Cellular Solutions: Evaluating Single-Cell Proteins as Sustainable Feed Alternatives in Aquaculture

Abstract

The rapid expansion of the global population has intensified the demand for protein-rich food sources, positioning aquaculture as a crucial sector in the endeavor to alleviate global hunger through the provision of high-quality aquatic protein. Traditional protein sources such as fishmeal have historically served as the foundation of aquafeeds; however, their elevated costs and limited availability have catalyzed the search for sustainable alternatives. These alternatives encompass plant-based proteins, insect meals, and, more recently, single-cell proteins (SCPs), which are derived from microorganisms including bacteria, yeast, fungi, and microalgae. Nonetheless, SCP remains in its nascent stages and currently accounts for only a minor fraction of aquafeed formulations relative to other established alternatives. The production of SCP utilizes low-cost substrates, such as agricultural and dairy wastes, thereby supporting waste mitigation and principles of the circular economy. This review elucidates the nutritional value of SCPs, their potential for biofortification, and their emerging roles as functional feeds with immunomodulatory and nutrigenomic effects. Additionally, the review underscores the potential of endophytes as a novel SCP source, highlighting their underutilized capacity to foster sustainable innovations in aquafeeds.

Keywords: alternative protein; biofortification; circular economy; nutrigenomics; single-cell protein.

Figure 4

Flow chart of SCP production and evaluation. Modified based on [24,155,158]. GMP: Good Manufacturing Practice.

Figure 6

Nutrigenomic effects of different types of single-cell proteins (SCPs). Sources: [58,97,165,173,178,181,182]. This diagram illustrates some nutrigenomic impacts of SCPs on various immune and growth-related molecular markers in fish (IGF-I: Insulin-like Growth Factor I, IGF-II: Insulin-like Growth Factor II, MHCIIα: Major Histocompatibility Complex Class II alpha chain, CSF1R: Colony Stimulating Factor 1 Receptor, β-defensin: Beta-Defensin, SOD: Superoxide Dismutase, CAT: Catalase, IL-1β: Interleukin-1 Beta, HSP70: Heat Shock Protein 70, TNF-α: Tumor Necrosis Factor Alpha, TGFβ: Transforming Growth Factor Beta, IL-4: Interleukin-4, IL-8: Interleukin-8, IL-10: Interleukin-10).

Figure 1

SCP market segmentation. Modified based on [29,43].

Figure 2

Extraction of endophytic SCPs from a plant.

Figure 3

Strategies for SCP Biofortification to Enhance Nutritional Quality in Aquafeeds.

Figure 5

Nutritional Value and Functionality of Single-Cell Proteins (SCPs) in Aquafeeds. This diagram illustrates the bioavailability and functional roles of SCPs, highlighting key nutritional components such as protein, carbohydrates (e.g., β-glucan, mannan, chitin), lipids, nucleic acids, amino acids (e.g., leucine, valine, lysine, phenylalanine), minerals (e.g., phosphorus (P) and potassium (K)), and vitamins and provitamins (e.g., B₁ (thiamine), B₂ (riboflavin), B₃ (niacin), B₅ (pantothenic acid), B₆ (pyridoxine), B₇ (biotin), B₉ (folate), B₁₂ (cobalamin), C (ascorbic acid), E (tocopherol), and β-carotene). Functionally, SCPs contribute to nutrigenomics, immunomodulation, growth performance, feed intake, nutrient digestibility, and gut health.