Deacetylated Konjac Glucomannan (DKGM) and Konjac Oligo-glucomannan (KOGM) as two most widely used derivatives in food industry are structurally and physiologically distinct from Konjac glucomannan (KGM). However, the roles of their distinct structures and physicochemical properties in directing microbiota community and the following outcomes are not fully understood. This paper aims to build links between structural complexity of KGM and its derivatives and microbial metabolism. Results showed that structural alterations changed molecular chain aggregation and water binding ability, thus affected the susceptibility to enzymatic degradation, leading to the distinct microbial composition and outcomes profile. Explicitly, KOGM was distinctive in higher abundances of Catenibacterium and Megasphaera, and lacking Prevotella, which was additionally enriched by KGM and DKGM. KOGM, owned the same butyrate-dominant profile with KGM, was utilized fast. However, KGM possessed the highest fermentability. Severe deacetylation reduced fermentability and led DKGM to a propionate-dominant pattern.