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Fucoxanthin is the main carotenoid produced in brown algae as a component of the light-harvesting complex for photosynthesis and photoprotection. In contrast to the complete elucidation of the carotenoid biosynthetic pathways in red and green algae, the biosynthetic pathway of fucoxanthin in brown algae is not fully understood. Recently, two models for the fucoxanthin biosynthetic pathway have been proposed in unicellular diatoms; however, there is no such information for the pathway in brown seaweeds to date. Here, we propose a biosynthetic pathway for fucoxanthin in the brown seaweed, Ectocarpus siliculosus, derived from comparison of carotenogenic genes in its sequenced genome with those in the genomes of two diatoms, Thalassiosira pseudonana and Phaeodactylum tricornutum. Currently, fucoxanthin is receiving attention, due to its potential benefits for human health. Therefore, new knowledge regarding the medical and nutraceutical properties of fucoxanthin from brown seaweeds is also summarized here. 

In Malaysia, the uses of water for domestic, commercial and industrial purposes is increasing considerably, resulting in a rapid increase in the wastewater volume and pollutants. The mariculture industries are also facing the same problems. This research focuses on the impact of shrimp farming activities on the environment. The continuing discharge of contaminants from the pond obviously shows that no concern to conform with environmental regulations and good farming practices. Therefore, an efficient treatment system must be developed to improve the water quality at low operational cost and environmentally viable. In the present study, the performance of Gracilaria changii and Gracilaria edulis as biofilters for nutrients removal from shrimp pond in a laboratory scale and outdoor environment were assessed. The outdoor experiments were conducted in an Outdoor Recirculating Culture System (ORCS). The water flow rate was 200 L/hr. In the laboratory batch culture experiments, both species demonstrated considerably high nutrient removal efficiencies for ammonium, nitrate and phosphate concentrations. The removal efficiencies were 72.5%, 58.8% and 45.9% for G. edulis, and 71%, 56.8% and 43.5% for G. changii, respectively. The mean specific growth rate (SGR) for G. edulis was 3.5 ± 1.0 % day-1, while G. changii was 3.3 ± 0.9 % day-1. As for experiments conducted in ORCS, the nutrient removal efficiencies for ammonium, nitrate and phosphate were 86.2%, 59.3% and 52.0% for G. edulis, and 78.1%, 55.5% and 65.9% for G. changii, respectively. The mean SGR for G. edulis was 3.91 ± 1.0 % day-1 and G. changii was 3.69 ± 0.6 % day-1. The removal efficiency and SGR of G. edulis and G. changii in ORCS were higher compared to the laboratory batch culture experiments. The efficiency of biosand filters (BSF) to reduce total suspended solid, turbidity and chlorophyll-a of shrimp pond water was also assessed. The results showed that total suspended solid, turbidity and chlorophyll-a concentrations decreased significantly. The BSFdepicted 70.6%, 70.0% and 60.0% efficiencies in the reduction of TSS, turbidity and chlorophyll-a, respectively. The integration of shrimp culture with G. edulis in ORCS was conducted as well, and the study proved to be successful. Results showed that shrimp and seaweed grew well in the system. The mean SGR for shrimp and G. edulis were 1.31 ± 0.76 % d-1 and 4.4 % d-1, respectively. High survival rate of shrimp (91%) was observed in the treatment unit. The design considerations, the combination of cultured species and application of G. edulis as biofilter in this study provides useful information for aquaculture field. The findings include improvement of shrimp water quality to an acceptable level that ultimately enhances shrimp and seaweeds productivity and produces an ecologically sustainable treatment and cultivation system. 

The growing world population demands an in- crease in animal protein production. Seaweed may be a valu- able source of protein for animal feed. However, a biorefinery approach aimed at cascading valorisation of both protein and non-protein seaweed constituents is required to realise an eco- nomically feasible value chain. In this study, such a biorefinery approach is presented for the green seaweed Ulva lactuca containing 225 g protein (N × 4.6) kg−1 dry mat- ter (DM). The sugars in the biomass were solubilised by hot water treatment followed by enzymatic hydrolysis and centri- fugation resulting in a sugar-rich hydrolysate (38.8 g L−1 sugars) containing glucose, rhamnose and xylose, and a protein-enriched (343 g kg−1 in DM) extracted fraction. This extracted fraction was characterised for use in animal feed, as compared to U. lactuca biomass. Based on the content of essential amino acids and the in vitro N (85 %) and organic matter (90 %) digestibility, the extracted fraction seems a promising protein source in diets for monogastric animals with improved characteristics as compared to the intact U. lactuca. The gas production test indicated a moderate rumen fermentation of U. lactuca and the extracted frac- tion, about similar to that of alfalfa. Reduction of the high content of minerals and trace elements may be required to allow a high inclusion level of U. lactuca products in animal diets. The hydrolysate was used suc- cessfully for the production of acetone, butanol, ethanol and 1,2-propanediol by clostridial fermentation, and the rhamnose fermentation pattern was studied. 

Wastewater and activated sludge present a major challenge worldwide. Wastewater generated from large and small-scale industries, laundries, human residential areas and other sources is emerging as a main problem in sanitation and maintenance of smart/green cities. During the last decade, different technologies and processes have been developed to recycle and purify the wastewater. Currently, identification and fundamental consid- eration of development of more advanced microbial-based technologies that enable wastewater treatment and simultaneous resource recovery to produce bioenergy, biofuels and other value-added compounds (organic acids, fatty acids, bioplastics, bio-pesticides, bio-surfactants and bio-flocculants etc.) became an emerging topic. In the last several decades, significant development of bioprocesses and techniques for the extraction and recovery of mentioned valuable molecules and compounds from wastewater, waste biomass or sludge has been made. This review presents different microbial-based process routes related to resource recovery and wastewater application for the production of value-added products and bioenergy. Current process limitations and insights for future research to promote more efficient and sustainable routes for this under-utilized and continually growing waste stream are also discussed.