Microbial community-based protein derived from food-processing wastewater supports substantial fishmeal replacement and survival in Pacific white shrimp (Litopenaeus vannamei)

Abstract

The growing demand for aquaculture feeds requires sustainable alternatives to fishmeal. Microbial community-based single-cell protein (SCP) produced from soybean-processing wastewater offers a circular approach that combines nutrient recovery with aquafeed production. We evaluated SCP as a fishmeal replacement for Pacific white shrimp (Litopenaeus vannamei) across four feeding trials lasting 42-84 days, involving shrimp from different hatcheries and SCP produced at laboratory and pilot scales. Diets containing 0-100% fishmeal replacement, corresponding to up to 220 g SCP kg-1 feed, were tested. Replacement of 50% was consistently supported across trials, while levels up to 90% maintained several key performance outcomes, including specific growth rate, feed conversion ratio, and survival, without significant differences from the fishmeal control. Complete replacement reduced growth in one trial, potentially reflecting the lower protein content and less favourable amino acid balance of SCP relative to fishmeal, particularly its lower lysine and methionine proportions. Shrimp tissue proximate and amino acid compositions showed no clear adverse responses to SCP inclusion in the trial in which they were assessed. Cross-trial analysis revealed a positive association between SCP replacement and survival after accounting for trial-specific baseline differences, with survival increasing by an estimated 1.53 percentage points for every 10-percentage-point increase in replacement (HC3 95% CI: 0.90-2.17; P < 0.001). Although the mechanisms underlying this association remain to be established, the findings support investigation of potential functional effects through targeted challenge and mechanistic studies. Overall, performance across four heterogeneous trials supports substantial fishmeal replacement by microbial community-based SCP and demonstrates its potential for practical application as a circular aquafeed ingredient.