Another example of something that improves gut health that comes to mind is the lactic acid bacillus. In keeping with its image, the lactic acid bacillus is useful in maintaining the intestinal environment. Research has shown that the natto bacillus can not only coexist with the lactic acid bacillus in the intestine, it also aids the activity of the lactic acid bacillus.

The activity of the lactic acid bacillus is impeded in environments with active oxygen such as hydrogen peroxide, and its ability to propagate is impaired. However, the lactic acid bacillus lacks the enzymes and catalase needed to break down hydrogen peroxide.
What about the natto bacillus? It turns out that, yes, the natto bacillus is able to secrete catalase.
In experiments, it was observed that adding natto bacillus culture extract and catalase to lactic acid bacillus whose activity had become impaired and that was unable to propagate instantly revitalized the lactic acid bacillus and enabled it to propagate. Even when a different enzyme, nattokinase, was added, the propagative ability of the lactic acid bacillus was restored in the same manner.
Although these were only experiments, the results suggest that it is possible that the same thing may occur in the intestine.
_pdf (jst.go.jp)