Effects of a green seaweed from the Atlantic coast (Ulva lactuca) on gut microbiota, using an in vitro colon model

Recently, it has been seen that carbohydrates from seaweeds can modify the composition of the gut microbiota and stimulate the production of short chain fatty acids. Seaweed as an interesting alternative to animal protein and possesses, in addition to these carbohydrates, other bioactive components of interest. For this reason, we evaluated the effects of the whole green seaweed Ulva lactuca on the intestinal with in vitro colonic simulation. Proximate analysis showed that U. lactuca is rich in fibre and calcium. In addition, in vitro colonic fermentation of this seaweed indicated that it could be used as a carbon source by the gut microbiota; it did not show significant differences in amplicon sequence variants compared with inulin fermentation. Compared with the negative control, the predominant bacterial species after fermentation of U. lactuca were Parabacteroides distasonis and Bacteroides ovatus. Moreover, although to a lesser extent than did inulin, fermentation of U. lactuca stimulated the production of short-chain fatty acids. Regarding to the metabolic pathways, statistical differences were found among assays, founding 11 pathways increased for the assays with U. lactuca (e.g. PWY-5507 or TOMCAT-PWY, among other 8 and 2 for those developed with inulin (PWY-5304 and PWY-6572). Although more studies are necessaries to confirm the positive effect of U. lactuca on the human gut microbiota, this study showed that it has a similar behaviour to inulin, opening new opportunities to investigate the effects of consumption of this whole seaweed in the human health.