EFFECT OF LIGHT QUALITY AND NUTRIENTS ON GROWTH OF HYDROCARBON-RICH MICROALGAE, BOTRYOCOCCUS BRAUNII

K. Toyoda, M. Gishi, I. Ihara
Botryococcus braunii is a green-colonial alga containing significant quantities of hydrocarbons with a composition similar to that of heavy oil and has attracted a lot of academic and industrial researchers. One of their interests is how culture conditions affect the alga growth and the hydrocarbon production in order to find the optimal culture condition. In this study, Botryococcus braunii was incubated at 25±1°C one month under continuous illumination with monochromatic LEDs of red, green and blue which have peak wavelengths of 630, 520 and 460 nm respectively. Three kinds of culture media of BG11, AF-6 and BBM were used which have different nitrogen to phosphate ratios; 75:2 (BG11), 10:11 (AF-6) and 54:5 (BBM). The growth of the alga was monitored by the turbidity measurement of alga suspension using a spectrophotometer and the absorbance of the suspension was measured at 660 nm near the wavelength of chlorophyll a and b. The produced hydrocarbon was investigated by ATR-FTIR spectroscopy. The result of turbidity measurement showed that the light quality affected the growth dominantly and that the growth level decreased in the order of red, blue and green illuminations. Especially, the growth of alga cultured under green light approached the saturation value at low growth level after ten cultivation days. The different wave numbers of the major peaks in the ATR-FTIR spectra of alga suspension were observed which depended on the combination of the light quality and the culture medium. The light quality influenced the spectra pattern stronger than the culture medium. Obvious spectral peaks at 2920 and 2850 cm-1 were observed which are attributed to CH2 vibrations from algaenan and those peaks may be available for estimating the mount of hydrocarbon produced by the alga.
Toyoda, K., Gishi, M. and Ihara, I. (2011). EFFECT OF LIGHT QUALITY AND NUTRIENTS ON GROWTH OF HYDROCARBON-RICH MICROALGAE, BOTRYOCOCCUS BRAUNII. Acta Hortic. 907, 255-258
DOI: 10.17660/ActaHortic.2011.907.40
https://doi.org/10.17660/ActaHortic.2011.907.40
growth rate, phosphate, nitrogen, turbidity, ATR-FTIR
English

Acta Horticulturae