Characterization of a highly pathogenic Bacillus thuringiensis strain isolated from common cockchafer, Melolontha melolontha

Demirbag, Zihni/0000-0001-5487-1977WOS: 000246813500006PubMed: 17575913A bacterial isolate (Mm2) of Melolontha melolontha was identified and characterized. Based on various morphological, physiological, biochemical and molecular characteristics, it was identified as Bacillus thuringiensis subsp. tenebrionis. This isolate was compared to the reference strains by electron microscopy, SDS-PAGE analysis, plasmid pattern, cry gene content and insecticidal activity. Cells of the isolate harbored flat square inclusions containing a protein component of approximate to 65 kDa. After trypsin digestion of solubilized crystals, SDS-PAGE resolved a unique proteinase-resistant peptide of approximate to 50 kDa. Plasmid pattern showed similar bands to those of the reference strain, PCR analysis showed that the isolate has cry3 gene. Toxicity tests (against 5 coleopteran species) showed 80% insecticidal activity against the larvae of M. melolontha. The isolate Mm2 may be valuable as biological control agent for M melolontha and other coleopteran insects

Purification and Characterization of the Bacteriocin Thuricin Bn1 Produced by Bacillus thuringiensis subsp kurstaki Bn1 Isolated from a Hazelnut Pest

Demirbag, Zihni/0000-0001-5487-1977WOS: 000315547800006PubMed: 23412058A novel bioactive molecule produced by Bacillus thuringiensis subsp. kurstaki Bn1 (Bt-Bn1), isolated from a common pest of hazelnut, Balaninus nucum L. (Coleoptera: Curculionidae), was determined, purified, and characterized in this study. The Bt-Bn1 strain was investigated for antibacterial activity with an agar spot assay and well diffusion assay against B. cereus, B. weinhenstephenensis, L. monocytogenes, P savastanoi, P syringae, P lemoignei, and many other B. thuringiensis strains. The production of bioactive molecule was determined at the early logarithmic phase in the growth cycle of strain Bt-Bn1 and its production continued until the beginning of the stationary phase. The mode of action of this molecule displayed bacteriocidal or bacteriolytic effect depending on the concentration. The bioactive molecule was purified 78-fold from the bacteria supernatant with ammonium sulfate precipitation, dialysis, ultrafiltration, gel filtration chromatography, and HPLC, respectively. The molecular mass of this molecule was estimated via SDS-PAGE and confirmed by the ESI-TOF-MS as 3,139 Da. The bioactive molecule was also determined to be a heat-stable, pH-stable (range 6-8), and proteinase K sensitive antibacterial peptide, similar to bacteriocins. Based on all characteristics determined in this study, the purified bacteriocin was named as thuricin Bn1 because of the similarities to the previously identified thuricin-like bacteriocin produced by the various B. thuringiensis strains. Plasmid elution studies showed that gene responsible for the production of thuricin Bn1 is located on the chromosome of Bt-Bn1. Therefore, it is a novel bacteriocin and the first recorded one produced by an insect originated bacterium. It has potential usage for the control of many different pathogenic and spoilage bacteria in the food industry, agriculture, and various other areas.TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [110T030]The Authors thank Dr. Daniel R. Zeigler (BGSC, Bacillus Genetic Stock Center) for the generous gift of bacteriocinogenic strains of B. thuringiensis and B. cereus. The Authors also wish to thank Dr. Halil Ibrahim Ugras (Giresun University, Turkey) for helping with the ESI-TOF-MS analysis. This work was supported by TUBITAK (110T030)

Thermal conductivity and interfacial energy of solid Bi solution in the Bi-Al-Zn eutectic system

The equilibrated grain boundary groove shapes for solid Bi solution (Bi-6.1 at.%Zn-0.38 at.%Al) in equilibrium with the Bi-Al-Zn eutectic liquid have been observed from quenched sample with a radial heat flow apparatus. The Gibbs-Thomson coefficient, solid-liquid interfacial energy and grain boundary energy of solid Bi solution have been determined from the observed grain boundary groove shapes. The variations of thermal conductivity with temperature for solid Bi solution (Bi-6.1 at.%Zn-0.38 at.%Al) has been measured up to five degree below the melting temperature by using radial heat flow technique. The ratio of thermal conductivity of equilibrated Bi-Al-Zn eutectic liquid phase to solid Bi solution (Bi-6.1 at.%Zn-0.38 at.%Al) phase has also been measured with a Bridgman type growth apparatus at the melting temperature. (C) 2010 Elsevier B.V. All rights reserved

A highly pathogenic strain of Bacillus thuringiensis serovar kurstaki in lepidopteran pests

Nalcacioglu, Remziye/0000-0003-0527-9541; Demirbag, Zihni/0000-0001-5487-1977WOS: 000252058900013PubMed: 18176540In order to detect and identify the most toxic Bacillus thuringiensis strains against pests, we isolated a B. thuringiensis strain (Bn1) from Balaninus nucum (Coleoptera: Curculionidae), the most damaging hazelnut pest. Bn1 was characterized via morphological, biochemical, and molecular techniques. The isolate was sero-typed, and the results showed that Bn1 was the B. thuringiensis serovar, kurstaki (H3abc). The scanning electron microscopy indicated that Bn1 has crystals with cubic and bipyramidal shapes. The Polymerase Chain Reactions (PCRs) revealed the presence of the cry1 and cry2 genes. The presence of Cry1 and Cry2 proteins in the Bn1 isolate was confirmed via SDS-PAGE, at approximately 130 kDa and 65 kDa, respectively. The bioassays conducted to determine the insecticidal activity of the Bn1 isolate were conducted with four distinct insects, using spore-crystal mixtures. We noted that Bn1 has higher toxicity as compared with the standard B. thuringiensis subsp. kurstaki (HD-1). The highest observed mortality was 90% against Malacosoma neustria and Lymantria dispar larvae. Our results show that the B. thuringiensis isolate (Bn1) may prove valuable as a significant microbial control agent against lepidopteran pests

Determination of interfacial energies in the aminomethylpropanediol-neopentylglycol organic alloy

The grain boundary groove shapes for solid aminomethylpropanediol in equilibrium with eutectic aminomethylpropanediol-neopentylglycol liquid were directly observed by using a horizontal temperature gradient stage. From the observed grain boundary groove shapes, the Gibbs-Thomson coefficient, solid-liquid interfacial energy and grain boundary energy of solid aminomethylpropanediol in equilibrium with eutectic aminomethylpropanediol-neopentylglycol liquid have been determined to be (5.3 +/- 0.5) x 10 (8) K m, (8.5 +/- 1.3) x 10 (3) J m (2) and (16.8 +/- 2.9) x 10 (3) J m (2), respectively. (C) 2008 Elsevier B.V. All rights reserved

Determination of thermo-electrical properties in Sn based alloys

The variation of thermal conductivity of solid phase versus temperature for Sn-21 wt.% Bi, Sn-25 wt.% In and Sn-35 wt.% In-26 wt.% Bi alloys were measured with a radial heat flow apparatus. From the graphs of thermal conductivity versus temperature, the thermal conductivity of the solid phases at their melting temperatures and the thermal temperature coefficients for the same alloys were obtained. The ratios of thermal conductivity of liquid phase to solid phase for the same materials were measured with a Bridgman type directional solidification apparatus. The variations of electrical conductivity of solid phases versus temperature for the same alloys were determined from the Wiedemann-Franz law by using the measured values of thermal conductivity. From the graphs of electrical conductivity versus temperature, the electrical temperature coefficients for the same alloys were also determined. According to present experimental results it can be concluded that the thermal and electrical conductivity of Sn based alloys depend on the thermal and electrical conductivity of the alloying elements. If the thermal and electrical conductivity of the alloying elements are lower than the thermal conductivity of Sn, the thermal conductivity of Sn based alloys decreases, whereas, otherwise, it increases

High insecticidal activity of Leclercia adecarboxylata isolated from Leptinotarsa decemlineata (Col.: Chrysomelidae)

Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), is an important pest on solanaceous crops worldwide. CPB has developed resistance to insecticides used for its control. In this study, in order to find a more effective and safer biological control agent against L. decemlineata, we studied the bacterial flora of CPB, and tested them for insecticidal effects on it. The highest insecticidal effect determined on L. decemlineata within 5 days was 100% and this effect was exhibited by Ld1 isolate. According to the morphological, physiological and biochemical tests, and 16S rRNA sequence homologies, Ld1 was identified as Leclercia adecarboxylata. This is the first time that this bacterium has been isolated from any insect pests. Our results indicate that Lecl. adecarboxylata may be valuable as a biological control agent for L. decemlineata

Purification and characterization of an antibacterial substance produced by pest-originated Serratia marcescens Mm3

The aim of this investigation was to determine, purify, and characterize an antibacterial substance produced by Serratia marcescens Mm3 (Sm-Mm3) isolated from a common pest of hazelnut in Turkey, Melolontha melolontha, which is also a significant pest all over the world. A highly active antibacterial substance produced by Sm-Mm3 was purified by ammonium sulfate precipitation and high-performance liquid chromatography, respectively, and identified by spectrometric analysis (TOF-MS). Finally, we showed that this molecule is heat-stable, stable in the pH range of 5–9, and insensitive to organic solvents and proteinase K. The molecular mass was determined as 479 Da. Plasmid elimination demonstrated that the gene responsible for this antibacterial substance of the Sm-Mm3 strain is located on the plasmid. Based on the determined characteristics, the antibacterial substance was identified as a bacteriocin-like substance. Although this active substance is similar to bacteriocin because of many features such as mode of action and physicochemical properties, it differs by having a low molecular weight and by being insensitive to proteinase K. This active substance has potential to control many different pathogenic bacteria in various areas, particularly in agriculture, against plant pathogenic bacteria

Determination of thermodynamic properties of aluminum based binary and ternary alloys

In the present work, the Gibbs-Thomson coefficient, solid-liquid and solid-solid interfacial energies and grain boundary energy of a solid Al solution in the Al-Cu-Si eutectic system were determined from the observed grain boundary groove shapes by measuring the thermal conductivity of the solid and liquid phases and temperature gradient. Some thermodynamic properties such as the enthalpy of fusion, entropy of fusion, the change of specific heat from liquid to solid and the electrical conductivity of solid phases at their melting temperature were also evaluated by using the measured values of relevant data for Al-Cu, Al-Si, Al-Mg, Al-Ni, Al-Ti, Al-Cu-Ag, Al-Cu-Si binary and ternary alloys. (C) 2015 Elsevier B.V. All rights reserved

Thermal conductivity and interfacial energies of solid Sn solution in the Sn-Ag-In ternary alloy

The equilibrated grain boundary groove shapes of solid Sn solution in equilibrium with the Sn-Ag-In liquid have been observed from quenched sample. The Gibbs-Thomson coefficient, solid-liquid interfacial energy and grain boundary energy of solid Sn solution have been determined. The thermal conductivity values for solid Sn solution (Sn-2.1 at.%In) and eutectic solid (Sn-4.4 at.%Ag-2.1 at.%In) and the thermal conductivity ratio of eutectic liquid phase to eutectic solid for Sn-4.4 at.%Ag-2.1 at.%In alloy at the melting temperature have also been measured with a radial heat flow apparatus and Bridgman type growth apparatus, respectively. (C) 2010 Elsevier B.V. All rights reserved