Algae Research Articles

The effect of nanoparticle surface charge on freshwater algae growth, reproduction, and lipid production

Using functionalized carbon dots as models, positively charged nanoparticles were found to cause growth inhibition and aggregation in microalgae. Negative and near-neutral negative particles were associated with morphological changes.

New molecular evidence of the genus Hydrurus (Chrysophyceae) and descriptions of Hydrurusfoetidus (Villars) Trevisan on the basis of morphology and phylogeny.

The genus Hydrurus contains a solitary species, Hydrurusfoetidus. Its thalli exhibit a remarkable structure, consisting of a firm central axis surrounded by peripheral branches, all enveloped within a viscous, gelatinous coating. Molecular data pertaining to the genus Hydrurus are scarce, necessitating further investigation into its phylogenetic relationships. A new site with benthic freshwater alga Hydrurusfoetidus (Villars) Trevisan has been discovered in the Fenhe River in Shanxi Province, China. The physical and chemical parameters of water were meticulously measured and documented. Detailed morphological observations were conducted on the specimen, measuring different cell categories. The SSU, LSU, ITS and rbcL DNA sequence data of H.foetidus collected from Shanxi were determined. An extensive three-gene phylogenetic tree was constructed, revealing a strong relationship between the specimen in this study and H.foetidus specimen from Norway. Time-calibrated molecular phylogenetic analysis further indicated that the genus Hydrurus diverged approximately 125 million years ago (Early Cretaceous), while the two H.foetidus strains from Shanxi, China and Norway diverged approximately 6 million years ago (Neogene). The results of this study supplement new molecular evidence for H.foetidus and contribute significantly to our understanding of the geographical distribution and evolutionary history of the genus Hydrurus.

Source identification of sedimentary organic carbon in coastal wetlands of the western Bohai Sea

Coastal wetlands play a vital role in mitigating climate change, yet the characteristics of buried organic carbon (OC) and carbon cycling are limited due to difficulties in assessing the composition of OC from different sources (allochthonous vs. autochthonous). In this study, we analyzed the total organic carbon (TOC) to total nitrogen (TN) ratio (C/N), stable carbon isotope (δ13C) composition, and n-alkane content to distinguish different sources of OC in the surface sediments of the coastal wetlands on the western coast of the Bohai Sea. The coupling of the C/N ratio with δ13C and n-alkane biomarkers has been proved to be an effective tool for revealing OC sources. The three end-member Bayesian mixing model based on coupling C/N ratios with δ13C showed that the sedimentary OC was dominated by the contribution of terrestrial particulate organic matter (POM), followed by freshwater algae and marine phytoplankton, with relative contributions of 47 ± 21 %, 41 ± 18 % and 12 ± 17 %, respectively. The relative contributions of terrestrial plants, aquatic macrophytes and marine phytoplankton assessed by n-alkanes were 56 ± 8 %, 35 ± 9 % and 9 ± 5 % in the study area, respectively. The relatively high salinity levels and strong hydrodynamic conditions of the Beidagang Reservoir led to higher terrestrial plants source and lower aquatic macrophytes source than these of Qilihai Reservoir based on the assessment of n-alkanes. Both methods showed that sedimentary OC was mainly derived from terrestrial sources (plant-dominated), suggesting that vegetation plays a crucial role in storing carbon in coastal wetlands, thus, the coastal vegetation management needs to be strengthened in the future. Our findings provide insights into the origins and dynamics of OC in coastal wetlands on the western coast of the Bohai Sea and a significant scientific basis for future monitoring of the blue carbon budget balance in coastal wetlands.

Metastable atomic-ordered configurations for Al1/2Ga1/2N predicted by Monte-Carlo method based on first-principles calculations

Metastability of Al n /12Ga1−n/12N (n= 2–10: integer) with the 1–2 monolayer (ML) in-plane configuration towards the c [0001] direction has been demonstrated recently. To theoretically explain the existence of these metastable structures, relatively large calculation cells are needed. However, previous calculations were limited to the use of small calculation cell sizes to estimate the local potential depth (Δσ) of ordered Al1/2Ga1/2N models. In this work, we were able to evaluate large calculation cells based on the interaction energies between proximate Al atoms (δE Al–Al) in AlGaN alloys. To do this, δE Al–Al values were estimated by first-principles calculations (FPCs) using a (5a 1 × 5a 2 × 5c) cell. Next, a survey of the possible ordered configurations using various large calculation cell models was performed using the estimated δE Al–Al values and the Monte-Carlo method. Then, various Δσ values were estimated by FPCs and compared with the configurations previously reported by other research groups. We found that the ordered configuration obtained from the (4a 1 × 2a 2 × 1c) calculation cell (C 42) has the lowest Δσ of −9.3 meV/cation and exhibited an in-plane configuration at the c(0001) plane having (–Al–Al–Ga–Ga–) and (–Al–Ga–) sequence arrangements observed along the planes. Hence, we found consistencies between the morphology obtained from experiment and the shape of the primitive cell based on our numerical calculations.

Can freshwater plants and algae act as an effective feed supplement to reduce methane emissions from ruminant livestock?

Methane production by livestock is a substantial component of greenhouse gas emissions worldwide. The marine red algae, Asparagopsis taxiformis, has been identified as a possible supplement in livestock feeds due to its potent inhibition of methane production but currently is unable to be produced at scale. Finding additional taxa that inhibit methane production is therefore desirable. Here we provide foundational evidence of methanogenesis-inhibiting properties in Australian freshwater plants and algae, reviewing candidate species and testing species' chemical composition and efficacy in vitro. Candidate plant species and naturally-occurring algal mixes were collected and assessed for ability to reduce methane in batch testing and characterised for biochemical composition, lipids and fatty acids, minerals and DNA. We identified three algal mixes and one plant (Montia australasica) with potential to reduce methane yield in in vitro batch assay trials. All three algal mixes contained Spirogyra, although additional testing would be needed to confirm this alga was responsible for the observed activity. For the two samples that underwent multiple dose testing, Algal mix 1 (predominantly Spirogyra maxima) and M. australasica, there seems to be an optimum dose but sources, harvesting and storage conditions potentially determine their methanogenesis-inhibiting activity. Based on their compositions, fatty acids are likely to be acting to reduce methane in Algal mix 1 while M. australasica likely contains substantial amounts of the flavonoids apigenin and kaempferol, which are associated with methane reduction. Based on their mineral composition, the samples tested would be safe for livestock consumption at an inclusion rate of 20%. Thus, we identified multiple Australian species that have potential to be used as a feed supplement to reduce methane yield in livestock which may be suitable for individual farmers to grow and feed, reducing complexities of supply associated with marine alternatives and suggesting avenues for investigation for similar species elsewhere.

Tuning of the Berreman mode of GaN/AlxGa1-xN heterostructures on sapphire: The role of the 2D-electron gas in the mid-infrared

We investigated the mid-infrared optical properties of GaN/Al(x)Ga(1-x)N-type heterostructures on sapphire substrate grown by the Metal-Organic Chemical Vapor Deposition. We show how the polarization-dependent reflection spectrum is affected by the presence of the strain-induced 2D electron gas at the interfaces between Al(x)Ga(1-x)N and GaN layers. In particular, we show that the 2D electron gas contribution, modeled from its density and transport properties, can play a relevant role at the Berreman mode excitation condition. In this framework, our results offer an advanced approach for the optimization and design of GaN-based broadband optoelectronic and energy management devices.

Toxicity of hexagonal boron nitride nanosheets to freshwater algae: Phospholipid membrane damage and carbon assimilation inhibition

Hexagonal boron nitride (h-BN) nanomaterials have attracted numerous attentions for application in various fields, including environmental governance. Understanding the environmental implications of h-BN is a prerequisite for its safe and sustainable use; nevertheless, information on the negative effect of h-BN on aquatic organisms and the underlying toxicity mechanisms is scarce. The present study found that low exposure doses (0.1–1 μg/mL) of micron-sized h-BN lamella apparently suppressed (maximally 45.3%) the growth of Chlorella vulgaris (a freshwater alga) via membrane damages and metabolic reprogramming. Experimental and simulation results verified that h-BN can penetrate into and then extract phospholipids from the cell membrane of algae due to the strong hydrophobic interactions between h-BN nanosheets and lipids, resulting in membrane permeabilization and integrity reduction. Oxidative stress-triggered lipid peroxidation also contributes to membrane destruction of algae. Metabolomics assay demonstrated that h-BN down-regulated the CO2-fixation associated Calvin cycle and glycolysis/gluconeogenesis pathways in algae, thereby inhibiting energy synthesis and antioxidation process. Despite releasing soluble B inside cells, the B species exhibited negligible toxicity. These findings highlight the phenomena and mechanisms of h-BN toxicity in photosynthetic algae, which have great implications for guiding their safe use under the scenarios of global carbon neutrality.

Palynological reconstruction of the habitat and diet of Iguanodon bernissartensis in the Lower Cretaceous Morella Formation, NE Iberian Peninsula

The recent discovery of iguanodontid remains from the new Palau-3 site in the Lower Cretaceous Morella Formation is the most complete non-articulated skeleton of Iguanodon bernissartensis on the NE Iberian Peninsula. To elucidate the paleoenvironment of the Palau-3 site, a palynological analysis was carried out on matrix samples collected from around the skeleton. The palynological assemblage is found to correspond to an upper Barremian age. While the assemblage is composed of bryophytes, pteridophytes, gymnosperms, freshwater algae, dinoflagellate cysts and fungal spores, the palynoflora is mostly dominated by the Cheirolepidiaceae conifer (Classopollis) and Anemiaceae fern (mainly Cicatricosisporites) families. The absence of angiosperm pollen in this flora is also noteworthy, as angiosperm remains have been recorded previously elsewhere in the Morella Formation. At the Palau-3 site, the fronds of Cyatheaceae and Anemiaceae ferns, as well as the foliage of the Cheirolepidiaceae conifers, may have been the major sources of nutrition of I. bernissartensis and other herbivorous iguanodontians. The paleobotany of the four major localities bearing I. bernissartensis remains in western Europe was surveyed to determine the habitat and feeding preferences of this styracosternan dinosaur. These localities are Bernissart (Belgium), Isle of Wight (England), Nehden (Germany), and Morella (Spain). In accordance to this survey, the habitat preferences of I. bernissartensis and association with specific plant communities show that this ornithopod species was adapted to a wide variety of paleoenvironments.

Phase equilibria, thermodynamic assessment, and the mechanical property of B2 phase of the Al-Ga-Ni ternary system

Ni-based alloys, known for their exceptional mechanical properties and high corrosion resistance in harsh environments, are extensively utilized in gas-turbine engines for propulsion and energy generation. Of particular interests are the L12-Ni3Al and B2-NiAl phases in Al-Ni alloy, which can be the strengthening phases for superalloy and high temperature structural materials, respectively. After Ga addition in the Al-Ni system, these promising intermetallic compounds form a continuous compositional range encompassing the L12-Ni3(Al, Ga) and B2-Ni(Al, Ga) phases. They exhibited distinct mechanical properties contingent on the ratio of Al to Ga. Additionally, Ni and Al are the commonly used substrates in the electronic package and Ga has been used as a filler material for interconnection. Hence, the Al-Ga-Ni phase equilibria are of practical importance for designing L12-Ni3(Al, Ga) and/or B2-Ni(Al, Ga) phase-dispersed Ni-based alloys as well as for evaluating interfacial reactions in the Al/Ga/Ni contacts. However, the Al-Ga-Ni ternary system remains relatively unexplored. In this study, Al-Ga-Ni isothermal sections at 600 (Ni-lean), 900, and 1000 (Ni-rich) °C were experimentally constructed based on equilibrated alloys. Additionally, a CALPHAD-type thermodynamic assessment for the Al-Ga-Ni ternary system was comprehensively performed based on all available experimental information. Furthermore, the Young's modulus and hardness of four B2-Al(Ga, Ni) compounds were determined, revealing that the addition of Ga to B2-NiAl phase would lead to a significant decrease in Young's modulus but a notable enhancement in hardness.

Strategic utilization of microalgae byproducts for sustainable biofertilization of Camellia sinensis (green tea)

Green algae are well known for their plant growth-promoting role, but the biofertilization potential of some industrial algae waste has yet to be tested. Industrial algae production facilities are increasing rapidly yearly, but most growing liquids are unused and remain as waste. Here we examined the effects of various microalgae byproducts as tea plant growth biostimulants. The roles of cell-free supernatant (CFS), sonicated microalgae biomass and living cells of the freshwater alga Chlorella vulgaris in promoting tea plant growth were investigated through real field applications. All three algae by-products of the same culture were applied to the tea plants three times either from aerial parts or from the soil. After 40 days of incubation, it was determined that all microalgae waste, even CFS, significantly improved the vegetative growth of the treated tea plants. CFS were also able to improve chlorophyll accumulation, node length, leaf length, and leaf width by 23%–26%, 62%–69%, 5%–36%, and 23%–54%, respectively. Notably, the sonicated microalgae effluents were able to improve the node growth by 123%. To our knowledge, this is the first study revealing the significant biofertilization potential of C. vulgaris CFS for shoot growth of tea plants. The obtained results highlight the agricultural potentials of both microalgae culture broths and degreased microalgae wastes as sustainable and environmentally-friendly biofertilizers for Camellia sinensis organic farming.

Formation of boehmite through desilication of volcanic-ash-altered kaolinite and its retention for gallium: Contribution to enrichment of aluminum and gallium in coal

Multiple parting bands within Permo–Carboniferous coal that are generally enriched in critical metals in the northern North China have been confirmed to be altered from volcanic ash (tonsteins). The tonsteins and adjacent coal in some areas contain boehmite with varying contents. Whether or not the boehmite has a relationship with the volcanic-ash-altered kaolinite remains poorly understood. Herein, petrographical, mineralogical, whole-rock geochemical, and in-situ elemental analyses, combined with U–Pb–Hf isotopic analysis of zircon, were performed for the boehmite-bearing/rich partings and coal collected from the eastern edge of the Datong and Jungar coalfields. Except for the boehmite, well-ordered kaolinite is predominant in the parting samples, where the columnar/tabular and vermicular kaolinite are commonly present. Additionally, the zircons separated from the representative parting and coal samples are mostly igneous origin with only one age population of ca. 300 Ma, almost same with the depositional age of the coal, suggesting that the kaolinite in the inorganic constitutes of the investigated coal seams were mainly altered from volcanic ash. Numerous fine-grained boehmite exhibit textural features of replacement for columnar/tabular and vermicular kaolinite along the cleavage cracks in the parting samples, suggesting that such boehmite were formed from desilication of volcanic-ash-altered kaolinite. The tonsteins and coal along the eastern edge of the coalfields were uplifted and influenced by fault activities due to Indosinian and Yanshan orogeny, which were probably experienced intensive leaching by silica-undersaturated percolating water and groundwater, resulting in desilication of volcanic-ash-altered kaolinite and precipitation of residual Al as boehmite. The Ga, preserved in the alumina octahedral sheets of volcanic-ash-altered kaolinite, were retained by boehmite due to its very similar geochemical behavior with Al. The formation of boehmite and its retention for Ga made a contribution to the genesis of high–Al–Ga coal in the northern North China.

Nanophytosome formulation of β-1,3-glucan and Euglena gracilis extract for drug delivery applications

Euglena gracilis (EG) is a unicellular freshwater alga known for its high β-1,3-glucan (BG) content with well-known biological properties and immune response. The high molecular weight structure of BG traditionally poses a challenge in terms of its size and absorption. Therefore, the aim of this study was to develop a novel drug delivery mechanism of BG and EG to nanophytosomes (NPs) by converting the heavy molecular weight of BG and EG into lipid phosphatidylcholine (PC), which plays an important role in improving their bioavailability and entrapment in captivity. The BG and EG NPs were developed by the solvent evaporation method while varying time and temperature to optimize their drug delivery ability. The size of BG-PC and EG-PC obtained by the Dynamic Light Scattering (DLS) method was 134.62 and 158.38 nm, respectively. Chemical (Fourier Transform Infra-Red) and structural (X-Ray Diffraction) characterization of NPs improved the binding capacity and the amorphous nature of both NPs. The shape of the NPs by Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) revealed their spherical, vesicular nature. The encapsulation efficiency of BG-PC and EG-PC was 82 ± 1.62 % and 87 ± 3.22 %, respectively, which improves the bioavailability. The developed methodology has thus proven effective in synthesizing BG-PC and EG-PC, which may be useful as NP drug delivery carriers. Future research could demonstrate the safety and effectiveness of long-term storage conditions for medical and pharmaceutical applications.•Nanophytosomes are tailored in size, shape and composition to optimize the delivery of phytochemicals/phytocompounds through nanoscale size and surface modification for better physiological absorption.•Nanophytosomes increase the stability of phytochemicals/phytocompounds and protect them from degradation due to heat or chemical reactions, leading to longer shelf life and improved therapeutic efficacy.•In this method, optimal conditions were created for the formation of β-1,3-glucan and Euglena gracilis extract nanophytosomes for successful development of drug delivery system that can effectively deliver bioactive compounds.

Palynological study of archaeometallurgical artefacts from the Late Bronze Age copper smelting sites (Georgia): First results

This article focuses on the palynological (pollen and non-pollen palynomorphs) study of material found with artefacts from Late Bronze Age archaeometallurgical sites in the Lechkhumi area of the mountainous south-west Caucasus region of ancient Colchis. The analysis of organic residues recovered from voids in slag and crucible fragments have revealed an abundance of pollen and spores of diverse plant taxa. Many non-palynological palynomorphs were also found. In total, more than 50 palynomorphs were identified. It was observed that the chemical composition of the copper smelting slag fragments has contributed to the good preservation of the pollen grains, though detailed chemical analyses and experiments are needed. The spectrum from slag includes taxa that are more poorly preserved in sediments, including soil. This preservation undoubtedly makes palynological research of slag residues promising in the future. The range of fossilized plants and spores recovered proves that during the Late Bronze Age in Lechkhumi, forests dominated by chestnut (Castanea sativa) occupied a much larger area than today. Other thermophilic trees, such as zelkva (Zelkova carpinifolia), oak (Quercus), lime (Tilia), and hornbeam (Carpinus betulus) were also present. Thermophilic ferns thrived in the undergrowth as well. In the 13th–9th centuries BC, the existence of warmer climatic conditions in Lechkhumi compared to that we have now is additionally confirmed by the presence of freshwater thermophilic algae Pseudoschizaea, Spirogyra and other Zygnemataceae found in the spectra. Spores of bracken fern (Pteridium aquilinum) and fungus Ustulina most probably reflect felling and human exploitation of the woodland in the close neighbourhood of the site. Comparison of palynological and wood charcoal analyses has demonstrated that the metallurgists of that time used the nearby woods as a source of fuel. Thanks to favourable climatic conditions, beside copper smelting some small-scale agricultural activities were performed which was visible in the composition of herbaceous plant taxa.

Impact of post-deposition annealing on the electronic properties of Al2O3/GaN interface by first-principles study

The electronic properties of Al2O3/GaN interface are investigated by first-principles calculations to explore the effects of post-deposition annealing (PDA) in O2 or N2 ambient. It is found that for the initial Al2O3/GaN interface without post-annealing, there are traps with a wide energy range in the GaN band gap, mainly caused by dangling bonds (DBs) of Ga, Al, and N atoms. However, with proper PDA in O2 ambient, the trap states induced by Al DBs completely merge into GaN conduction band, while the trap states induced by Ga DBs and N DBs completely merge into GaN valence band. Therefore, the interface shows a cleaner band structure. Nevertheless, excessive interface O content can lead to trap states around the valence band maximum induced by N DBs and O DBs. For PDA in N2 ambient, the trap states induced by Al DBs and Ga DBs can be completely suppressed under appropriate interface N content. Unfortunately, deep and shallow traps caused by N DBs can be introduced in the GaN band gap. This study systematically reveals the physical mechanism by which PDA in O2 ambient compared to N2 can significantly reduce the interface state density and improve threshold voltage stability of the device.

Toxic effects of thallium (Tl+) on prokaryotic alga Microcystis aeruginosa: Short and long-term influences by potassium and humic acid

Thallium (Tl) is a priority pollutant regulated by the US EPA. It is also a critical element commonly used in high technology industries; with an increasing demand for semiconductors nowadays, wastewater discharges from manufacturing plants or metal mining activities may result in elevated levels of thallium in receiving water harming aquatic organisms. Regarding the impact of thallium on freshwater algae, little attention has been paid to prokaryotic physiology through various exposure periods. In this bench-scale study, prokaryotic alga Microcystis aeruginosa PCC 7806 was cultured in modified BG11 medium and exposed to Tl+ (TlNO3) ranging from 250 to 1250 μg/L for 4 and 14 days. Throughout the experiment using flow cytometry assays, algal population, cell membrane integrity, oxidation stress level, and chlorophyll fluorescence were exacerbated following the exposure to 750 μg Tl/L (approximately 4-day effective concentration of Tl+ for reducing 50% of algal population). Potassium and humic acid (HA) (1–5 mg/L) were added to study their influences on the thallium toxicity. With the additions of potassium, thallium toxicities to algal population and physiology were not significantly changed within 4 days, while they were alleviated within 14 days. With the addition of HA at 1 mg/L, cell membrane integrity was significantly attenuated within 4 days; ameliorating effects on algal population and oxidative stress were not observed until day 14. Thallium toxicities on oxidative stress level and photosynthesis activity were exacerbated in the presence of HA at 3–5 mg/L. The study provides useful information for further studies on the mode of toxic action of Tl+ in prokaryotic algae; it also demonstrates the necessity of considering short and long-term exposure durations while incorporating water chemistry into assessment of thallium toxicity to algae.

Exploring cyanobacteria seed resources and corresponding gas-vesicle-biosynthetic elements for producing ultrasound molecular imaging probes

Use of gas vesicles (GVs) as biosynthetic ultrasound molecular imaging (UMI) probes has become a hot topic of research in recent years owing to their advantages of high stability, low risk of toxicity, genetic engineering characterization, easy post-modification, and drug-loading potential. Exploration of natural GV biosynthetic resources and their corresponding biosynthetic elements for various ultrasonic diagnosis and treatment needs to be developed in this field. In this study, we utilized the sequenced cyanobacteria resources preserved in the Freshwater Algae Culture Collection at the Institute of Hydrobiology (FACHB) to screen seed cells and corresponding synthetic elements for biosynthesis of UMI probes. GV operons from the genomes of 158 strains of cyanobacteria were analyzed to identify their natural GV biosynthetic elements. Based on the ultrasound screening method (VINNO D860LAB, 2D transducer X6-16L, 50 % output power mode, MI: 1.116), 57 seed resources with biosynthetic UMI probe potential from 10 genera were selected from 158 strains of cyanobacteria, corresponding to 28 types of effective biosynthetic elements. These results provide a theoretical basis for future mass production of customized GVs in chassis cells and their application in UMI.

Electroporation-based delivery of proteins in Penium margaritaceum and other zygnematophycean algae.

Zygnematophycean algae represent the streptophyte group identified as the closest sister clade to land plants. Their phylogenetic position and growing genomic resources make these freshwater algae attractive models for evolutionary studies in the context of plant terrestrialization. However, available genetic transformation protocols are limited and exclusively DNA-based. To expand the zygnematophycean toolkit, we developed a DNA-free method for protein delivery into intact cells using electroporation. We use confocal microscopy coupled with fluorescence lifetime imaging to assess the delivery of mNeonGreen into algal cells. We optimized the method to obtain high efficiency of delivery and cell recovery after electroporation in two strains of Penium margaritaceum and show that the experimental setup can also be used to deliver proteins in other zygnematophycean species such as Closterium peracerosum-strigosum-littorale complex and Mesotaenium endlicherianum. We discuss the possible applications of this proof-of-concept method.

New Records for the Turkish Freshwater Algal Flora in Twenty Five River Basins of Türkiye, Part I: Bacillariophyta

The present study aimed to contribute to the algal flora of Türkiye by Bacillariophyta (diatom) as new records for the Turkish freshwater. Phytobenthos and phytoplankton were sampled three times (spring, summer, and autumn) a year between 2017 and 2019. Samples of the phytoplankton were collected with a water sampler from three depths, and samples of diatoms were obtained as epiphytic in the littoral zone of the lakes. However, if macrophytes were absent, epilithic or epipelic diatoms were sampled in lakes. Also, samples of phytobenthos were preferred as epilithic in rivers. However, if stones were absent, epiphytic or epipelic diatoms were sampled. During the studied period, a total of 895 diatom taxa were determined as planktonic (378 taxa) and benthic (860 taxa) in lakes and rivers of 25 river basins of Türkiye, and a total of 39 new records were identified. The highest diatom taxa were determined in the Fırat-Dicle, Konya, Antalya, and Büyük Menderes basins with 11, 11, 10, and 6 taxa, respectively. On the other hand, new records were not detected in 10 basins.

Amino acid-based biostimulant improves the productivity of Radish (Raphanus sativus L.) under saline stress


 The radish culture is highly sensitive to salinity. The use of an amino acid-based biostimulant can, therefore, be an attenuator of the deleterious effect of salinity on the radish crop. The aim was to evaluate the effectiveness of a biostimulant based on amino acids and freshwater algae extract on radish (Raphanus sativus L.) cultivated under irrigation conditions with saline water. The experiment was carried out in a greenhouse. The saline levels evaluated were 0.15, 1.8, and 2.8 dS.m-1 and four doses of biostimulant were applied (0, 2, 4, and 6 mL/L). The statistical design was completely randomized, in a 4x3 factorial scheme with 4 replications. Biometric and biomass analyses, sodium and potassium contents, and soluble solids were performed. Was observed that plants submitted to high salinity levels (2.8 dS m-1) with application of 6mL/L of the biostimulant showed high values in height (12.2 cm), stem (5mm) and tuber (6mm) diameter, leaf area (50cm2), fresh and dry mass of aerial part (3.5 g) and underground system (5.8 g). The application of the biostimulant 6 mL/L, at the salinity level of 2.8 dS.m-1, favored the increase of saline ions in the tuber of the plants. The application the biostimulant provided a higher content of soluble solids. Applications of the biostimulant in plants with saline stress showed beneficial responses in the performance of the radish, therefore the dose of 6 mL/L is recommended for a satisfactory response of the performance of the radish in saline conditions.

Amino acids profile of six freshwater Algae in the northern region of Bangladesh: A solution for the protein supplement of poultry feed

Algae is an important natural source of protein, specifically amino acid source, which are the building blocks of enzymes, hormones, nucleic acids, etc. Herein, the amino acid composition was investigated in six commonly growing fresh-water algae. The number of amino acids in Oscillatoria brevis, Spirulina platensis, Pithophora kewensis, Euglena viridis, Hydrodictyon reticulatum, and Aphanocapsa holsatica were detected 15, 12, 17, 15, 14, and 15, respectively. Among studied algal species, the amino acids: proline (29239.3 ± 276.4 μg/g), histidine (10056.8 ± 85.4 μg/g), aspartic (3030.6 ± 48.6 μg/g), threonine (1492.3 ± 31.8 μg/g) were detected in the highest amount in O. brevis, S. platensis, P. kewensis, A. holsatica, respectively. It is reported that the range of the ratio between 50/50 to 60/40 of essential amino acid/(nonessential amino acid + conditional essential amino acid) promotes maximum growth performance and best energy utilization. The obtained results of this study suggested that a combination of A. holsatica, H. reticulatum, and O. brevis can provide a good ratio (48/52) of amino acids and the noble source of essential amino acids for feed or food supplements, especially for poultry's stamina and, consequently, welfare.