Work

Canola meal protein hydrolysate as a sustainable medium for heterotrophic cultivation of Euglena gracilis

Year: 2026

Type: article

Abstract: Euglena gracilis , a Generally Recognized as Safe (GRAS) microorganism, is of growing biotechnological interest due to its ability to accumulate diverse cellular metabolites under heterotrophic conditions. This study evaluated canola meal protein hydrolysate (CMPH) as a protein-derived organic nitrogen source to partially substitute conventional complex supplements (yeast extract and tryptone) in heterotrophic E. gracilis cultivation. CMPH was produced by enzymatic hydrolysis of canola meal using trypsin (3000 U mL -1 , pH 8.0, 37 °C, 24 h). The hydrolysate contained 74.28 ± 5.92% protein (micro-Kjeldahl), and X-ray fluorescence analysis indicated phosphorus (6.8%), calcium (16.7%), potassium (1.7%), and magnesium (1.2%) as major mineral components. A Box–Behnken design coupled with response surface methodology (BBD-RSM) was applied to optimize growth conditions in CMPH-supplemented medium. Cultures inoculated at 1.0 × 10 5 cells mL -1 were incubated at 25 °C in the dark for 168 h. RSM identified pH 6.8, 1 g L -1 CMPH, and 120 h as statistically optimal conditions within the tested design space, yielding 9.8 × 10 5 cells mL -1 in the absence of added glucose, with a specific growth rate of 0.69 ± 0.23 d -1 . Higher cell densities were obtained at increased CMPH concentrations and upon glucose supplementation, reaching levels comparable to standard Hutner’s medium. These results indicate that the RSM-derived optimum reflects efficient nitrogen utilization rather than maximal biomass accumulation. Overall, CMPH demonstrates potential as a functional organic nitrogen supplement for heterotrophic E. gracilis cultivation, supporting the valorization of canola meal as a protein-rich agricultural by-product. • Canola meal protein hydrolysate (CMPH) was prepared as a fermentation substrate. • CMPH contained high protein (74.3%) and essential minerals for microalgal growth. • Euglena gracilis growth was optimized using Box-Behnken response surface design. • Optimal CMPH conditions achieved cell density of 9.8 × 10⁵ cells/mL. • CMPH valorizes canola meal, offering a sustainable medium for algal bioprocessing.

Source: New Biotechnology

DOI: 10.1016/j.nbt.2026.01.008

Authors: Ifeyomi Olobayotan, Nirpesh Dhakal, Bishnu Acharya, Darren R. Korber

Institution: University of Saskatchewan

Language: English

Topic: Algal biology and biofuel production

Subfield: Renewable Energy, Sustainability and the Environment

Field: Energy

Domain: Physical Sciences

SDGs: Zero hunger, Responsible consumption and production

Open Access status: gold

Estimated APC paid: $3,670