Not just "change in microbiome". It caused a change such that a gut flora transplant to mice caused the mice to have the same glucose reactions. So the artificial sweeteners change glucose metabolism, at least partly mediated by gut flora.

(This has actually been known for at least 3 or 4 years.)

As with most science it's a "warrants further investigation" kind of issue

Science compounds so even if this doesn't tell you why the gut microbiome changed, it's useful to know that it did.

Yeah, I really want to see a breakdown of the before and after species. I'm very interested in gut microbiome, but frustratingly what's available from the paper outside the paywall doesn't give any details on what the change was. Changes in gut microbiome composition can be very positive or very negative, or mildly positive or mildly negative... What was it in these cases?

The thing about the GI changes in the mice in interesting but I really want more details on the bacteria changes!