Figure 2.

Schematic of mFLOW-Seq for identifying fecal microbiota targeted by systemic antibodies obtained from serum samples. Bacteria are isolated from stool or culture, then incubated with serum antibodies as a primary stain, and then stained with fluorescently labeled anti-IgA, -IgG (or -IgM)-specific secondary antibodies. The bacteria are separated into populations based on IgG and/or IgA binding using fluorescence-activated cell sorting. The sorted populations are then analyzed by 16S rRNA gene sequencing to determine which microbes are enriched in the IgA, IgG, and unbound fractions.