| Selenium is an essential trace element for human health.In China,average selenium intake is far below the national recommended level.Therefore,there is a huge demand for selenium-enriched foods or function foods.Chlorella pyrenoidosa has great potential for the development of selenium-enriched products due to its advantages of fast growth,capable of high productivity,and high ability to accumulate trace element.In this paper,C.pyrenoidosa was cultured for development of selenium enriched foods.First,the optimal conditions for mixotrophic culture of C.pyrenoidosa were determined in small vessels.Then,the cultivation conditions for selenium accumulation were optimized also in small vessels.Finally,the microalgal cultivation was amplified in a ten little vessel,and the algal biomass was used to produce for selenium-enriched chlorella powder and selenium-enriched algal protein powder.The results and conclusions were as follows:（1）Study on the mixotrophic culture conditions of C.pyrenoidosa.Through single factor experiments,the effects of nutrient conditions（type of medium,glucose concentration,Na NO3 concentration）and non-nutrition conditions（pH,light）on the biomass,growth rate and protein content of C.pyrenoidosa were studied.As results,under the conditions of glucose concentration 50 g/L,Na NO3 concentration 7.36 g/L,Basal medium,pH 5.5,and 4000 lx light,C.pyrenoidosa grew fast,the algal biomass yield reached to 18.9 g/L,and the algal protein content reached at 43.69%.（2）Based on the optimal culture conditions,the researches on the selenium accumulation cultivation of C.pyrenoidosa were carried out to investigate biomass yields,algal growth rate and the cell selenium content.First,the effects of sodium selenite concentration,illumination intension,harvest time,and sulfur content on the selenium accumulation in C.pyrenoidosa were investigated.Then,a two-stage cultivation strategy was applied,in which the algal biomass cultivation and the selenium accumulation were carried out separately.The effects of formulas of media and the accumulation time on the selenium accumulation were studied in the second stage.As the results,under the conditions of 10 mg/L sodium selenite,2 mmol/L sulfur content,4000 lx illumination,the highest amount of algal biomass was harvested on 8 d,and the cell selenium content was 56.04μg/g and the selenium absorption rate reached at 23.7%.In selenium accumulation stage,a sulfur reduced Basal medium was applied to culture alga for 24 hours with the addition of sodium selenite,and the selenium absorption rate was measured to be the highest one of58.5%,and the cell selenium content was 154.09μg/g.（3）The amplified experiments were carried out in a 10 L vessel,and the biomass of C.pyrenoidosa was obtained to produce selenium-enriched Chlorella powder and selenium-enriched algae protein powder.In the amplified experiment,the biomass yield of C.pyrenoidosa was 18.7 g/L,and the algal protein content was 41.59%.The total selenium content of selenium-enriched chlorella powder was 149.68μg/g,and the organic selenium was 77.69%in total selenium.The total selenium content of selenium-enriched chlorella protein powder was 224.38μg/g,and the proportion of organic selenium was 92.12%.The microbial content and heavy metal content of the two products met the national standard for corresponding food（GB4789.2—2016 and GB T 16919-1997）. |
