Culturing a novel strain of Haematococcus pluvialis, LSBB612 - ALG App006

  • By algenuity
  • 20 Jul, 2016

Background 

The genus Haematococcus is found globally, with reports of isolates from all continents with the exception of Antarctica, with hostile areas of isolation including the artic circle (Klochkova et al., 2013).   H. pluvialis is of commercial interest due to its ability to produce copious amounts of astaxanthin, reaching up to 5 % dry weight in the encysted aplanospore state (Wayame et al., 2013). Astaxanthin is sold as a pigment for aquaculture and in animal feed, and is marketed as an antioxidant for the nutraceutical market. The H. pluvialis derived astaxanthin industry is commercially successful; however, several constraints are ever-present including issues of contamination and grazing, high extraction costs, high light requirements for encystment, and conversely, photo-bleaching (Shah et al., 2016).  

 

Astaxanthin is produced under high light and nutrient deplete conditions (García-Malea et al., 2008). High temperature is rarely imple­mented to induce astaxanthin production, as it was reported to severely reduce biomass yield, and thus decrease astaxanthin productivity (Tjahjono et al. 1994). Currently the red stage of astaxanthin production is constrained by biomass production in the green stage, which requires strictly controlled culture conditions. Optimal reported temperatures for the vegetative growth of H. pluvialis are between 20 and 28°C (Wan et al., 2014), with temperatures in excess of 30°C shown to induce transition from the green vegetative stage to the red stage with the formation of aplanospores. Domínguez-Bocanegra et al., (2004) demonstrated optimal growth at an irradiance of 177 µmol photons/m²/s with higher density cultures achieved under continuous light.

Aim

To demonstrate the growth characteristics of the novel H. pluvialis strain LSBB612 with an unusually high temperature optimum using the Algem labscale photobioreactor.

Experimental Design

H. pluvialis LSBB612 starter cultures were grown under 40 µmol photons/m²/s continuous red/blue (3:1) light in TAP ( Chlamydomonas Resource Centre) + B12 medium (0.001 mg/L cyanocobalamin), with aeration at 15 cm³/min 5% CO₂ in air, shaking at 120 rpm. Algem flasks (1L) containing 400 ml TAP + B12 medium were inoculated at 4 x 10⁴  cells/ml. Flasks were cultured in the Algem in duplicate at 20, 25 or 30°C, 100 µmol photons/m-²/s continuous light (85:15 white/red mix), intermittent aeration, with 5 % CO to maintain pH 7, and agitation at 120 rpm.

Results

Growth curves of algae cultures growing at three different temperatures

Figure 1 - H. pluvialis LSBB612 growth under different temperatures (20°C, 25°C and 30°C)

Microscope images of algae cells

Figure 2 - a) motile macrozooids and b) palmelloids observed during growth

Discussion

H. pluvialis LSBB612 is classified as non-motile according to the categorisation of Han et al. (2012) as the culture predominates in the palmelloid form rather than the green motile macrozooid. In this experiment it was shown that under the conditions tested, 30°C resulted in the highest growth rate, attaining a maximum doubling time of ~12 h. Growth was shown to plateau for all temperatures at a similar OD due to acetate depletion. This strain of H. pluvialis offers commercial interest as it is able to tolerate temperatures greater than conventional culture conditions (Wan et al., 2014) and did not encyst during the whole culturing period. A mixture of green motile macrozooids and green palmelloids were maintained. Further experiments will be conducted to ascertain the upper-temperature limit for vegetative growth of this strain.

References

Domínguez-Bocanegra A. R., Guerrero Legarreta I., Martinez Jeronimo F., Tomasini Campocosio A. (2004) Influence   of environmental and nutritional factors in the production of astaxanthin from Haematococcus   pluvialis . Bioresource Technology , 92, pp. 209–214

García-Malea, M.C., Sánchez, E. D. R., López, J. C., Fernández, F. A., Sevilla, J. F., Rivas, J., Guerro, M.G. & Grima, E.   M. (2006) Comparative analysis of the outdoor culture of Haematococcus pluvialis in tubular and   bubble column photobioreactors, Journal of Biotechnology , 123 (3), pp. 329-342

Han, D., Wang, J., Sommerfeld, M. & Hu, Q. (2012) Susceptibility and protective mechanisms of motile and non   motile cells of Haematococcus pluvialis (chlorophyceae) to photooxidative stress, Journal of   Phycology , 48 (3), pp. 693-705

Klochkova, T.A., Kwak, M.S., Han, J.W., Motomura, T., Nagasato, C. & Kim, G.H. (2013) Cold-tolerant strain of   Haematococcus pluvialis (Haematococcaceae, Chlorophyta) from Blomstrandhalvøya (Svalbard),   Algae , 28 (2), pp. 185-192

Sarada, R., Bhattacharya, S. & Ravishankar, G. (2002) Optimization of culture conditions for growth of the green alga Haematococcus pluvialis , World Journal of Microbiology and Biotechnology , 18 (6), pp. 517-521

Shah, M.M.R., Liang, Y., Cheng, J.J. and Daroch, M. (2016) Astaxanthin-producing green microalga   Haematococcus pluvialis : from single cell to high value commercial products. Frontiers in Plant Science , 7, p. 531

Tjahjono, A.E., Hayama, Y., Kakizono, T., Terada, Y., Nishio, N. & Nagai, S. (1994) Hyper-accumulation of astaxanthin in a green alga Haematococcus pluvialis at elevated temperatures, Biotechnology Letters , 16 (2), pp. 133-138

Wan, M., Hou, D., Li, Y., Fan, J., Huang, J., Liang, S., Wang, W., Pan, R., Wang, J. & Li, S. (2014) The effective photoinduction of Haematococcus pluvialis for accumulating astaxanthin with attached cultivation,   Bioresource  Technology , 163, pp. 26-32

Wayama, M., Ota, S., Matsuura, H., Nango, N., Hirata, A. & Kawano, S. (2013) Three-Dimensional Ultrastructural Study of Oil and Astaxanthin Accumulation during Encystment in the Green Alga Haematococcus pluvialis’ ,   PLOS One , 8 (1)

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