Dietary supplementation of astaxanthin-enriched Rhodosporidiobolus ruineniae PBMB1 improves growth, immunity, disease resistance, and pigmentation in shrimp.

Infectious diseases are a major challenge in the farming of Litopenaeus vannamei, and multiple strategies are required to improve shrimp health and resilience. This study evaluated the astaxanthin-enriched yeast Rhodosporidiobolus ruineniae PBMB1 as a dietary supplementation at 2% (MB2%), 4% (MB4%), and 6% (MB6%) (wet weight), with a focus on immune-related gene responses. Gene expression analysis revealed dose-dependent increases in several immune- and metabolism-related genes in shrimp gills, including RPS3a, HSP70, LYZ, Trypsin, TPI, GAT, STAT, ASAH-52, GPX, Relish, Catalase (Catal), ADK, and Lipase (Lip), with the highest expression levels observed in the MB6% group. These molecular responses were associated with improved growth performance (WG, ADG, and SGR), reduced mortality following challenge with Vibrio parahaemolyticus (VPAHPND), and lower copy numbers of Enterocytozoon hepatopenaei (EHP). PBMB1 supplementation was also associated with variations in pigmentation and crude protein content as indicators of meat quality across treatments. Overall, the findings suggest that R. ruineniae PBMB1 may contribute to improved shrimp health, potentially through modulation of gene expression related to immune defense and metabolism, supporting its potential application as a functional dietary yeast additive in sustainable shrimp aquaculture.