| Eicosapentaenoic acid(EPA), Arachidonic acid(AA) and Docosahexenoic acid(DHA) play important roles of enhancing human health, thus they have been widely used in food, medicine and agriculture industries. Compared with method of tissue extraction of animal and plant, EPA, AA and DHA production by microbial fermentation has the characteristics of high production efficiency and product quality. This is because that the fermentation process is easy to control and has shorter fermentation time, higher density cultivation. Therefore using the microorganism fermentation to produce EPA and AA is a research hotspot in recent years.This paper explored the fermentation conditions and drying conditions of Mortierella alpina CCFM 442, which had been modified with gene engineering technology in our laboratory. Furthermore, we conducted the experiment on laying hens feeding to research on the Mortierella alpina as additive in the feed of laying hens. The purpose is to provide a reference for the Mortierella alpina application in animal husbandry. The main research results are as follows:(1) The medium components and culture conditions were optimized in this study. The effect of different carbon and nitrogen sources on fatty acids production in Mortierella alpina CCFM 442 was evaluated. The results showed that when taking glucose or composite nitrogen as sole carbon source or nitrogen source, the production of EPA reached 158.73 mg/L and 135.40 mg/L respectively. Based on the results, the impact of temperature and cultivate time on fatty acids production in Mortierella alpina CCFM 442 was investigated. With a two-stage temperature shift strategy, the EPA production increased 2.7 times. In the 7.5 L-batch experiment, the dry weight reached 42.7 g/L, and the total fatty acids(TFA), AA and EPA production improved to 6.20 g/L, 1.57 g/L and 417.88 mg/L respectively, as the AA and EPA production was 1.2 and 4 times than before.(2) The influence of different drying process on EPA content of Mortierella alpina CCFM 442 were researched. The results showed that the freeze drying had minimal impact on AA and EPA content of Mortierella alpina, and their loss rate is only 12.48% and 16.26% respectively. But the hot air drying had maximum impact on AA and EPA content of Mortierella alpina CCFM 442, and the loss rate of EPA can reach 39.41% and 55.71% respectively at 50 and 80 degree Celsius. The hot air drying at 50 degree Celsius was chose to dry Mortierella alpina CCFM 442 as the expense of drying and loss rate of AA and EPA was took into consideration.(3) The results of experiment on laying hens feeding showed that: there were no significant influence(P>0.05) on the laying hens’ average egg weight, body weight, egg production, average daily feed intake, feed conversion, RCF value of egg yolk and so on, after 5% or 10% Mortierella alpina were added to the hen’ diet. EPA in Mortierella alpina CCFM 442 was converted to DHA in egg yolk, and was barely accumulated in yolk lipids in the form of EPA. After hens were fed a diet containing 10% Mortierella alpina CCFM 442 for 15 days, egg yolk content of DHA increased two times and AA doubled compared with control eggs, respectively. The ratio of ω-6 to ω-3 polyunsaturated fatty acids in these eggs was well balanced to 14:1 compared to the control group(only 31:1). It showed that Mortierella alpina CCFM 442 may thus represent a valuable alternative source to produce functional eggs enriched with DHA and AA. |
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