| The prospect of biodiesel is becoming more and more promising because of the rising prices of worldwide oil in fluctuation. But high production cost is still the major factor to hinder the large-scale production of biodiesel.A very promising approach presented in our eyes is the production of microbial oil via fermentation from monosodium glutamate wastewater by Rhodotorula glutinis. This way not only can reduce the environmental pollution greatly by discharging less wastewater, but also can produce microbial oils, which would be used as an inexpensive raw for biodiesel production. Therefore, the study is concerned widely for the double meaning of its economy and environment. However, the high ammonium-N concentration (15-25g·L-1) in the wastewater has a negative influence on the production of lipid accumulation.The oleaginous yeast was cultured in the high nitrogen environment and some growth, lipid accumulation and ATP:citrate lyase and malic enzyme were studied in this paper. In the high nitrogen simple media, the maximum biomass obtained was 6.3g-L-1 after 72-hour cultivation, which was 51.14% of that when the concentration of ammonium sulfate was 2g·L-1. Levels of ammonium sulfate in excess of 20g-L-1 suppressed the growth of microorganism significantly while cellular lipid content was slightly rising. The maximum values of total and specific ATP:citrate lyase activities were observed at the level of 60g-L-1.The lipids were mainly composed of four kinds of fatty acids (FAMEs), including palmitic acid (C16:0), linoleic acid (C18:2), oleic acid (C18:1) and stearic acid (C18:0).In the mixed monosodium glutamate wastewater, the growth took on a similar tend with that in the above media. Though the biomass is much lower at the same level of ammonium sulfate, the composition of fatty acids (FAMEs) has no difference. In addition, there is a simple linear relationship between the lipid content and the total activity of malic enzyme and the correlation coefficient is 0.9697. |
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