Scenedesmus Communis Research Articles

A synergic approach for nutrient recovery and biodiesel production by the cultivation of microalga species in the fertilizer plant wastewater

The combination of wastewater treatment and biodiesel production using algal cultivation was studied in the present work. The two main goals of the work were achieved by the cultivation of freshwater microalgae such as Chlamydomonas sp., Scenedesmus ecornis, and Scenedesmus communis in two different dilutions of fertilizer plant wastewater (FWWD1 and FWWD2) collected from Yara Suomi Oy, Finland. The growth pattern of different algal species in FWWD1 and FWWD2 was observed. The effect of pH on biomass concentration, lipid content, biomass productivity, and lipid productivity by all three algal species in FWWD1 and FWWD2 were monitored. The maximum biomass concentration and productivity were observed in FWWD1 at pH7.5 for Chlamydomonas sp. and at pH 8.5 for S. ecornis and S. communis. The maximum lipid content was detected in Chlamydomonas sp at pH5.5, followed by S. ecornis and then S. communis at pH 7.5 in FWWD2 obtained after co-solvent extraction method. The most significant removal percentage of COD by all algal species were observed in FWWD1, whereas the highest removal percentage of TN and TP were detected in FWWD2, respectively. The fatty acid methyl ester (FAME) characterization of each algal species in FWWD1 and FWWD2 at their optimum pH was investigated to determine the quality of obtained biodiesel.

Seasonal dependence and functional implications of macrophyte–phytoplankton allelopathic interactions

AbstractInvasive plant species such as Ludwigia hexapetala might have a competitive advantage if they produce allelopathically active compounds against primary producers. Both phytoplankton and plant community structure may be affected due to different, species‐specific sensitivity to allelochemicals. Moreover, such allelopathic interactions could vary over the year depending on (i) the plant's phenological stage and (ii) the abilities of the native macrophytes to suppress—or the non‐native macrophytes to stimulate—the non‐native macrophyte population. We tested the allelopathic effects of aqueous leaf extracts of L. hexapetala on the photosynthetic activity of three target phytoplankton strains (Scenedesmus communis, a toxic Microcystis aeruginosa strain and a non‐toxic Microcystis aeruginosa strain) over three seasons of development (spring, summer and autumn). We also tested seasonal allelopathic effects of aqueous leaf extracts of both L. hexapetala (i.e. the non‐native invasive species) and the native Mentha aquatica on L. hexapetala seed germination. Finally, we identified three main secondary compounds present in the aqueous leaf extracts of L. hexapetala and we tested each individual compound on the phytoplankton's photosynthetic activity and on L. hexapetala seed germination. We observed marked seasonal and species‐specific patterns of L. hexapetala allelopathy on phytoplankton. The photosynthetic activities of S. communis and the toxic M. aeruginosa strain were stimulated by L. hexapetala aqueous leaf extracts in autumn and spring, respectively, whereas the non‐toxic M. aeruginosa strain was strongly inhibited in these two seasons. In summer, photosynthesis of all phytoplankton strains was inhibited. The germination rate of L. hexapetala seeds was stimulated by both L. hexapetala and M. aquatica aqueous leaf extracts, especially in summer, concomitant with the strong negative effects observed on the three phytoplankton strains. Three flavonoid glycosides (myricitrin, prunin and quercitrin) were identified as the main secondary compounds present in the L. hexapetala aqueous leaf extracts. The photosynthetic activity of S. communis was slightly stimulated by the three compounds. The photosynthetic activity of the toxic M. aeruginosa strain was stimulated by myricitrin and quercitrin, whereas that of the non‐toxic M. aeruginosa strain was inhibited by prunin. Finally, the germination rate and the germination velocity of L. hexapetala seeds were stimulated by myricitrin and prunin. These findings suggest that L. hexapetala could favour the photosynthetic activity of toxic cyanobacteria in spring and reduce their photosynthetic activity in summer, potentially leading to drastic changes in the phytoplankton communities and therewith ecological functioning of invaded ponds. Moreover, the stimulation of its seed germination could give a strong competitive advantage to L. hexapetala, thus promoting its invasiveness.

Selective growth inhibition of cyanobacteria species (Planktothrix agardhii) by a riparian tree leaf extract

Natural leaf litter inputs is one factor that may help to minimize the likelihood of excessive algal growth. We tested the allelopathic effect of the grey willow (Salix atronicerea) on two phytoplankton species: Planktothrix agardhii (toxic and non-toxic cyanobacterial strains) and Scenedesmus communis (a chlorophyte). Effect was evaluated by combining leaf extracts and pulse amplitude modulation (PAM) chlorophyll fluorescence yield to measure photosynthetic activity responses. Phototrophic growth of the cyanobacterial species was suppressed even at very low concentrations of the extract while growth of the chlorophyte species was not affected. In the two cyanobacteria strains, inhibition of the chlorophyll fluorescence yields was significantly higher in the microcystin-free strain. Polyphenols are suspected to cause oxidative damage to cyanobacteria and thereby induce selective growth inhibition, similarly to hydrogen peroxide treatments against harmful cyanobacteria. Our results evidence willow extract or exudate as a promising agent selectively affecting cyanobacterial growth, but further studies are needed to determine the environmental impact and the inhibiting process.

Relationship between phytoplankton composition and environmental variables in an artificial pond

Relation between phytoplankton composition and environmental variables was explored in a shallow artificial pond in Gaziantep, Turkey from June to December 2011, using canonical correspondence analyses (CCA) and weighted average (WA) regressions. The number of phytoplankton species increased during the fall season. The most dominant group was Chlorophyta (21 taxa), followed by Cyanobacteria (5 taxa), and Charophyta (5 taxa). Pediastrum boryanum, Scenedesmus communis, Golenkinia paucispina, Pediastrum duplex, Kirchneriella contorta, and Cosmarium leaves were the frequently found taxa which were closer to the center of CCA ordination. The first two axes of CCA explained 91.2% of the correlation between species and environmental variables and 17.9% of cumulative variance of species data. Explanatory factors (dissolved oxygen, temperature, PH, and redox potential) played a significant role in the distribution of species. According to the results of WA, phytoplankton species had different ecological preferences at different environmental conditions. Commonly recorded phytoplankton taxa with cosmopolitan characteristics had a relatively high tolerance and broad optimum ranges.

Chemical fingerprinting of algaenans using RuO 4 degradation

The freshwater green microalgae, Oocystus solitaria Wittrock f. maior Wille, Pediastrum braunii Wartmann, Pediastrum kawraiskyi Schmidle, Sorastrum spinulosum Nägeli and Coelastrum reticulatum (Dangeard) Senn were investigated with respect to the presence of algaenan and the corresponding RuO 4 chemical fingerprint. All species, with the exception of O. solitaria, were shown to possess a cell wall resistant toward strong acid and base treatment. By analysis of the RuO 4 chemical degradation products from these materials a molecular fingerprint was obtained having similar features to the RuO 4 fingerprints of Tetraedron minimum, Scenedesmus communis and Pediastrum boryanum algaenans reported in earlier studies. Previously it had been shown that these RuO 4 fingerprints could also be obtained from ancient sediments, indicating the presence of algaenan as part of the organic matter. The results from this study show that the chemical composition of algaenans is possibly a chemotaxonomic feature and can be used to chemically explore the algal contribution to sedimentary organic matter on a family level. Furthermore, it illustrates that the use of RuO 4 degradation combined with gas chromatography is a suitable analytical tool for the purpose of chemical fingerprinting of algaenans.

Occurrence of high molecular weight lipids (C 80+) in the trilaminar outer cell walls of some freshwater microalgae. A reappraisal of algaenan structure

The purified cell walls of mother cells (CWM) were isolated from three strains of trilaminar sheath (TLS)- and algaenan-containing freshwater microalgae Chlorella emersonii, Tetraedron minimum and Scenedesmus communis. The chemical structures of CWM and algaenans were investigated by means of tetramethylammonium hydroxide (TMAH) hydrolysis and tetramethylammonium hydroxide thermochemolysis. The compounds released were characterised by 1H and 13C-NMR, gel permeation chromatography and desorption chemical ionisation mass spectrometry. The results show that the outer cell walls of the microalgae are constituted, at least in part, of linear (poly)esters containing extremely long chain alcohol and acid moieties (up to C 80) and that algaenans are mainly composed of extremely long chain (di)carboxylic acids up to C 120. The present results which are in direct contrast to the previous three-dimensional architecture proposed for algaenans, led us to re-interpret the algaenan structure.

High molecular weight lipids from the trilaminar outer wall (TLS)-containing microalgae Chlorella emersonii, Scenedesmus communis and Tetraedron minimum

High molecular weight lipids were isolated from Chlorella emersonii, Scenedesmus communis and Tetraedron minimum, thin trilaminar outer wall (TLS)-containing freshwater microalgae producing an insoluble non-hydrolysable biopolymer (i.e. algaenan). Molecular weight determination by gel permeation chromatography indicated that their molecular weights range from ca. 400 to 2000 Da. Flash pyrolysis with in situ methylation using tetramethylammonium hydroxide (TMAH) and alkaline hydrolysis showed that the high molecular weight lipids isolated from C. emersonii and S. communis are mainly composed of saturated n-C26 and n-C28 fatty acids and alcohols and of saturated n-C30 and n-C32 α,ω-diols and ω-hydroxy acids. In contrast the high molecular weight lipids isolated from T. minimum are predominantly composed of long-chain fatty acids and ω-hydroxy acids. Aromatic moieties were also identified in small amounts in the thermochemolysate and in the hydrolysate. Chemical structural models containing long-chain mono- and polyesters were proposed for the high molecular weight lipids isolated from the three microalgae in agreement with analytical and spectroscopic data. Structural similarity between the outer cell wall of these microalgae and the cuticular membrane of higher plants is suggested.

Identification of protein remnants in insoluble geopolymers using TMAH thermochemolysis/GC–MS

Thermochemolysis with tetramethylammonium hydroxide (TMAH) was utilized to analyze peptide-like material in insoluble residues of geochemical samples. Product identification was performed by gas chromatography/mass spectrometry using bovine albumin and di-, tri- and oligo-peptides. Most of the identified amino acid derivatives originate from the cleavage of the peptide bonds and subsequent methylation of the carboxylic and the amino groups. Some products are explained by deamination of aromatic amino acids. Only two products were identified that experienced chemical rearrangement after methylation. TMAH/thermochemolysis of algal material resulted in products comparable to those obtained from albumin. Amino acid derivatives were also identified among the TMAH/thermochemolysis products of refractory biopolymer of the alga Scenedesmus communis and the HCl-hydrolysis residue of the humin from an algal sapropel. These results strongly indicate that for those samples, hydrolysis fails to extract all proteinaceous and peptide-like components, possibly because these approaches rely on extraction of peptides and amino acids into solution and some of these are entrapped within a non-extractable hydrophobic network. However, alternative explanations for this behavior are possible. For example, at the higher temperatures and pressures and strongly basic conditions used in TMAH themochemolysis, penetration of this hydrophobic barrier takes place thus allowing breakdown and methylation of protein remnants.

Molecular structure of the resistant biopolymer in zygospore cell walls of Chlamydomonas monoica

The unicellular green alga Chlamydomonas monoica Strehlow is known to produce zygospores with a cell wall that is resistant against microbial and chemical attack. This resistance is thought to be due to the presence of a sporopollenin-like material. However, the resistant nature of sporopollenin-like materials seriously hampers their structural analysis. With complementary techniques such as 13C-nuclear magnetic resonance spectroscopy, Curie-point pyrolysis-gas chromatography/mass spectroscopy and RuO4 chemical degradation, the chemical composition of resistant biopolymer in the isolated cell walls of C. monoica zygospores was determined. This material is composed of C22–C30 linear alcohols and carboxylic acids, intermolecularly linked via ester and ether-linkages similar to the resistant aliphatic biopolymers encountered in the walls of the vegetative cells of the algae Tetraedron minimum, Scenedesmus communis and Pediastrum boryanum.

Chemical structure of algaenans from the fresh water algae Tetraedron minimum, Scenedesmus communis and Pediastrum boryanum

The cell walls of the fresh water green microalgae Tetraedron minimum, Scenedesmus communis and Pediastrum boryanum are composed of highly resistant, non-hydrolyzable aliphatic biopolymers as revealed by 13C-NMR, FTIR and thermal and chemical degradations. The biopolymers are composed of long-chain even-carbon-numbered ω 9-unsaturated ω-hydroxy fatty acid monomers varying in chain length from 30 to 34 carbon atoms. These monomers are intermolecularly ester linked to form linear chains in which the unsaturations act as the starting position of ether cross-linking. S. communis biosynthesises a more densely cross-linked algaenan than T. minimum and P. boryanum. The monomers of T. minimum have, on average, larger chain lengths than those of P. boryanum and S. communis. The polyether nature of these algaenans makes them highly resistant against degradation, so that they are selectively preserved in the sedimentary record. Therefore, these algaenans probably are important precursors for Type I kerogens.

Cell wall-specific ω-hydroxy fatty acids in some freshwater green microalgae

Ester-bound lipids from the cell walls of the green algae, Tetraedron minimum, Scenedesmus communis and Pediastrum boryanum, were analysed by gas chromatography-mass spectrometry. The double bond positions of the C 30, C 32 and C 34 mono- and C 30 and C 32 diunsaturated ω-hydroxy fatty acids obtained were determined by derivatisation with dimethyl disulphide (DMDS) prior to mass spectrometric identification. All unsaturated ω-hydroxy fatty acids have a double bond located at the ω9-position, whilst the C 30 and C 32 diunsaturated acids have a second double bond at the ω19 and ω18 positions, respectively. Unsaturated ω-hydroxy fatty acids are released upon saponification of the isolated cell walls in all three algae, but the distribution patterns of these compounds differ between species. ω-Hydroxy fatty acids are the main building blocks of the highly cross-linked constituent of the cell walls, herein termed algaenan, in which linear chains of esterified monomers are ether cross-linked at the position of the double bonds. Because none of these monomeric compounds were observed in the cytosolic fraction of the cells, it is believed that they are rapidly secreted and incorporated in the aliphatic cell walls of these algae.

An improved method for the isolation of artifact-free algaenans from microalgae

A new process for the isolation of algaenans (insoluble non-hydrolysable, highly aliphatic biopolymers of microalga cell walls) which avoids their contamination with melanoidin-like polymer artifacts is presented and the algaenans of two species from the Chlorophyceae ( Scenedesmus communis and Botryococcus braunii) are re-examined. Preliminary release of the polysaccharides from these microorganisms by trifluoroacetic acid hydrolysis affords a pure, or much less contaminated, algaenan for the two species. Re-examination of the pyrolysate of S. communis algaenan indicates that the long-chain n-alkylnitriles, previously detected when the algaenan was isolated by the usual process ( Berkaloff et al., 1983), do not actually originate from this biopolymer. We suggest that some nitrogen-containing molecules present in S. communis (or in other Chlorophyceae species) are incorporated into the structure of the melanoidin-like polymers generated when the algaenan is isolated by the usual process which lead, upon pyrolysis, to nitriles. Consideration of previous data, on the pyrolysates of numerous kerogens, suggests that a similar process occurs under natural conditions during early diagenesis.

Biosynthetic effects on the stable carbon isotopic compositions of algal lipids: implications for deciphering the carbon isotopic biomarker record

Thirteen species of algae covering an extensive range of classes were cultured and stable carbon isotopic compositions of their lipids were analysed in order to assess carbon isotopic fractionation effects during their biosynthesis. The fatty acids were found to have similar stable carbon isotopic compositions to each other in all the algae with the exceptions of the C 28 fatty acid in Scenedesmus communis and the polyunsaturated fatty acids in Ampidinium sp. and Gymnodinium simplex which are 3.5‰ more depleted in 13C and up to 8‰ more enriched in 13C, compared to the C 16 fatty acid, respectively. Phytol is consistently enriched in 13C by 2–5‰ compared with the C 16 fatty acid in all algae. The sterols are, however, enriched in 13C by 0–8‰ compared to the C 16 fatty acid, possibly due to a different pool of isopentenyl diphosphate in the cytosol. These large ranges in carbon isotopic compositions of compounds biosynthesized by the same eukaryotes can significantly complicate the interpretation of δ 13C values of sedimentary biomarkers.

The tumbling reactor: a new reactor design for biotechnology Cultivation of the phototrophic micro-alga Scenedesmus communis

A new system for the growth of mammalian cells was developed and its biotechnological suitability was proven by the sterile cultivation of the phototrophic micro-alga Scenedesmus communis, as an easy to cultivate model organism. For this purpose, the bioreactor was combined with a newly developed equipment for irradiation of large scale cultures of phototrophic micro-organisms. Cultivation was performed in a 40 liter scale at 25°C and a pH of 6.0 to 6.5. The aeration gas consisted of 2% or 7% of CO2 in N2. The aeration rate was Vgas = 19.6 L.h-1, the stirring speed was n = 70 or 56 min-1. The new reactor consists of 8 totally immersed fluorescent tubes located around a cylinder for bubble free aeration which is moving within the cultivation broth. Results of the cultivation reveal the suitability of this newly designed system for biotechnological use and its high scale-up potential.