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The red alga Pyropia yezoensis is an economically important marine crop whose life cycle includes two distinct stages: conchocelis and blades. These two types of thalli live in significantly different environments and have distinct shapes and physiological features. The photosynthetic apparatus of red algae, especially the light harvesting antenna, is unique. However, little is known about the photosynthetic apparatus of P. yezoensis. We studied the composition and organization of thylakoid membranes in conchocelis and blades of P. yezoensis and found that the photosynthetic complexes differed between the two stages. Conchocelis had much higher photosystem I (PSI)/ photosystem II and PSI/Cytochrome b6/f ratios compared with blades. Additionally, a macromolecular protein complex that bound with lutein and Chlorophyll a was detected in conchocelis but not in blades. The number and types of light harvesting complex subunits associated with PSI and the corresponding pigment binding also varied between conchocelis and blades. These differences are an important strategy that allows the two P. yezoensis stages to adapt to various environments.

This study investigated the large-scale use of the red macroalga Gracilaria tenuistipitata to extract partially purified R-phycoerythrin in combination with the sequential extraction of agar. The main objective was to investigate the purification of R-PE, the extraction of agar and treatment of wastewater from the whole extraction process using the green macroalga Ulva prolifera. Results showed that the processing of 1 kg fresh biomass of G. tenuistipitata yielded a 30.34 μg/g R-phycoerythrin (purification ratio > 4) with 13.83% extraction efficiency. Initial phycobiliprotein extraction had no effect on the agar yield. The physicochemical properties of the agar had industrial applications. This method of extraction reduced the water volume and alkali requirement compared with that from direct extraction from algae. In addition, the removal rates (mean ± standard deviation) from wastewater of BOD, COD, total nitrogen, inorganic nitrogen, ammonia nitrogen, nitrate, nitrite, total phosphorus and inorganic phosphorus were 28.34 ± 0.10%, 23.50 ± 3.47%, 45.59 ± 6.31%, 63.82 ± 2.94%, 40.77 ± 0.95%, 74.06 ± 5.63%, 70.37 ± 2.59%, 65.26 ± 5.77%, and 72.40 ± 5.43% after the treatment with 2 days respectively. This extraction and subsequently eco-friendly wastewater treatment method could have practical application in the agar industry.

Ulva sp. is a large intertidal species of green algae that has been a causative species in green tide in the Qingdao sea area of China since 2008. To explore the physiological basis of outbreaks, we investigated the photosynthetic carbon sequestration mechanism of Ulva sp. Growth and breeding capacity, chlorophyll fluorescence parameters, chlorophyll content, and enzyme activities of carbonic anhydrase and other important enzymes in the C4 pathway were measured when different inorganic carbon sources were provided (0, 400, 1500, 20,000 μL·L−1 of CO2 or HCO3−). When CO2 was absent (0 μL·L−1 CO2), chlorophyll fluorescence parameters [Fv/Fm, Y (II), Y(I)] and chlorophyll content decreased significantly, but NPQ parameters and MDH and PEPC enzyme activities increased significantly and PEPCK enzyme activity was not affected significantly. When HCO3− was added, chlorophyll content and NAD-ME enzyme activity decreased significantly. These results indicated that lack of CO2 could stimulate photoprotection of Ulva sp. containing decreasing the synthesis of chlorophyll and reducing the PSII reaction center of the open state. Ulva sp. may not have the PEPCK C4 type CCM and might use the NAD-ME C4 type CCM to tolerate the stress caused by the lack of CO2.

Hydrogen is recognized as a promising fuel for the future because it is renewable, environmentally harmless and cost-effective. Systematic research on the process of hydrogen production is important for increasing hydrogen yield and identification of suitable strains of bacteria. We investigated the hydrogen production pathways of Enterobacter cloacae. The maximum hydrogen yield was -707 ml L-1, the H-2 content of the gasphase was in the range 30-35% and the overall rate of hydrogen production was -70.70 ml h(-1) L-1. Ethyl alcohol and 2,3-butanediol were the major fermentative products, indicating the hydrogen-producing fermentation pathway of E. cloacae was the 2,3butanediol pathway. Proteins and enzymes involved in the 2,3-butanediol pathway were generally detected by proteomics analysis, providing further evidence for the presence of the 2,3-butanediol pathway in E. cloacae. Both C-13 labeling experiments and proteomics analysis indicated the Embden-Meyerhof-Pamas (EMP) pathway was the major pathway and the hexose monophosphate (HMP) pathway had a weaker role, or did not participate, in glucose catalysis in E. cloacae. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

The attachment of Ulva prolifera to Pyropia rafts can cause severe economic losses during the cultivation of Pyropia because it can reduce the yield, harvest, and quality of the Pyropia. The existing methods for removing U. prolifera from the Pyropia raft have many limitations, such as low removal efficiency, Pyropia damage, and environmental pollution. In this study, we developed method that can effectively remove U. prolifera attached to the raft during Pyropia cultivation. After 3 h of citric acid (pH 4.0) and high light treatment (1200 μmol photons m2− s1−), followed by recovery in seawater for 24 h, the U. prolifera was completely dead, but the Pyropia was still active. We also studied the response mechanism of U. prolifera to acid and high light, and our results showed that under acidic and high light conditions, H+ may penetrate the interior of U. prolifera cells, causing obvious synergistic injury with high light to PSII in U. prolifera. The degradation of Cyt f in this process severely hindered electron transport and slightly reduced PSI activity. Acid also destroyed the U. prolifera photoprotective mechanism, as shown by the high non-photochemical quenching (NPQ) values and xanthophyll cycle pigment contents. This study provides a solid base for further research on optimizing the treatment of U. prolifera and improving its removal efficiency.