To study the productivity of single cell protein from the petroleum hydrocarbon utilizing yeasts, 242 soil samples, such as oil soaked soil of gas stations and garage, coal, farm soil, and sewage, from 135 places in Korea were collected. From these samples 468 yeast strains which utilize petroleum hydrocarbon as a sole organic carbon source were isolated and identified by observing the growth rates.
For the identified strains optimum culture conditions were determined and analysis of cell components were performed.
1. 90.8% of petroleum hydrocarbon utilizing yeast strains were found from oil soaked soil and about 10% from coal, farm soil and sewage etc.
2. The yeast strain of the highest cell productivity was isolated from oil soaked soil and was identified as Candida curvata HY-69-19.
3. The optimum culture conditions for the selected yeast strain were found to be pH 5.0, 28℃ and affluent aerated state.
4. Candida curvata HY-69-19 was found to utilize favorably the heavy gas oil fractionated at above 268.9℃ as carbon source and urea as inorganic nitrogen source.
5. The growth curve of this strain on heavy gas oil medium showed that the yeast has a lag phase up to 18 hours and logarithmic growth phase between 24 to 42 hours. Generation time was found to be between 3.8 and 4.5 hours during the logarithmic growth phase.
6. About 300 ㎎ dried cells per heavy gas oil was harvested under the culture conditions of adjusted pH to 5.0 at time intervals of 6 hours for 54 hours and heavy gas oil urea for shaking culture medium.
7. Chemical composition of the yeast cell was found to be 40.25%, 14.81%, 24.32% and 10.63% for crude protein, crude lipid, carbohydrate and ashes, respectively.
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