Abstract:
Experiments were made by using the isolated fungi from soil and water in Thailand as well as fungi from stock cultures at the department of Microbiology, Faculty of science, Chulalongkorn University, and examine for their ability in decolorizing molasses pigments, especially from alcohol factory. From totally 228 strains, it has been found that 9 strains have depolarization activity of 50% or more. All these 9 strains require different sources of nitrogen, glucose concentration and ph. Especially, the isolated strain D90 required 2.5% glucose, 0.2% yeast extract, pH 6.0 and 0.15% inoculums for growth and gave the highest depolarization activity of 93.0% within 10 days. Comparison for decolorizing ability of the isolated strain D90 in molasses waste water collected from three locations of waste water treatment, i.e. stillage of alcohol factory, anaerobic pond and aerobic pond. Isolated strain D90 showed highly effect in decolorizing molasses waste water from stillage. The result of isolated strain D90 grew in stiillage gave the decolorization activity of 91% within 10 days and B.O.D. was reduced to 81.0% within 12 days. This strain when grew in the molasses waste water from anaerobic pond and anaerobic pond presented the ability to decolorize only 65.0% and 60.0%, moreover, B.O.D. was reduced to and 95.5% , respectively. Experiments revealed that if supplemented nutrients were added to stillage, the decolorization activity of the isolated strain D90 would be more effective. The decolorzation activity were 22.5%, 87.5%, 85.0% and 82.5% when the media were not supplemented with any of the following components, glucose, sodium nitrate, potassium dihydrogen phosphate, magnesium sulfate, respectively. It has also been found that non-supple-mented nutrients in media gave 17.5% of decolorizing ability. Decolorization of molasses waste water were studied to compare the inoculation and non-inoculation effects of isolated strain D90 under non-sterile condition. The results showed that the inoculation with isolated strain D90 gave better decolorization activity than non-inoculation in all three case. The isolated strain D90 also gave the highest effects with molasses waste water from stillage, the color intensity was reduced to 70% from original within 11 days and B.O.D. was reduced to 90.4% within 15 days. Semi-continuous decolorization of stillage by the isolated strain D90 also gave interesting results.
Decolorization activity was 80.0% and cell mass was 1.15 gm/100 ml dry weight within 10 days for the first batch, while the decolorization activity was 78.0% and cell mass was 1.19 gm/100 ml dry weight within 6 days in case of second batch, for the third batch the decolorization activity was 78.6% and cell mass was 1.40 gm/ 100 ml dry weight within 7 days. Semi-continuous decolorization of stillage by the isolated strain D90 allowed similar results when using molasses pigments. Decolorization activity was 80% and B.O.D. was reduced to 74.23% within 9 days for the first batch, for the second batch the decolorization activity was 78.0% and B.O.D. was reduced to 7.5% within 7 days, while the third batch the decolorization activity was 78.6% and B.O.D. was reduced to 65.85% within 7 days. The isolated strain D90 was identified in class Deuteromycetes due to characteristic of forming septate hyphue, without spore nor clamp connection formation, eventhough it was grown in different kinds of media. By the use of transmission electron microscope, the cross-section of hyphae of the isolated strain grew in the media contained molasses pigments showed many electron dense materials in the cell while these structure was not found in fungi which grow in potato dextrose broth. These electron dense materials could be the molasses pigments which were absorbed intracellulary.