Selection Of Algae Research Articles

Characterization and hydrolysis optimization of Sargassum cinereum for the fermentative production of 3G bioethanol

Third-generation biofuels are gaining commercial interest because of the rapid growth rate, high productivity of nutrients, and the carbon dioxide sequestration ability of the feedstock, algae. But the selection of algae, cultivation method, and pretreatment techniques remain challenging. The present work describes the high suitability of brown seaweed as a promising feedstock for the production of bioethanol. Sargassum cinereum is a carbohydrate-rich and fast-growing brown seaweed in all marine environments and abundantly available in Gulf of Mannar, India. Proximate, ultimate, and biochemical analysis has demonstrated the potential carbohydrates in the brown seaweed composition. Preliminary studies on S. cinereum revealed that the H2SO4-assisted hydrolysis had produced more fermentable sugars than the tested. A statistical optimization method with 16 runs was employed to optimize the H2SO4 loading concentration (% w/v), residence time (min), and incubation temperature (°C) for the enhancement of fermentable sugars from the biomass. Optimization results have shown a 133% increase in reducing sugars yield. Furthermore, the obtained sugars were fermented to ethanol at a yield of 0.465 ± 0.024 g ethanol/reducing sugars using Saccharomyces cerevisiae MTCC170. The observed high ethanol yield from seaweed sugars was closer to the theoretical yield based on glucose as a substrate.

A rapid live-cell ELISA for characterizing antibodies against cell surface antigens of Chlamydomonas reinhardtii and its use in isolating algae from natural environments with related cell wall components.

BackgroundCell walls are essential for most bacteria, archaea, fungi, algae and land plants to provide shape, structural integrity and protection from numerous biotic and abiotic environmental factors. In the case of eukaryotic algae, relatively little is known of the composition, structure or mechanisms of assembly of cell walls in individual species or between species and how these differences enable algae to inhabit a great diversity of environments. In this paper we describe the use of camelid antibody fragments (VHHs) and a streamlined ELISA assay as powerful new tools for obtaining mono-specific reagents for detecting individual algal cell wall components and for isolating algae that share a particular cell surface component.ResultsTo develop new microalgal bioprospecting tools to aid in the search of environmental samples for algae that share similar cell wall and cell surface components, we have produced single-chain camelid antibodies raised against cell surface components of the single-cell alga, Chlamydomonas reinhardtii. We have cloned the variable-region domains (VHHs) from the camelid heavy-chain-only antibodies and overproduced tagged versions of these monoclonal-like antibodies in E. coli. Using these VHHs, we have developed an accurate, facile, low cost ELISA that uses live cells as a source of antigens in their native conformation and that requires less than 90 minutes to perform. This ELISA technique was demonstrated to be as accurate as standard ELISAs that employ proteins from cell lysates and that generally require >24 hours to complete. Among the cloned VHHs, VHH B11, exhibited the highest affinity (EC50 < 1 nM) for the C. reinhardtii cell surface. The live-cell ELISA procedure was employed to detect algae sharing cell surface components with C. reinhardtii in water samples from natural environments. In addition, mCherry-tagged VHH B11 was used along with fluorescence activated cell sorting (FACS) to select individual axenic isolates of presumed wild relatives of C. reinhardtii and other Chlorphyceae from the same environmental samples.ConclusionsCamelid antibody VHH domains provide a highly specific tool for detection of individual cell wall components of algae and for allowing the selection of algae that share a particular cell surface molecule from diverse ecosystems.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0244-0) contains supplementary material, which is available to authorized users.

Feeding rates of Littorina striata and Osilinus atratus in relation to nutritional quality and chemical defenses of seaweeds

Algae frequently suffer attack by herbivores and in some cases complete destruction has been observed. Despite the role of herbivores in structuring marine algal communities, herbivore food choice and the algal traits that herbivores use to choose foods are poorly documented. There has been much discussion and disagreement regarding the best method of assessing food preference. Experiments designed to detect preferential feeding involve offering a selection of food types to one or more individual consumers. Ideally, the potential foods are presented simultaneously to the consumer within a single experimental arena so that the consumer has the opportunity to express a dietary choice. However, some experimental designs allow individual consumers to feed for a constant time on individually presented alternative foods, which permits comparisons of feeding rates on these different foods. Such an experiment is not a true feeding preference experiment because no food choice is provided, but the results can reflect differences in attractiveness or palatability of various potential foods that may also be expressed when choices are offered. In this work, discrimination in selection of algae was tested in two invertebrate species common on intertidal rocks in Gran Canaria (Littorina striata and Osilinus atratus) by measuring their feeding rates on 20 common algal species in no-choice laboratory experiments. The algae represented the major floral elements of the local intertidal community. L. striata and O. atratus exhibited high feeding rates on Enteromorpha muscoides and Ulva rigida, whereas Alsidium corallinum and Laurencia corrallopsis were refused. The majority of algal species were readily consumed by these two generalist herbivores. No clearly defined trends in the concentrations of ash, nitrogen, carbon, soluble carbohydrates, soluble proteins, and caloric content in the seaweeds were found to account for these differences in feeding rates. In contrast, feeding rates varied according to the presence of secondary metabolites. The low susceptibility to grazing by snails in the least-consumed algae seems to be associated with the presence of secondary metabolites. We suggest that feeding rates of L. striata and O. atratus on algae are primarily due to avoidance of algal chemical defenses, whereas positive aspects of food quality probably play a lesser role in determining consumption.

Calanoid copepod grazing on phytoplankton: seasonal experiments on natural communities

Calanoid copepods are major components of most lacustrine ecosystems and their grazing activities may influence both phytoplankton biomass and species composition. To assess this we conducted four seasonal, in situ, grazing experiments in eutrophic Lake Rotomanuka, New Zealand. Ambient concentrations of late stage copepodites and adults of calanoid copepods (predominantly Calamoecia lucasi, but with small numbers of Boeckella delicata) were allowed to feed for nine days on natural phytoplankton assemblages suspended in the lake within 1160 litre polyethylene enclosures. The copepods reduced the total phytoplankton biomass of the dominant species in all experiments but were most effective in summer (the time of highest grazer biomass) followed by spring and autumn. In response to grazing pressure the density of individual algal species showed either no change or a decline. There were no taxa which increased in density in the presence of the copepods. The calanoid copepods suppressed the smallest phytoplankton species (especially those with GALD (Greatest Axial Linear Dimension) < µm) and there appeared to be no selection of algae on the basis of biovolume. Algal taxa which showed strong declines in abundance in the presence of the copepods include Cyclotella stelligera, Coelastrum spp., Trachelomonas spp., Cryptomonas spp., and Mallomonas akrokomos. Calanoid copepods are considered important grazers of phytoplankton biomass in this lake. The study supports the view that high phytoplankton:zooplankton biomass ratios and large average algal sizes characteristic of New Zealand lake plankton may, at least partly, be caused by year round grazing pressure on small algae shifting the competitive balance in favour of larger algal species.

A choice chamber experiment on the selection of algae as food and substrata by Nais elinguis (Oligochaeta: Naididae)

SUMMARY. A choice chamber experiment was performed in the laboratory to quantify the selection of benthic algae as food and substrata by Nais elinguis. Most worms actively chose filamentous algae and/or diatoms as substrata whereas unicellular or colonial chiorophycean algae were discriminated against. Diatoms were selected in preference to latex beads but the worms could not discriminate between living filaments and nylon monofilaments. A thigmotactic response to filaments and a chemotactic response to diatoms may be implicated. The worms ingested unicellular algae at a greater rate than colonial and filamentous algae. The rates at which the algae were ingested were negatively correlated with the lengths of the algae. A filament 200 μm long was the largest item ingested, representing about 63% of the length of the pharynx of the worm. Ivlev's electlvity indices were positive when the rates at which the algae were ingested exceeded about 20 individuals h‐1. The index was negatively correlated with the lengths of the algae, but the time periods spent by the worms in association with the algae were unrelated to the electivity index. The data confirmed previous observations on the selection of algae as food and substrata by Nais elinguis in a natural habitat.