Intestinal flora is a common phrase in English, too. Or “gut flora”. It’s one of those old 19th century scientific phrases which has stuck around.

Like this, err, gentleman (who apparently wants to drag us back to that past) we used to believe gut bacteria to be plant-based. Science caught up, but the term has had sticking power. It seems to be a favorite of marketers of probiotic supplements.

“Microbiota” or just the straightforward “gut bacteria” would be more accurate and modern.