Antihypertensive and Probiotic Effects of Hidakakombu (Saccharina angustata) Fermented by Lacticaseibacillus casei 001

Hidakakombu (Saccharina angustata), commonly known as kelp, is an edible macroalgae mainly grown in the Hidaka region of Hokkaido. Hidakakombu is graded based on its shape and color. Low-grade Hidakakombu has low value and is distributed at a low price. It is desired to establish a method to add value to low-grade Hidakakombu. In this study, low-grade Hidakakombu was fermented by Lacticaseibacillus casei 001 to add value. Fermentation of Hidakaombu enhanced the inhibition of blood pressure elevation due to ACE inhibition. L. casei 001 in fermented Hidakakombu remained viable in simulated gastric and intestinal juices. The ACE inhibitory component in L. casei 001-fermented Hidakakombu was isolated from the fraction below 3 kDa using high-performance liquid chromatography. The purified amino acid was identified as D-Trp using nuclear magnetic resonance, mass spectroscopy, and optical rotation measurements. This is the first report on the ACE inhibitory activity of D-Trp in L. casei 001-fermented Hidakakombu. Hidakakombu fermented by L. casei 001 was shown to be a source of probiotics and functional components against hypertension. Therefore, fermentation by L. casei 001 was found to be an effective means of adding high value to low-grade Hidakombu.

Extensive transfer of genes for edible seaweed digestion from marine to human gut bacteria

SummaryHumans harbor numerous species of colonic bacteria that digest the fiber polysaccharides in commonly consumed terrestrial plants. More recently in history, regional populations have consumed edible macroalgae seaweeds containing unique polysaccharides. It remains unclear how extensively gut bacteria have adapted to digest these nutrients and use these abilities to colonize microbiomes around the world, especially outside Asia. Here, we show that the ability of gut bacteria to digest seaweed polysaccharides is more pervasive than previously appreciated. Using culture-based approaches, we show that known Bacteroides genes involved in seaweed degradation have mobilized into many members of this genus. We also identify several previously unknown examples of marine bacteria-derived genes, and their corresponding mobile DNA elements, that are involved in degrading seaweed polysaccharides. Some of these genes reside in gut-resident, Gram-positive Firmicutes, for which phylogenetic analysis suggests an origin in the Epulopiscium gut symbionts of marine fishes. Our results are important for understanding the metabolic plasticity of the human gut microbiome, the global exchange of genes in the context of dietary selective pressures and identifying new functions that can be introduced or engineered to design and fill orthogonal niches for a future generation of engineered probiotics.

Proximate biochemical composition and mineral content of edible species from the genus Cystoseira in Portugal

Macroalgae are valuable resources for human consumption in many countries. This work reports for the first time a comparative evaluation of the nutritional properties of five edible macroalgae from the genus