Properties Of The Crude Extract Of Bacillus Cereus 041381 And Purification Of Antifungal Protein

Bacillus cereus strain 041381 was isolated from sea sediments and was found to produce bioactivity against C.albicans. This thesis report the separation of the active substances and their properties.The supernatant of the culture of strain 041381 was centrifuged and deposited by ammonium sulfate. It was showed that concentration of ammonium sulfate between 60% and 65% was the best saturation for collecting the active fraction of protein. The obtained crude protein was insensitive to heat and pressure(121°C, 1.01x105 Pa), not affected by proteinase K; The crude protein was soluable in water and butanol. They were not toxic against turner cells (B16, Hela, Smmc-721, and K562) tested, neither filamentous fungi, but strongly against yeasts such as Candida albicans, Cyptococcus neoformans,.In this thesis, the method of methylene blue-MK3 that is a new way of screening anti-yeasts active substances from a large quantity of sample was modified to get more accurate quantitative analysis for activity level from 2 μg/mL to 16μg/mL.Antifungal protein produced by strain 041381 was isolated and purified to homogeneity by precipitation of (NH₄)₂SO₄ followed by Sephadex G-75 , DEAE-Sephadex A-25 andSephadex G-50 column chromatography. The molecular weight of the purified protein, which was about 2.5 kD, was determined by SDS-PAGE.