The effects of filtration and centrifugation on the gut microbiota in fecal microbiota transplantation preparation

Background The preparation method of fecal microbiota suspensions is crucial for reliable fecal microbiota transplantation research. However, current protocols vary significantly in processing parameters, potentially compromising the comparability of studies. Systematic comparisons of how different preparation techniques affect the microbial community are still lacking. Methods Fresh fecal samples from nine adult volunteers were processed via filtration and centrifugation at various speeds. Microbial viability was assessed via live/dead staining and colony forming unit enumeration. 16S rDNA sequencing was performed to analyze bacterial diversity and taxonomic composition. Results The microbial composition and functional potential did not differ between the filtration alone group and the fresh fecal group, and filtration resulted in the lowest bacterial mortality. Mortality increased with increasing centrifugation speed. Centrifugation selectively affected the abundance of some genera (e.g., Delftia and Acinetobacter ). High-speed supernatants presented markedly lower OD 600 values than low-speed supernatants did, and differential centrifugation visibly reduced the amount of debris. Conclusion Filtration alone best preserved fecal microbial viability, composition and functional potential. Centrifugation enrichment becomes selective at high speeds. Differential centrifugation offered superior impurity removal. The preparation strategy should be tailored to the research or therapeutic goal.