Cultivation of microalgae- Chlorella sorokiniana and Auxenochlorella protothecoides- in shrimp boiling water residues

Journal article, 2022

Based on the ability of microalgae to purify industrial processing waters, the overall aim of this study was to evaluate whether currently wasted shrimp processing waters could be used as microalgal growth media to produce new protein-enriched food and feed ingredients. Low molecular weight (LMW) fractions of shrimp boiling water (SBW) which had been pre-flocculated using alginate (AL), carrageenan (CA), chitosan (CH) or Superfloc C-592 to recover shrimp protein via flotation, were used for cultivation of Chlorella sorokiniana and Auxenochlorella protothecoides to produce a protein-enriched microalgal biomass. CH-derived media induced the highest growth rates for both species with A. protothecoides out-performing C. sorokiniana. A. protothecoides best assimilated phosphate-phoshorous (P-PO4) and total phosphorous (TP) in all media; <63 mg/L and < 45 mg/L after 4 days, respectively. In upscaled aerated cultures of A. protothecoides in CH- and AL-derived media, P and TP uptake increased up to 85 and 127 mg/L, respectively. Further, 63% of the free amino acids (AA) were assimilated in both waters. Biomasses derived from SBW contained 37-43% protein and 15.0-17.4% fatty acids (FA) per DW; with 38-40% essential AA (EAA) and 21.3-22.5% polyunsaturated FA (PUFA), respectively Corresponding numbers for biomass cultivated in control media were 11 and 53%, protein and FA, respectively, and with 38% and 15.6% EAA and PUFA, respectively. Ability of A. protothecoides to assimilate TP and AA, and to generate a protein-rich biomass from LMW-fractions derived from SBW was thus revealed for the first time, and paves the way for a SBW-based biorefinery comprising chemical, physical and microbial processes to produce multiple products.