Identification of antigens from nosocomial <Emphasis Type="Italic">Acinetobacter baumannii</Emphasis> clinical isolates in sera from ICU staff and infected patients using the antigenome technique

Nosocomial infections with a bacterial origin are considered one of the most dangerous threats to global health. Among the causes of these infections, Acinetobacter baumannii is playing a significant role, and the present study aimed? to determine the immunogenic proteins of this bacteria. Clinical isolates of A. baumannii were obtained from positive sputum cultures of intensive care unit (ICU) patients confirmed by Polymerase chain reaction (PCR) of the OXA-51 gene, and sera was obtained from 20 colonized patients. In addition, 20 and 30 serum samples were collected from ICU nurses and healthy controls, respectively. All the samples were screened in the presence of antibodies against A. baumannii by enzyme-linked immunosorbent assay (ELISA). IgG purified from the serum samples by affinity chromatography was used to isolate the bacteria by the Magnetic-activated cell sorting (MACS) procedure. After the bacteria were cultured, the identified antigen proteins were studied by western blotting and Mass spectrometry (MS). The MS results were analyzed with MASCOT software and revealed a 35 KD protein, which corresponds to outer membrane protein A (OmpA) of A. baumannii, a 25 KD band, which is a carbapenem-associated resistance protein precursor, and a 60 KD protein band, identified as a stress-induced bacterial acidophilic repeat motif protein. According to the properties of immunogen antigens and bio informatics tools, the outer membrane proteins (OMPs) can be used as a vaccine candidate in animal models.     

Antimicrobial Activity of Silver Nanoparticles in a Carboxymethyl Chitin Matrix Obtained by the Microwave Hydrothermal Method

Silver nanoparticles have been obtained in a matrix of 6-O-carboxymethyl chitin in the presence of D-glucose as a reducing agent by microwave hydrothermal synthesis. The TEM results show that the silver nanoparticles have a spherical shape; the particle size range is 3–20 nm. The resulting colloidal solution of silver nanoparticles had a strong bacterial effect on gram-positive bacteria Staphylococcus aureus ATCC 21027 (=209 P), Bacillus subtilis ATCC 6633, and, to a lesser extent, on gram-negative bacteria Escherichia coli АТСС 25922. The synthesized silver nanoparticles showed pronounced fungistatic activity against A. niger INA 00760.     

Isolation and partial characterization of bacteria with potential antimicrobial activity from the Caspian Sea

Due to the constant increasing of bacterial resistance against known antibiotics, it is now necessary to find new sources of antimicrobials including the marine environment. The aim of this study was to evaluate antimicrobial activity of bacterial strains isolated from different coastal regions of the Caspian Sea and to provide phylogenetic analyses of antibiotic producing strains. Water samples collected from the Caspian Sea were serially diluted and plated on selective media. Isolates were tested against a panel of reference strains (Streptococcus pyogenes, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa) by microbial antagonism and disc diffusion assay. Unweighted Pair Group Method with Arithmetic Mean (UPGMA) method was also employed to produce a phylogenetic tree based on 16S rDNA sequences. Amongst 162 isolates, 8 strains (4.93%) showed antibacterial activity. Isolated bacteria displayed more activity against gram-positive bacteria than gram-negative bacteria. Moreover, the 16S sequences obtained for the 8 selected strains were compared using a BLAST algorithm and allowed us to determine the strains genus as followed: Bacillus (RS28, RS54, RS56, RS82, RS116, and NS53), Brevundimonas (RS32), and Arthrobacter (NS25). The findings of the present study recommend that culturally marine bacteria collected from the Caspian Sea might be a potent source of novel bioactive compounds such as antibiotics.     

Antimicrobial activity of endogenous peptides of the moss <Emphasis Type="Italic">Physcomitrella patens</Emphasis>

Plant and animal cells contain pools of endogenous peptides, which are the degradation products of functionally active proteins. It is known that these peptides can possess biological activity; however, the functions of most of them are unknown. The goal of the present study was to estimate the antimicrobial potential of endogenous peptides resulting from the degradation of functional proteins in cells of the moss Physcomitrella patens. Earlier, 117 peptides possessing an antimicrobial potential predicted in silico have been identified in the peptidomes of three types of P. patens cells by mass spectrometry. In the present work, the antimicrobial activity of six of these peptides toward the gram-positive bacteria Bacillus subtilis SHgw and Clavibacter michiganensis pv. michiganensis and gram-negative bacteria Escherichia coli K12 and Xanthomonas arboricola 3004 has been revealed. The results have shown that three of six peptides inhibit the growth of the phytopathogenic bacteria X. arboricola and C. m. pv. michiganensis; four peptides inhibit the growth of the gram-negative bacterium E. coli K12, and one peptide inhibits the growth of the gram-positive bacterium B. subtilis. It has been found that the peptides inhibiting the bacterial growth are predominantly the fragments of ribosomal proteins. The work confirms the potential of the biological activity of peptides that are the degradation products of functional proteins.     

Trypsin Hydrolysed Protein Fractions as Radical Scavengers and Anti-bacterial Agents from <Emphasis Type="Italic">Ficus deltoidea</Emphasis>

Different molecular sizes of protein hydrolysates were prepared from the crude protein extract of Ficus deltoidea using the technique of membrane ultrafiltration after trypsin hydrolysis. Gel electrophoretic images shows the presence of 12, 8, 7 and 7 protein bands for the protein fractions prepared from the molecular weight cut-off of 3, 10, 30 and 100 kDa, respectively. The protein hydrolysates were found to have higher radical scavenging activity than those unhydrolysed fractions at the similar molecular size. They exhibited significant differences in the radical scavenging activities based on one-way analysis of variance, except for the protein hydrolysates of 30 and 100 kDa. The smallest protein hydrolysates, 3 kDa appeared to have the comparable activity (30%) with bovine serum albumin as a positive control in this study. Similarly, the 3 kDa protein hydrolysates achieved the highest inhibitory activity (87.5%) against Pseudomonas aeruginosa at the concentration of 128 µg/mL. The protein hydrolysates were found to be more effective against gram negative bacteria (P. aeruginosa and Escherichia coli) because of lower minimum inhibitory concentration (MIC) and effective inhibitory concentration at 50% (EC₅₀) than gram positive bacterium (Staphylococcus aureus). Trypsin catalysed hydrolysis seemed to improve the anti-bacterial activity of protein hydrolysates in a bacterial strain dependent manner. The MIC could achieve 1–55 µg/mL at different molecular sizes of protein fractions. Mass spectra matching revealed that 26% of 226 identified proteins belonged to the category of plant defensive proteins in stress management and metal handling.     

Comparative muscle proteomics/phosphoproteomics analysis provides new insight for the biosafety evaluation of <Emphasis Type="Italic">fat</Emphasis>-<Emphasis Type="Italic">1</Emphasis> transgenic cattle

The biosafety of fat-1 transgenic cattle has been a focus of our studies since the first fat-1 transgenic cow was born. In this study, we used tandem mass tag labeling, TiO₂ enrichment, and nanoscale liquid chromatography coupled with tandem mass spectrometry (nanol LC–MS/MS) to compare proteomic and phosphoproteomic profiling analyses of muscle between fat-1 transgenic cows and wild-type cows. A total of 1555 proteins and 900 phosphorylation sites in 159 phosphoproteins were identified in the profiling assessments, but only four differentially expressed proteins and nine differentially expressed phosphopeptides were detected in fat-1 transgenic cows relative to wild-type cows. Bioinformatics analyses showed that all of the identified proteins and phosphoproteins were mainly related to the metabolic processes of three major nutrients: carbohydrates, lipids, and proteins. All of these differentially expressed proteins might take part in DNA recombination, repair, and regulation of the immune system. In conclusion, most of the identified proteins and phosphoproteins exhibited few changes. Our results provide new insights into the biosafety of fat-1 transgenic cattle.     

Isolation Purification and Characterization of Antimicrobial Peptides from <Emphasis Type="Italic">Cuminum cyminum</Emphasis> L. Seeds

In this work, antimicrobial peptides from Cuminum cyminum L. seeds were isolated and purified for the first time by 50% ethanol extraction, C18 reverse phase column chromatography and ion exchange chromatography for separation different peptides fraction. Then isolated fractions were characterized by Gel electrophoresis (SDS-PAGE), high-pressure liquid chromatography and the peptides components and molecular weights were determined by liquid chromatography and mass spectrometry. The extracts were tested against some strains of bacteria (E. coli and Staphylococcus aureus) and one strain of fungi (Candida albicans) using well diffusion and broth dilution assays. The extracts from C. cyminum L. seeds demonstrated a high degree of activity (some antibacterial effect) against the bacteria strains and аntifungal activity against the Candida albicans. However, the study indicates that the crude peptide extracts from C. cyminum L. seeds have promising antimicrobial and antioxidant activities that can be harnessed as leads for potential bioactive compounds.     

Study of ectoparasitism of ultramicrobacteria of the genus <Emphasis Type="Italic">Kaistia</Emphasis>, strains NF1 and NF3 by electron and fluorescence microscopy

Transmission electron and fluorescence microscopy was used to study the character of the interaction of free-living ultramicrobacterial (UMB) strains NF1 and NF3, affiliated with the genus Kaistia, and seven species of gram-positive and gram-negative heterotrophic bacteria. Strains NF1 and NF3 were found to exhibit parasitic activity against gram-positive Bacillus subtilis and gram-negative Acidovorax delafildii. UMB cells are tightly attached to the envelopes of the victim cells and induce their lysis, thus demonstrating the features of typical ectoparasitism. The selectivity of parasitism of the studied UMB to the victim bacteria has been shown: only two soil microorganisms of the seven test objects, B. subtilis ATCC 6633 and an aerobic gramnegative bacterium A. delafildii 39, were found to be sensitive to UMB attack. Other bacteria (Micrococcus luteus VKM Ac-2230, Staphylococcus aureus 209-P, Pseudomonas putida BS394, Escherichia coli C 600, and Pantoea agglomerans ATCC 27155) were not attacked by UMB. It was established for the first time that free-living UMB may be facultative parasites not only of phototrophic bacteria, as we have previously demonstrated [1], but of heterotrophic bacteria as well. The UMB under study seem to play an important role in the regulation of the quantity of microorganisms and in the functioning of microbial communities in some natural ecotopes.     

Characterization of new <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> strains from Iran,based on cytocidal and insecticidal activity,proteomic analysis and gene content

Characterization of new Bacillus thuringiensis strains is a valuable tool to discover novel insecticidal toxins and to manage resistance problems. In this study, seven Iranian Bt strains were selected according to their toxicity against Plodia interpunctella, to be thoroughly characterized based on their toxicity, protein profiling, proteomic analysis, gene content and β-exotoxin production. The toxicity was assessed by insect bioassays and cell viability assays (a less cost, time and material consuming technique), using four lepidopteran pests and four lepidopteran cell lines from Trichoplusia ni (Hi5), Helicoverpa zea (HzGUT), Spodoptera exigua (UCR-SE) and Spodoptera frugiperda (Sf21). The selected Bt strains showed similar protein electrophoretic profiles, but differed in toxicity. LC–MS/MS analysis of solubilized crystal proteins and gene content analyses (PCR screening) were compared and correlated with the toxicity results. Based on our data, three Bt strains could be considered as candidates for development of future bioinsecticides.     

Chemotaxonomy of fungi in the <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> species complex performing GC/MS metabolite profiling

Hyphal anastomosis testing and molecular methods have been the primary criteria employed to understand the evolutionary and taxonomic relationships of the soil-borne fungal plant pathogen Rhizoctonia solani species complex. In this study, a metabolomics-based approach for characterizing and identifying isolates of R. solani using gas chromatography/mass spectrometry (GC/MS) metabolite profiling and footprinting was developed. Multivariate and hierarchical cluster analyses of GC/MS data provided resolution of isolates belonging to anastomosis groups (AGs) 1–6, 9, and 10 of R. solani. Clustering of R. solani AG-3 isolates, based on host origin, was also observed and attributed to metabolite-biomarkers belonging to amino, carboxylic and fatty acids. The chemotaxonomic approach using metabolomics is a high-throughput methodology that complements existing molecular approaches for the taxonomic investigation of Rhizoctonia isolates and monitoring of fungal metabolism.     

Erratum to Bacterial diversity in toxic<Emphasis Type="Italic"> Alexandrium tamarense</Emphasis> blooms off the Orkney Isles and the Firth of Forth

The genetic diversity of the bacterial community associated with Alexandrium tamarense blooms was studied in blooms of the toxic dinoflagellates in the waters around the Orkney Isles and the Firth of Forth (Scotland). For toxin and molecular analysis of the bacterial communities associated with the toxic bloom, water samples were taken in 1998 and 1999 from A. tamarense blooms. The bacterial community structure, as determined by DGGE (denaturing gradient gel electrophoresis) showed clear differences between all three investigated size fractions (dinoflagellate-associated bacteria, attached bacteria and free-living bacteria), with high diversity within each sample. DNA sequence analysis of the dominant and most frequent DGGE bands revealed the dominance of α Proteobacteria, mainly of the Roseobacter clade, with similarities of 91–99%. Moreover, DGGE bands occurring at the same position in the gel throughout in most samples corroborate the presence of several specific α Proteobacteria of the Roseobacter clade. Overall, 500 bacteria were isolated from the bloom and partly phylogenetically analysed. They were members of two prokaryotic phyla, the Proteobacteria and the Bacteroidetes, related to Proteobacteria of the α and γ subdivisions (Alteromonas, Pseudoalteromonas and Colwellia). All bacteria were tested for the production of sodium channel blocking (SCB) toxins using mouse neuroblastoma assay. No production of SCB toxins was found and high performance liquid chromatography (HPLC) analysis confirmed these results. The content of total paralytic shellfish poisoning (PSP) toxin in the water samples, as measured within the toxic dinoflagellate blooms using HPLC, ranged from 53 to 2191 ng PSP l^?1 in 1998 and from 0 to 478 ng PSP l^?1 in 1999. Changes in PSP toxin content were not accompanied by changes of DGGE band patterns. We therefore presume that the bacterial groups identified in this study were not exclusively associated with toxic A. tamarense, but were generally associated with the phytoplankton.     

Orange protein from <Emphasis Type="Italic">Desulfovibrio alaskensis</Emphasis> G20: insights into the Mo–Cu cluster protein-assisted synthesis

A novel metalloprotein containing a unique [S₂MoS₂CuS₂MoS₂]^3? cluster, designated as Orange Protein (ORP), was isolated for the first time from Desulfovibrio gigas, a sulphate reducer. The orp operon is conserved in almost all sequenced Desulfovibrio genomes and in other anaerobic bacteria, however, so far D. gigas ORP had been the only ORP characterized in the literature. In this work, the purification of another ORP isolated form Desulfovibrio alaskensis G20 is reported. The native protein is monomeric (12443.8 ± 0.1 Da by ESI–MS) and contains also a MoCu cluster with characteristic absorption bands at 337 and 480 nm, assigned to S–Mo charge transfer bands. Desulfovibrio alaskensis G20 recombinant protein was obtained in the apo-form from E. coli. Cluster reconstitution studies and UV–visible titrations with tetrathiomolybdate of the apo-ORP incubated with Cu ions indicate that the cluster is incorporated in a protein metal-assisted synthetic mode and the protein favors the 2Mo:1Cu stoichiometry. In Desulfovibrio alaskensis G20, the orp genes are encoded by a polycistronic unit composed of six genes whereas in Desulfovibrio vulgaris Hildenborough the same genes are organized into two divergent operons, although the composition in genes is similar. The gene expression of ORP (Dde_3198) increased 6.6 ± 0.5 times when molybdate was added to the growth medium but was not affected by Cu(II) addition, suggesting an involvement in molybdenum metabolism directly or indirectly in these anaerobic bacteria.     

Antimicrobial activities of some synthesized 1-(3-(2-methylphenyl)-4-Oxo-3<Emphasis Type="Italic">H</Emphasis>-quinazolin-2-yl-4-(substituted)thiosemicarbazide derivatives

The substituted thiosemicarbazide moiety was placed at the C-2 position and 2-methylphenyl group at N-3 position of quinazoline ring and obtained compounds were tested for their antitubercular activities and antibacterial activities against selected gram-positive and gram-negative bacteria. The target compounds 1-(3-(2-methylphenyl)-4-oxo-3H-quinazolin-2-yl)-4-(substituted) thiosemicarbazides were obtained by the reaction of 2-hydrazino-3-(2-methylphenyl) quinazolin-4(3H)-one with different dithiocarbamic acid methyl ester derivatives. All synthesized compounds were also screened for their antimicrobial activity against selective gram-positive and gram-negative bacteria by agar dilution method. Among the series, 1-[3-(2-methylphenyl)-4-oxo-3H-quinazolin-2-yl]-4-[4-chlorophenyl]-thiosemicarbazide exhibited the most potent activity against S. typhi, E. coli, and B. subtilis, while 1-[3-(2-methylphenyl)-4-oxo-3H-quinazolin-2-yl]-4-[4-nitrophenyl]-thiosemicarbazide was the most potent against E. coli, B. subtilis, P. aeruginosa, S. typhi, and S. flexneri. These two compounds exhibited the antitubercular activity at the minimum concentration (3 μg/mL) that offered potential for further optimization and development of new antitubercular agents. The obtained results demonstrated promising antimicrobial and antitubercular activities of the synthesized quinazoline compounds which could be used as new scaffolds for improving their antimicrobial activity.     

Symbiotic cornucopia of the monophagous planthopper <Emphasis Type="Italic">Ommatidiotus dissimilis</Emphasis> (Fallén, 1806) (Hemiptera: Fulgoromorpha: Caliscelidae)

In contrast to Cicadomorpha, in which numerous symbiotic bacteria have been identified and characterized, the symbionts of fulgoromorphans are poorly known. Here, we present the results of histological, ultrastructural, and molecular analyses of the symbiotic system of the planthopper Ommatidiotus dissimilis. Amplification, cloning, and sequencing of bacterial 16S RNA genes have revealed that O. dissimilis is host to five types of bacteria. Apart from bacteria Sulcia and Vidania, which are regarded as ancestral symbionts of Fulgoromorpha, three additional types of bacteria belonging to the genera Sodalis, Wolbachia, and Rickettsia have been detected. Histological and ultrastructural investigations have shown that bacteria Sulcia, Vidania, and Sodalis house separate bacteriocytes, whereas bacteria Wolbachia and Rickettsia are dispersed within various insect tissue. Additionally, bacteria belonging to the genus Vidania occupy the bacteriome localized in the lumen of the hindgut. Both molecular and microscopic analyses have revealed that all the symbionts are transovarially transmitted between generations.     

Review of the <Emphasis Type="Italic">Chromis xanthura</Emphasis> species group (Perciformes: Pomacentridae), with description of a new species

A taxonomic review of the Chromis xanthura species group, defined here as having 13 dorsal-fin spines, three upper and three lower procurrent caudal-fin rays, two black bands at the preopercular and opercular margins, and a yellow caudal fin when juvenile, resulted in the recognition of three species, Chromis xanthura (Bleeker 1854), Chromis opercularis (Günther 1867), and Chromis anadema sp. nov. Chromis xanthura and C. opercularis, the Pacific and Indian Ocean paired sister species, respectively, are redescribed, with confirmation of two color types of C. xanthura (having a white or black caudal peduncle and fin) as a single species on the basis of morphological and molecular analyses. Chromis anadema sp. nov., described from the oceanic islands of the Pacific Ocean on the basis of 21 specimens, is characterized by having 28–33 gill rakers; longest dorsal-fin soft ray length 20.0–24.7% of standard length (SL); first anal-fin spine length 5.0–6.1% of SL; caudal-fin length 33.4–43.8% of SL; posterior tips of caudal-fin lobes not filamentous in adults; broad black bands along preopercular and opercular margins, sum width of two bands 28.9–38.7% of head length; distal half of soft-rayed portion of dorsal fin transparent in adults; triangular black blotches at upper and lower caudal-fin base in adults; caudal peduncle and fin bluish black in adults; and body grayish, and all fins (except for pectoral fin) bright yellow in juveniles.     

Antimicrobial Activities of Novel Peptides Derived from Defensin Genes of <Emphasis Type="Italic">Brassica hybrid</Emphasis> cv Pule

Plant defensins are small and basic antimicrobial peptides characterized by conserved cysteine stabilizing structure with α-helix and triple strand antiparallel β-sheet. In the present study, two novel defensin genes, designated as BhDef1 and BhDef2, was isolated from Brassica hybrid cv Pule, a native unexplored Brassicaceae species found in Thailand. The full-length cDNA of BhDef1 and BhDef2 were 240 and 258 bp encoding a 79 and 85 amino acid residues with 29 and 25 amino acid signal peptide at N-terminal, respectively. The putative BhDef1 and BhDef2 mature proteins showed significant similarity to other Brassicaceae defensins. Their secondary structure comprises of one α-helix and a triple stranded β-sheet stabilized by four disulphide bridges of eight cysteines. BhDef1 and BhDef2 also contain a highly conserved γ-core and α-core motif exhibiting antifungal activity against Colletotrichum gloeosporioides causing anthracnose disease. Six out of eight synthetic BhDef peptide derivatives showed antibacterial activity against both gram-positive bacteria and gram-negative bacteria used in this study. BhDef14, the derivative of BhDef1, showed the highest activity against two test pathogenic bacteria. This activity could probably due to a net positively charge and alpha-helical conformation which are known as the key determinant for the bacterial membrane disruption. To our knowledge, this is the first report on defensin genes isolated from B. hybrid cv Pule. The synthetic peptides designed from their sequences showed antifungal and antibacterial activity.     

Comparative pan genome analysis of oral <Emphasis Type="Italic">Prevotella</Emphasis> species implicated in periodontitis

Prevotella is part of the oral bacterial community implicated in periodontitis. Pan genome analyses of eight oral Prevotella species, P. dentalis, P. enoeca, P. fusca, P. melaninogenica, P. denticola, P. intermedia 17, P. intermedia 17-2 and P. sp. oral taxon 299 are presented in this study. Analysis of the Prevotella pan genome revealed features such as secretion systems, resistance to oxidative stress and clustered regularly interspaced short palindromic repeat (CRISPR)-Cas systems that enable the bacteria to adapt to the oral environment. We identified the presence of type VI secretion system (T6SS) in P. fusca and P. intermedia strains. For some VgrG and Hcp proteins which were not part of the core T6SS loci, we used gene neighborhood analysis and identified putative effector proteins and putative polyimmunity loci in P. fusca and polymorphic toxin systems in P. intermedia strains. Earlier studies have identified the presence of Por secretion system (PorSS) in P. gingivalis, P. melaninogenica and P. intermedia. We noted the presence of their homologs in six other oral Prevotella studied here. We suggest that in Prevotella, PorSS is used to secrete cysteine proteases such as interpain and C-terminal domain containing proteins with a “Por_secre_tail” domain. We identified subtype I-B CRISPR-Cas system in P. enoeca. Putative CRISPR-Cas system subtypes for 37 oral Prevotella and 30 non-oral Prevotella species were also predicted. Further, we performed a BLASTp search of the Prevotella proteins which are also conserved in the red-complex pathogens, against the human proteome to identify potential broad-spectrum drug targets. In summary, the use of a pan genome approach enabled identification of secretion systems and defense mechanisms in Prevotella that confer adaptation to the oral cavity.     

Nearline acquisition and processing of liquid chromatography-tandem mass spectrometry data

Liquid chromatography–mass spectrometry (LC–MS) is a commonly used analytical platform for non-targeted metabolite profiling experiments. Although data acquisition, processing and statistical analyses are almost routine in such experiments, further annotation and subsequent identification of chemical compounds are not. For identification, tandem mass spectra provide valuable information towards the structure of chemical compounds. These are typically acquired online, in data-dependent mode, or offline, using handcrafted acquisition methods and manually extracted from raw data. Here, we present several methods to fast-track and improve both the acquisition and processing of LC–MS/MS data. Our nearly online (nearline) data-dependent tandem MS strategy creates a minimal set of LC–MS/MS acquisition methods for relevant features revealed by a preceding non-targeted profiling experiment. Using different filtering criteria, such as intensity or ion type, the acquisition of irrelevant spectra is minimized. Afterwards, LC–MS/MS raw data are processed with feature detection and grouping algorithms. The extracted tandem mass spectra can be used for both library search and de-novo identification methods. The algorithms are implemented in the R package MetShot and support the export to Bruker, Agilent or Waters QTOF instruments and the vendor-independent TraML standard. We evaluate the performance of our workflow on a Bruker micrOTOF-Q by comparison of automatically acquired and extracted tandem mass spectra obtained from a mixture of natural product standards against manually extracted reference spectra. Using Arabidopsis thaliana wild-type and biosynthetic gene knockout plants, we characterize the metabolic products of a biosynthetic pathway and demonstrate the integration of our approach into a typical non-targeted metabolite profiling workflow.     

Characterization of Antimicrobial Peptides Isolated from the Processing by-Products of African Catfish <Emphasis Type="Italic">Clarias gariepinus</Emphasis>

Antimicrobial peptides (AMPs) as components of innate immunity system have been isolated from fish and other species. In this study, the crude proteins extracted with gradient ammonium sulfate precipitation technique from the processing by-products of African catfish Clarias gariepinus (C. gariepinus) were purified by size-exclusion chromatography and all the four obtained fractions, Clarias antimicrobial peptides I(CAP-I), CAP-II, CAP-III and CAP-IV, showed antimicrobial activity. Among of these fractions, CAP-IV showed the highest antimicrobial activity against Staphylococcus aureus, Aeromonas sobria, Aeromonas hydrophila, Escherichia coli by agar diffusion plate test and the diameter of inhibition zone was 8.34, 9.27, 6.76, 6.13 mm, respectively. The molecular weight of main peptides of CAP-IV was around 4.1 KD by SDS-PAGE analysis. CAP-IV showed antimicrobial activity against both gram-negative and gram-positive bacterial pathogens at minimum inhibitory concentrations (MICs) ranging from 105 to 420 μg/mL. The antimicrobial activity of CAP-IV was stable at wide pH range, 3–11 and was also heat-stable when temperature was below 80 °C. Freeze-thawing treatment also only had slight effects on the antimicrobial activity of CAP-IV. Besides, CAP-IV was not sensitive to the hydrolysis by pepsin and trypsin, except for protease K. These results suggest that CAP-IV isolated from C. gariepinus is potential to be developed as a new antimicrobial peptide and may partially explain the high disease resistance of African catfish C. gariepinus.     

Synthesis of new 1-alkyl-, 1-benzyl-, and 1-aryloxyethyl-substituted 4,5-dichloroimidazoles and their antimicrobial,protistocidal, and fungistatic properties

Previously unknown 1-alkyl-, 1-benzyl-, and 1-aryloxyethylderivatives of dichloroimidazoles and products of their structural transformation were synthesized from 4,5-dichloroimidazole or 2-methyl-4,5- dichloroimidazole using alkyl, benzyl or aryloxyethyl halides. These N-substituted compounds were shown to have a weak antibacterial activity against some pathogenic gram-positive and gram-negative bacteria (Staphylococcus aureus and Escherichia coli). At the same time, some of the obtained compounds demonstrated a significant protistocidal activity against Colpoda steinii, which can exceed in strength the activity of clinically used veterinary drug Baycox. Moreover, these compounds showed a pronounced fungistatic effect.