Fresh Algae Research Articles

Effect of desalination of Sargassum algae on its potential use as a stabilizer in sustainable earth-based bricks

Since 2011, Caribbean beaches have been flooded by massive quantities of pelagic Sargassum, causing environmental, health and financial problems. The use of Sargassum ash as a stabilizer in the manufacture of bricks can help mitigate the economic impact of Sargassum grounding by adding value. This study assesses the effect of the Pelagic Sargassum algae desalination process on the properties of the biomass as well as the potential application of their ash as a stabilizer in soil-based bricks. Fresh Sargassum algae was subjected to two cycles of immersion in water, then calcined under different conditions (temperature and time) and characterized. The desalinated Sargassum ash (SA) was used to partially replace cement in the stabilization of earth bricks. Characterization of raw and desalted Sargassum shows a reduction in ash content from 28.44 to 17.25 % after desalination. Furthermore, the thermo gravimetric analysis show a slight reduction in the initial degradation temperature between 204 and 602 °C, which is associated with a reduction in the amount of residual char from 35 % to 27 %. The results of the XRF analysis of the SA showed a very low alumiosilica content (SiO3 + Al2O3 < 4 %), but a significant increase in CaO content after desalination from 21.96 to 50.17 %. The XRD results of the SA are consistent with the XRF analysis which reveals that the desalination process significantly increased the CaCO3 content from 19 to 67 %, while KCl decreased significantly from 26 to 8 %. Furthermore, the characterization of the composites reveal that partial substitution of 10 wt% cement by SA calcined at 700 °C for 2 h has no significant effect on water absorption, density, compressive strength and chemical composition of earth bricks. This material could help reduce pollution linked to the decomposition of sargassum on Caribbean coasts and beaches, as well as greenhouse gas emissions linked to cement production.

Haliotis tuberculata coccinea grow-out performances according to diet and production systems

ABSTRACT Haliotis tuberculata coccinea is a candidate of growing interest to diversify aquaculture in the Canary Islands, principally based on fish production, to improve aquaculture development opportunities. The economic viability of commercial abalone farming depends largely on the rearing system employed and the feeding sources employed during the grow-out culture period. We studied the effects of two land-based culture systems on the growth performance of abalone and the nutritional quality of their tissues, in a crossed design. Recirculated (RAS) and open flow (FLOW) culture systems were compared. Fresh macro algae (FMA) (Gracilaria cornea and Ulva rigida) were compared to manufactured compound feed (CF) and a mixture of both (MIX). Survival rates were high (97–100%) regardless the treatments tested. MIX and FMA diets produced the best results for Shell Growth Rate, Specific growth rates for shell growth (SGRsl) and weight (SGRw) as well as Food Conversion Ratio (FCR). The highest value for feed intake was recorded for the MIX diet. A positive relationship has been observed between the amounts of protein and lipids in diets and the disposition of these in the viscera of animals fed such diets. The rearing system used had no significant effect on growth and nutritional parameters.

Effective removal of microplastics by filamentous algae and its magnetic biochar: Performance and mechanism

In recent years, filamentous algae blooms and microplastics (MPs) pollution have become two major ecological and environmental problems in urban water systems. In order to solve these two problems at the same time, this study explored the loading capacity of MPs on fresh filamentous algae, and successfully synthesized magnetic filamentous algae biochar loading with Fe3O4 by hydrothermal method, with the purpose of removing MPs from water. The magnetic filamentous algal biochar was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and so on. Experiments on adsorption kinetics, adsorption isotherms and optimum pH were carried out to explore the adsorption mechanism of MPs on magnetic filamentous algal biochar. The adsorption kinetics and adsorption isotherm models were evaluated, and the selection criterion for the appropriate model was determined by using the residual sum of squares (RSS) and Bayesian information criterion (BIC). Microscope images revealed that fresh filamentous algae could interact with MPs in the form of entanglement, adhesion and encapsulation. The average load of MPs in filamentous algae samples was 14.1 ± 5 items/g dry weight. The theoretical maximum adsorption capacities of polystyrene MPs (PS-MPs) by raw biochar (A500) and magnetic biochar with Fe3O4 (M2A500) were 176.99 mg/g and 215.58 mg/g, respectively. The adsorbent materials gave better reusability because they could be reused up to five times. Overall, these findings have provided new insights into the use of filamentous algae for in situ remediation of fluvial MPs pollution, as well as feasible strategies for the recycling of algal waste.

Green Synthesis of Copper and Copper Oxide Nanoparticles From Brown Algae Turbinaria Species' Aqueous Extract and Its Antibacterial Properties.

Background Copper and copper oxide nanoparticlessynthesized by green methods have attracted considerable attention due to their environmentally friendly properties and potential applications. Green synthesis involves non-hazardous and sustainable techniques used in the production of a wide range of substances, including nanoparticles, pharmaceuticals, and chemicals. These methods often use different organisms, including bacteria, fungi, algae, and plants, each offering different advantages in terms of simplicity, cost-effectiveness, and environmental sustainability. The environmentally friendly nature of these green synthesis methods responds to the growing need for sustainable nanotechnologies. Brown algae have gained popularity due to their distinct morphological characteristics and diverse biochemical composition. This research focuses on the process of synthesizing copper and copper oxide nanoparticlesfrom the brown algae Turbinaria. It emphasizes the natural ability of the bioactive compounds contained in the algae extract to reduce and stabilize the nanoparticles. The green synthesis of copper and copper oxide nanoparticlesfrom brown algae has demonstrated a wide range of applications, including antibacterial activity. Materials and methods Fresh Turbinaria algae were collected from marine environments to ensure that they were free of contaminants. The algae underwent a purification process to remove impurities and were dried. An aqueous extract was prepared by pulverizing the dried algae and mixing them with distilled water. A copper salt solution utilizing copper nitrate was prepared. The algae extract was mixed with the copper salt solution. There are bioactive compounds in the algae extract that help reduce copper ions, which makes copper and copper oxide nanoparticles come together. The reaction mixture was incubated in a controlled environment to facilitate the growth and enhance the stability of the nanoparticles. To separate the nanoparticles from the reaction mixture, centrifugation was employed, or filtration was done with Whatman filter paper (Merck, Burlington, MA). The nanoparticles were dried to yield a stable powder. Results Copper and copper oxide nanoparticles derived from brown algae extract showed antibacterial effects against Streptococcus mutans,Klebsiella sp.,andStaphylococcus mutans. The scanning electron microscopy (SEM) analysis verified the irregular shape and elemental content of the synthesized copper and copper oxide nanoparticles. The X-ray diffraction (XRD) analysis indicated that the synthesized nanoparticles exhibited a crystallinity nature and were composed of a mixture of copper and copper oxide species, namely face-centered cubic and monoclinic structures. The transmission electron microscopy (TEM) images showed copper and copper oxide nanoparticles that were evenly distributed and had a rectangular shape. They exhibited substantial antimicrobial activity against both Gram-positive and Gram-negative bacteria. Conclusions This study enhances the field of green synthesis techniques by showcasing the adaptability of Turbinaria brown algae to synthesize copper and copper oxide nanoparticles. It underscores the potential advantages of these nanoparticles in terms of their antibacterial properties.

Food web structures of irrigated rice fields estimated from carbon and nitrogen stable isotopes: Special reference to the role of filamentous green algae as a food resource of aquatic consumers

AbstractRice fields are characterized by high algal production and dense mats of filamentous green algae, and they function as habitats for various aquatic organisms. However, how algal production supports the secondary production of aquatic consumers in rice fields has not been assessed. Herein, aquatic food web structures in two adjacent rice fields in northeastern Japan were examined using carbon and nitrogen stable isotope analyses. Filamentous algae often showed higher δ13C values (mean, −23.1‰ to −21.4‰) than other organic matter sources, including particulate organic matter, benthic microalgae, and soil organic matter (−30.1‰ to −25.4‰). A δ13C‐based isotopic mixing model estimated that among 19 taxa of herbivores and omnivores, most taxa depended on filamentous algae‐derived carbon (ca. &gt;30%). Particularly, Peltodytes intermedius larvae, a specialist feeder for filamentous algae, showed the highest reliance (mean, 66.7%–80.0%). The microcrustacean, Ostracoda sp. also utilized a diet consisting of a substantial proportion of filamentous algae‐derived carbon (57.6%). Seven out of 10 carnivorous taxa showed reliance on filamentous algae‐derived carbon by &gt;30%. Particularly, larvae of beetles (Berosus sp., Enochrus sp., and Hydrochara affinis) showed the highest reliance (40.2%–44.3%). They could assimilate filamentous algae‐based carbon by consuming herbivores, such as P. intermedius. Because fresh filamentous green algae were eaten less by aquatic consumers, the herbivores could consume decomposed filamentous algae rather than fresh ones. Our results suggest that filamentous algae are one of the major organic matter sources supporting secondary production in rice field food webs.

SẢN XUẤT SINH KHỐI TẢO Nannochloropsis oculata QUY MÔ HÀNG HÓA TẠI HUYỆN QUỲNH LƯU, NGHỆ AN

The research was conducted to complete technological protocol of biomass production of algae Nannochloropsis oculata with both culture methods in plastic bags and photo-bioreactor systems. The results show that in the nylon bag system, algae reached a peak of biomass density at day-8 of culture with 80 million cells per ml. In the photo-bioreactor systems, algae were higher density (180 million cells per ml), and longer period of culture (15 days of culture) than in plastic bags. The total products of 404.4 kg of fresh concetrated algae and 57.6 kg of dried algae powder which were suitable produced under climate conditions in Nghe An. All the algae products met the quality and requirements for use as food for aquatic animals as well as raw materials for the production of functional foods for humans.

Brine-Processed Caulerpa lentillifera Macroalgal Stability: Physicochemical, Nutritional and Microbiological Properties.

Caulerpa lentillifera is a type of green macroalga that is commonly consumed as fresh seaweed, particularly in Southeast Asia. The effects of different salt types and concentrations on C. lentillifera during brine processing were investigated using table, sea and flower salt at 10-30% levels. The colour and texture of C. lentillifera varied across different treatments. After storage in brine for 12 weeks, lightness (L*) decreased, greenness (a*) decreased and yellowness (b*) increased while firmness increased in all treatments compared to fresh algae. The nutritional composition did not change significantly over time. To ensure the safety and quality of seaweed for consumption, the optimal salt level for brine processing should not exceed 30% table salt. The morphology and elements contained in different types of salt were also observed, and the microbiological safety of seaweed was evaluated. The popularity of Caulerpa macroalgae is rapidly increasing among consumers, leading to a growing demand for ready-to-eat Caulerpa products. However, food safety and security standards must be maintained.

Monitoring holopelagic Sargassum spp. along the Mexican Caribbean coast: understanding and addressing user requirements for satellite remote sensing

Massive influxes of holopelagic Sargassum spp. (Sargassum natans and S. fluitans) have been causing major economic, environmental and ecological problems along the Caribbean coast of Mexico. Predicting the arrival of the sargassum as an aid to addressing these problems is a priority for the government, coastal communities and the society; both mitigating the impacts and providing opportunities for its use. Lack of data concerning precise locations and times of sargassum beachings means that public and private funds are being spent inefficiently and most actions are reactive. The dynamic nature of sargassum beachings/influxes render conventional ground-based monitoring insufficient. Earth observation and cloud-based processing services offer tools to track, quantify and understand sargassum beaching remotely in a frequent, systematic and reliable manner with the temporal and spatial resolutions required for its management. In order to find the right solutions to address this problem, in this paper the needs and requirements of stakeholders are taken into consideration for the development of an Earth observation-based service to monitor sargassum along the Mexican Caribbean coast. Routine monitoring of sargassum over a large area will be cost effective and help mitigate the negative effects of sargassum influxes. The combination of imagery from Planet, specifically their SuperDove systems that provide daily data at 3 m spatial resolutions, with the freely available EU Copernicus data would be useful for many different stakeholders and potential users. A prototype of the service is presented, based on the main user requirements. The system would enable public and private organizations to allocate resources appropriately in affected areas quickly and efficiently, thereby minimizing economic, social and environmental impacts and enhancing the resilience of local communities. It would also assist the sargassum industry in the collection of fresh algae for onward processing. The system could easily be implemented for similar types of environmental monitoring in the Greater Caribbean and beyond.

Thallium-mediated NO signaling induced lipid accumulation in microalgae and its role in heavy metal bioremediation

Thallium (Tl+) is a trace metal with extreme toxicity and is highly soluble in water, posing a great risk to ecological and human safety. This work aimed to investigate the role played by Tl+ in regulating lipid accumulation in microalgae and the removal efficiency of Tl+. The effect of Tl+ on the cell growth, lipid production and Tl+ removal efficiency of Parachlorella kessleri R-3 was studied. Low concentrations of Tl+ had no significant effect on the biomass of microalgae. When the Tl+ concentration exceeded 5 μg L−1, the biomass of microalgae showed significant decrease. The highest lipid content of 63.65% and lipid productivity of 334.55 mg L−1 d−1 were obtained in microalgae treated with 10 and 5 μg L−1 Tl+, respectively. Microalgae can efficiently remove Tl+ and the Tl+ removal efficiency can reach 100% at Tl+ concentrations of 0–25 μg L−1. The maximum nitric oxide (NO) level of 470.48 fluorescence intensity (1 × 106 cells)−1 and glutathione (GSH) content of 343.51 nmol g−1 (fresh alga) were obtained under 5 μg L−1 Tl+ stress conditions. Furthermore, the exogenous donor sodium nitroprusside (SNP) supplemented with NO was induced in microalgae to obtain a high lipid content (59.99%), lipid productivity (397.99 mg L−1 d−1) and GSH content (430.22 nmol g−1 (fresh alga)). The corresponding analysis results indicated that NO could participate in the signal transduction pathway through modulation of reactive oxygen species (ROS) signaling to activate the antioxidant system by increasing the GSH content to eliminate oxidative damage induced by Tl+ stress. In addition, NO regulation of ROS signaling may enhance transcription factors associated with lipid synthesis, which stimulates the expression of genes related to lipid synthesis, leading to increased lipid biosynthesis in microalgae. Moreover, it was found that the change in Tl+ had little effect on the fatty acid components and biodiesel properties. This study showed that Tl+ stress can promote lipid accumulation in microalgae for biodiesel production and simultaneously effectively remove Tl+, which provided evidence that NO was involved in signal transduction and antioxidant defense, and improved the understanding of the interrelation between NO and ROS to regulate lipid accumulation in microalgae.

Extraction of Mycosporine-like Amino Acids and Proteins from the Agarophyte Gelidium corneum Using Pulsed Power Techniques

Gelidium corneum (syn. sesquipedale) is an industrially and ecologically important species of red alga used for the production of high-quality agar. However, the species is also of growing interest for the production of other valuable compounds, such as mycosporine-like amino acids (MAAs), with potential cosmeceutical and biomedical applications. Novel methods using two pulsed power techniques, high-voltage electrical discharges (HVED) and pulsed electrical fields (PEF), were evaluated for efficacy of MAA extraction. Algal suspensions were prepared at two ratios (1:20 and 1:40 w:v). Four different extraction protocols were compared: (i) high-voltage electrical discharges, (ii) pulsed electric fields, (iii) maceration at room temperature, and (iv) maceration at 50 °C. The algae were treated in three states: freshly harvested, dried, and powdered. HVED and PEF treatments were effective when performed on fresh algae, and in particular the HVED treatment resulted in yields of MAAs twenty times higher than the control: 0.81 ± 0.05 mg/gDry Weight (DW) vs. 0.037 ± 0.002 mg/gDW. This effect was not observed to the same extent when the algae were dried or powdered, although HVED remained the most selective method overall.

Mathematical model validation of floating PV parks impact on the growth of green algae using experimental chamber

ABSTRACT The demand for clean energy increases around the globe and for that purpose the need for new renewable installations increases. Floating photovoltaic power plants are being increased to accommodate the extraordinary usage of active land. These solar plants offer new investment opportunities for clean energy producers, but the rise of floating photovoltaic power plants is impacting marine ecosystems. This study aims to gauge the growth of green algae that is affected due to floating power plants by using a mathematical decay model and experimental results. A mathematical model is applied that consists of an ordinary differential equation for green algae decay estimation due to the unavailability of a light source. Additionally, an experimental chamber is constructed to create an artificial environment with an absence of high irradiance to determine the algal growth. Different sensors are installed that include temperature, humidity, and lux for data logging on each instance. The fresh green algae were kept in the experimental chamber to measure the decay rate. The result shows that the weight of fresh green algae drops from 40.9 to 37.7 g and the color transformed from green to dark brown, which shows the decrement in chlorophyll level in the period of 7 days. The mathematical model is simulated in MATLAB that validates the experimental results which show the decrement in NADPH concentration at minimum irradiance. Linear regression analysis was applied to the quantitative data obtained during the experimentation process that shows a linear relationship between a number of days and the decay of algae in the chamber. The experimental results also concluded that not only green algae were affected, but underwater oxygen levels were also reduced. Therefore, it is recommended to have a complete marine environmental analysis before the installation of a huge floating photovoltaic power plant.

Bioactive compounds from fresh water green macro algae of Ganga water

Bioactive compounds from fresh water green macro algae of Ganga water

Molecular Identification of Brown Algae Sargassum sp. from the Lombok Coastal Waters

Sargassum is a well-known genus of brown algae in Indonesia that has long been investigated due to its economic importance. To support its biological research, it is important to identify and classify the species studied. Morphological identification had greatly contributed to taxonomy, however, it cannot distinguish Sargassum species accurately due to its plasticity. The current study aims to identify Lombok Sargassum molecularly using an ITS2 DNA barcode. Fresh algae were collected from Ekas Bay (EB) and Aan Cape (AC) in Lombok. DNA was first purified, and then its gene product was amplified using ITS2 primers. DNA sequences were examined and traced using the Basic Local Alignment Search Tool (BLAST). DNA sequences were processed in MEGA-X to reconstruct the phylogenetic tree and estimate the genetic distance. Three species were identified based on the BLAST results: Sargassum cf granuliferum, Sargassum polycystum, and Sargassum oligocystum. The base length obtained ranged from 521 to 637 bp, with a similarity percentage of 99.25 to 100%. The phylogenetic tree exhibited each recognized Sargassum species was clustered with the same species from the gene bank. Interspecies genetic distance was 0,000-0,0039, while amongst Sargassum species it's 0,0136-0,2395. The genetic distance between Sargassum and Ulva adherens (outgroup) was &gt;1. Sargassum species found in Lombok were closely related to other similar species in the GenBank.

TAXONOMIC STUDIES OF FRESH WATER ALGAE FROM CHISHTIAN CITY, DISTRICT BHAWALNAGAR

Chishtian city was being explored for the collection of fresh water algae in the present study and for those purpose 12 samples of fresh algae from different areas was being collected. From those samples total 28 species was being collected that belong to 16 genera, 11 families, 7 orders and total 4 phylum including, Cyanophycota, Volvocophycota, Bacillariophycota and Chlorophycota. Those samples were being collected from September 2019 to December 2019. After they were classified and identified taxonomically upto species level by using Shameel classification [25,26]. Those 28 species that are being obtained in the total research work: Kingdom Monera has been acknowledged with phylum one; Cyanophycota that omits two classes, two orders, two families four genera and eight species that were following; Chroococus turgidus, Merismopedia punctate, Oscillatoria rubescens, O. priencp, O. tenuis, O. ornate, Spirulina gigantea and Arthospira platensis. Kingdom Protista has been identified with two phylum; Volvocophycota and Bacillariophycota with three classes, four orders, eight families, 11 genera and 18 species which were following; Hydrodictyon reticulatum, Scenedesmus armatus, S. dimorphus, S. bijuga, Cosmerium botrytis, C. microsphinctum, C. pseudopyramiolatum, Closterium turgidum, Fragilaria ulna, F. crotonensis, Ghomphonemia ghosea, Navicula exigua, Nitzschia acicularis, Gyrosigma acuminatum, G. scalproides, Cymbella ventricosa, Cyclotella operculata, C. meneghiniana. Kingdom protoctista have one phylum; Chlorophycota that have 1 class, one order, one family and two species that are following, Spirogyra pratensis and S. acquinoctialis.

Statistical optimization for simultaneous removal of methyl red and production of fatty acid methyl\xa0esters using fresh alga Scenedesmus obliquus

Microalgae are a diverse group of microorganisms, the majority of which are photosynthetic in nature. Microalgae have different applications, the most important of which is the biological treatment of wastewater. Microalgae grow in various types of wastewater, such as wastewater polluted by Azo dyes, due to microalgae using wastewater as a culture medium, which contains many nutrients like nitrogen, phosphate, and carbon sources. Microalgae grow in various types of wastewater, such as wastewater polluted by Azo dyes, due to microalgae using wastewater as a culture medium, which contains many nutrients like nitrogen, phosphate, and carbon sources. So, microalgae are used for bioremediation of wastewater due to the efficiency of growing in wastewater and for the high production of lipids followed by trans-esterification to biodiesel. Face-centered central composite design (FCCCD) was used to determine the factors that have the most significant impact on the simultaneous decolorization of methyl red and lipid production by the fresh green alga Scenedesmus obliquus. The predicted results indicated that the alga decolorized 70.15% methyl red and produced 20.91% lipids by using 1 g/L nitrogen, an incubation time of 10 days, a pH of 8, and the concentration of methyl red is 17.65 mg/L. The dry biomasses of S. obliquus were also examined by SEM and FTIR before and after treatment with methyl red. SEM and FTIR showed that the properties of dry S. obliquus were altered after the biosorption of methyl red. According to GC–MS analysis of hexane extracts of S. obliquus, the lipid profile differed before and after methyl red decolorization. The results proved that it is possible to use S. obliquus to remove dyes and produce renewable fuels such as biodiesel. The novelty of this study is that this is the first time in which the effect of nitrogen concentrations in the medium used for algal growth on the removal of dye has been studied.

Changes of DOM and its correlation with internal nutrient release during cyanobacterial growth and decline in Lake Chaohu, China

The seasonal changes in dissolved organic matter (DOM), and its correlation with the release of internal nutrients during the annual cycle of cyanobacteria in the eutrophic Lake Chaohu, China, were investigated from four sampling periods between November 2020 and July 2021. The DOM fluorescence components were identified as protein-like C1, microbial humic-like C2, and terrestrial humic-like C3. The highest total fluorescence intensity (FT) of DOM in sediments during the incubation stage is due to the decomposition and degradation of cyanobacteria remains. The lowest humification of DOM and the highest proportion of C1 in waters during the initial cyanobacterial growth indicate that fresh algae are the main source. The highest molecular weight of DOM and FT of the C2 in sediments during cyanobacterial outbreaks indicate the concurrent deposition of undegraded cyanobacterial remains and microbial degradation. The components of DOM are affected mainly by the dissolved total phosphorus in waters, while the temperature drives the annual cycle of cyanobacteria. The decreasing C1 in sediments and increasing nutrients in waters from the cyanobacterial incubation to outbreak indicate that mineralization of algal organic matter contributes importantly to the release of internal nutrients, with the strongest release of phosphorus observed during the early growth of cyanobacteria. The humic-like C2 and C3 components could also affect the dynamics of internal phosphorus through the formation of organic colloids and organic–inorganic ligands. The results show that the degradation of DOM leads to nutrients release and thus supports the continuous growth of cyanobacteria in eutrophic Lake Chaohu.

Acute damage from the degradation of Ulva prolifera on the environmental microbiota, intestinal microbiota and transcriptome of Japanese flounder Paralichthys olivaceus

Green tide outbreaks caused by overgrowth of Ulva prolifera in the Yellow Sea of China can cause serious ecological stress with concomitant economic hardships, especially to marine fisheries. In this study, short-term effects (14 days) were evaluated using fresh algae U. prolifera (FU), and a 7-day assessment of the effects of decomposing U. prolifera (DU) algal effluent was conducted to determine the effects on the environmental and intestinal microbiota, intestinal transcriptome and mortality of the commercial marine benthic fish, Japanese flounder (Paralichthys olivaceus). The results revealed that algal degradation altered the microbial community structure of fish farm water and fish intestines and increased the relative abundance of the pathogens Flavobacteriaceae in water and Vibrio in fish intestines. Fish intestinal tissue structure appeared to be damaged, as indicated in pathological sections, and transcriptome analysis showed intestinal inflammation after exposure, which may have caused an increase in fish mortality. The degradation of U. prolifera led to a bloom of potential pathogenic bacteria and the inflammation of fish intestines, which resulted in disease in the flounder population that reduced fish harvests and might pose a potential health threat.

Hyperosmotic stress-induced microtubule disassembly in Chlamydomonas reinhardtii

BackgroundLand plants respond to drought and salinity by employing multitude of sophisticated mechanisms with physiological and developmental consequences. Abscisic acid-mediated signaling pathways have evolved as land plant ancestors explored their habitats toward terrestrial dry area, and now play major roles in hyperosmotic stress responses in flowering plants. Green algae living in fresh water habitat do not possess abscisic acid signaling pathways but need to cope with increasing salt concentrations or high osmolarity when challenged with adverse aquatic environment. Hyperosmotic stress responses in green algae are largely unexplored.ResultsIn this study, we characterized hyperosmotic stress-induced cytoskeletal responses in Chlamydomonas reinhardtii, a fresh water green algae. The Chlamydomonas PROPYZAMIDE-HYPERSENSITEVE 1 (PHS1) tubulin kinase quickly and transiently phosphorylated a large proportion of cellular α-tubulin at Thr349 in G1 phase and during mitosis, which resulted in transient disassembly of microtubules, when challenged with > 0.2 M sorbitol or > 0.1 M NaCl. By using phs1 loss-of-function algal mutant cells, we demonstrated that transient microtubule destabilization by sorbitol did not affect cell growth in G1 phase but delayed mitotic cell cycle progression. Genome sequence analyses indicate that PHS1 genes evolved in ancestors of the Chlorophyta. Interestingly, PHS1 genes are present in all sequenced genomes of freshwater Chlorophyta green algae (including Chlamydomonas) but are absent in some marine algae of this phylum.ConclusionPHS1-mediated tubulin phosphorylation was found to be partly responsible for the efficient stress-responsive mitotic delay in Chlamydomonas cells. Ancient hyperosmotic stress-triggered cytoskeletal remodeling responses thus emerged when the PHS1 tubulin kinase gene evolved in freshwater green algae.

Assimilation of Particular Organic Matter and Dissolved Organic or Inorganic Compounds by Cribroelphidium selseyense (Foraminifera)

Marine carbon and nitrogen processing through microorganisms’ metabolism is an important aspect of the global element cycles. For that purpose, we used foraminifera to analyze the element turnover with different algae food sources. In the Baltic Sea, benthic foraminifera are quite common and therefore it is important to understand their metabolism. Especially, Cribroelphidium selseyense, also occurring in the Baltic Sea, has often been used for laboratory feeding experiments to test their effect on carbon or nitrogen turnover. Therefore, foraminifera were collected from the Kiel Fjord and fed with six different algal species in two qualities (freeze-dried algae vs. fresh algae, all 13C- and 15N-labeled). Also, labeled dissolved inorganic C and N compounds and glucose were offered to the foraminifera to test direct assimilation of dissolved compounds (carbon and nitrogen) from the water column. Our experiments showed that after 15 days of incubation, there were highly significant differences in isotope labeling in foraminifera fed with fresh algae and dry algae, depending on algal species. Further, different algal species led to different 13C and 15N enrichment in the studied foraminifera, highlighting a feeding preference for one diatom species and an Eustigmatophyte. A significant carbon assimilation from HCO3– was observed after 7 days of incubation. The N assimilation from NH4+ was significantly higher than for NO3– as an inorganic N source. The uptake of glucose showed a lag phase, which was often observed during past experiments, where foraminifera were in a steady state and showed no food uptake at regular intervals. These results highlight the importance of food quality on the feeding behavior and metabolic pathways for further studies of foraminiferal nutrition and nutrient cycling.

The use of artificial feed in Haliotis squamata farming in submerged cage culture system at Lae-Lae island, Makassar

This study investigated the use of a combined formula of artificial feed and fresh marine algae Gracilaria sp in a submerged cage culture system and its effect on Haliotis squamata relative growth and survival rates. The experiment was performed in Lae-Lae Island, Makassar from May to October 2016. The sample Abalone juvenile larvae were 1.5 cm in size and stocked at a density of 30 pcs/cage. The cage size was 30 cm x 15 cm x 7 cm and equipped with a 2-inch Paralone pipe. This experiment employed a completely random design (CRD) with 3 treatments and 3 replicates. The applied treatment included the combination of artificial feed and fresh marine algae Gracilaria sp. Each treatment included: A. 25% artificial feed + 75% fresh marine algae, B. 50% artificial feed + 50% fresh marine algae, C. 75% artificial feed + 25% fresh marine algae, and was given at the proportion of 20% of the abalone's weight. The results of the study indicated that the use of a combined artificial feed with fresh marine algae (Gracilaria sp.) had no significant effect on relative growth and survival rates of Haliotis squamata. Although feed treatment did not significantly affect the relative growth and survival rate, descriptively, treatment A contributed to the most optimal relative growth and the survival rate compared to treatments B and C.