| Astaxanthin is famous with excellent anti-oxidative ability.Medical experiments confirmed that astaxanthin can effectively protect human cells and DNA,due to the remarkable characteristics of anti-tumor,immunity,anti-aging and prevention of cardiovascular and cerebrovascular disease.A lot of industries,including pharmaceutical,health care,cosmetics,food and feed,pay more and more attention to the research and development of astaxanthin in recent years.Due to chemical synthesized astaxanthin exists an application security issue,the demand for natural astaxanthin is growing.As the best source of natural astaxanthin,is a kind of green algae producing astaxanthin more easily for animal to absorb,therefore has attracted the attention of many researchers and enterprises.However,there are only few enterprises around the world that have achieved the H.pluvialis industrial production due to the H.pluvialis is very sensitive to the natural environmental impact.For example,it is easily polluted by the bacteria and protozoa in the cultivation stage.Thus,it is very difficult to establish a stable and highly efficient culture system for H.pluvialis.In the pilot test of industrialization,it need not only to optimize culture environments of H.pluvialis,,but also to design the culture and control process for industrial production.In this study,the specie of H.pluvialis preserved by the Cai Minggang group of Xiamen University was used to study the five following aspects:(1)Selecting the optimal medium under different volumes:the results show that the dry weight of H.pluvialis increased in both 3N-BBM and BG11 medium with the increase of culture volume.The final dry weights in 3N-BBM and BG11 medium under 250 mL culture volume were similar,251 mg/L and 255 mg/L,respectively;compared with the initial dry weight,the final dry weight increased about 1.45 times in 3N-BBM and increased about 1.86 times in BG11.The final dry weights under 3 L culture volume in 3N-BBM and BG11 medium were also similar,315 mg/L with increased 2.36 times and 357 mg/L with increased 3.02 times,respectively.However,there had a gap of dry weights under 10 L culture volume,namely 540 mg/L with increased 4.91 times in 3N-GGM and 400 mg/L with increased 5.00 times in BG11.Expanding cultured volume is conducive to the improve dry weight of haematococcus pluvialis.The pH buffer capacity of 3N-BBM medium is better than BG11 medium and conducive to the industrialization needs.(2)Studying the influences of fluorescent lamp and light emitting diode(LED)on the population growth:the concentration of H.pluvialis increased with the light intensity.Under 1200 lux of fluorescent lamp,the cell density of H.pluvialis reached the peak on the 10th day,was 32.5×104 cell/mL,which was about 38.3%and 66.7%higher than those of 1000 lux and 800 lux.Under 1200 lux,1000 lux and 800 lux of LED,the maximum cell densities of H.pluvialis were similar on the 10th day.Compared with the fluorescent lamp,the cell density of H.pluvialis is 10%higher under LED,and the growth rates under different intensities of LED are stable,all about 0.2 d-1.Therefore,LED can better meet the needs of industrial production.(3)Studying for the cultivation stage and the stress stage of H.pluvialis with nitrogen deficiency:nitrogen deficiency had negative effects on the growth of H.pluvialis.The density of H.pluvialis increased with the increase of nitrogen concentration.The maximum cell density is 117.9×104 cell/mL under 0.25 N g/L,and the growth rate of the highlight control group is 1.157 d-1;high light stress was more likely to produce spores than N deficiency stress,where the spored rate under O.OOg N g/L stress is only 50%of that under high light stress;the lower nitrogen concentration,the more the astaxanthin content in the cell.The highest of H.pluvialis outputs under N starvation condition are closed than under high light,about 20.57 pg/cell.(4)Development and application of culture system:including development of the three-stage culture system,construction of microalgae culture laboratory,development of intelligent culture system with LED,and design of intelligent culture system.First,development of three-stage culture system:3 L conical flask was improved to form primary culture equipment;transparent barrel and small flat-panel photobioreactor were improved that supplemented by piping and mixing tank connected to form secondary culture equipment;and transparent acrylic plate and 100 L photobioreactor that connected with the mixing tank culture to form tertiary culture equipment.In the test,all culture equipments can meet the culture requirements,meanwhile,plate reactor culture was more efficient compared with the transparent barrel reactor.Second,construction of microalgae culture laboratory:the laboratory space is divided into clean areas,algae storage area,culture area and CO2 cylinder area;the probe was used to monitor the laboratory,achieving LED control,temperature control,CO2 alarm,ozone alarm and ventilation;function zoning and condition control of laboratory can avoid confusion of function,reduce the risk of algae pollution,improve the efficiency of culture and experiment safety.Third,development of intelligent culture system with LED:the system used special LED and electronic circuit technology,which can control the light source of microalgae culture,and solely control the light source in different culture areas.It also can control temperature(5?50 ?),light(the full-band wavelength of the visible range with 0-100%output frequency),humidity and CO2.System with programming functions,can set the 0?24 h cycle conditions according to the requirements.Matched photobiological culture racks can adjust the space height to meet the cultivation requirements of 100 L three-stage culture.Fourth,design of intelligent culture system:integrated LED microalgae intelligent culture system,LED photobiological culture racks,photobioreactor and air pump,gas source and other related equipment,to design intelligent microalgae culture system.(5)Exploring the rapid detection of chlorophyll and astaxanthin by 1st derivative UV-Spectrophotometry:the method is feasible if the proportion of chlorophyll a and chlorophyll ? is constant,but it needs more tests for pilot-scale and industrial production. |
PDF Full Text Request