Investigating a novel β-glucan source to enhance disease resistance in Pacific white shrimp (Penaeus vannamei)

β-glucans supplements are known for enhancing disease resistance and performance in shrimp aquaculture, but their effectiveness depends on their source and structure. This study investigated a novel β-glucan derived from the insect fungus Ophiocordyceps dipterigena BCC 2073 as a potential feed additive for Pacific white shrimp (Penaeus vannamei). To determine its feasibility, juvenile shrimps were fed diets supplemented with 0%, 0.1%, and 0.4% β-glucan oligosaccharide for 30 days prior to their performance evaluation. The groups with β-glucan supplementation showed improved immune levels and significantly higher survival rates (p-value < 0.05) when exposed to the pathogen Vibrio harveyi. Transcriptome, microbiome, and metabolome were employed to understand mechanisms of β-glucan supplement. The feed additive altered the expression of host genes linked to immunity, inflammation, and intestinal barrier function. Moreover, Vibrio spp. and Pseudoalteromonas spp. abundances were significantly modulated (p-value < 0.05) with specific Vibrio clades responding differently depending on the β-glucan concentration. Metabolomic analysis revealed immune-supporting metabolites such as hydroquinone and nicotinic acid, potentially promoting homeostasis, consistent with the observed gene expression profiles. This study highlights the potential of O. dipterigena BCC 2073 β-glucan as a novel feed additive to improve disease resistance and shrimp health.