Spirulina subsalsa powder produced from seawater-wastewater: a nutrient-rich and safe alternative for aquaculture...

Elevated expense of chemical media spurs a shift to non-chemical media in microalgal cultivation, while ensuring the safety of the resulting powder poses a challenge. No previous studies have evaluated the safety and application of Spirulina subsalsa powder cultivated in monosodium glutamate wastewater (MSGW) and seawater. In this study, an analysis of basic nutritional components in Spirulina subsalsa powder indicated that this algal powder had high protein content, low lipid content and rich mineral content. Main fatty acids were palmitic acid (C16:0) and linoleic acid (C18:2), accounting for 45.81% and 38.37%, respectively. Eighteen amino acids were identified in this algal powder, encompassing all essential amino acids, with leucine (2.32%), valine (1.48%), and phenylalanine (1.46%) being particularly abundant. Mineral analysis showed that the calcium and zinc contents in the algal powder are respectively 32.8 g/kg and 68.40 mg/kg, making it suitable for producing mineral-fortified functional foods or aquaculture feed. Furthermore, pollution evaluation demonstrated Spirulina subsalsa powder was free of pathogens and heavy metals were negligible. Besides, toxicity tests on mice confirmed its safety (LD₅₀ > 15000 mg/kg). The unique advantages of Spirulina subsalsa powder over traditional feed were further demonstrated in terms of improving body wall quality of sea cucumber, highlighting its potential as a high-nutrition feed for aquaculture.