| Abstract | Biochemical composition of freshwater microalgae isolates from Alberta, Canada was determined. Growth rate (0.98 ± 0.07 d− 1), biomass production (0.35 ± 0.03 g DW L− 1) and daily productivity (0.14 ± 0.01 g DW L− 1 d− 1) were the same for Chlorella vulgaris (AB02-C-U-BBM), Nannochloris bacillaris (AB03-C-F-PLM), Tetracystis sp. (AB04-C-F-PLM02) and Micractinium reisseri (AB05-C-U-BBM02). Whole algal biomass (WAB) contained low ash (~ 2 g 100 g DW− 1) and protein (13–15 g 100 g DW− 1), high esterifiable lipid (32–36 g 100 g DW− 1), carbohydrate (27–30 g 100 g DW− 1) and energy (26–28 MJ kg DW− 1). Oil fractionation was relatively ineffective for C. vulgaris and M. reisseri while oil was effectively extracted from N. bacillaris and Tetracystis sp. Accordingly, lipid-extracted biomass (LEB) from N. bacillaris and Tetracystis sp. contained higher protein (22 g 100 g DW− 1) and carbohydrate (43–44 g 100 g DW− 1) and lower residual esterifiable lipid (6–9 g 100 g DW− 1) than C. vulgaris and M. reisseri at 17–18 g 100 g DW− 1 (protein), 34–36 g 100 g− 1 DW (carbohydrate) and 28–32 g 100 g DW− 1 (residual esterifiable lipid). Biomass had favorable essential amino acid (EAA) profiles with high EAA indices (0.9–1.1); rich in first-limiting EAA lysine (0.9–1.5 g 100 g DW− 1). Fatty acids (% of total) were predominantly monounsaturated fatty acids (MUFA; 40–53%), high in polyunsaturated fatty acids (PUFA; 27–40%) and low in saturated fatty acids (14–24%). N. bacillaris and Tetracystis sp. were particularly rich (9–12%) in α-linolenic acid (18:3n − 3), had attractive n − 3:n − 6 ratios (0.5–0.7:1), were rich in iron (800–1616 mg kg DW− 1), had attractively low Ca:P ratios (0.6–0.9:1) and were virtually absent of contaminating heavy metals. |
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