Author: Yunita Irawadi
Irawadi, Yunita, 2018 Growth performance and biochemical profiles of Arthrospira spp. grown in a tubular Wuhan Friendship New Tech CO. LTD. photobioreactor, Flinders University, College of Medicine and Public Health
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Arthrospira is a useful microalga with applications in nutraceuticals, cosmetics, agriculture and aquaculture. It has been cultivated for commercial purpose mainly in open pond systems due to cost consideration. Recently, cultivation in closed system photobioreactors has gained attention, as the health outcomes of fresh Arthrospira are predicted to be greater. A 120-litre tubular photobioreactor (PBR) has been designed specifically to produce fresh Arthrospira biomass. This project aimed to investigate basic growth performance and downstream effects on the biochemical profile of Arthrospira spp. in this tubular Wuhan Friendship New Tech CO. LTD. photobioreactor. The effect of batch and semi-continuous cultivation on total biomass production was also investigated. As a control system, a traditional 10 L bubble column inoculator was used and contrasted with the results obtained in the tubular Wuhan Friendship New Tech CO. LTD. photobioreactor. Environmental conditions (temperature, nutrients) between the tubular Wuhan Friendship New Tech CO. LTD. photobioreactor and the bubble column inoculator were kept identical, except for system-dependent differences in light intensity and the mixing process. Growth experiments were conducted with three independent replicates on time series conducted over 7 days. Growth performance was evaluated based on specific growth rate (μ) and biomass productivity (Px). For biochemical characterization of the biomass, phycocyanin content was determined spectrophotometrically, total lipid gravimetrically, total protein as the sum of amino acids, and total carbohydrate determined by difference. The results revealed that the specific growth rate and biomass productivity of Arthrospira spp. were almost two-fold higher in the bubble column (μ=0.26 g day-1 and Px=89.54 mg L-1 day-1) than in the tubular Wuhan Friendship New Tech CO. LTD. photobioreactor (μ=0.16 g day-1 and Px=46.90 mg L-1 day-1). Growth system also had a significant effect on phycocyanin content, which was 14% higher in the bubble column compared to the tubular Wuhan Friendship New Tech CO. LTD. photobioreactor (95.5 vs 81.5 mg g-1 DW, respectively). In contrast, growth system had no significant effect on total lipid, protein, carbohydrate and ash content (bubble column: 17%, 64.17%, 12.43% and 6.4% DW respectively and tubular PBR: 14.16%, 61.09%, 19.4% and 5.3% DW respectively) (P>0.05 = not statistically different). Total biomass obtained from semi-continuous operation was higher than for batch operation with 58.6 and 48.5 g DW, respectively. A higher culture suspension efficiency in the bubble column inoculator are suspected to have led to effects of light and dissolved CO2, triggering improved growth performance of Arthrospira spp. in the bubble column inoculator. Growth systems had a significant impact on phycocyanin content (P<0.05), which might be attributable to better light penetration in the bubble column inoculator. Although the tubular Wuhan Friendship New Tech CO. LTD. photobioreactor underperformed compared to the bubble column under basic operational conditions, it may still be adequate for Arthrospira’s mass production, especially when semi-continuous harvesting is integrated in the production process. Results from this study can be used as base line data for studies aiming to optimize system performance and on developing fresh Arthrospira product.
Keywords: Arthrospira spp., growth performance, biochemical profiles, tubular photobioreactor
Subject: Biotechnology thesis
Thesis type: Masters
Completed: 2018
School: College of Medicine and Public Health
Supervisor: A/Prof. Kirsten Heimann