Microbial proteins offer a sustainable alternative for animal nutrition. Rossellomorea marisflavi NDS, a bacterium isolated from seawater, was previously identified as a promising candidate due to its high protein content. This study aimed to enhance its single cell protein production through systemic fermentation optimization. Single-factor optimization in shake flask determined the optimal conditions to be: a salinity of 20‰ NaCl, a temperature of 32 °C, and an initial pH of 7.3, and a medium composed of 1% (w/v) corn flour, 1% peptone, 0.3% beef extract, and 0.2% KCl. Scaling up to a 10 L bioreactor demonstrated that a two-stage agitation strategy (150 rpm for the first 20 h followed by 180 rpm for the remaining 12 h) enhanced single cell protein yield. Furthermore, allowing the pH to fluctuate freely was more beneficial for protein production than maintaining a constant pH of 7.3 ± 0.02. Under these optimized conditions, the biomass composition (wet weight) was determined to be 2.3767 ± 0.0205% crude ash, 15.6013 ± 0.0082% crude protein, 0.1023 ± 0.0026% crude lipid, and 2.6997 ± 0.0021% carbohydrates. Amino acid analysis revealed a rich profile, with lysine and glutamic acid being the predominant essential and non-essential amino acids, respectively. Fatty acids analysis indicated that C14:1n5 was the most dominant. These findings underscore the potential of R. marisflavi NDS as a high-quality dietary protein supplement and provide a solid foundation for its industrial-scale production.

Spirulina (Arthrospira platensis) is globally recognized for its high nutritional value and potential as a sustainable food source. However, the influence of targeted nutrient supplementation on its biochemical composition and microbial safety under tropical open-pond conditions remains underexplored, particularly in sub-Saharan Africa. This study evaluated the effects of three nutrient supplementation regimes (compositions A, B, and C) and a control on Spirulina cultivated over 30 days in raceway ponds at the Nomayos Spirulina Production Farm in Cameroon. All treatments maintained physicochemical parameters within ranges favorable for Spirulina growth. Composition A significantly enhanced protein content (60.38 ± 0.68%), while composition C promoted carbohydrate accumulation (28.02 ± 0.41%). Microbial assessments revealed variable contamination levels, with composition B exhibiting the highest Escherichia coli (1.05 ± 0.075 × 10⁵ CFU/g) and Salmonella/Shigella (4.09 ± 1.81 × 10⁵ CFU/g) counts, potentially due to nutrient-induced changes or post-harvest handling factors. Correlation analyses revealed a moderate positive relationship between nitrogen input and protein synthesis (r = 0.309), which was not statistically significant (p = 0.329). Additionally, higher pH was significantly correlated with total mesophilic counts (r = 0.661, p = 0.019) and E. coli (r = 0.655, p = 0.020). These findings highlight the importance of nutrient formulation and environmental management in improving nutritional quality while minimizing microbial risks during Spirulina cultivation in tropical, low-tech settings.

Butyrate, a short-chain fatty acid (SCFA), is increasingly recognized as a functional feed additive in aquaculture. However, its effects on crustacean health and performance remain unclear. This meta-analysis synthesizes findings from 23 studies (2011–2025) examining butyrate supplementation across four crustacean groups: shrimp, crabs, crayfish, and prawns. Effect sizes were calculated for growth performance (final body weight, specific growth rate, survival rate), feed efficiency (feed conversion ratio, protein efficiency ratio), and digestive enzyme activities (amylase, lipase, alkaline phosphatase, total protease) in freshwater and marine environments. Results indicate that butyrate supplementation generally enhanced the digestive enzyme activity in both freshwater and marine environments, although the magnitude of the effect varied among enzyme types and habitats, with freshwater species showing improvements in alkaline phosphatase, amylase, lipase, and total protease, and marine species showing improvements in amylase, lipase, and total protease. Feed efficiency improved in freshwater (protein efficiency ratio) and marine species (feed conversion ratio). Growth-related outcomes, including final body weight and survival rate, were generally improved across both environments. Dose–response analyses indicated that dietary inclusion levels of 1–2% were associated with the most consistent improvements in digestive enzyme activity and growth performance. These findings support the potential use of butyrate as a functional feed strategy to improve productivity and sustainability in crustacean aquaculture. These effects may be mediated by multiple mechanisms, including improved intestinal epithelial integrity, the modulation of gut microbiota, and the regulation of immune and metabolic processes.

Aquaculture intensification has increased the demand for nutritional strategies that support immune responses and oxidative balance in cultured finfish and crustaceans, thereby reducing disease susceptibility and improving production stability. Butyrate, a short‐chain fatty acid increasingly incorporated into aquafeeds as a functional feed additive, has shown promise in enhancing immune responses and antioxidant defenses, but reported effects vary widely across species, life stages, and supplementation levels. This systematic review and meta‐analysis synthesizes findings from 65 studies (1174 dose–control comparisons) across 23 aquaculture species to assess butyrate’s effects on innate and adaptive immunity, oxidative stress, and antioxidant capacity. Dietary butyrate generally enhanced innate immune responses ( g = 2.14, 95% CI: 1.66–2.63) and antioxidant enzyme activity ( g = 1.59, 95% CI: 1.07–2.12), increased IL‐10 ( g = 0.64), and reduced MDA ( g = −1.36). Effects on adaptive immunity were positive but more heterogeneous among studies ( g = 0.98, 95% CI: 0.33–1.63), and pooled effects on pro‐inflammatory cytokines, chemotactic cytokines, and immune signaling pathways were not significant. Trim‐and‐fill adjustment attenuated the pooled estimates for innate immunity ( g = 1.33) and antioxidant enzymes ( g = 0.84), indicating possible small‐study effects. In dose–response meta‐regression, dietary inclusion level explained little of the heterogeneity (pseudo‐ R ² ≤6.3%), and no inclusion range was consistently associated with stronger responses. These findings support butyrate as a promising functional feed additive, while indicating that dose recommendations require species‐specific dose–response trials.