RESUMO
A bacterial strain BH072 isolated from a honey sample showed antifungal activity against mold. Based on morphological, biochemical, physiological tests, and analysis of 16S rDNA sequence, the strain was identified to be a new subspecies of Bacillus sp. It had a broad spectrum of antifungal activity against various mold, such as Aspergillus niger, Pythium, and Botrytis cinerea. Six pairs of antifungal genes primers were designed and synthesized, and ituA, hag, tasA genes were detected by PCR analysis. The remarkable antifungal activity could be associated with the co-production of these three peptides. One of them was purified by 30-40% ammonium sulfate precipitation, Sephadex G-75 gel filtration and anion exchange chromatography on D201 resin. The purified peptide was estimated to be 35.615 kDa and identified to be flagellin by micrOTOF-Q II. By using methanol extraction, another substance was isolated from fermentation liquor, and determined to be iturin with liquid chromatography-mass spectrometry (LC-MS) method. The third possible peptide encoded by tasA was not isolated in this study. The culture liquor displayed antifungal activity in a wide pH range (5.0-9.0) and at 40-100°C. The result of the present work suggested that Bacillus BH072 might be a bio-control bacterium of research value.
Assuntos
Antifúngicos/farmacologia , Ascomicetos/efeitos dos fármacos , Aspergillus niger/efeitos dos fármacos , Bacillus/metabolismo , Mel/microbiologia , Peptídeos/farmacologia , Pythium/efeitos dos fármacos , Antifúngicos/química , Antifúngicos/isolamento & purificação , Bacillus/classificação , Bacillus/genética , Bacillus/isolamento & purificação , Técnicas de Tipagem Bacteriana , Cromatografia em Gel , Cromatografia por Troca Iônica , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Espectrometria de Massas , Peso Molecular , Peptídeos/química , Peptídeos/isolamento & purificação , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNARESUMO
Lysozyme crystals in the presence of 1-butyl-3-methylimidazolium tetrafluoroborate ([C(4)mim]BF(4)), 1-butyl-3-methylimidazolium chloride ([C(4)mim]Cl), 1-butyl-3-methylimidazolium bromide([C(4)mim]Br), and 1,3-dimethylimidazolium iodine([dmim]I) were prepared, and the influence of ionic liquids (ILs) on the structure and activity change of lysozyme was investigated. Fourier transform infrared spectroscopy revealed the major secondary structures of α-helix and ß-sheet for lysozyme. It was interesting to note that increases of the band near 2,935 and 1,656 cm(-1) from Raman spectroscopy are attributed to the unfolding of lysozyme molecules. A shift in amide III from 1,230 to 1,270 cm(-1) in adding [dmim]I occurs, indicating a transformation from ß-sheet to random coil. With regard to adding [C(4)mim]BF(4), [C(4)mim]Cl, and [C(4)mim]Br, α-helix and ß-sheet are the predominant structures for lysozyme. The activity study showed that the ILs used brought a positive effect. Especially, [dmim]I leads to a drastic increase in relative activity, and its value reaches 50 %.
