Klebsormidium Flaccidum Research Articles

UV-B light (radiation) affects the metabolism of pigments and fatty acids in green algae Edaphochlorella mirabilis and Klebsormidium flaccidum in vitro

Algae offer a rich source of bioactive compounds suitable for food products and bioenergy. Environmental challenges such as nutrient scarcity, extreme pH and temperature, high light intensity, and UV radiation usually trigger algae to produce excess of lipids, antioxidants, and other bioprotective molecules as part of their adaptations for survival. Algal cultivation provides proteins, lipids, carbohydrates, vitamins, antioxidants, and trace elements. This study focused on understanding how UV-B irradiance, as an abiotic stressor, can influence the growth and metabolite production of two green algal species, Edaphochlorella mirabilis (Chlorophyta) and Klebsormidium flaccidum (Charophyta). Using a temporary immersion system bioreactor for in-vitro algal growth, the results showed no significant difference in biomass for both algal species after the exposure to UV-B rays. However, the assessment of malondialdehyde levels revealed a significantly higher tendency towards lipid peroxidation in treated E. mirabilis (+ 90 %) compared to control. Conversely, K. flaccidum did not display significant differences, thereby highlighting a more advanced adaptive capacity against UV-B radiation. Overall, both algal species treated with UV-B showed increased pigment accumulation. K. flaccidum exhibited an average pigment increase of over 53 %, while E. mirabilis showed a lower increase, over 30 % on average. The notable rise in antioxidant compounds (lutein, β-carotene, and chlorophyll a) in UV-B exposed K. flaccidum samples also suggested a more suitable adaptive strategy to mitigate oxidative stress in Charophyta. In K. flaccidum, the increase in polyunsaturated fatty acids can be associated with increased production of antioxidant compounds. Conversely, E. mirabilis appeared to protect itself by decreasing polyunsaturated fatty acids in favor of saturated ones. In both algal species, the increase in secondary metabolites under UV stress highlighted potential as a novel food source for human consumption, deserving further investigation.

Специфика фототрофных наземных микробных комплексов в посевах пшеницы

The article presents the results of determining the species and quantitative composition of algae and cyanobacteria in terrestrial growths under wheat crops. The wheat seeds were inoculated with various microorganisms in mono-, binary and triple combinations before sowing. Algocyanoflora of the “blooming” soil was represented by 24 species: Cyanobacteria – 7; Chlorophyta + Streptophyta – 12; Bacillariophyta – 5. The inoculants were representatives of prokaryotic and eukaryotic microorganisms – antagonists of Fischerella muscicola, Trichoderma sp. and the phytopathogen Fusarium culmorum. In one of the experimental variants, pre-sowing treatment with the fungicide “Maksim”® was used. It has been shown that during the formation of soil “blooming” the dominant microbiomes are green algae (Chlorococcum infusionum, Klebsormidium flaccidum) and cyanobacteria (species of the genera Leptolyngbya, Phormidium). When determining the number of phototrophic populations, it was found that their density ranges from 1.8 to 8.1 million cells/cm2. At the same time, the maximum development of phototrophs was found in the control variant, and the minimum number was found in the variant with a chemical disinfectant. In variants with microbial inoculation, the peak development of microphototrophs is typical for treatment with a triple mixture and a binary mixture of Fischerella + Trichoderma. Determination of the structure of microbial populations showed that the strongest dominance of cyanobacteria (80,2%) was detected on an artificial infectious background caused by pre-sowing inoculation of wheat seeds with the phytopathogen F. culmorum. A relatively high content of cyanobacteria (up to 60%) is observed in 4 experimental variants (Fischerella, Fischerella + Trichoderma, Trichoderma + Fusarium, Fischerella +Fusarium) and in the remaining 4 variants there is some dominance of microscopic algae ranging from 52 to 58%. Therefore, according to the results obtained, microbial inoculation does not lead to radical changes in the state of terrestrial phototrophic microbial communities, while chemical fungicide significantly suppresses the development of algae and cyanobacteria.

Productivity and competitive dominance of freshwater filamentous macroalgal cultivars for nutrient bioremediation of primary municipal wastewater

ABSTRACT Algal bioremediation using macroalgae is a promising approach to wastewater treatment. This study compared the productivity and bioremediation performance of the freshwater filamentous algal cultivars; Klebsormidium flaccidum, Oedogonium calcareum, and Oedogonium sp., in primary municipal wastewater in outdoor high-rate filamentous algal pond mesocosms. K. flaccidum had the highest biomass productivity (3.09 g dry weight m−2 day−1 ± 0.20 SE) and bioremediation performance, reducing total ammoniacal-N by 51% to 14.80 mg L−1 (± 0.81 SE), nitrate-N by 59% to 0.30 mg L−1 (± 0.02 SE), and dissolved reactive phosphorous by 15% to 3.52 mg L−1 (± 0.07 SE). This cultivar achieved the greatest reductions in total suspended solids (54%), carbonaceous biochemical oxygen demand (93%), and chemical oxygen demand (74%). K. flaccidum and Oedogonium sp. reduced Escherichia coli by 98%. Competitive dominance of K. flaccidum and Oedogonium sp. was assessed in bicultures at three stocking densities. By day 12, K. flaccidum's proportion increased from 50 to 64% (± 6.1 SE) and 73% (± 5.0 SE) at a stocking density of 0.25 g and 0.5 g FW L−1, respectively. Based on superior biomass productivity, bioremediation performance, and competitive dominance, K. flaccidum was identified as a target cultivar for bioremediation of primary municipal wastewater.

Siloxane Containing Polyether Groups-Synthesis and Use as an Anti-Biocorrosion Coating.

In the presented study, the effectiveness of a siloxane polyether (HOL7) coating on glass against microbiological colonization was assessed using microalgae as a key component of widespread aerial biofilms. The siloxane polyether was successfully synthesized by a hydrosilylation reaction in the presence of Karstedt's catalyst. The product structure was confirmed by NMR spectroscopy and GPC analysis. In addition, the thermal stability of HOL7 was studied by thermogravimetric measurement. Subsequently, the surfaces of glass plates were modified with the obtained organosilicon derivative. In the next step, a microalgal experiment was conducted. A mixture of four strains of algal taxa isolated from building materials was used for the experiment-Chlorodium saccharophilum PNK010, Klebsormidium flaccidum PNK013, Pseudostichococcus monallantoides PNK037, and Trebouxia aggregata PNK080. The choice of these algae followed from their wide occurrence in terrestrial environments. Application of an organofunctional siloxane compound on the glass reduced, more or less effectively, the photosynthetic activity of algal cells, depending on the concentration of the compound. Since the structure of the compound was not based on biocide-active agents, its effectiveness was associated with a reduction in water content in the cells.

Semi-continuous cultivation for enhanced protein production using indigenous green microalgae and synthetic municipal wastewater

Cultivation of microalgae has gained significant interest as an alternative protein source, potentially becoming a target commodity recovered from microalgae-based wastewater treatment. This study examined a semi-continuous cultivation strategy to optimize protein accumulation of the indigenous freshwater chlorophytes, Lobochlamys segnis and Klebsormidium flaccidum, and simultaneously remove nutrients from wastewater efficiently. A strain-specific regime was made based on a fixed biomass concentration at the start of 24-h cultivation cycle, i.e., a constant initial cell density, which regulated harvesting and fresh medium supply volume according to the dilution rate. Six cultivation cycles were conducted in lab-scale 1L reactors with a synthetic municipal wastewater. Lobochlamys segnis and K. flaccidum grew exponentially in all cycles. The biomass productivity was 573 and 580 mg L–1 day–1, in which the total protein consisted of 62 and 45% of dry cell weight (dw), respectively. When a culture medium deficient in nitrogen and phosphorus was used, protein level was significantly reduced. L. segnis consumed all NH4+ and PO43– supplied by the medium replacement, giving the removal rate of 9.2 and 5.2 mg L–1 day–1. Whereas K. flaccidum removed 13.8 mg L–1 day–1 NH4+ without completing PO43– removal. The amino acid profile of both strains was characterized by glutamic acids content (4–5% dw). We concluded that the designed cultivation regime would support a constant biomass production with stable and high protein content, along with an efficient removal of nutrient from the wastewater.

Allene oxide synthase 1 contributes to limiting grain arsenic accumulation and seedling detoxification in rice

Arsenic (As) is a cancerogenic metalloid ubiquitously distributed in the environment, which can be easily accumulated in food crops like rice. Jasmonic acid (JA) and its derivatives play critical roles in plant growth and stress response. However, the role of endogenous JA in As accumulation and detoxification is still poorly understood. In this study, we found that JA biosynthesis enzymes Allene Oxide Synthases, OsAOS1 and OsAOS2, regulate As accumulation and As tolerance in rice. Evolutionary bioinformatic analysis indicated that AOS1 and AOS2 have evolved from streptophyte algae (e.g. the basal lineage Klebsormidium flaccidum) – sister clade of land plants. Compared to other two AOSs, OsAOS1 and OsAOS2 were highly expressed in all examined rice tissues and their transcripts were highly induced by As in root and shoot. Loss-of-function of OsAOS1 (osaos1–1) showed elevated As concentration in grains, which was likely attributed to the increased As translocation from root to shoot when the plants were subjected to arsenate [As(V)] but not arsenite [As (III)]. However, the mutation of OsAOS2 (osaos2–1) showed no such effect. Moreover, osaos1–1 and osaos2–1 increased the sensitivity of rice plants to both As(V) and As(III). Disrupted expression of genes involved in As accumulation and detoxification, such as OsPT4, OsNIP3;2, and OsOASTL-A1, was observed in both osaos1–1 and osaos2–1 mutant lines. In addition, a As(V)-induced significant decrease in Reactive Oxygen Species (ROS) production was observed in the root of osaos1–1 but not in osaos2–1. Taken together, our results indicate OsAOS1 modulates both As allocation and detoxification, which could be partially attributed to the altered gene expression profiling and ROS homeostasis in rice while OsAOS2 is important for As tolerance.

Влияние навозных стоков на почвенные фототрофные микроорганизмы

Soil phototrophic microorganisms (algae, cyanobacteria) play a very important role in functioning of anthropogenic systems. They take an active part in soil self-purification by directly absorbing biogenic elements, as well as by stimulating the activity of mineralizing microorganisms at the expense of disengaged oxygen. The research was carried out at a plough field with sod-podzol soil situated near a large pig-breeding farm. Neutralization took place due to natural microbiological processes during the time of disgorging the liquid fraction in the lagoons. Long-term application of manure runoff from pig-breeding farms into plough soil had an impact on species diversity of phototrophic microorganisms, which was considered in the research. Groups of species tolerant to the impact formed in the soil in course of long-term application of liquid manure fraction. The influence of long-term runoff of manure from pig breeding farms on specious diversity of soil phototrophic microorganisms was assessed. In plough soils affected by liquid manure runoff a group of species tolerant to this impact has formed. Their basis is represented by green algae: Klebsormidium flaccidum, K. nitens, Chlorococcum infusionum, Chlorella vulgaris, as well as by the heterocyst-free cyanobacteria Phormidium autumnale and the diatom alga Hantzschia amphioxys. On the surface of plough soil these species make microscopically marked films, i. e. soil “blooming” takes place. General species diversity of microphototrophs in soil of the experimental site is lower than that of the control site. Jaccard coefficient of the experimental and control sites of the field is 47.8%. Nitrogen-fixing cyanobacteria are not represented in the microphototrophic community; it indicates that the natural microcoenosis is damaged in the plough soils and nitrogen content is high.

Screening and optimization of starch from marine microalgae isolated from Penang sea water Malaysia

Starch is a major carbohydrate source in human staple foods and a component of raw materials for non-food applications. Microalgae are the subject of extensive investigation due to their high carbohydrate content, ease of growth, and capacity to absorb more carbon dioxide while still producing greenhouse gases during photosynthesis. Two marine microalgae strains from Malaysia's Penang Sea Water have been successfully isolated and are designated as Klebsormidium flaccidum GN-2, and Nannochloropsis oculata YG-2. K. flaccidum GN-2 produced 16.84% of starch, biomass 0.81 g/L whereas N. oculata YG-2 contained 3.06% and 0.40 g/L of starch and biomass, respectively. K. flaccidum GN-2 was selected to proceed for optimization using Response Surface Methodology (RSM). The starch produced was 19.06% and 0.98 g/L of biomass under the optimized conditions of 35.53 ppt salinity, 23 h of light exposure, and a flow rate of 1 v/v of carbon dioxide. Subsequent nutrient deprivation experiments showed a decrease in biomass and starch. In conclusion, marine microalgae isolated from the Penang Sea successfully produced starch. Further study should be carried out to improve the condition and factors to produce higher starch content in K. flaccidum GN-2 and make it a new promising starch source.

On the evolution of the plant phytochrome chromophore biosynthesis.

Phytochromes are biliprotein photoreceptors present in plants, algae, certain bacteria, and fungi. Land plant phytochromes use phytochromobilin (PΦB) as the bilin chromophore. Phytochromes of streptophyte algae, the clade within which land plants evolved, employ phycocyanobilin (PCB), leading to a more blue-shifted absorption spectrum. Both chromophores are synthesized by ferredoxin-dependent bilin reductases (FDBRs) starting from biliverdin IXα (BV). In cyanobacteria and chlorophyta, BV is reduced to PCB by the FDBR phycocyanobilin:ferredoxin oxidoreductase (PcyA), whereas, in land plants, BV is reduced to PФB by phytochromobilin synthase (HY2). However, phylogenetic studies suggested the absence of any ortholog of PcyA in streptophyte algae and the presence of only PФB biosynthesis-related genes (HY2). The HY2 of the streptophyte alga Klebsormidium nitens (formerly Klebsormidium flaccidum) has already indirectly been indicated to participate in PCB biosynthesis. Here, we overexpressed and purified a His6-tagged variant of K. nitens HY2 (KflaHY2) in Escherichia coli. Employing anaerobic bilin reductase activity assays and coupled phytochrome assembly assays, we confirmed the product and identified intermediates of the reaction. Site-directed mutagenesis revealed 2 aspartate residues critical for catalysis. While it was not possible to convert KflaHY2 into a PΦB-producing enzyme by simply exchanging the catalytic pair, the biochemical investigation of 2 additional members of the HY2 lineage enabled us to define 2 distinct clades, the PCB-HY2 and the PΦB-HY2 clade. Overall, our study gives insight into the evolution of the HY2 lineage of FDBRs.

Indigenous Green Microalgae for Wastewater Treatment: Nutrient Removal and Resource Recovery for Biofuels and Bioproducts

Microalgae biotechnology can strengthen circular economy concepts in the wastewater treatment sector. This study investigated the Norwegian microalgae strains of Tetradesmus wisconsinensis, Lobochlamys segnis, and Klebsormidium flaccidum for their efficiency in nutrient removal. Their biomass productivity and compositions were evaluated for bioenergy and bi-products development. In the laboratory batch experiment with synthetic municipal wastewater, all strains accomplished total removal of nitrogen and phosphorus. L. segnis removed all NH4+ and PO43− (initial concentration of 28 and 15 mg/L, respectively) earliest among others. T. wisconsinensis biomass was superior in total carbohydrates content (40%) and fatty acid profile that imply biorefinery potential. The fatty acid (TFA) content was the highest in L. segnis (193 ± 12 mg/g dry cells), while K. flaccidum accumulated fatty acids that consisted largely of polyunsaturated fatty acids (82% of TFA). The highest protein level was measured in K. flaccidum (53%). Observed variations in biomass components can be used for a strategic production of targeted compound in resource recovery scenarios for biofuel generation.Graphical

Biodeterioration potential of algae on building materials - Model study

Although biodeterioration of building materials is a well-recognized problem, unlike heterotrophic organisms the influence of aerophytic algae has been so far attributed only to aesthetical and indirect biodeterioration. This article concentrates on determining the influence of mixed algal cultures of Coenochloris signiensis, Stichococcus bacillaris, Klebsormidium flaccidum and Chlorococcum infusionum on brick and plaster samples, studied in model environment. Inoculated and incubated for 28 days samples were examined with chlorophyll a measurements, cell density estimation, microscopic observations, water absorptivity tests, pH determination and metabolome profiling. Algal growth led to the lowering pH values of plaster samples by 0.53–0.54 and brick samples by 0.29–0.36 as well as increasing water absorptivity by 4.65% and 4.76% respectively. CIE L*a*b color measurements revealed material discoloration of ΔE = 16.11 ± 1.38 for brick and ΔE = 16.59 ± 0.73 for plaster samples. Metabolome analysis confirmed high activity of biofilms with 112 metabolites detected on brick and 203 on plaster samples. 25 and 35 metabolic pathways were confirmed respectively. Compounds with documented biodeteriorative potential such as acetic, isobutyric and citric acid were found. The acquired results suggest that the impact of green algae on building substrates goes beyond aesthetic and indirect biodeterioration and should be further explored.

First Report on a 5-Year Monitoring of Lampenflora in a Famous Show Cave in Serbia

Many show caves are vulnerable to various disturbances, meaning that conservation of such habitats, which would include monitoring of their ecological parameters and lampenflora (a growing problem worldwide), should be a priority. For the first time in Serbia, lampenflora was monitored continously for 5 years (2016–2020), three times per year during the tourist season, in the Lazar Cave. Artificial light created favorable conditions for the proliferation of phototrophic microorganisms that were developed not only as epiliths, but also endoliths, which poses a greater danger for cave substratum and structures. Although a higher diversity in general was found in Cyanobacteria (coccoid forms mostly), Chlorophyta were more widespread and abundant in samples, among which Chlorella, Stichococcus bacillaris, and Klebsormidium flaccidum stood out. Chlorella is one of the genera making lampenflora dangerous, as it can switch from an autotrophic to a mixotrophic, and finally to a heterotrophic lifestyle. The mosses protonema and mosses itself were also present. Even though the cave is closed for 6 months every year, lampenflora “legacy” always persisted on all sites from the previous year, spreading further over the years. Measured parameters (temperature, relative air humidity, light intensity, substrate pH, and substratum moisture), primary production, and biofilm parameters showed yearly, seasonal, or sampling site variations. Statistical analyses were used to examine the effect of the sampling year, the season, and sampling site on the selected measured parameters, while multivariate analyses were performed with taxa in relation to year, season, site, and main ecological parameters.

Participation of Rossiulus kessleri (Diplopoda, Julida) in the Formation of Algae Assemblages of Urbanized Territories

Epi- and endozoochory are well explored phenomena that contribute to the distribution patterns of plant seeds, spores or fruits by vertebrates. It is less known how soil algae may be redistributed due to analogous interactions. We describe the participation of saprophage Rossiulus kessleri (Julidae, Diplopoda) in soil algae redistribution. The research was carried out in a park area of a large industrial megacity in the Dnipro steppe region (Ukrainian North Steppe subzone), Dnipro city. Research material was collected according to zoological and algological methods. The leaf litter of tree species (ash maple Acer negundo, Italian poplar Populus deltoides, locust Robinia pseudoacacia, European white elm Ulmus laevis, Norway maple Acer platanoides) and living diplopods were collected within 1 m2 quadrats along transects. Millipedes were maintained without feeding for five days, after which they were fed with the litter collected previously. Identification of algoflora was conducted in washes from the surface of diplopods’ bodies, its gut washes, in diplopods’ excretions and leaf litter washes. In the leaf litter, as R. kessleri’s feeding base, 14 soil algae species were identified—Nostoc punctiforme, Bracteacoccus minor, Mychonastes homosphaera, Neospongiococcum sp., Chlamydomonas sp., Chlorella vulgaris, Stichococcus bacillaris, Pseudococcomyxa simplex, Desmococcus olivaceus, Trebouxia spp., Klebsormidium flaccidum, Nephrodiella phaseolus, Navicula pelliculosa and Vischeria magna. In body surface washes, five soil algae species were identified, in gut washes seven algae species were found, while in excretions, just four were observed. It was established that not all algae species from the gut washes of R. kessleri were present in excretions. The presence of some representatives of soil algae, for example, Chlorella vulgaris and Vischeria magna, in natural park litter, body surface washes, gut washes and in excretions of R. kessleri, suggests that the given species pass through the diplopod’s gut and stay undamaged. This indicates that soil saprophage R. kessleri contributes to the dispersal of some soil algae representatives through epi- and endozoochory. Our results represent novel contributions to the knowledge of zoochory. It was shown that animals can be involved in dispersal of not only plant parts but also entire organisms, although it is unknown at what scale diplopods contribute to the diversity and dispersal of algae.

Культури водоростей як модельний об’єкт для вивчення альгобактеріальних угруповань (консорцій)

An information on the results of the microbiological analysis of xenic cultures of green (<i>Chlorophyta</i>) and charophytes (<i>Charophyta</i>) algae is given. Algal xenic cultures are regarded as communities (consortia) of heterogeneous organisms connected with each other by trophic and topic interactions and composed of a center nucleus (autotrophic algae of one species) and consorts (several species of heterotrophic bacteria). Twelve algal xenic cultures of freshwater (<i>Сhlorella vulgaris</i> Beij., <i>Coelastrum</i> <i>rugosum</i> (P.G. Richt.,<i> Tetradesmus dimorphus</i> (Turpin) M.J.Wynne) and aerophitic (<i>Klebsormidium flaccidum</i> (Kütz.) Silva, Mattox et Blackwell) algae from the collection of M.G. Kholodny Institute of Botany NAS of Ukraine were used in investigations. Each species was represented by three strains isolated in 1961–2018 years from the territories of Ukraine and other countries of Eurasia. Overall, 82 bacterial strains were isolated and identified according to some phenotypic (morphological, chemotaxonomic, physiological and chemical) features. The study revealed complexes of four types which consisted 7 species of bacterial consorts. A qualitative composition of complexes was the same in cultures (strains) of one certain algal species but strictly different in cultures of another algal species. Although, some bacterial species were found in several complexes of different type. It is evident a tight association the heterotrophic bacterial consorts with the autotrophic determinant of consortia and conforms the consortium character of algal-bacterial communities in general. It was proposed an express method based on the use of a numerical system for morphological evaluation of bacterial colonies in preliminary study peculiarities, features and functions of consortia.

Enzymatic Synthesis of Xylan Microparticles with Tunable Morphologies.

Xylans are a diverse family of hemicellulosic polysaccharides found in abundance within the cell walls of nearly all flowering plants. Unfortunately, naturally occurring xylans are highly heterogeneous, limiting studies of their synthesis and structure–function relationships. Here, we demonstrate that xylan synthase 1 from the charophyte alga Klebsormidium flaccidum is a powerful biocatalytic tool for the bottom-up synthesis of pure β-1,4 xylan polymers that self-assemble into microparticles in vitro. Using uridine diphosphate-xylose (UDP-xylose) and defined saccharide primers as substrates, we demonstrate that the shape, composition, and properties of the self-assembling xylan microparticles could be readily controlled via the fine structure of the xylan oligosaccharide primer used to initiate polymer elongation. Furthermore, we highlight two approaches for bottom-up and surface functionalization of xylan microparticles with chemical probes and explore the susceptibility of xylan microparticles to enzymatic hydrolysis. Together, these results provide a useful platform for structural and functional studies of xylans to investigate cell wall biosynthesis and polymer–polymer interactions and suggest possible routes to new biobased materials with favorable properties for biomedical and renewable applications.

Soil algae for combating soil degradation – greenhouse experiment with different soil amendments

Context Our research contributes to the knowledge of using soil algae to combat soil degradation. Aims We tested green algae (Klebsormidium flaccidum) and a field soil algae community in a 3-month greenhouse experiment and studied their performance on two substrates: (1) sand from the Ordos Desert; and (2) artificial desert sand (washed sand). Methods A rapid fluorescence microscopy-Image J method was developed to estimate the abundance of algae. We studied the effects of four soil amendments (biochar, clay, organic matter, geohumus) on the development of green algae, field algae and biological soil crusts. Key results The field algae preferred washed sand. All amendments had a positive effect on the abundance of K. flaccidum and field algae. Biological soil crusts were generally lower in control and organic matter treatments, but relatively higher in biochar and clay treatments. No relationship between algal abundance and soil crust stability was found in this short-term experiment. Conclusions Our rapid fluorescence microscopy-Image J method quantitatively estimated algal abundance aunder different conditions, providing an indirect indicator of their growth status. Implications This method can be used to make recommendations on soil amendments and their effect on algal growth studies.

Distribution and Functions of Monodehydroascorbate Reductases in Plants: Comprehensive Reverse Genetic Analysis of Arabidopsis thaliana Enzymes.

Monodehydroascorbate reductase (MDAR) is an enzyme involved in ascorbate recycling. Arabidopsis thaliana has five MDAR genes that encode two cytosolic, one cytosolic/peroxisomal, one peroxisomal membrane-attached, and one chloroplastic/mitochondrial isoform. In contrast, tomato plants possess only three enzymes, lacking the cytosol-specific enzymes. Thus, the number and distribution of MDAR isoforms differ according to plant species. Moreover, the physiological significance of MDARs remains poorly understood. In this study, we classify plant MDARs into three classes: class I, chloroplastic/mitochondrial enzymes; class II, peroxisomal membrane-attached enzymes; and class III, cytosolic/peroxisomal enzymes. The cytosol-specific isoforms form a subclass of class III and are conserved only in Brassicaceae plants. With some exceptions, all land plants and a charophyte algae, Klebsormidium flaccidum, contain all three classes. Using reverse genetic analysis of Arabidopsis thaliana mutants lacking one or more isoforms, we provide new insight into the roles of MDARs; for example, (1) the lack of two isoforms in a specific combination results in lethality, and (2) the role of MDARs in ascorbate redox regulation in leaves can be largely compensated by other systems. Based on these findings, we discuss the distribution and function of MDAR isoforms in land plants and their cooperation with other recycling systems.

Differential Membrane Lipid Profiles and Vibrational Spectra of Three Edaphic Algae and One Cyanobacterium.

The membrane glycerolipids of four phototrophs that were isolated from an edaphic assemblage were determined by UPLC–MS after cultivation in a laboratory growth chamber. Identification was carried out by 18S and 16S rDNA sequencing. The algal species were Klebsormidium flaccidum (Charophyta), Oocystis sp. (Chlorophyta), and Haslea spicula (Bacillariophyta), and the cyanobacterium was Microcoleus vaginatus (Cyanobacteria). The glycerolipid profile of Oocystis sp. was dominated by monogalactosyldiacylglycerol (MGDG) species, with MGDG(18:3/16:4) accounting for 68.6%, whereas MGDG(18:3/16:3) was the most abundant glycerolipid in K. flaccidum (50.1%). A ratio of digalactosyldiacylglycerol (DGDG) species to MGDG species (DGDG/MGDG) was shown to be higher in K. flaccidum (0.26) than in Oocystis sp. (0.14). This ratio increased under high light (HL) as compared to low light (LL) in all the organisms, with its highest value being shown in cyanobacterium (0.38–0.58, LL−HL). High contents of eicosapentaenoic acid (EPA, C20:5) and hexadecenoic acid were observed in the glycerolipids of H. spicula. Similar Fourier transform infrared (FTIR) and Raman spectra were found for K. flaccidum and Oocystis sp. Specific bands at 1629.06 and 1582.78 cm−1 were shown by M. vaginatus in the Raman spectra. Conversely, specific bands in the FTIR spectrum were observed for H. spicula at 1143 and 1744 cm−1. The results of this study point out differences in the membrane lipid composition between species, which likely reflects their different morphology and evolutionary patterns.

High diversity of microalgae as a tool for the synthesis of different silver nanoparticles: A species-specific green synthesis

Autotrophic microorganisms can be useful for the green synthesis of nanoparticles (NPs), but there is a lack of knowledge to affirm if the high variety of microorganisms is connected to a potential high diversity of NPs. Here, aqueous extracts of two cyanobacteria (Synechococcus elongatus and Microcystis aeruginosa) and four microalgae (the chlorophytes Coelastrum astroideum and Desmodesmus armatus; and the charophytes Cosmarium punctulatum and Klebsormidium flaccidum) were used for the biosynthesis of silver nanoparticles (AgNPs). The nanoparticle characterization was performed by UV–Visible absorption spectrum, Fourier Transforms Infrared (FT-IR), Transmission Electron Microscopy (TEM) and Energy Dispersive X-Ray Spectroscopy (EDS). This is the first study trying to establish some connection between the taxonomical diversity of microalgae and cyanobacteria and the synthesis of different silver nanoparticles. All algal and cyanobacterial extracts resulted in the synthesis of well-disperse and crystalline AgNPs, with no agglomerate formation. TEM analysis showed spherical AgNPs shape with size range within 1.8–5.4 nm. FTIR analysis demonstrated the presence of hydroxyl groups of peptidoglycan nature acting as stabilizing agents in the surface of the AgNPs. The nanoparticle shape and kind of stabilizing biomolecules were highly similar, but their size was significantly different, which can affect the NP properties. There was no pattern for the AgNPs in terms of the microorganism phyla. Our results showed a very high potential for the use of cyanobacteria and microalgae in the green synthesis of NPs since the variety of AgNPs obtained was species-specific.

The mechanism of auxin transport in lateral root spacing

The mechanism of auxin transport in lateral root spacing