Hydrogen production by sequential dark and photofermentation using wet biomass hydrolysate of Spirulina platensis: Response surface methodological approach

Microalgae and cyanobacteria can be used as a potential biomass to produce hydrogen from stored glycogen and starch through fermentation and photofermentation. In this study, the potential of algal biomass i.e. Spirulina platensis hydrolysate as a substrate for sequential fermentative (I-stage) and photo-fermentative (II-stage) biohydrogen production was evaluated. Response Surface Methodology (RSM) was employed to find the optimum photofermentation conditions. From the preliminary optimization experiments, it was found that the significantly affecting factors for H₂ production were pH, dilution fold (D.F.) of fermentate and Fe(II) sulfate concentration during photofermentation (second stage). In the present study, 1% (w/v) Spirulina platensis hydrolyzate produced 23.06 ± 3.63 mmol of H₂ with yield of 1.92 ± 0.20 mmol H₂/g COD reduced. In the second stage experiment 1510 ± 35 mL/l hydrogen was produced using inoculum volume-20.0% (v/v) and inoculum age-48 h of co-culture of Rhodobacter sphaeroides NMBL-01 and Bacillus firmus NMBL-03 under conditions pH-5.95, D.F. of dark fermentate-20.30 folds, Fe(II) sulfate concentration-0.412 μM, temperature-32±2 °C and light intensity-2.5 klux.     

A comprehensive life cycle analysis of cofiring algae in a coal power plant as a solution for achieving sustainable energy

Algae cofiring scenarios in a 360 MW coal power plant were studied utilizing an ecologically based hybrid life cycle assessment methodology. The impacts on the ecological system were calculated in terms of cumulative mass, energy, industrial exergy, and ecological exergy. The environmental performance metrics, including efficiency, loading, and renewability ratios were also quantified to assess the sustainability of cofiring scenarios from a holistic perspective. The analysis results revealed that cumulative mass and ecological exergy consumption were higher for algae cofiring compared to single coal firing due to high material and energy inputs for the algae cultivation. On the contrary, total energy and industrial exergy utilization were reduced with an increasing share of algae cofiring where algae is dried with solar energy. Additionally, natural gas dried algae cofiring scenarios had a lower renewability ratio in comparison with single coal firing. The results of this study are vital for the policy makers to decide on more environmentally friendly algae cofiring options by considering the potential impacts on ecological system.     

Algae as a sustainable energy source for biofuel production in Iran: A case study

Algae can be converted directly into energy, such as biodiesel, bioethanol and biomethanol and therefore can be a source of renewable energy. There is a growing interest for biodiesel production from algae because of its higher yield non-edible oil production and its fast growth that does not compete for land with food production. About 50% of algae weight is oil that this lipid oil can be used to make biodiesel. Algae is capable of yielding 30 times more oil per acre than the crops currently used in biodiesel production. Processes for biodiesel production from algae-oil are similar to food and non-food crops derived biodiesel processes. Because of disadvantages of fossil fuels, renewable energy sources are getting importance for sustainable energy development and environmental protection. Among the renewable sources, Iran has high biofuel energy potential. The Iranian government is considerable attention to the utilization of renewable energy, especially biofuels. Iran has enough land in order to algae cultivation that does not compete with food production. A salt lake (Lake Orumieh) in Iran's West Azarbaijan province, Maharlu salt lake in Iran's Fars province, Qom salt lake in Iran's Qom province have given rise to a new species of algae for biofuel. Algae are frequent in the shallow-marine lime stones in Zagros Mountains in north of Fars province. Greenish blooms of algae can be seen in the Persian Gulf and Caspian Sea, south and north of Iran respectively. This study presents a brief introduction to the resource, status and prospect of algae as a sustainable energy source for biodiesel production in Iran. The main advantages of using algae for biodiesel production in Iran are described.     

绿色生态环境材料湖藻吸音减振作用机理的研究

湖藻是水体中的一种浮游生物，是鱼虾的基本饲料。在显微状态下，它显多孔海绵状，由于其结构的特殊性，在军事上有重要应用价值。本文通过对这种新型生态材料吸音减振作用机理的研究，推导建立了其吸音减振数学模型，为该材料的实际应用奠定了理论基础。     

生物进化中的多肽生长因子探讨

长期以来，人们认为多肽生长因子只能来自人体与哺乳动物的特异组织或除体。本文研究发现一类低等微体生物（藻类）的蛋白质中，存在一种能强烈刺激鼠Ｈ４肝癌细胞生长的组分。其分子量＞３５００道尔顿，可能是一种多肽生长因子。本文进而探讨了多肽生长因子在生物进化系统中的可能分布。     

Lipidomic Analysis: From Archaea to Mammals

Lipids are among the most important organic compounds found in all living cells, from primitive archaebacteria to flowering plants or mammalian cells. They form part of cell walls and constitute cell storage material. Their biosynthesis and metabolism play key roles in faraway topics such as biofuel production (third‐generation biofuels produced by microorganisms, e.g. algae) and human diseases such as adrenoleukodystrophy, Zellweger syndrome, or Refsum disease. Current lipidomic analysis requires fast and accurate processing of samples and especially their characterization. Because the number of possible lipids and, more specifically, molecular species of lipids is of the order of hundreds to thousands, it is necessary to process huge amounts of data in a short time. There are two basic approaches to lipidomic analysis: shotgun and liquid chromatography–mass spectometry. Both methods have their pros and cons. This review deals with lipidomics not according to the type of ionization or the lipid classes analyzed but according to the types of samples (organisms) under study. Thus, it is divided into lipidomic analysis of archaebacteria, bacteria, yeast, fungi, algae, plants, and animals.     

Properties and Biotechnological Applications of Acyl‐CoA:diacylglycerol Acyltransferase and Phospholipid:diacylglycerol Acyltransferase from Terrestrial Plants and Microalgae

Triacylglycerol (TAG) is the major storage lipid in most terrestrial plants and microalgae, and has great nutritional and industrial value. Since the demand for vegetable oil is consistently increasing, numerous studies have been focused on improving the TAG content and modifying the fatty‐acid compositions of plant seed oils. In addition, there is a strong research interest in establishing plant vegetative tissues and microalgae as platforms for lipid production. In higher plants and microalgae, TAG biosynthesis occurs via acyl‐CoA‐dependent or acyl‐CoA‐independent pathways. Diacylglycerol acyltransferase (DGAT) catalyzes the last and committed step in the acyl‐CoA‐dependent biosynthesis of TAG, which appears to represent a bottleneck in oil accumulation in some oilseed species. Membrane‐bound and soluble forms of DGAT have been identified with very different amino‐acid sequences and biochemical properties. Alternatively, TAG can be formed through acyl‐CoA‐independent pathways via the catalytic action of membrane‐bound phospholipid:diacylglycerol acyltransferase (PDAT). As the enzymes catalyzing the terminal steps of TAG formation, DGAT and PDAT play crucial roles in determining the flux of carbon into seed TAG and thus have been considered as the key targets for engineering oil production. Here, we summarize the most recent knowledge on DGAT and PDAT in higher plants and microalgae, with the emphasis on their physiological roles, structural features, and regulation. The development of various metabolic engineering strategies to enhance the TAG content and alter the fatty‐acid composition of TAG is also discussed.     

A stochastic Lagrangian approach for simulating the effect of turbulent mixing on algae growth rate in a photobioreactor

It is well known that mixing caused by fluid turbulence can cause significantly increased growth rate of algae in photobioreactor flows under certain conditions. In general, flows in which the light penetrates into only a small fraction of the reactor flow field have the largest growth rate enhancement in the presence of fluid mixing. The current paper seeks to develop a computationally efficient prediction method for algae growth rate in practical photobioreactors using a combination of commercially available RANS turbulence models and a stochastic Lagrangian model for the turbulence fluctuations. The stochastic Lagrangian algae growth rate model is first validated by comparison with simulations of algae growth rate obtained by direct numerical simulation of homogeneous turbulence. We then demonstrate the stochastic Lagrangian model approach for prediction of algae growth rate in turbulent pipe flow, which is representative of the primary photoreaction component in many tubular algae production facilities. The results illustrate how algae growth rate increases as the pipe flow Reynolds number is increased.