Wilson Thau Lym Yong

Chemical composition of farmed and micropropagated Kappaphycus alvarezii (Rhodophyta, Gigartinales), a commercially important seaweed in Malaysia

Micropropagation technologies play an important role in enhancing the nutritional composition of seaweeds. Kappaphycus alvarezii explants, obtained from two types of seedling production system viz. micropropagation and farm propagation, were analyzed. Results obtained from the post-farm cultivation seaweeds showed significantly higher total lipids in micropropagated compared to farm-propagated K. alvarezii. In the mineral and trace element analyses, micropropagated K. alvarezii yielded significantly higher calcium, magnesium, beryllium, cobalt, copper, lithium, manganese, and zinc compared to farm-propagated K. alvarezii. A lower concentration of metal contaminants was detected in micropropagated K. alvarezii compared to farm-propagated K. alvarezii. Both sources of K. alvarezii showed high SFA compared to MUFA and PUFA, where C16:0 and C18:0 were found to be in abundance. The study suggests micropropagated K. alvarezii is a better food source for consumption compared to farm-propagated K. alvarezii and justifies the rationale of using micropropagation technique for seedling production in the seaweed industry.

Evaluation of growth rate and semi‐refined carrageenan properties of tissue‐cultured Kappaphycus alvarezii (Rhodophyta, Gigartinales)

This study aimed to evaluate and compare the quality of κ‐carrageenan obtained from tissue‐cultured and field‐cultured Kappaphycus alvarezii. Carrageenan properties including yield, viscosity, gel strength and sulfate content were studied. After 60 days of cultivation, tissue‐cultured K. alvarezii showed a higher growth rate (6.3 ± 0.01% day−1) than field‐cultured seedlings (3.4 ± 0.3% day−1). The obtained carrageenan yield from tissue‐cultured (67.3 ± 16.4%) was higher than field‐cultured K. alvarezii (51.5 ± 21.0%). Gel viscosity of carrageenans from tissue‐cultured K. alvarezii (1280.0 ± 25.0 cP) was found significantly higher than field‐cultured samples (87.8 ± 20.9 cP). The 1.5% gel solution of tissue‐cultured and field‐cultured K. alvarezii exhibited gel strengths of 703.5 ± 14.1 and 288.3 ± 19.3 g cm−2, respectively. The average sulfate content of carrageenans was found to be significantly different between tissue‐cultured and field‐cultured K. alvarezii with 34.2 ± 10.9 and 7.5 ± 6.7%, respectively. Tissue culture is recommended to produce high quality seedlings by providing optimized culture conditions to the seaweed. This approach can serve as an alternative way to solve the seedling shortage problems currently faced by the seaweed industry.

Micro-propagation of Kappaphycus and Eucheuma : Trends and Prospects

Among the red algae, Kappaphycus and Eucheuma are the two most commercially important carrageenophytes farmed extensively in Southeast Asian countries; they rank top in production in terms of volume of raw material produced. The farming of carrageenophytes has emerged as a successful enterprise and provides a promising, alternative livelihood option for low-income, coastal communities in a number of countries. In 2014, carrageenophyte production worldwide, surpassed other red seaweeds and was placed at the top of the production rankings with 10.99 million MT wet weight (77% of total production of farmed red seaweed) and Indonesia being a major producer. However, over time, the productivity of the crop (carrageenophytes) has declined in some regions due to sourcing of seedlings from single, selected genetic stocks considered to have higher yield potential which resulted in strain fatigue, or loss of vigour. The incidences of disease and epiphytic infestations are on rise in recent times which have severely affected biomass production, as well as the yield and product quality (carrageenan). In order to circumvent the crop productivity issues arising from clonal propagation, the raising of planting materials from spores, derived through the red algal sexual reproductive cycle, has been initiated to support the sustainability of selected, farmed carrageenophytes. Alternatively, in vitro tissue culture techniques have also been explored to not only rejuvenate the vigour of seedlings (i.e. the out-planting material) but also to seek seedlings resilient to stress, disease and epiphytes to act as an invigorated mother stock. These efforts have succeeded to a great extent in the development of appropriate techniques for explant culture, callus induction, callus sub-culture and regeneration to micro-propagules with improved traits. The present chapter briefly summarizes the developments and success achieved in micro-propagation of Kappaphycus and Eucheuma and also provides pointers to both gaps and priority areas for future research required for the advancement of sustainable farming of these carrageenophytes.