Scenedesmus Species Research Articles

Cultivation of Microalgae Using Sewage and Organic Component Evaluation

AbstractOutdoor cultivation of microalgae was carried out in 20‐L tanks using sewage influent or effluent, at an actual sewage treatment plant. The microalgae could be cultured by supplying only sewage influent or effluent without additional microalgal stock or nutrient salts. Adding air and CO2 to the culture water promoted not only the cultivation of green algae but also the consumption of nitrogen. Increasing the hydraulic retention time also promoted consumption and cultivation. In particular, adding CO2 to the sewage influent achieved a 59‐fold increase in the cell number of specific Scenedesmus species useful as components for fuel. The microalgae culture progressed even in the autumn/winter. The major organic components eluted by n‐hexane were fatty acids such as palmitic and 11‐hexadecenoic acid. The applicability of sewage culture microalgae as biofuel was demonstrated.

Comparative transcriptomics reveals molecular components associated with differential lipid accumulation between microalgal sp., Scenedesmus dimorphus and Scenedesmus quadricauda

Scenedesmus is considered as a potential oil-producing green microalgae having higher lipid content with suitable fatty acid profile (high oleic acid) for biodiesel production. Comparative transcriptome analysis of two Scenedesmus sp., viz. Scenedesmus dimorphus (26%) and Scenedesmus quadricauda (14%) having equivalent biomass and variable lipid content was performed to uncover molecular mechanisms controlling differential lipid production. 76,969 and 40,979 CDSs were predicted from the transcriptomes of S. dimorphus and S. quadricauda respectively, which were subsequently mapped to metabolic pathways. Overall up-regulation of metabolic pathways contributing precursors to storage lipid biosynthesis was observed in S. dimorphus. Glyceraldehyde 3-phosphate dehydrogenase, enolase, acetyl-CoA synthetase, pyruvate dehydrogenase, ATP citrate lyase, glycerol kinase, citrate synthase were identified as major regulators of high lipid content in S. dimorphus. Further, WRINKLED1 transcription factor significantly correlated with high lipid accumulation as revealed by reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) in three growth stages of two species. This study provides a broad view of storage lipid production in Scenedesmus species with potential implications in designing suitable genetic interventions towards increase in lipid content vis-à-vis central carbon metabolism.

Differential effects of P25 TiO2 nanoparticles on freshwater green microalgae: Chlorella and Scenedesmus species

P25 TiO2 nanoparticles majorly used in cosmetic products have well known detrimental effects towards the aquatic environment. In a freshwater ecosystem, Chlorella and Scenedesmus are among the most commonly found algal species frequently used to study the effects of metal oxide nanoparticles. A comparative study has been conducted herein to investigate differences in the toxic effects caused by these nanoparticles towards the two algae species. The three different concentrations of P25 TiO2 NPs (0.01, 0.1 & 1μg/mL, i.e., 0.12, 1.25 and 12.52μM) were selected to correlate surface water concentrations of the nanoparticles, and filtered and sterilized fresh water medium was used throughout this study. There was significant increase (p<0.001) in hydrodynamic diameter of nanoparticles with respect to both, time (0, 24, 48 and 72h) as well as concentration under all the exposure conditions. Although, significant dose-dependent morphological (surface area & biovolume) interspecies variations were not observed, it was evident at the highest concentration of exposure within individuals. At 1μg/mL exposure concentration, a significant difference in toxicity was noted between Chlorella and Scenedesmus under only visible light (p<0.001) and UVA (p<0.01) irradiation conditions. The viability data were well supported by the results obtained for oxidative stress induced by NPs on the cells. At the highest exposure concentration, superoxide dismutase and reduced glutathione activities were assessed for both the algae under all the irradiation conditions. Increased catalase activity and LPO release complemented the cytotoxic effects observed. Significant interspecies variations were noted for these parameters under UVA and visible light exposed cells of Chlorella and Scenedesmus species, which could easily be correlated with the uptake of the NPs.

Removal of nutrients and organic pollution load from pulp and paper mill effluent by microalgae in outdoor open pond

A mixed culture of microalgae, containing two Scenedesmus species, was analysed to determine its potential in coupling of pulp and paper mill effluent treatment and microalgal cultivation. Laboratory studies suggested that 60% concentration of wastewater was optimum for microalgal cultivation. A maximum of 82% and 75% removal of BOD and COD respectively was achieved with microalgal cultivation in outdoor open pond. By the end of the cultivation period, 65% removal of NO3-N and 71.29% removal of PO4-P was observed. The fatty acid composition of mixed microalgal culture cultivated with effluent showed the palmitic acid, oleic acid, linoleic acid and α-linolenic acid as major fatty acids. The results obtained suggest that pulp and paper mill effluent could be used effectively for cultivation of microalgae to minimise the freshwater and nutrient requirements.

Lipid content in Scenedesmus species correlates with multiple genes of fatty acid and triacylglycerol biosynthetic pathways

The feasibility of microalgae based biodiesel depends upon the selection of strains having high lipid content without compromising growth. The molecular basis governing storage lipid biosynthesis is poorly understood in microalgae including Scenedesmus, which has been identified as a potential oil-producing microalga. Eighteen genes of fatty acid and triacylglycerol biosynthesis were identified in Scenedesmus dimorphus through comparative genomics and transcriptome mining and their expression was examined in three growth stages viz., exponential, early stationary, late stationary phase and two stress conditions induced by nitrogen deficiency and high salinity among two lipid contrasting strains of S. dimorphus, SD12 (26%), SD16 (5%) and one strain of Scenedesmus quadricauda SQ19 (14%). Most of the genes showed relatively higher expression in high lipid strain, SD12 with up to 50 folds and 25 folds increase in transcript abundance of 9 genes compared to SD16 and SQ19, respectively. Eleven genes showed upregulation at late stationary phase and under stress conditions, suggesting role of multiple genes in controlling lipid content. Comparison of gene expression across differential conditions among three contrasting strains unveiled six key genes, ACP, FATA, KASII, LPAAT, PAP and DGAT that can be chosen as potential targets for designing a genetic intervention strategy for further enrichment of lipid profile in Scenedesmus species.

Algae-Mediated Valorization of Industrial Waste Streams

Abstract Pulp and paper mills have an abundance of underutilized waste wood with the potential for use as feedstock for the production of algae biomass. Enzymatic hydrolysates originating from pine softwood, southern hardwoods, and northern hardwoods pretreated using a proprietary process were tested for their ability to support heterotrophic growth of microalgae. Focusing on Hawaiian Chlorella and Scenedesmus species, growth varied with each type of wood hydrolysate, depending on the pentose (C5) and hexose (C6) sugar composition as well as process residuals such as organic acids and alcohols. Both species were able to utilize pentose sugars. A 1.6-fold higher biomass productivity, of 2.87 g/L/day in batch culture, was obtained on a medium with Bleached Southern Pine (BSP) hydrolysate than with the equivalent C5 and C6 model sugars alone, suggesting enhanced growth stimulation on wood hydrolysates compared to purified sugar streams. Biomass yield per gram of sugar consumed ranged from 0.45:1 in BSP hydro...

Culture, growth, pigments and lipid content of Scenedesmus species, an extremophile microalga from Soda Dam, New Mexico in wastewater

We isolated an extremophile green alga from Jemez New Mexico; 18S rDNA sequencing confirmed it as Scenedesmus species Novo. Cultures in TAP medium (24±1°C, 132–148μmolphotonsm−2s−1) attained peak biomass (27.4×106cellsml−1, 49.11μgchl aml−1 and 24.93μgcaroteneml−1) and a division rate of 0.54day−1. Under outdoor harsh conditions (6524–7360μmolphotonsm−2s−1 and 40°C), biomass peaked at 10.41×106cells, 6.92μgchl a, and 4.49μgcarotene. Indoor wastewater cultures enriched with TAP yielded 63 to 94.3pg lipid cell−1 and 16.7 to 36.6pg lipid cell−1 in outdoor cultures which are amongst the highest for microalgae; lipid as dry cell weight reached peak values of 85% and 33%, respectively. Total carotenoids (pg cell−1) ranged from 1.52 to 3.58 in indoor cultures and 0.34 to 1.08 for outdoor cultures comparable to 0.24–4.75 to literature values. Because of its ability to produce high levels of biomass, lipids and carotenes in wastewater under harsh ambient climatic conditions, Scenedesmus species Novo has the potential to sustain biotechnological applications. We recommend continued exploration of extremophile algal species native to New Mexico and beyond, to develop strategies for a viable and sustainable bio-economy.

Effect of light intensity and pH condition on the growth, biomass and lipid content of microalgae Scenedesmus species

The physiological factors for microalgae cultivation are the preliminary steps to overcome the potential biomass demand. In this regard, the influence of light intensity (at six levels: 27, 40.5, 54, 67.5, 81 and 94.5 µmol m−2s−1) and pH conditions (5.0, 6.0, 7.0, 8.0 and 9.0) on the growth and lipid production of Scenedesmus species ADIITEC-II and GUBIOTJT116 was compared in the batch culture. Among the studied species, maximum specific growth (0.334 ± 0.002 day−1) and highest biomass yield (0.41 ± 0.021 g L−1) was achieved for Scenedesmus species ADIITEC-II at light intensity 81 µmol m−2s−1. Similarly, Scenedesmus species GUBIOTJT116 showed increased growth and biomass production at 81 µmol m−2s−1. However, illumination under 94.5 µmol m−2s−1 showed higher lipid production (0.533 ± 0.001 g L−1 and 0.551 ± 0.001 g L−1) for Scenedesmus sp. ADIITEC-II and GUBIOTJT116, respectively. The significant variation in effective pH tolerance, growth and biomass production was observed in the studied pH range. The result obtained in this study provides a potential insight of the strains and could be further explored to improve the biomass and lipid yield.

Reliable production of microalgae biomass using a novel microalgae platform

A microalgae platform, consisting of four photobioreactor units incorporating a novel biomimetic design, has been installed at the Biosolar Center in Koethen, Germany. The novel photobioreactor consists of a flexible, tubular double-wall hose system (silicone based) with integrated temperature control in a closed cycle. The modular-arranged platform system (total cultivation volume 1700 L) has been designed for stable long-term cultivation of microalgae biomass in outdoor use. Cultures with Scenedesmus and Chlorella species have been grown outdoors at their optimal growth temperature (avg. 26 °C) for 145 days during spring and summer and were tested successfully for the stable production of microalgae (avg. biomass productivity 0.3 g L−1 day−1 (max. 0.75 g L−1 day−1)) with an overall photosynthetic conversion efficiency of 7.2 % based on photosynthetically active radiation. The average calorific value of the produced biomass is 23.25 MJ kg−1 with defined product quality (content relating to biomass dry weight: proteins 0.40 g g−1, lipophilic compounds 0.38 g g−1 and total carotenoids 11 mg g−1). This outdoor concept is continuously adjustable to maintain an optimal environment for microalgae cultures (in particular light entry, temperature control and limiting of oxygen levels).

Minimizing the Energy Requirement of Dewatering Scenedesmus sp. by Microfiltration: Performance, Costs, and Feasibility

The harvesting of the microalgae Scenedesmus species using a 200 L pilot-scale microfiltration system was investigated and critically assessed. The energy requirement was determined and correlated to the different operating parameters, such as transmembrane pressure (ΔP), membrane area, temperature, and initial biomass concentration. A filtration model was developed and showed a strong correlation with experimental data up to 20.0 g of dry cell weight (DCW)/L. The non-optimized filtration system had an energy requirement of 2.23 kWh/m(3) with an associated cost of $0.282/kg of microalgae. The investigation into the influence of the operating parameters and scale-up effects showed that the energy requirement could be substantially reduced to 0.90 kWh/m(3) and $0.058/kg of microalgae harvested. Maintenance costs associated with cleaning were estimated to be 0.23 kWh or $0.029/batch of microalgae processed. Dependent upon the operating conditions, harvesting may represent 6-45% of the energy embedded in the microalgae with a carbon footprint of 0.74-1.67 kg of CO2/kg of microalgae. Microfiltration was demonstrated to be a feasible microalgae harvesting technology allowing for more than 99% volume reduction. The energy requirement and associated carbon footprint of microalgae harvesting reported here do not forfeit the need for an industrial-scale study; however, the information provided presents a more realistic approximation than the literature reported to date.

Isolation and heterotrophic cultivation of mixotrophic microalgae strains for domestic wastewater treatment and lipid production under dark condition

Cultivating microalgae heterotrophically could overcome the light dependency, and thus increase the yield of microalgal lipid per unit area. In this study, three newly isolated strains of microalgae (Scenedesmus sp. ZTY2, Scenedesmus sp. ZTY3 and Chlorella sp. ZTY4) from a domestic wastewater treatment plant were heterotrophically cultivated in domestic wastewater with no illumination. During the cultivation, the algal densities of Scenedesmus species and Chlorella species were increased by 203.0% and 60.5% comparing with the initial densities, respectively. After 11-day cultivation, the lipid contents of Scenedesmus sp. ZTY2, Scenedesmus sp. ZTY3 and Chlorella sp. ZTY4 reached 69.1%, 55.3% and 79.2%, respectively. The DOC removal efficiencies of these three strains were 63.4%, 52.9% and 64.4%, and the biomass yield were 1.65, 1.98 and 2.31mg biomass/mg DOC, respectively. This is the first report about the heterotrophic cultivation of microalgae strains for domestic wastewater treatment and lipid production under dark condition.

Genus scenedesmus from different habitats of nashik and its environs (M.S.) India

Among the organisms frequently encountered in investigations of freshwater habitats are members of the genus scenedesmus. Species are delimited on the basis of the size and shape of the cells, as well as position and number of spines, if present. Thirty Two species of Scenedesmus are being identified from different collected samples from different aquatic habitats of Nasik, between Jan 2008 to Dec. 2012. Some species are rare and some are common among them. Scenedesmus acutus f. costulatus (Chodat) Uherkovich is first time reported from Maharashtra.

Influence of barley straw (Hordeum vulgare L.) extract on phytoplankton dominated by Scenedesmus species in laboratory conditions: the importance of the extraction duration

The response of a natural phytoplankton assemblage dominated by algae of the genus Scenedesmus to the addition of barley straw extract was studied in a laboratory experiment. The aim of the study was to compare the inhibiting effect of water extracts obtained by soaking the straw for 1, 2 and 3 months. We analysed the response of four species, Scenedesmus subspicatus, Scenedesmus ecornis, Scenedesmus quadricauda and Scenedesmus acuminatus, during 14 days of their exposure to different types of barley straw extract. S. subspicatus and S. ecornis responded with decreasing numbers only to the addition of the 3-month solution (ANOVA; F = 290.1, p <0.001; and F = 11.8, p <0.01, respectively); the two other species were inhibited by all types of extracts. The results indicate the need for more research on the importance of extraction duration to the inhibitory abilities of barley straw which can be applied in the management of water quality in water bodies.

Carbon sequestration potential of Scenedesmus species (Microalgae) under the fresh water ecosystem

The study was conducted to investigate the carbon sequestration potential of Scenedesmus species (a microalgae species) under the fresh water ecosystem. Biofixation of CO2 by microalgae mass cultures represents an advanced, climate friendly biological process that enables the direct utilization of fossil CO2 streams produced from concentrated sources, such as power plants. The study was done in Nagpur region, the sample of Scenedesmus species (a microalgae species) were collected from fresh water ponds scattered over in Nagpur area. Collected samples were isolated for Scenedesmus species with Streak plate and Pour plate method by using serial dilution, purification was done by antibiotic treatment. The growth of Scenedesmus species was tested under different concentration of CO2, heavy metal treatment and different pH values and also chlorophyll contents were estimated over the various concentrations of CO2. Results revealed that the highest growth reported at 36% of CO2 treatment, 7.4 to 8.0 pH values and growth inhibited under high concentration of heavy metals. Chlorophyll synthesis was reported highest at 36% of CO2 treatment. With the results it concluded that the Scenedesmus species having good carbon sequestration potential as it can tolerate up to 48% CO 2 concentration in the medium, and can give excellent biomass accumulation under the 36% CO2 contents in the medium. This Scenedesmus species can be exploited as good source of bio-fixation of environmental CO2.

Fatty acid profiling and molecular characterization of some freshwater microalgae from India with potential for biodiesel production

We determined the fatty acid compositions of six species of freshwater microalgae belonging to the Chlorophyta, which were isolated from freshwater bodies in Assam, India. All six microalgae -Desmodesmus sp. DRLMA7, Desmodesmus elegans DRLMA13, Scenedesmus sp. DRLMA5, Scenedesmus sp. DRLMA9 Chlorella sp. DRLMA3 and Chlorococcum macrostigmatum DRLMA12-showed similar fatty acid profiles 16:0, 16:4, 18:1, 18:2, and 18:3 as major components. We also compared fatty acid compositions during the late exponential and stationary growth phases of D. elegans DRLMA13 and Scenedesmus sp. DRLMA9 in BG11 medium. We observed enhanced percentages of total saturated and monounsaturated fatty acids with a concomitant decrease in polyunsaturated fatty acid content upon the prolonged cultivation of both microalgae. Distinct morphological features of microalgal isolates were determined by scanning electron microscopic (SEM) studies. An ornamented cell wall was found in D. elegans DRLMA13, which is characteristic of small spineless species of Desmodesmus. The isolated microalgae were further distinguished through analysis of internal transcribed spacer 2 (ITS2) secondary structures and compensatory base changes (CBCs). Analysis of CBCs showed the relatedness of Chlorella sp. DRLMA3 with other Chlorella-like organisms, but it does not belong to the clade comprising Chlorella sensu stricto, which includes Chlorella vulgaris. The CBC count between Scenedesmus sp. DRLMA9 and other species of Scenedesmus provides evidence that this isolate represents a new species.

Effect of copper and salicylic acid on phenolic metabolites and free amino acids in Scenedesmus quadricauda (Chlorophyceae)

Species of the genus Scenedesmus are frequently used in studies focused on heavy metal toxicity and phenols represent important tool for stress protection. However, deeper knowledge about accumulation of phenolic metabolites in algae still absents. We therefore studied selected metabolic responses of widely distributed green algal species Scenedesmus quadricauda to short-term (24 h) effect of copper (Cu), salicylic acid (SA) and their combined application (25 μM for both). Exposure to Cu led to decrease in chlorophylls while SA stimulated increase in chlorophylls. Soluble proteins and total soluble phenols were depressed by Cu treatment while SA had no effect and did not reverse influence of Cu in combined variant. Endogenous SA decreased in Cu + SA treatment and this depletion had no direct effect on the accumulation of the majority of detected phenolic acids, while individual amino acids seemed to be affected. Considerable accumulation of benzoic acids and their noticeable responses to SA may suggest involvement in protection against Cu toxicity since intracellular Cu remained unchanged by exposure to Cu + SA. These observations are discussed in the context of biosynthesis of phenols and possible signalling mechanisms are also suggested.

Effect of Glyphosate on Growth of Four Freshwater Species of Phytoplankton: A Microplate Bioassay

The acute toxicity of glyphosate herbicide was tested on the four species of freshwater phytoplankton, Scenedesmus acutus, Scenedesmus subspicatus, Chlorella vulgaris and Chlorella saccharophila. Herbicide concentrations eliciting a 50% growth reduction over 72 h (EC(50)) ranged from 24.5 to 41.7 mg L(-1), whilst a 10% growth inhibition is achieved by herbicide concentrations ranging from 1.6 to 3.0 mg L(-1), difficult to find neither in paddy fields (it is not used in rice) nor in the lake of the Albufera Natural Park. Chorella species are less sensitive to the herbicide than Scenedesmus species. It can be concluded that glyphosate has a low potential risk for the tested organisms.

Spatial and temporal variation in phytoplankton community structure in a southeastern U.S. reservoir determined by HPLC and light microscopy

Spatial and temporal variation in phytoplankton community structure within a large flood-control reservoir (Sardis Reservoir, MS, USA) was investigated in relation to variation in physicochemical properties, location within the reservoir, hydraulic residence time (HRT), nutrient concentrations, temperature, and light conditions over a 14-month period. During periods of short HRT, phytoplankton communities throughout the reservoir were homogeneous in biomass, composition, and production. With a gradual increase in HRT from spring to summer, spatially heterogeneous phytoplankton communities developed along the longitudinal axis of the reservoir. During this period of longer HRT, diatoms and chlorophytes were a larger proportion of total phytoplankton biomass at shallow and more turbid locations near the head of the reservoir, whereas cyanobacteria were a larger proportion of the community at deeper and less turbid locations closer to the outflow. Seasonal succession of the phytoplankton community was represented by high abundance of diatoms in spring, increasing biomass of cyanobacteria through summer, and a secondary bloom of diatoms in fall. Species of Cyclotella, Asterionella, Nitzschia, and Ankistrodesmus were among the first colonizers in the early growing season, closely followed by Aulacoseira, whereas species of Staurastrum and Tetraedron appeared later in the spring. Species of Synedra, Crucigenia, Selenastrum, Scenedesmus, and Merismopedia occurred throughout the sampling period. As the diatoms started to decrease during mid-spring, cryptophytes increased, prior to dominance of species of Pseudanabaena in summer. Reservoir management of HRT, in combination with spatial variation in reservoir morphology and seasonal variation in temperature and riverine nutrient inputs, creates seasonally variable yet distinct spatial patterns in phytoplankton community biomass, composition, and production.

The diversity of Scenedesmus and Desmodesmus (Chlorophyceae) in Itasca State Park, Minnesota, USA

J.L. Johnson, M.W. Fawley and K.P. Fawley. 2007. The diversity of Scenedesmus and Desmodesmus (Chlorophyceae) in Itasca State Park, Minnesota, USA. Phycologia 46: 214–229. DOI: 10.2216/05-69.1Species of Scenedesmus and Desmodesmus are ubiquitous in freshwater ecosystems. However, phenotypic plasticity coupled with the minute variations between named species make the identification of taxa by light microscopy extremely difficult, especially from field samples. As a result, the actual level of diversity and distributions of these genera are not known. In this study, the diversity of Scenedesmus and Desmodesmus from Itasca State Park (ISP), Minnesota, USA was studied using culture techniques followed by light microscopy and internal transcribed spacer (ITS-2) rDNA sequence analysis. From 100 characterized isolates of Scenedesmus, Desmodesmus and allied isolates, 34 different sequence types were detected, 24 of which are different enough from each other to correspond to distinct taxa. This diversity greatly exceeds that described for these genera in previous studies of ISP algae using light microscopy alone. The sequences of five ISP isolates identically matched those of previously described species or isolates, and sequences of six ISP isolates differed by eight bases or less from those of previously described species. The isolation of Desmodesmus species from Itasca State Park with sequences identical to those from isolates from highly disjunct locations around the world suggests that these species are widely distributed. Results from this study also indicate that isolates with very similar (< 8 substitutions) ITS-2 sequences tend to have only very slight morphological variation. We conclude that culturing and ITS-2 sequence analysis is an effective technique for investigating species level diversity in Scenedesmus and Desmodesmus.

Influence of Nitrate Feeding on Carbon Dioxide Fixation by Microalgae

In this study, the effects of nitrate feeding on microalgal growth and associated CO2 fixation were evaluated, as a strategy to enhance carbon fixation by increasing the duration of the exponential phase of cell growth in the batch operation of a photobioreactor. Two species of green algae, Chlorella and Scenedesmus, and two species of cyanobacteria, Microcystis ichthyoblabe and Microcystis aeruginosa, were used after adaptation to a 15% (v/v) CO2 environment. In the absence of nitrate feeding, nitrate concentrations declined rapidly and soon became a limiting factor. Nitrate feeding, administered in fed-batch mode to maintain 15–20 ppm of NO3-N, allowed for an extension of the exponential growth phase by more than 3 days, as well as a higher cell density, which subsequently resulted in an increase in photoautotrophic carbon fixation. The increases in the carbon fixation rate were in the ranges of 56.1–56.6% for the green algae, and between 68.2–68.8% for the cyanobacteria. The results indicated that intermittent nitrate feeding was a viable strategy for the augmentation of fixation productivity, and may thus be effectively applied as a substitute for conventional medium change, which has traditionally been employed in order to prolong the active growth duration.