Marine Bacteria Antifungal Active Substances Screening

Amounts to 256 strains were isolated from three sampling, including 186 strains of bacteria, 30 strains of actinomycetes and 40 strains of fungi. Fifty six strains were screened out from 816 isolates of our research group that showed activity against C. albicans, which was 6.6%of the total isolates. Strain 041381 possessed higher stability and repeatability of activity against C. albicans, and was further studied.Strain 041381 was isolated from seamuds, optional concentration of NaCl for its growth was 6%, and its maxium tolerant concentration of NaCl was 20%. It produced strong antifungal bioactive substance on medium containing 4% of starch, 0.5% of yeast extract and 75% of stale seawater cultured at 28 for 96h. The antifungal substance was stable at high temperature and acidic-alkaline condition. It was soluable in water, disoluable in alcohol and lipid. Its activity was strongly against to yeasts such as Candida albicans, Cyptococcus neoformans, not to filamentous fungi. It showed activity against positive and negative bacteria and no cell toxicity.An antifungal protein, named as B16, was purified from the supernatant of the fermentation broth of strain 041381 by 80% saturation ammonium sulfate, desalt and gel filtration on Sephadex G-75, which with molecular weight at about 30-40 KD on the basis of SDS-PAGE. It was suggested that the bioactive antifungal substance produced by strain 0413 81 was protein.In this thesis, a new economic method employed methylene blue(MB) was established for screening anti-yeasts active substances from a large quantity of samples. The operation of this new method was as follows: samples and Candida albicans of cells 105 CFU/mL were seeded into 96-well plate with 100 μL/wellrespectively. Plates were incubated for 24h , and methylene-blue was added into the plates at 20μL/well. Plates were keeped for 10 min and detected by a microELISA spectrophotomer at A630 . The active sample were screened out by...