Combinatorial Microalgae Strategy in Different Trophic Biofloc Systems: A Multiscale Nexus of Microbiota Succession, Nitrogen Cycling, and Nutraceuticals

Abstract

Microalgae, valued for their ecological significance and nutritional benefits, play an increasingly critical role in biofloc technology. However, their interactions with different trophic bioflocs and subsequent impacts on Litopenaeus vannamei cultivation remain poorly characterized. This study investigates microalgae-enhanced autotrophic and heterotrophic biofloc systems. A microalgae consortium (Chlorella, Platymonas, and Haematococcus pluvialis) increased nitrite removal in autotrophic bioflocs by 40.8%, while enhancing ammonia and nitrite removal in heterotrophic bioflocs by 13.0% and 73.0%. Autotrophic bioflocs harbored nitrifying genera, whereas microalgae enrichment elevated probiotics and functional bacteria linked to nitrogen cycling. Microalgae supplementation significantly improved shrimp survival (24.9–26.3%, p < 0.05), zootechnical performances (p < 0.05), and muscle astaxanthin content (up to 176.3%; p < 0.05). Biofloc trophic type influenced shrimp muscle polyunsaturated fatty acid profiles, with heterotrophic systems showing higher ω-3 PUFA levels. These findings demonstrate microalgae’s dual role in enhancing nitrogen cycling, shrimp productivity, and nutraceuticals in BFT systems.

Keywords: Microalga, Trophic Type, Nitrogen metabolism pathway, Astaxanthin, PUFA