Filter cake extract from the beet sugar industry as an economic growth medium for the production of Spirulina platensis as a microbial cell factory for protein

• Published in: Microbial cell factories 2023-07, Vol.22 (1), p.136-136, Article 136
• Main Authors: Saad, Sara, Hussien, Mervat Hosny, Abou-ElWafa, Ghada Samir, Aldesuquy, Heshmat Soliman, Eltanahy, Eladl
• Format: Article
• Language: English
• Subjects: Algae; Amino acids; Animal nutrition; Animals; Antioxidants; Beet filter cake; Beta vulgaris; Biomass; Carbohydrates; Carbon; Carotenoids; Chlorophyll; Crystallization; Culture media; Cyanobacteria; Dry cells; Economic aspects; Economic Development; Economic growth; Experiments; Factories; Filter cake; Human nutrition; Humans; Methods; Microorganisms; Plant Extracts; Production processes; Proteins; Response surface methodology; Single cell protein; Sodium bicarbonate; Spirulina; Spirulina platensis; Sucrose; Sugar beet; Sugar beets; Sugar industry; Sugarcane
• ISSN: 1475-2859; 1475-2859
• DOI: 10.1186/s12934-023-02146-7

Beet filter cake (BFC) is a by-product of sugar beet processing, which is difficult to dispose of and involves severe environmental concerns. Spirulina platensis is a microalga with a high protein content essential for human and animal nutrition. The present study aimed to utilize the beet filter cake extract (BFCE) to produce Spirulina platensis commercially. However, the cultivation of S. platensis on BFCE to produce economically single-cell protein has not been reported previously. The batch experiment revealed the maximum dry weight at Zarrouk's medium (0.4 g/L) followed by 0.34 g/L in the treatment of 75% BFCE. The highest protein content was 50% in Zarrouk's medium, followed by 46.5% in 25% BFCE. However, adding a higher concentration of 100% BFCE led to a protein content of 31.1%. In the adaption experiment, S platensis showed an increase in dry cell weight and protein content from 25 to 75% BFCE (0.69 g/L to 1.12 g/L and 47.0% to 52.54%, respectively) with an insignificant variation compared to Zarrouk's medium (p ≤ 0.05), indicating that S. platensis can be economically produced when cultivated on 75% BFCE The predicated parameters from response surface methodology were NaNO (2.5 g/L), NaHCO (0.67 g/L), BFCE (33%) and pH = 8, which resulted in biomass yield and protein content (0.56 g/L and 52.5%, respectively) closer to that achieved using the standard Zarrouk's medium (0.6 g/L and 55.11%). Moreover, the total essential amino acid content was slightly higher in the optimized medium (38.73%) than SZM (36.98%). Therefore, BFCE supplemented medium could be used as a novel low-cost alternative growth medium for producing a single-cell protein with acceptable quantity and quality compared to the standard Zarrouk's medium.