Dinoflagellates blooms have resulted in adverse effects on the marine ecosystem and public health. However, little is known about the cell cycle regulation mechanisms in situ. We compared the protein profiles of Prorocentrum donghaiense at different cell cycle phases and identified differentially expressed proteins using iTRAQ-based proteomic approach combining the transcriptomic database. The results showed that cells of P. donghaiense during blooms development completed an integrated cell cycle within 24 hours and a two hours ahead of the laboratory cell cycle was detected. Here, we compared the protein profiles at five time points of the cell cycle phases (early G1, middle G1, late G1, S and G2/M), 2595 of 6118 proteins detected were identified as high-confidence proteins matching two or more peptides and proteins involved in carbohydrate, amino acid metabolism and translation ranked the top three abundant categories. Among them, differential expressions analysis showed that: proteins involved in ribosome, RNA metabolism, ABC transporters were more abundant in the dark cycle, while proteins participating in photosynthesis, carbohydrate metabolism and amino acid biosynthesis resented higher expressions in the light cycle. Moreover, some cell cycle related proteins which may regulate the cell cycle proceeding identified. This study, so far to our knowledge, was for the first time to reveal the potential major biological processes occurring at different cell cycle phases of P. donghaiense blooms in situ, which might provide new insights into the mechanisms regulating the cell cycle and growth of dinoflagellates.

Phosphorus (P) is a major limiting nutrient affecting the growth of phytoplankton in lots of aquatic ecosystem. Much efforts have been done on physiological response to P depletion, but molecular mechanisms are poorly understood. In this study, We compared the protein profile of Alexandrium catenella grown in four controlled levels of phosphate availability, encompassing dissolved inorganic P-replete(DIP), P-deplete(PD), inorganic P-resupplied(DIPR) and dissolved organic P-resupplied (DOPR) conditions using physiological and iTRAQ-based quantitative proteomic approaches. The result showed maximal photochemical efficiency, Fv/Fm maintained high levels and no significant difference among four controlled levels. Alkaline phosphatase (AP) was highly expressed and cell density remained low in the PD culture. AP activity (APA) was drastically reduced in 4 hours in DIPR condition, while APA continued to increase in 4 hours and rapidly decreased after 4 hours in DOPR condition. No significant difference were found in cell density between two groups . Totally 4312 proteins were identified from Alexandrium catenella, and proteins involved in biosynthesis of secondary metabolites, ribosome, glycolysis/gluconeogenesis, protein processing in endoplasmic reticulum and spliceosome pathway were high abundant. Our results showed that Alexandrium catenella can adapt to the environment with P limitation through enhancing P transport and cellular P allocation, and switched to utilize DOP, it shed light on the future proteomic study of other phytoplankton for P.

As an important nutritive element, nitrogen is closely related to the growth of plants, animals and microbiology and various metabolic decided to their bodies. In previous study, we found that the dinoflagellate Prorocentrum lima produced more toxins like okadaic acid (OA) under nitrogen limited condition. However, we remain unknown if there are any other changes except for the content of OA, especial in metabolism associated with OA production. In this paper, to better understand the responses in molecules and cellular level of P. lima to N-limited and provide information on OA synthesis pathway, transcriptome profiling was performed. Total 42798 of unigenes were predicted. Among them, 1055 genes were significantly up-regulated, and 362 genes were down-regulated. Genes related to photosynthesis, porphyrin and chlorophyll metabolism, fatty acid metabolism were down-regulated. In contrast, some genes encoding fatty acid biosynthesis and associated amino acid metabolism were up-regulated. Accordingly, some stress-shock proteins were also up-regulated. Obvious changes in substructure, especially in chloroplast of P. lima cells were found, and content of unsaturated fatty acid increased under N-limited condition in transmission electron microscopy. It is of note that some of ABC transports superfamily, including MDR, ABCB1 and ABCG2 were found in P. lima and were up-regulated under N-limited. Our findings might provide global information for the response or adaptation of P. lima to N-limited.

Genus of Eucalyptus has been demonstrated to be highly phytotoxic towards terrestrial plant. The dinoflagellate Prorocentrum donghaiense Lu is a representative harmful algae which formed recurrent blooms in the coastal waters of China, Japan, and South Korea. This study explored the cytotoxic effect of aqueous extracts from different biological components of Eucalyptus tereticornis, including trunk, branches, leaves and roots, against the noxious alga P. donghaiense and its physiological response. The aqueous extracts of leaves significantly inhibited (p<0.05) the growth of tested algae with obvious dosage response whereas other biological components showed little inhibition effects (p>0.05) even at the highest concentration (0.50 g·L^-1). The chlorophyll fluorescence yield tend to decrease and the parameter Mo that reaction to the change of the acceptor side had significant increased (up to 71% and 59%) after 48 h and 96 h incubation exposed in the 0.50 g·L^-1 leaves aqueous extracts. Both S_m and ΦE_o that indicated electron flow from PSII to PSI in 0.50 g·L^-1 leaves aqueous extracts treatment group decreased significantly compared with the control treatment. The leaves aqueous extracts also triggered the activity of microalgae antioxidant enzymes, such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and the content of Glutathione (GSH) increased significantly at high concentration that may disrupted the cell structure. We concluded that the aqueous extracts of E. tereticornis leaves possess algal-inhibiting ability and could control P. donghaiense bloom as a potential source in the future.

Bisphenol A (BPA) - degrading algal strain was identified as Desmodesmus sp. both by morphological and molecular study. The effects of BPA on growth (OD₆₈₀) and photosynthesis activity (Fv/Fm) of Desmodesmus sp. and its detoxication and biodgradation by algal culture were investigated. Results showed no significant inhibition up to 33 mg L^-1of BPA exposure for initial OD₆₈₀0.2, while a slight suppression at the early stage of test for initial OD₆₈₀0.04, however, nearly complete inhibition till the last 10 days of the study when recovery of growth and photosynthesis were shown for the initial OD₆₈₀0.008. Desmodesmus sp. was able to remove almost all BPA in the concentration ranged from 3 to 33 mg L^-1 for initial OD₆₈₀0.2. Nevertheless, 75%, 82.3% were achieved at 33mg L^-1 by algal cultures at the initial OD₆₈₀0.008 and 0.04, respectively. In the present study, metabolites of BPA were identified. To our knowledge, we first reported 2-hydroxy-3-hydroxymethybisphenol A and its glycoside as the metabolites of BPA hydroxylation and glycosylation. Moreover, we demonstrated that BPA glycosides could be digested to BPA, and also BPA and its derivatives could be cleaved to form monophenols for further mineralization by algal culture. Therefore, we should focus more on the level of BPA glycosides in the environment and algal culture such as Desmodesmus sp. with the ability to degrade BPA completely would be considered to be an appropriate candidate for BPA removal from water environment . In addition, the metabolic pathways of BPA detoxication and biodegradation were proposed in this study.

There are many different social and environmental problems in recent decades, especially for energy shortage and global warming, so the demand of renewable energy is increasing rapidly. In order to solve a global energy crisis, many scientists started to investigate the feasibility of developing different alternatives so as to lower the social-economic-environmental impact. Due to higher turnover rate of microalgae production, many professional parties started to use them as a new potential green energy resource. Many past studies were investigated different ways to increase the productivity of microalgae for biofuel production. So, LED photo-bioreactor was one of the best choices to optimize the productivity. Various Light-emitting diodes (LEDs) light intensity and wavelength mixing ratio with different light wavelengths were employed to explore the effect of LED on microalgae cultivation. Results showed that optical density increased in white, blue, red LED was 88%, 75%, 27% respectively. Besides, white light was the best performance for microalgae growth. However, different wavelength mixing ratio (Red: Blue - 6:0, 5:1, 4:2, 3:3, 2:4, 1:5 and 0:6) had no effect on growth of microalgae in terms of dry biomass production, but monochromic blue light had positive impact on lipid content, the highest yield was produced when blue light was fully illuminated. For the cost aspect, blue light was the lowest energy consumption for microalgae cultivation, but the white light was the most cost-effective one. Based on the above results, a new photo-bioreactor system with the optimal lighting condition will be setup for cultivating a selected microalga, Haematococcus pluvialis (H. pluvialis), so as to produce a high-valued extract astaxanthin in further study.

In order to collect a massive production of microalgae rapidly for commercialization, there are many different types of harvesting technologies developed in recent decades. In literature review, it was found that electro-coagulation-flotation (ECF) method was a feasible method to harvest the microalgae as it was relatively lower cost in operation. In order to optimize the harvesting efficiency with lower energy consumption, six parameters, including (1) material of electrode plates (Aluminum, Iron, Carbon), (2) number of plates, (3) degree of salinity (NaCl), (4) distance between electrode plates, (5) provision of current density and (6) pH value of microalgae culture, affecting the ECF process were investigated. The results showed that aluminum plate electrode had the best performance in microalgae harvesting. Also, the use of three electrode plates, addition of 4 g/L NaCl, shorter distance between electrodes and provision of 1.875 A resulted in the highest harvesting efficiency. Besides, the ECF process at pH 10 could enhance the harvesting efficiency.

Choice of cultivation system, strains of microalgae, pH, carbon dioxide concentration, light intensity and dissolved oxygen level were investigated as these influential factors would affect mass cultivation of microalgae for biodiesel production. Different types of photo-bioreactors were examined in past few decades for optimizing the production of the productivity. Based on a geometric design to enhance the light penetration and mixing rate, a minimal diameter of U-tube design was developed. Results showed that the cultivation of microalgae in U-bended tubular type was better than a vertical type due to higher light penetration with well-mixed water flow.

A wastewater treatment system was designed for treating domestic greywater so as to make a beneficial way in limited freshwater resource in Hong Kong. In this study, the quality of greywater could be improved by three major treatment processes - preliminary, primary and secondary treatments which were designed referring to Hong Kong Shatin sewage treatment processes. A polypropylene filter, nitrification tank, flocculation tank and UV light equipment were applied for removal of suspended solids (>5.0 micron dia.), ammonia, phosphate and pathogens from the greywater. Results showed that the removal efficiency of following parameters, including total suspended solids, ammoniacal-nitrogen, total nitrogen, Ortho-phosphate phosphorus, BOD5 and E-coli, was very high. It could meet the reclaimed water discharge standards of Shek Wu Hui Sewage Treatment Works (Tertiary Treatment). Besides, use of immobilized microalgae can enhance the treatment efficiency.

This study was to design a systematic photo-bioreactor (PBR) for both algae cultivation and wastewater treatment that benefit to human and environment. This vertical-column photo-bioreactor with semi-continuous culture system was applied in this design. In order to optimize the microalgae cultivation, innovative design of LED lighting system (e.g. red, blue and white colour with different photoperiods) was built in. After huge of amount of microalgae was produced, a sedimentation tank was used for harvesting. As the harvested microalgae was used for treating the food waste leachate in the photo-bioreactor system, both physical and chemical factors such as pH, temperature, dissolved oxygen, nitrogen, phosphate and Chemical Oxygen Demand were monitored under data logging system. When running the system, the leachate could be used to supply nitrogen and phosphorus, the main nutrients was required for the cultivation of algae. All of parameters, such as nitrogen, phosphate and its derivatives were removed effectively. The COD and BOD5 were also recorded in lower level after the treatment. Therefore, based on this principle, wastewater could be treated and help for the cell cultivation at the same time. Through this sustainable and environmental friendly system, microalgae could be collected for down-stream product usage.

The effect of nitrogen and phosphorus on growth and lipid content of a freshwater microalgae Chlorella vulgaris were investigated under autotrophic conditions in various culture medium. Nitrogen and phosphorus presented significant effect on biomass and lipid production. The highest lipid content, lipid concentration, and lipid productivity were 53.202%, 287.291 mg L^-1, and 23.457 mg L^-1 day^-1, respectively, obtained under the Bold basal medium - NControlPDeprivation condition. Nitrogen presented significant statistical effect on biomass production. The highest obtained cell density, growth rate and biomass productivity of 2.19 x 10 ⁸ cells mL^-1, 0.257 d^-1 and 72.083 mg L^-1 day^-1, respectively, obtained under the BBM - NControlPlimited condition. This study demonstrated that it was possible to maximize the cell growth and lipid content by altering the medium NP content for producing biodiesel feedstock.

The gross biological dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) production in surface and bottom water along the coasts of the northern South China Sea (SCS) were investigated during summer from July to August, 2000. In the surface water, the averaged concentrations of particulate DMSP (DMSPp) and DMS were 42.60 nM (4.33~100.62 nM) and 2.12 nM (1.01~6.79 nM); and in the bottom water, the mean DMSPp and DMS concentrations were 26.37 nM (3.58~70.38 nM) and 2.09 (0.83~7.34 nM), respectively. Both the contents of DMSPp and DMS significantly varied spatially (P<0.05, n=40), but not vertically (P>0.05, n=40). The highest DMSPp concentration (100.62 nM) was recorded in surface of Shenzhen waters, while the lowest (4.33 nM) was recorded in surface of Zhanjiang waters. DMS fluctuated correspondingly, with the highest value (6.79 nM) occurred in surface of Shenzhen waters, while the lowest (0.83 nM) occurred in bottom water of Nanao Island (Shantou). Correlation analysis further revealed that the production of DMS/DMSPp were not closely related to salinity and chlorophyll a content (P>0.05, n=40), but the bottom seawater DMS positively increased with increasing temperature when it is lower than 28.2 oC (r² = 0.52, P<0.01, n=13), while negatively decreased as temperature further increases (r²=0.86, P<0.01, n=8). Moreover, in surface waters, the light intensity showed a significant positive effect on the DMSPp production (r²=0.37, P<0.01, n=20), with elevated DMSP content under high irradiance. Although no light effect was observed on surface DMS directly, a negative correlation was further found in terms of the DMS percentage (DMS/(DMSPp+DMS)) (r²=0.34, P<0.01, n=20). The sea-to-air fluxes of DMS were estimated to be 0.24~15.07 μmol m^-2 d^-1, with a mean flux of 2.12 μmol m^-2 d^-1 across the coastal area of the northern SCS in summer.

In this work, the particles of two seaweeds, Enteromorpha clathrata (E. clathrata) and Sargassum natans (S. natans), were combusted in a fluidized bed. It was found that while combustion of E. clathrata particles was stable, there was a substantial slagging period during the combustion of S. natans particles. Seaweed and its bottom ash samples were collected, and their pore structures were determined with both mercury intrusion method and N2 adsorption-desorption method. The structural analysis revealed that the number of porosity, pore volume and specific surface area were all increased and the internal pore in ash samples was expanded after combustion. Fractal analysis showed that while the surface of original seaweed was smooth it became irregular and rough after combustion. This study has suggested that the ash of seaweeds with porous structure can be valuable for comprehensive utilization.