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Culture of Botryococcus Brauni

Zhang, Jize (2013) Culture of Botryococcus Brauni. Masters by Research thesis, Murdoch University.

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Botryococcus braunii is a potential source of renewable energy due to high lipid yield and the ability of hydrocarbon excretion B. braunii 807/2 was successfully grown in outdoor paddle wheel driven raceway ponds for over 5 months. The growth of this alga in tubular photobioreactor (Biocoil) was also successful for up to a month, but was inhibited by high cell sticking to the coils. There was no significant difference in growth rate and biomass productivity between these two systems. The lipid productivity B. braunii culture in the open pond was 0.008 ± 0.004 at a specific growth rate of 0.06 ± 0.03 day-1, and the indoor culture was 0.04 g.L-1 .day-1 at growth rate of 0.04 ± 0.03 day-1. B. braunii was found to have highest photosynthesis under 30℃ at 100 μmol photons.m-2.s-1. Lower temperature (10℃) reduced photosynthesis by 58% at 6 mg.L-1 O2 and 84% at 2 mg.L-1 O2. B. braunii was light saturated at 100 μmol photons.m-2.s-1, and no significant photoinhibition was observed even under 1900 μmol photons.m-2.s-1. Photosynthesis was inhibited by 40 to 80% when O2 was increased from 2 mg.L-1 to 6 mg.L-1. Interestingly increasing oxygen concentrations decreased the dark respiration rate. Increasing temperature by 5℃ in open ponds increases lipid productivity, but had no effect on biomass productivity and growth rate. However, lowering pond depth by 5 cm (in winter) had no effect on growth and biomass/lipid yield. It was also found that aerating the pond reduces the O2 concentration and this can be potentially useful for reducing photoinhibition.

Item Type: Thesis (Masters by Research)
Murdoch Affiliation(s): School of Veterinary and Life Sciences
Supervisor(s): Borowitzka, Michael
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