Dietary addition of recombinant Bacillus subtilis expressing a fungal phytase increases phosphorus fixation in muscle of Pacific white shrimp Litopenaeus vannamei.

Phosphorus is an essential mineral present in the vegetable matter in the form of phytate, which is considered an antinutritional factor. Phytate can be degraded by phytases, which have been used in commercial feeds. However, these enzymes undergo costly isolation and purification processes. In the present study, a genetically modified (GM) Bacillus subtilis strain that expresses a fungal phytase was used as a feed additive. The GM probiotic was added to the commercial feed of shrimp Litopenaeus vannamei and its effects on zootechnical performance, proximate composition of muscle, lipid concentration in hepatopancreas, and expression of genes related to digestion, amino acid metabolism, and antioxidant defenses were analyzed. Although the genetically modified probiotic had no impact on growth parameters, there was a 39% increase in phosphorus content in muscle. In addition, genes related to digestion were downregulated in shrimp hepatopancreas, as well as an increase in lipids in this tissue. These results demonstrate that the GM probiotic increased the efficiency of the use of plant-derived phosphorus, which may imply a decrease in the addition of this element in the diets, as well as minimizing the impact of shrimp farms on the eutrophication of adjacent ecosystems. [ABSTRACT FROM AUTHOR]