent results. The aims of this study were to evaluate the in vitro antibacterial activity of aqueous extracts of P. paucicapitatum corms against six bacteria as well as to determine the chemical composition of the extracts in order to identify bioactive molecules inhibiting bacterial reproduction. The extract inhibited six bacteria evaluated in a range of MIC90 at 2034–5238mg/L. The antibacterial activity of aqueous extract is attributed to the identified compounds, which are: ethyl iso-allocholate; imidazole-4-carboxylic acid, 2-fluoro-1-methoxymethyl-, ethyl ester and tetra acetyl-d-xylonic nitrile. The extract of P. paucicapitatum represents an alternative to be used as a new antibacterial botanical drug which could substitutes the use of synthetic drugs.

Heterologous expression of an acidophilic multicopper oxidase in Escherichia coli and its applications in biorecovery of gold

BackgroundCopper oxidase is a promising enzyme for detection of oxidation, which can function as a biosensor and in bioremediation. Previous reports have revealed that the activity of the multicopper oxidase (MCO, EC 1.10.3.2) from the Proteus hauseri ZMd44 is induced by copper ions, and has evolved to participate in the mechanism of copper transfer.ResultsFrom P. hauseri ZMd44, a full-length, 1497-base-pair gene, lacB, encoding 499 amino acids without signal peptide, was cloned into Escherichia coli (E. coli) to obtain high amounts of MCO. The use of the pET28a vector yielded better enzyme activity, which was approximately 400 and 500 U/L for the whole cell and soluble enzyme extracts, respectively. The crude enzyme showed activity at an optimal temperature of 55 °C and it remained highly active in the range of 50–65 °C. The optimal pH was 2.2 but the activity was significantly inhibited by chloride ions. This MCO has great potential for Au adsorption (i.e., 38% w/w) and the Au@NPs were directly adsorbed on enzyme’s surface.ConclusionAn acidophilic MCO from bioelectricity generating bacterium, P. hauseri, is first cloned and heterologously expressed in E. coli with high amounts and activity. This MCO has great potential for Au adsorption and can be used as a biosensor or applied to bioremediation of electronic waste.

A self-contained microfluidic in-gel loop-mediated isothermal amplification for multiplexed pathogen detection

In this work, we propose a microfluidic in-gel loop-mediated isothermal amplification (gLAMP) containing preloaded reagents as a self-contained microdevice for simultaneous detection of multiple pathogenic bacterial DNA in near point of care settings. The microchip consists of multiple channels with reaction chambers accommodating low-melting-point agarose and all LAMP reagents except the DNA samples, which can be kept at 4°C for long-term storage. The current microchip enables simultaneous tests of four different bacterial DNA targets. After DNA samples were introduced into the microchip, gLAMP reactions were carried out on a hot plate at 65°C. The gLAMP reaction conditions including the concentrations of the fluorescence indicator, Bst DNA polymerase, primers, and Mg2+ ions were further optimized. Under the optimized conditions, detection of foodborne bacteria in serum samples, including Escherichia coli, Proteus hauseri, Vibrio parahaemolyticus, and Salmonella subsp. Enterica were demonstrated with high selectivity and sensitivity (as low as 3 copies/μL). The gLAMP microchip provides a simple and easy-to-operate platform for LAMP-based pathogen detection, which holds high potential for future applications in point-of-care settings.

A new fish cell line derived from the caudal fin of freshwater angelfish Pterophyllum scalare: development and characterization

In this study, a new cell line derived from the caudal fin of the freshwater angelfish Pterophyllum scalare was developed and characterized. The cell line was designated angelfish fin (AFF) and subcultured 44 times since its development. These cells grew well in Leibovitz's -15 medium supplemented with 10% foetal bovine saline (FBS) at 28° C and the modal chromosome number (2n) was 48. The AFF cell-line is mainly comprised of epithelial cells as confirmed by immunocytological technique using anti-cytokeratin antibodies, an epithelial cell marker. This cell line was tested for growth in a temperatures range from 20 to 37° C and at various FBS concentrations of 5-20% at 28° C. The cell line was cryopreserved at different passage levels and revived successfully with 80% survival rate. Polymerase chain reaction amplification and sequencing of partial mitochondrial 16s rRNA and coI genes confirmed that the AFF cell-line originated from angelfish. Mycoplasma sp. contamination was not detected in AFF cells and checked by Hoechst 33258 fluorescence staining. At the 42nd passage the cells were transfected with 2 μg of pAcGFP1-N1 expression vector. The AFF cells exhibited cytotoxic effects when exposed to the bacterial extra cellular products from Serratia marcescens and Proteus hauseri. The AFF cells and cells from kidney and brain did not show cytopathic effect when exposed to cyprinid herpes virus2 and viral nervous necrosis virus. The newly developed AFF cell line will be useful for the isolation of viruses affecting angelfishes, such as iridoviruses, in the future.

Actinomadurol, an Antibacterial Norditerpenoid from a Rare Actinomycete, Actinomadura sp. KC 191.

A new secondary metabolite, actinomadurol (1), was isolated along with the known compound JBIR-65 (2) from a rare actinomycete, Actinomadura strain KC 191. The structure of 1 was established as a rare member of the bacterial C-19 norditerpenoid class by NMR data and ECD calculations. The absolute configuration of 2, which was previously reported without stereochemical analysis, was determined by using the modified Mosher's method and ECD calculations. Actinomadurol (1) exhibited potent antibacterial activity against pathogenic strains, such as Staphylococcus aureus, Kocuria rhizophila, and Proteus hauseri (MIC = 0.39-0.78 μg/mL), whereas JBIR-65 (2) showed no antibacterial activity.

Antibacterial Activity and Cytotoxicity of Silver(I) Complexes of Pyridine and (Benz)Imidazole Derivatives. X-ray Crystal Structure of [Ag(2,6-di(CH2OH)py)2]NO3.

Selected aspects of the biological activity of a series of six nitrate silver(I) complexes with pyridine and (benz)imidazole derivatives were investigated. The present study evaluated the antibacterial activities of the complexes against three Gram-negative strains: Pseudomonas aeruginosa ATCC 15442, Escherichia coli ATCC 25922 and Proteus hauseri ATCC 13315. The results were compared with those of silver nitrate, a silver sulfadiazine drug and appropriate ligands. The most significant antibacterial properties were exerted by silver(I) complexes containing benzimidazole derivatives. The cytotoxic activity of the complexes was examined against B16 (murine melanoma) and 10T1/2 (murine fibroblasts) cells. All of the tested silver(I) compounds were not toxic to fibroblast cells in concentration inhibited cancer cell (B16) viability by 50%, which ranged between 2.44–28.65 µM. The molecular and crystal structure of silver(I) complex of 2,6-di(hydroxymethyl)pyridine was determined by single-crystal X-ray diffraction analysis. The most important features of the crystal packing and intermolecular non-covalent interactions in the Ag(I) complex were quantified via Hirshfeld surface analysis.

Gene Sequencing and Haemolysis of Bacteria in Clarias gariepinus From Ajilete Location on Yewa River

Gene sequencing and haemolysis of bacteria in Clarias gariepinus post juveniles sampled from Ajilete location on Yewa River, Ogun state, Nigeria was carried out. Bacteria were isolated from the gut, gills and skin of the fish. Thirty bacteria isolates were selected and the DNAs were extracted using hexadecyltrimethylammonium bromide (CTAB) method and Polymerase Chain Reaction (PCR) amplification of the isolates was carried out using universal primer for bacteria. The purification of PCR product was done using ethanol precipitation and thereafter the DNAs were sequenced using automated DNA sequencer. The sequence data were analyzed on the GenBank database (NCBI) using Basic Local Alignment Search Tool (BLAST) to find the nearest related sequence, and to construct the phylogenetic relationship. The haemolysis of the selected isolates were also carried out. Data collected were subjected to descriptive statistics. Nine genera of bacteria isolated were Escherichia, Staphylococcus, Enterobacter, Proteus, Pseudomonas, Klebsiella, Citrobacter, Streptococcus and Bacillus. The 16S rRNA gene sequencing method identified the isolates as strains of Brevibacillus agri, Bacillus cereus, Ignatzschineria indica, Comamonas kerstersii, Proteus vulgaris, Lysinibacillus sphaericus, Proteus hauseri, Clostridium bifermentans, Proteus mirabilis, Pseudomonas putida, Escherichia coli, Comamonas jiangduensis, Enterobacter cloacae, Serratia marcescens, Alcaligenes faecalis, Lysinibacillus fusiformis, Myroides odoratimimus. Haemolysis showed that M. odoratimimus, B. cereus, C. kerstersii, P. vulgaris, C. bifermentans, E. coli and E. cloacae all had β-haemolysis. A. faecalis displayed α- haemolysis while, B. agri, I. indica, L. sphaericus, P. hauseri, L. fusiformis, S. marcescens were non-haemolytic. This study confirms the reliability of the 16S rRNA gene sequencing method. This study also concludes that there are different pathogenic bacteria species that are associated with C. gariepinus.

Significance and Roles of Proteus spp. Bacteria in Natural Environments.

Proteus spp. bacteria were first described in 1885 by Gustav Hauser, who had revealed their feature of intensive swarming growth. Currently, the genus is divided into Proteus mirabilis, Proteus vulgaris, Proteus penneri, Proteus hauseri, and three unnamed genomospecies 4, 5, and 6 and consists of 80 O-antigenic serogroups. The bacteria are known to be human opportunistic pathogens, isolated from urine, wounds, and other clinical sources. It is postulated that intestines are a reservoir of these proteolytic organisms. Many wild and domestic animals may be hosts of Proteus spp. bacteria, which are commonly known to play a role of parasites or commensals. However, interesting examples of their symbiotic relationships with higher organisms have also been described. Proteus spp. bacteria present in soil or water habitats are often regarded as indicators of fecal pollution, posing a threat of poisoning when the contaminated water or seafood is consumed. The health risk may also be connected with drug-resistant strains sourcing from intestines. Positive aspects of the bacteria presence in water and soil are connected with exceptional features displayed by autochthonic Proteus spp. strains detected in these environments. These rods acquire various metabolic abilities allowing their adaptation to different environmental conditions, such as high concentrations of heavy metals or toxic substances, which may be exploited as sources of energy and nutrition by the bacteria. The Proteus spp. abilities to tolerate or utilize polluting compounds as well as promote plant growth provide a possibility of employing these microorganisms in bioremediation and environmental protection.

Antibacterial and antifungal potential of wild basidiomycete mushroom Ganoderma applanatum

Hot water extract (AN), partially purified polysaccharides (AP) and hot alkali extract (ANa) obtained from wild mushroom G. applanatum were examined for their antibacterial and antifungal activity. Five Gram negative (Proteus hauseri, Escherichia coli O157:H7, Salmonella Enteritidis, Shigella sonnei, Yersinia enterocolitica), five Gram positive (Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, Geobacillus stearothermophyllus, Enterococcus faecalis) bacterial strains, as well as two fungal strains (Candida albicans and Cryptococcus neoformans), all belonging to the American Type Culture Collection (ATCC), were tested by broth microdilution assay. In general, Gram-positive bacteria were more sensitive in the presence of tested extracts than Gram-negative bacterial species. Almost all tested extracts demonstrated a high microbistatic potential, and in most cases the microbicidal effect also has been reached. The best antibacterial effect of hot water alkali extract, ANa, was observed in the case of E. faecalis (MIC 0.039 mg/mL, MBC 1.25 mg/mL), while the same extract was the most effective antifungal agent towards C. neoformans (MIC 0.078 mg/mL, MFC 2.5 mg/mL). This research indicates possibility to use selected extracts, obtained from the mushroom G. applanatum, in order to prevent the development of some pathogenic microorganisms and food spoilage.

Effect of volatile organic compounds from bacteria on nematodes.

The five studied bacterial strains could produce volatile organic compounds (VOCs) that kill nematodes. Based on their 16S rRNA sequences, these strains were identified as Pseudochrobactrum saccharolyticum, Wautersiella falsenii, Proteus hauseri, Arthrobacter nicotianae, and Achromobacter xylosoxidans. The bacterial VOCs were extracted using solid-phase micro-extraction (SPME) and subsequently identified by GC/MS analysis. The VOCs covered a wide range of aldehydes, ketones, alkyls, alcohols, alkenes, esters, alkynes, acids, ethers, as well as heterocyclic and phenolic compounds. Among the 53 VOCs identified, 19 candidates, produced by different bacteria, were selected to test their nematicidal activity (NA) against Caenorhabditis elegans and Meloidogyne incognita. The seven compounds with the highest NAs were acetophenone, S-methyl thiobutyrate, dimethyl disulfide, ethyl 3,3-dimethylacrylate, nonan-2-one, 1-methoxy-4-methylbenzene, and butyl isovalerate. Among them, S-methyl thiobutyrate showed a stronger NA than the commercial insecticide dimethyl disulfide. It was reported for the first time here that the five bacterial strains as well as S-methyl thiobutyrate, ethyl 3,3-dimethylacrylate, 1-methoxy-4-methylbenzene, and butyl isovalerate possess NA. These strains and compounds might provide new insights in the search for novel nematicides.

Insights into copper effect on Proteus hauseri through proteomic and metabolic analyses

This is the first-attempt to use liquid chromatography coupled with tandem mass (LC-MS-MS) in deciphering the effects of copper ion on Proteus hauseri. Total 941 proteins in copper-addition (+Cu) group and 898 proteins in non-copper-addition (-Cu) group were found, which containing 221 and 178 differential proteins in+Cu and-Cu group, respectively. Differential proteins in both groups were defined into 14 groups by their functional classification which transport/membrane function proteins were the major different part between the two groups, which took 19.5% and 7.7%, respectively. The result of BioCyc and KEGG analyses on metabolic pathway indicated that copper could interrupted the pathway of chemotaxis CheY and inhibited the swarming of P.hauseri, which provided a potential in controlling the pathogenicity of this strain.

Mass mortality in ornamental fish, Cyprinus carpio koi caused by a bacterial pathogen, Proteus hauseri

Moribund koi carp, Cyprinus carpio koi, from a farm with 50% cumulative mortality were sampled with the aim of isolating and detecting the causative agent. Three bacterial species viz., Citrobacter freundii (NSCF-1), Klebsiella pneumoniae (NSKP-1) and Proteus hauseri [genomospecies 3 of Proteus vulgaris Bio group 3] (NSPH-1) were isolated, identified and characterized on the basis of biochemical tests and sequencing of the 16S rDNA gene using universal bacterial primers. Challenge experiments with these isolates using healthy koi carp showed that P. hauseri induced identical clinical and pathological states within 3 d of intramuscular injection. The results suggest P. hauseri (NSPH-1) was the causative agent. In phylogenetic analysis, strain NSPH-1 formed a distinct cluster with other P. hauseri reference strains with ≥99% sequence similarity. P. hauseri isolates were found sensitive to Ampicillin, Cefalexin, Ciprofloxacin and Cefixime and resistant to Gentamycin, Oxytetracycline, Chloramphenicol, and Kanamycin. The affected fish recovered from the infection after ciprofloxacin treatment.

Phenotyping and Genotyping Characterization of <i>Proteus vulgaris</i> After Biofield Treatment

Proteus vulgaris (P. vulgaris) is widespread in nature, mainly found in flora of human gastrointestinal tract. The current study was attempted to investigate the effects of Mr. Trivedi’s biofield treatment on lyophilized as well as revived state of P. vulgaris for antimicrobial susceptibility pattern, biochemical characteristics, and biotype. P. vulgaris cells were procured from Micro BioLogics Inc., USA, in sealed pack bearing the American Type Culture Collection (ATCC 33420) number and stored according to the recommended storage protocol until needed for experiments. Lyophilized vial of ATCC strain of P. vulgaris were divided in two parts, Gr. I: control and Gr. II: treatment. Group II was further subdivided into two parts, Gr. IIA and Gr. IIB. Gr. IIA was analysed on day 10. Gr. IIB was stored and analysed on day 143. After retreatment on day 143, the sample was divided into three separate tubes. First, second and third tubes were analysed on day 5, 10 and 15 respectively. All experimental parameters were studied using automated Micro Scan Walk-Away® system. The 16S rDNA sequencing of lyophilized treated sample was carried out to correlate the phylogenetic relationship of P. vulgaris with other bacterial species after treatment. The antimicrobial susceptibility and minimum inhibitory concentration showed 10.71% and 15.63% alteration respectively in treated cells of P. vulgaris as compared to control. It was observed that few biochemical reactions (6%) were altered in the treated groups with respect to control. Moreover, biotype number was substantially changed in treated cells, Gr. IIA (62060406, Proteus penneri) on day 10 as compared to control (62070406; Proteus vulgaris). 16S rDNA analysis showed that the identified sample in this experiment was Proteus vulgaris after biofield treatment. However, the nearest homolog genus-species was found to be Proteus hauseri. The results suggested that biofield treatment has impact on P. vulgaris in lyophilized as well as revived state.

Synthesis, characterization and antimicrobial activity of water-soluble silver(i) complexes of metronidazole drug and selected counter-ions.

A series of water-soluble silver(i) complexes of the type [Ag(MTZ)2X] [MTZ = 1-(2-hydroxyethyl)-2-methyl-5-nitro-1H-imidazole (metronidazole drug); X = NO3(-), ClO4(-), CF3COO(-), BF4(-) and CH3SO3(-)] was synthesised by the reactions of various Ag(i) salts with metronidazole (MTZ). All the complexes were characterized by ESI-MS spectrometry, solution NMR ((1)H and (13)C) and IR spectroscopy, and elemental analysis. Further evidence for the formation and molecular structure of all the complexes was provided by X-ray single-crystal crystallography. The different counter ions affect the crystal packing of the complexes and thus have an impact on the final geometries. The antimicrobial activities of the complexes against two Gram-positive strains: Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 12228, three Gram-negative strains: Pseudomonas aeruginosa ATCC 15442, Escherichia coli ATCC 25922, Proteus hauseri ATCC 13315 and yeast Candida albicans ATCC 10231 were evaluated and compared with antibacterial and antifungal properties of appropriate silver salts, metronidazole and silver sulfadiazine drugs. The newly synthesized compounds exhibited significant antibacterial activity against Gram-positive bacteria, better than the referenced silver sulfadiazine. The best active silver(i)-metronidazole complex contains a methanesulphonate counter-ion. Moreover, the complex inhibited the growth of yeast Candida albicans at a concentration 3-fold lower than that required for silver sulfadiazine. In addition, the complexes containing a tetrafluoroborate and a perchlorate as counter-ions were characterized as effective antibacterial agents against the tested Gram-negative bacteria.

Draft Genome Sequence of the Bioelectricity-Generating and Dye-Decolorizing Bacterium Proteus hauseri Strain ZMd44

Proteus hauseri ZMd44 (CGMCC 6746), as a crucial biodecolorizing, bioelectricity-generating, and copper-resistant bacterium, is distinguished from the urinary pathogens Proteus penneri and Proteus mirabilis. To further investigate the genetic functions of this strain, the genome sequence and annotation of its open reading frames, which consist of 3,875,927 bp (G+C content, 38.12%), are presented here.

Proteomics approach to decipher novel genes and enzymes characterization of a bioelectricity-generating and dye-decolorizing bacterium Proteus hauseri ZMd44

The first-attempt study employed a proteomics strategy for the identification of abundant proteins from a bioelectricity generation and dye decolorization bacterium Proteus hauseri ZMd44. By using the degenerated primers designed based on the peptide sequences from tandem mass spectroscopy and the whole genomics annotation of the closely associated strain, Proteus penneri ATCC 35198, the genes were successfully obtained for two full-length genes of 543 bp (laccase) and 1,086 bp (Omp F, porin) encoding to 181 amino acids and 362 amino acids, respectively. It explored laccase and NADH dehydrogenase involvement in the oxidation-reduction reaction as well, as porin played an important role in providing channels for related proteins in the accomplishment of electron transportation in P. hauseri. Detailed enzymatic assays indicated that laccase activity of 542.2 U/DCW could be stimulated by 2.5 mM copper induction in LB medium (ca. 293-fold to those without copper induction). Among intracellular proteins, NADH dehydrogenase activity of 257.2 U/mg via mediator riboflavin was in parallel with the decolorizing capability of azo dye Rb160 that only took place in LB medium. From the evaluation of kinetic parameters (Vmax and Km were 0.272 U/min and 0.393 mM with ABTS, 0.046 U/min and 43.8 μM with NADH), it is better to decipher the decolorization mechanism of ZMd44 indicating that laccase and NADH dehydrogenase played the most crucial role for azo dye decolorization.