The lectin accumulation, growth rate, carrageenan yield, and quality from the red alga Kappaphycus striatus cultivated at Camranh Bay, Vietnam

The red alga Kappaphycus striatus was cultivated at Camranh Bay of Vietnam. For a 30 day cultivation period, the alga showed the higher growth rates (4.1–5.8% day−1) and lectin contents (747–906 μg g−1 dry alga) from October 2014 to April 2015 and in September 2015, while lower growth rates (2.5–3.1% day−1) and lectin contents (63–324 μg g−1 dry alga) were found from May to August 2015. The bands of 28,000 Da of algal crude extracts from October 2014 to April 2015 and from August to September 2015 were detected for lectin by SDS-PAGE, whereas these bands were not recorded from May to July 2015. The carrageenan quality was determined for a 60-day cultivation period; the carrageenan yield and gel strength showed little variation with the higher values (28.1–28.7% and 855–935 g cm−2, respectively) obtained from November 2014 to March 2015 and lower ones (25.1–26.7% and 555–758 g cm−2, respectively) from April to September 2015. The data on moisture content (33.5–36.8%), clean anhydrous algal/salt ratio (0.92–1.07), and carrageenan yield obtained in this study fulfilled those of standards for carrageenophytes. This study shows that the red alga K. striatus can be grown in the tropical waters of the Camranh Bay during the northeast monsoon and a part of the southwest monsoon as a source not only of carrageenan, but also of valuable lectins for application.