Fewer studies have assessed the outdoor cultivation of Spirulina
maxima compared with S. platensis, although the protein
content of S. maxima is higher than S. platensis.
Spirulina growth medium requires an increased amount of
NaHCO3, Na2CO3, and NaNO3, which
increases the production cost. Therefore, the current study used a low-cost but
high-efficiency biomass production medium (Medium M-19) after testing 33 different
media. The medium depth of 25 cm (group A) was sub-divided into A1 (50% cover with a
black curtain (PolyMax, 12 oz ultra-blackout), A2 (25% cover), and A3 (no cover).
Similarly the medium depths of 30 and 35 cm were categorized as groups B (B1, B2, and
B3) and C (C1, C2, and C3), respectively, and the effects of depth and surface light
availability on growth and biomass production were assessed. The highest biomass
production was 2.05 g L-1 in group A2, which was significantly higher (p
< 0.05) than that in all other groups and sub-groups. Spirulina
maxima died in B1 and C1 on the fifth day of culture. The biochemical
composition of the biomass obtained from A2 cultures, including protein,
carbohydrate, lipid, moisture, and ash, was 56.59%, 14.42%, 0.94%, 5.03%, and 23.02%,
respectively. Therefore, S. maxima could be grown outdoors with the
highest efficiency in urea-enriched medium at a 25-cm medium depth with 25% surface
cover or uncovered.
