高产多糖小球藻新品系选育及其对南美白对虾的促生长和免疫调节作用

Breeding of A Chlorella Strain With High Yield of Polysaccharide and Its Effect on Growth and Immunoregulation of Litopenaeus Vannamei

小球藻是当前全球研究与应用规模仅次于螺旋藻的经济微藻,多糖为其主要的生物活性成分。针对现有小球藻品种的多糖含量普遍偏低这一关键生产技术难题,本文以12株小球藻中水溶性多糖含量最高的椭圆小球藻Chl-ZN5为出发品系,先经700Gy的60 Coγ-射线辐照,再用0.2%的EMS处理4h后,转接到固体培养基上,并用3kGy的60Coγ-射线辐照为压力进行筛选,得到1株高产多糖突变体Chl-ZN5-M2,其水溶性多糖含量和产率分别达25.3%和4.4mg.L-1.d-1,比Chl-ZN5的分别高70.9%和76%,而且在工厂化培植中性能稳定。在南美白对虾日粮中添加0.2%的Chl-ZN5-M2藻粉,能显著改善南美白对虾的免疫活性及相关生化指标,并使生长速率与成活率分别提升26.1%和3.3%。

Chlorella is the second economic microalgae after Spirulina on R ＆ D scale, and its main biological active component is polysaccharide. Polysaccharide contents in the existing Chlorella strains are usually low. To improve the production of polysaccharide, Chlorella ellipsoidea Chl-ZN5 was selected as starting strain for its relative higher contents of water-soluble polysaccharide among 12 determined Chlorella strains. After irradiated with 700Gy 60 Co ＂y-rays and then treated with 0. 2% EMS for 4h, Chl-ZN5 was inoculated onto solid media and then irradiated with 3kGy 60^Coγ-rays after cultivated for 15d. Finally, a mutant with increased polysaccharide production, named Chl-ZN5-M2, was obtained. Chl-ZN5-M2 showed a 25.3% water-soluble polysaccharide content and 4.4mg· L^-1· d^-1 water-soluble polysaccharide yield, which were 70.9% and 76% higher than those of Chl-ZN5, respectively. The production traits of Chl-ZN5-M2 in large-scale cultivation were stable. Furthermore, a feeding test by adding 0.2% Chl-ZN5-M2 dry powder to the diets of Litopenaeus vannamei, indicated that Chl-ZN5-M2 could significantly improve the immune activity and related biochemical indicators of L. vanname, and the growth rate and survival rate of L. vannamei were increased by 26. 1% and 3.3% , respectively.