Resistant starch (RS) fermentation is prevented by low potency antibiotics (AB) neomycin and ampicillin

Abstract

In a previous study we reduced bacterial genera that ferment RS with AB treatment then stopped AB prior to feeding RS. Subsequent fermentation of RS was good even without a transplant of microbiota from other rats fed RS and prior reduced bacterial genera increased (EB14). We now report use of the same AB (neomycin 0.5 g/L and ampicillin 1g/L in drinking water) at the same time as feeding RS. Sprague Dawley rats were assigned into one of four groups and fed ad libitum for four weeks. The groups included: 1. positive control (high RS, low fat diet [LF], no AB), 2. negative control (no RS, LF, no AB); 3. LF, high RS, AB; and 4. high fat (HF), high RS, AB. We measured effects of fermentation: pH of cecal contents, empty cecum weight (ECW), short‐chain fatty acids (SCFA), glucagon‐like peptide 1 (GLP‐1), RS in cecal contents, four bacterial genera known to be involved in fermentation of RS and total bacterial numbers. HF group 4 was included to see if AB might improve fermentation of RS compared to no AB because Cani et al. (2008) had reported that AB reduced endotoxemia in diet‐induced obesity. AB reduced Lactobacillus spp. and Bifidobacterium spp., but not Bacteroides spp. or total bacteria. Empty cecum weights of groups given AB and positive control were greater than the negative control. RS increased acetate and butyrate as well as decreased pH of cecal contents and increased empty cecum weights; AB treatment in both LF and HF prevented these effects (p<0.05). AB also had double the amount of GLP‐1 in serum and double the amount of RS in cecal contents compared to positive control, and negative control had minimal amounts of both GLP‐1 and RS. Thus, it appears that half of the RS was not fermented in the positive control and AB eliminated fermentation of RS when given at the same time as feeding of RS. However, increased ECW and GLP‐1 are a concern for future use of AB for reduction of fermentation of RS for mechanistic studies.Support or Funding InformationFunding: Ingredion Incorporated and LSU AgCenter.