High-quality seawater <i>Spirulina </i>strain obtained by space-breeding and use thereof

Abstract

A space-bred seawater Spirulina H11 strain. The strain exhibits high growth rate, capacity of simultaneously accumulating high contents of phycocyanin, Spirulina polysaccharides and β-carotene, and excellent adaptability to outdoor environment, thus can be used to produce high-quality Spirulina powders, phycocyanin, Spirulina polysaccharides, and β-carotene-rich Spirulina oil.

Claims

1. A method of using a Spirulina platensis H.sub.11 strain with an accession number CCTCC M 2017772 in producing phycocyanin or Spirulina polysaccharides or β-carotene, comprising: cultivating the Spirulina platensis H.sub.11 strain in a medium to produce biomass, wherein the medium is prepared by adding 5.0 g of NaHCO.sub.3, 0.5 g of NaNO.sub.3, 0.05 g of K.sub.2HPO.sub.4, and 0.01 g of FeSO.sub.4.7H.sub.2O into 1 L of natural seawater having a salinity of 25%; and extracting the phycocyanin or the Spirulina polysaccharides or the β-carotene from the biomass.

2. The method of claim 1, wherein the Spirulina platensis H.sub.11 strain is cultivated in the medium with a light intensity of 150 μmol photons/m.sup.2s and a temperature of 25° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows cellular morphology of the seawater Spirulina.

(2) FIG. 2 shows the screening of the seawater Spirulina H.sub.11 strain.

(3) FIG. 3 shows the comparison in phycocyanin content between the seawater Spirulina H.sub.11 strain and an existing unmutated wild Spirulina strain.

(4) FIG. 4 shows the comparison in Spirulina polysaccharide content between the seawater Spirulina H.sub.11 strain and an existing unmutated wild Spirulina strain.

(5) FIG. 5 shows the comparison in β-carotene content between the seawater Spirulina H.sub.11 strain and an existing unmutated wild Spirulina strain.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(6) In order to allow those skilled in the art better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to specific embodiments.

Embodiment 1

(7) 1. Selective Breeding of High-Quality Space Seawater Spirulina H.sub.11 Strain

(8) (1) Spirulina platensis strains which had once been cultivated in a space station were cultivated through an inoculum expansion process in 50-mL Erlenmeyer flasks. After the strains were grown to a certain density, a preliminary screening was carried out.

(9) (2) After isolating single filaments, the single-cell mutants were transferred to sterile 96-well plates and cultivated under light conditions for about 10 days. Color changes in the wells were monitored, and changes in OD.sub.750 values were determined with a microplate reader.

(10) (3) Strains with significantly higher growth rates in the 96-well plates were cultivated through an inoculum expansion process in 50-mL Erlenmeyer flasks, and then evaluation of the mutants was carried out with 500-mL Erlenmeyer flasks.

(11) (4) The seawater Spirulina H.sub.11 strain, which exhibited a better performance, was selected by measuring biomass concentration, polysaccharide content, phycocyanin content and β-carotene content in the Erlenmeyer flasks (FIG. 2).

(12) Morphology of the seawater Spirulina H.sub.11 strain (Spirulina platensis) (FIG. 1): Cylindrical, helical and unbranched filaments, a filament diameter of 5 to 10 μm, regularly helical, a helical number of 2 to 15, a length of 200 to 500 μm, no heterocyst or akinete, no gelatinous sheath or merely a thin sheath.

(13) The seawater Spirulina (Spirulina platensis) H.sub.11 strain (i.e., the Spirulina platensis SCSIO-44012-H11), has been deposited with the China Center for Type Culture Collection (CCTCC), located at Wuchang, Wuhan, China, on Dec. 8, 2017, and has been assigned the accession number: CCTCC M 2017772.

(14) 2. Obtaining Biomass from the Space Seawater Spirulina H.sub.11 Strain

(15) Culture medium: The medium was prepared by adding 5.0 g of NaHCO.sub.3, 0.5 g of NaNO.sub.3, 0.05 g of K.sub.2HPO.sub.4, and 0.01 g of FeSO.sub.4. 7H.sub.2O into 1 L of natural seawater having a salinity of 25‰, mixing evenly and sterilizing.

(16) The seawater Spirulina (Spirulina platensis) H.sub.11 strain and an unmutated wild seawater Spirulina (Spirulina platensis) strain (control) were respectively inoculated into the medium at a same inoculum size, and cultivated for 10 days with a light intensity of 150 μmol photons/m.sup.2s and a temperature of 25° C. 0.885 g/L of biomass was obtained from the seawater Spirulina (Spirulina platensis) H.sub.11 strain of the present invention, with a phycocyanin content of 16.24 g/100 g, a β-carotene content of 0.136 g/100 g, and a Spirulina polysaccharide content of 24.8 g/100 g. 0.802 g/L of biomass was obtained from the original seawater Spirulina (Spirulina platensis) strain as the control (i.e., the existing strain in FIGS. 3, 4 and 5), with a phycocyanin content of 13.7 g/100 g, a β-carotene content of 0.119 g/100 g, and a Spirulina polysaccharide content of 15.3 g/100 g. See FIGS. 3, 4 and 5 for details.

(17) After 30 cycles of subculture, the seawater Spirulina H.sub.11 strain exhibited stable inheritance in the biomass concentration, high polysaccharide content, high phycocyanin content and high β-carotene content, which were far higher than those of the existing strain.

(18) 3. Composition Analysis of Polysaccharides of the Space Seawater Spirulina H.sub.11 Strain

(19) Polysaccharide compositions in the Spirulina solutions which had been cultivated for 10 days in step 2 were analyzed. The results were as listed in Table 1. As can be seen from Table 1, the content of polysaccharides having a molecular weight of over 3500 Da was 21.28% of the dry weight of the seawater Spirulina H.sub.11 strain, which was increased by 76% as compared with the unmutated wild Spirulina strain, indicating high development potential.

(20) TABLE-US-00001 TABLE 1 Water-insoluble Over 3500 Da Below 3500 Da polysaccharides (% dry weight) (% dry weight) (% dry weight) H.sub.11 strain 21.28 ± 0.34 1.71 ± 0.03 1.82 ± 0.04 Existing strain 12.07 ± 0.15 1.78 ± 0.01 1.44 ± 0.01 Note: “H.sub.11 strain” refers to the seawater Spirulina H.sub.11 strain, and “existing strain” refers to an existing unmutated wild Spirulina strain.