Yeast Meyerozyma guilliermondii inoculation in mature and heterotrophic biofloc systems for Litopenaeus vannamei nursery rearing exhibits bioremediation potential and improvement of shrimp survival

This study aimed to isolate a yeast strain and evaluate its potential to be inoculated in the biofloc technology culture of Pacific white shrimp employing in vitro and in vivo assays. A yeast strain identified as Meyerozyma guilliermondii (CPQBA 1459/17 DRM-01) was isolated from the soil of an estuary. Its growth kinetics under different salinities (0%, 1.0%, 2.0%, 3.0% NaCl) and Vibrio alginolyticus inhibition were evaluated in vitro. For the in vivo assay, a factorial design was employed to evaluate the effects of yeast addition and biofloc management strategy in the nursery culture of Litopenaeus vannamei as regards shrimp growth performance, water quality and water microbiology. The two factors evaluated were biofloc (mature and heterotrophic) and yeast (addition or no addition), totaling four treatments. In the in vitro trials, the yeast strain was capable of growing under all salinities evaluated, but no pathogen inhibition was observed. In the in vivo experiment, the addition of yeast significantly reduced the concentration of total suspended solids (p < 0.05), in addition to promoting a higher post-larvae survival when considering only the two mature biofloc treatments (p < 0.05). No significant effects on water Vibrio spp. and total heterotrophic bacteria counts were found (p ≥ 0.05). In conclusion, the inoculation of yeast in the biofloc culture of L. vannamei exhibited bioremediation potential and improvement in shrimp survival, the latter being modulated by the biofloc management strategy.