High-dose supplementation of Chlorella and Spirulina increases beneficial gut Bacteria in healthy ICR mice: A 90-day feeding study

Microalgae are increasingly recognized as important protein sources, and their potential probiotic functions have recently gained attention. This study investigated the effects of microalgae biomass (ChB from Chlorella pyrenoidosa and SpB from Spirulina platensis ) on the gut microbiota of healthy ICR mice following a 90-day feeding experiment. Various health indicators were monitored to assess the health status of animals. Oral administration of ChB and SpB at doses of 0.82 g/kg and 4.10 g/kg did not result in any treatment-related impairment of physical indicators in mice. High-throughput sequencing of fecal 16S rRNA revealed that the mice receiving high-dose ChB and SpB supplementation showed increased abundance of beneficial bacteria, particularly Lactobacillaceae and Muribaculaceae, and decreased abundance of unfavorable bacteria, notably Erysipelotrichaceae and Staphylococcaceae. The ChB-H and SpB-H groups formed clusters that were distinctly separated from the control group based on PCoA analysis, although the α-diversity was not statistically significant. PICRUSt functional analysis revealed that high-dose treatments with ChB and SpB significantly altered pathways related to lipid and amino acid-related metabolism. A strong association was observed between the pathways and microbial families. These results suggest potential health effects mediated by gut microbiota modulation. The diversity and composition of gut microbiota in the low-dose groups were comparable to those in the control group. In summary, high-dose supplementation of ChB and SpB resulted in enhanced levels of beneficial bacteria in the mice gut, which may contribute to physiological changes in the host. Therefore, ChB and SpB could serve as prebiotics to promote health. • Chlorella and Spirulina biomass did not cause any treatment-related impairment of physical indicators in healthy mice following a 90-day feeding study • 4.10 g/kg Chlorella and Spirulina increased beneficial bacteria and reduced unfavorable ones, while 0.82 g/kg had no effect. • High-dose ChB and SpB could serve as prebiotics to promote health.