Nostochopsis lobatus Wood em. Geitler (Nostocales), edible algae in northern Thailand

Abstract

The blue-green alga, Nostochopsis lobatus Wood em. Geitler, consists of a dark green colony with a mucilaginous sheath out-growth and is attached on rocks. It is usually found together with Cladophora spp. and Microspora spp. in some shallow rivers or streams in certain water resources, especially in the Nan River of Nan Province in northern Thailand. Scattered branches with the lateral branch stretching parallel and upward to the main filament in a polysaccharide sheath are their unique descriptive characteristics. N. lobatus can rapidly grow under clear water during both the cool-dry season and the hot-dry season in which water quality appears to be clean to moderate. Local people have prepared it as a salad dish called "Yum Lon". The study of the bioactive compounds and other important compounds in N. lobatus showed a high polysaccharide content of 160.02 DP on BG11 medium, 76.77 DP in the samples of the Nan River and in some pigments; chlorophyll a: 8.26 mg/g cell dw, carotenoid: 0.339 mg/g cell dw, phycocyanin: 61.58 mg/g cell dw and allophycocyanin: 65.38 mg/g cell dw. Moreover, N. lobatus was found to contain a high protein content of 19.10 % dw, which is as high as freshwater fish. It was found to be 6,405 mg/100g cell dw of calcium, which was as high in content as the small fish, when eaten whole. In addition, this algae showed high content levels of certain vitamins and minerals, especially selenium, a well-known antioxidant (37 μg/100g dw). Thus, N. lobatus could come to be seen as an appropriate food source, which could grow well on semi-solid BG11 media on the laboratory scale. Furthermore, these algae should be considered as a source of supplemental food, as a therapeutic agent or for use as an ingredient in cosmetics in the future.