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The social concern with sustainable development encourages the study of new sources of starch; among these sources, the cultivation of macroalgae is a strategy for the development of a sustainable bioeconomy. This mini‐review aims to present the main aspects related to the current seaweed market, the extraction, composition, and properties of starch, as well as its prospects as a sustainable ingredient capable of generating income and health for the world's population. The green algae species Ulva has been suggested as a promising source for starch extraction; however extraction is a challenge mainly due to the difficulty in breaking down the cell walls and isolating the starch granules. The algal starch granule is small (1.7–7 µm), and another characteristic is the high amylose content, above 55%, which may indicate that it is a resistant starch or slow digestion. Seaweed starch still needs to be scaled its production, extraction, and application potential, as a main ingredient or as a co‐product of gum processing, which already have a production chain, as they have great potential as nutraceutical or functional starch for food of low calorie, or for applications as a thickener in the food, cosmetics, and other industries. [ABSTRACT FROM AUTHOR]

In situ and in vitro nitrate reductase (NR) activity assays designed for use in the field on Enteromorpha sp., Ulva sp., and Gelidium sp. are described. In optimizing each assay, a variety of compounds and assay conditions were tested for their ability to extract NR and preserve its activity. Enteromorpha sp. had similar levels of in vitro NR activity after exposure to the in situ assay buffer, demonstrating that neither NR induction nor activation likely occurs during the in situ assay. Storing freshly collected Enteromorpha sp. led to a reduction in NR activity over time. However, the use of liquid nitrogen to freeze algal tissue on site and subsequent storage at -80° C preserved NR activity and allowed for later laboratory use of the optimized in vitro assay. Application of the in situ and in vitro assays to stands of Enteromorpha sp., Ulva sp., and Gelidium sp. in the field consistently found NR activity. In situ NR activity over 9 consecutive days in January demonstrated that Enteromorpha sp. responds to increases in nitrate availability. The influence of light on diel patterns of in vitro NR activity in the field was demonstrated for the first time as well. For the three species tested, these two assays provide a reliable tool for field investigation of the interaction between environmental signals (e.g. nutrient levels) and physiological signals (e.g. tissue metabolite levels) on nitrate reduction. [ABSTRACT FROM AUTHOR]

In situ and in vitro nitrate reductase (NR) activity assays designed for use in the field on Enteromorpha sp., Ulva sp., and Gelidium sp. are described. In optimizing each assay, a variety of compounds and assay conditions were tested for their ability to extract NR and preserve its activity. Enteromorpha sp. had similar levels of in vitro NR activity after exposure to the in situ assay buffer, demonstrating that neither NR induction nor activation likely occurs during the in situ assay. Storing freshly collected Enteromorpha sp. led to a reduction in NR activity over time. However, the use of liquid nitrogen to freeze algal tissue on site and subsequent storage at -80° C preserved NR activity and allowed for later laboratory use of the optimized in vitro assay. Application of the in situ and in vitro assays to stands of Enteromorpha sp., Ulva sp., and Gelidium sp. in the field consistently found NR activity. In situ NR activity over 9 consecutive days in January demonstrated that Enteromorpha sp. responds to increases in nitrate availability. The influence of light on diel patterns of in vitro NR activity in the field was demonstrated for the first time as well. For the three species tested, these two assays provide a reliable tool for field investigation of the interaction between environmental signals (e.g. nutrient levels) and physiological signals (e.g. tissue metabolite levels) on nitrate reduction. [ABSTRACT FROM AUTHOR]