Here are a couple studies on RS and specific microbiome populations:
These findings might have an important implication for large bowel physiology since Cassidy et al. (1994) showed that there were strong inverse associations between the incidence of colorectal cancer and starch intake or the sum of dietary fiber and RS intake, while dietary fiber alone did not show any significant relationships.
Volunteers were provided successively with a control diet, diets high in resistant starch (RS) or non-starch polysaccharides (NSPs) and a reduced carbohydrate weight loss (WL) diet, over 10 weeks.
The second one was pretty cool:
In contrast to these responses to RS, there was little evidence that the high NSP diet resulted in major alterations in the composition of the faecal microbiota. In part, however, this may reflect the fact that a smaller increase was achieved in NSP intake (1.5-fold) than with RS intake (4.8-fold) when compared with the M diet. It is possible that larger changes in specific NSP components would affect the populations of specific groups of colonic bacteria, as was observed with RS. Significant decreases were observed for C. aerofaciens and for the E. rectale group on the WL diet. The WL changes do not show a simple relationship with RS and NSP intakes, and it is possible that the increased dietary protein content of this diet might have a role in altering microbiota composition.