Optimization of Fermentation Conditions for Enhanced Single Cell Protein Production by Rossellomorea marisflavi NDS and Nutritional Composition Analysis

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.