Identification and characterization of antibacterial compound(s) of cockroaches (Periplaneta americana)

Infectious diseases remain a significant threat to human health, contributing to more than 17 million deaths, annually. With the worsening trends of drug resistance, there is a need for newer and more powerful antimicrobial agents. We hypothesized that animals living in polluted environments are potential source of antimicrobials. Under polluted milieus, organisms such as cockroaches encounter different types of microbes, including superbugs. Such creatures survive the onslaught of superbugs and are able to ward off disease by producing antimicrobial substances. Here, we characterized antibacterial properties in extracts of various body organs of cockroaches (Periplaneta americana) and showed potent antibacterial activity in crude brain extract against methicillin-resistant Staphylococcus aureus and neuropathogenic E. coli K1. The size-exclusion spin columns revealed that the active compound(s) are less than 10 kDa in molecular mass. Using cytotoxicity assays, it was observed that pre-treatment of bacteria with lysates inhibited bacteria-mediated host cell cytotoxicity. Using spectra obtained with LC-MS on Agilent 1290 infinity liquid chromatograph, coupled with an Agilent 6460 triple quadruple mass spectrometer, tissues lysates were analyzed. Among hundreds of compounds, only a few homologous compounds were identified that contained isoquinoline group, chromene derivatives, thiazine groups, imidazoles, pyrrole containing analogs, sulfonamides, furanones, flavanones, and known to possess broad-spectrum antimicrobial properties, and possess anti-inflammatory, anti-tumour, and analgesic properties. Further identification, characterization and functional studies using individual compounds can act as a breakthrough in developing novel therapeutics against various pathogens including superbugs

Phenotypic and genotypic antibiotic resistance profiles of Escherichia coli O157 from cattle and slaughterhouse wastewater isolates

Gencay, Yilmaz Emre/0000-0002-2154-9663WOS: 000354724300054The aims of this study were to determine the minimal inhibition concentration of 20 different antibiotics on cattle and slaughterhouse wastewater Escherichia coli O157, including both Shiga toxigenic E. coli O157 (STEC O157) and non-Shiga toxigenic strains (non-STEC O157) by the Epsilometer test, and to determine the antibiotic resistance gene profiles of the isolates by PCR. A total of 102 cattle and slaughterhouse wastewater E. coli O157 isolates including 96 E. coli O157:H7(+) (81 non-sorbitol fermenting [NSF] STEC O157:H7, 12 NSF non-STEC O157:H7, and three sorbitol fermenting [SF] non-STEC O157:H7) and six non-STEC O157:H7(-) isolated from 744 cattle and slaughterhouse wastewater samples collected within a 2-year period were assessed. Of 93 NSF E. coli O157:H7 isolates, 19 were resistant to tetracycline and sulfamethoxazole, 14 to trimethoprim, 13 to cefoxitin, 11 to streptomycin, 10 to ampicillin, eight to chloramphenicol, six to cephalothin, four to cefaclor, four to aztreonam, and four to nalidixic acid. In six of the E. coli O157:H7(-) isolates, tetracycline resistance was detected while five of them were also resistant to ampicillin, sulfamethoxazole, and trimethoprim. In PCR analysis, 26.0 % (25/96) of the NSF E. coli O157:H7(+) and all of the E. coli O157:H7(-) isolates harbored one or more antibiotic resistance genes. While tetA, tetB, tetC, strA, strB, and sulI genes were detected from a number of the isolates, tetD, tetE, tetG, cmlA, floR, sulII, aadA, and ampC genes were not detected in any of the isolates. Results suggest a high antibiotic resistance in E. coli O157:H7(+)/H7(-) cattle and wastewater isolates. The majority of our resistant isolates, antibacterial resistance genes did not correlate with observed phenotypic resistance. Other resistance traits and regulatory factors that mediate antibiotic resistance should be included in further antimicrobial resistance investigations.Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [110R013]This study was supported by The Scientific and Technological Research Council of Turkey (TUBITAK, project no: 110R013)

Optoelectronic Structure and Related Transport Properties of Ag2Sb2O6 and Cd2Sb2O7

Pomocí metody the full-potential linearized augmented-plane wave byla zkoumána elektronická struktura a termoelektrické vlastnosti Ag2Sb2O6 a Cd2Sb2O7. Modifikovaný potenciál Becke-Johnson byl aplikován k výměně korelační energie. Elektronické pásmové struktury odhalují, že minimální hodnota valenčního pásma a minimální pásmo vodivosti se vyskytují v bodě C, což naznačuje, že Ag2Sb2O6 a Cd2Sb2O7 mají přímé polovodičové energetické pásmo. Vyskytla se silná hybridizace mezi stavy Ag (Cd) -s / p a O-s / p. Optické vlastnosti, tj. Komplexní dielektrická funkce, odrazivost, index lomu a funkce ztráty energie, odhalují vysokou odrazivost v oblasti ultrafialové energie, což ukazuje na užitečnost těchto materiálů na stínění vysokoenergetických záření. Kombinací transportní teorie a metody from the full-potential linearized augmented-plane wave byly termoelektrické vlastnosti analyzovány jako funkce teploty. Vzhledem k vysokému tepelnému výkonu a úzkému pásmu jsou Ag2Sb2O6 a Cd2Sb2O7 vhodnými materiály pro použití v optoelektronických a termoelektrických zařízeních.Using the full-potential linearized augmented-plane wave method, the electronic structure and thermoelectric properties of Ag2Sb2O6 and Cd2Sb2O7compounds have been explored. The modified Becke–Johnson potential was applied to treat the exchange–correlation energy term. The electronic band structures reveal that the valence-band maximum and conduction-band minimum occur at C point, indicating that Ag2Sb2O6 and Cd2Sb2O7 are direct energy bandgap semiconductors. Strong hybridization appeared between Ag (Cd)-s/p and O-s/p states. The optical properties, i.e., complex dielectric function, reflectivity, refractive index, and energy loss function, reveal high reflectivity in the ultraviolet energy range, indicating usefulness of these materials in shields from high-energy radiation. Combining transport theory and the outputs from the full-potential linearized augmented-plane wave calculations, the thermoelectric properties were analyzed as functions of temperature. Due to their high thermopower and narrow bandgap, Ag2Sb2O6 and Cd2Sb2O7 are suitable materials for application in optoelectronic and thermoelectric devices