| Abstract: | In vivo fermentation of Ulva lactuca was studied in previously germ-free rats inoculated with human flora obtained from non-, low- and high-methane producers (groups NMP, LMP and HMP, respectively), in comparison to germ-free rats. Rats were fed either a control diet or a diet containing 4% of dried Ulva lactuca. Production of metabolites varied according to the flora and diet. Ulva lactuca induced a specific high production of methane in the HMP group. With the three human flora, Ulva diet induced a similar increase in caecal pH. In the NMP and HMP groups, this increase was associated with a fall of lactic acid caecal concentration. In the LMP group it was related to a decrease in the concentration of short-chain fatty acids. Ulva lactuca appeared to be able to regulate the β-glucuronidase and β-glucosidase activities, reducing the relatively high levels observed in groups NMP and HMP and increasing the low levels obtained in the LMP group. Results show that, although it was poorly fermented, Ulva induced significant effects on the gut microflora metabolism. The methanogenic status of the human donor appeared to be an important factor. © 1998 SCI. |
