Bacterial Single-Cell Proteins as Sustainable Aquafeeds: A Meta-Analysis of Growth, Physiological Homeostasis, and Antioxidant Capacity

In aquaculture nutrition, alternative protein sources, such as those derived from bacteria, have recently garnered significant attention as safe and viable replacements for traditional protein sources, including fish meal (FM) and soybean meal (SBM). This is attributed to their rich protein content and a well-balanced amino acid profile that is comparable to that of FM. Likewise, their ease to be grown on industrial by-products or gas fermentation warrants a continuous supply. Given their global importance in aquaculture nutrition and health, this study was conducted to quantify the overall effect of dietary inclusion of bacterial single-cell proteins (BSCPs) on the specific growth rate (SGR), feed efficiency ratio (feed conversion ratio [FCR]), survival rate (SR), hepatosomatic index (HSI), viscerosomatic index (VSI), and biochemical responses (alanine aminotransferase [ALT], aspartate aminotransferase [AST], superoxide dismutase [SOD], and catalase [CAT] enzymatic activities) in several aquaculture species. Hedge’s g was computed to quantify the primary outcomes. Furthermore, the influence of several moderators, such as BSCP source, aquaculture species, and habitat, on Hedge’s g effect sizes was determined by a mixed-effects model. Except for the SR, the results indicated nonstatistically significant differences in SGR, FCR, HSI, VSI, ALT, AST, SOD, and CAT between the BSCP treatment groups and the control, and this was uniform among carnivorous, omnivorous, and herbivorous species. The results of the mixed-effects model revealed that the BSCP source and aquaculture species influenced the observed effect sizes of SOD and CAT. Similarly, BSCP source and habitat influenced the observed effect sizes for VSI. Overall, depending on the inclusion level, BSCPs are a safe and viable alternative to FM or SBMs, and their inclusion in aquaculture diets offers significant benefits.