From nutrient release to bioavailability in potato pulp co-fermentation: controls and microbial attribution

Zhao et al. present a broad bioprocessing framework in which Bacillus subtilis BSM1 and Aspergillus niger H1 co-fermentation deconstructs potato pulp and is followed by in vitro and piglet validation. The structural and compositional findings are promising, but three issues limit the inference that fermentation improved nutrient bioavailability. The animal experiment lacks an unfermented potato-pulp diet and reports an unclear number of study groups, preventing isolation of a fermentation-specific effect. Digestive-enzyme activity and villus morphology are not direct measures of nutrient digestibility or equivalence to corn. Finally, bacterial 16S profiling cannot track A. niger or verify the proposed temporal bacterial-fungal complementarity. We suggest a three-arm, nutritionally matched feeding design; direct ileal or total-tract digestibility and growth endpoints; dry-matter mass balance; and time-resolved, kingdom-inclusive microbial quantification. These additions would preserve the study's engineering contribution while aligning its conclusions with the evidence.