Diatom Algae Research Articles

Acclimation Strategies for the Black Sea Diatom Algae Ditylum brightwellii to High Intensity of Light

In cells of a culture of the large diatom Ditylum brightwellii (T. West) Grunow acclimated to faint light (17 μmol photons/(m2 s)), numerous chloroplasts are evenly distributed throughout the cell cytoplasm. After 10 min of exposure of algae to extremely high illumination (1100 μmol photons/(m2 s)), their aggregates gradually form in the center of the cell, and their formation continues until the end of the 2-h exposure period. At light intensities of 510–935 µmol photons/(m2 s) during short-term photoacclimation, the aggregation of chloroplasts is recorded for 20–60 min, after which their reverse movement and uniform distribution in the cytoplasm are revealed by the end of the second hour. Under conditions of a longer culture stay at a light intensity of 1100 μmol photons/(m2 s), the algae retains viability for only 6 h. Long-term photoacclimation of this species, which stops by the end of the second day, is detected when the light becomes half as weak. This is manifested in an increase in cell volume and in the C/Chl a ratio, in the increased aggregation of chloroplasts in the center of the cell, and in a decrease in a number of fluorescent parameters of the efficiency of photosystem II and of culture viability.

Systematic Structure and Ecological Diagnostic of the Diatom Algae in the Watershed of River Sebou (Morocco)

Systematic Structure and Ecological Diagnostic of the Diatom Algae in the Watershed of River Sebou (Morocco)

Combined effect of light and glyphosate herbicide on growth rate of marine diatom algae.

The effect of glyphosate herbicide at concentrations of 25, 100, 150 and 200 μg.L-1 on growth characteristics of diatoms C. caspia and T. weissflogii under accumulative growth conditions was investigated. Increasing herbicide concentration in the medium resulted in growth suppression of both species and decreased the final abundance of the cultures in the stationary growth phase. The calculated concentrations of herbicide EC10 and EC50 (10 and 90 μg.L-1 for C. caspia and 7 and 25 μg·L-1 for T. weissflogii, respectively) led to a 10 and 50% reduction in the abundance of the studied cultures relative to the control, are ecologically significant and correspond to the values recorded in aquatic areas. The combined effect of light (in the range of 20-250 µE.m-2.s-1) and glyphosate (calculated concentrations of EC10 and EC50) on the growth characteristics of microalgae was evaluated. An increase in algal sensitivity to light was observed with glyphosate exposure. In both species, the increase in the concentration of glyphosate in the medium led to a decrease in the initial angle of slope of the light curve of growth under conditions of light limitation, a reduction in the value of light saturation of growth, narrowing of the boundaries of the light optimum and an increase in the degree of light inhibition. It is shown that the effect of the combined action of light and glyphosate exceeds the sum of the effects of each factor. This fact should be taken into account in ecotoxicological monitoring when assessing the risks of glyphosate ingress into aquatic ecosystems. An increase in glyphosate concentration in water during periods with high values of solar insolation is potentially dangerous due to a decrease in the photosynthetic activity of algae and a reduction in diatom algae abundance.

Development of an artificial propagation and breeding method for the beehorn snail (Clithon diadema)

Beehorn snail (Clithon diadema), known for its vibrant colors, is threatened with extinction due to excessive field collection. Therefore, this study investigated the effects of different diets and salinity (0‰–35‰) on the gonadal development, capsule productivity, embryonic development, and larval survival and growth of C. diadema. Adult snails (shell length: 9.09 ± 0.87 mm) were fed diatoms, including pennate marine diatom (Nitzschia grossestriata), boat-shaped diatom algae (Navicula sp.) and Cylindrotheca sp., along with giant tiger prawn (Penaeus monodon) commercial feed, sea lettuce (Ulva lactuca), or Cladophora fascicularis, while snail larvae (shell length: 154.85 ± 6.03 μm) were fed Isochrysis galbana or Chaetoceros muelleri. The diatom group outperformed commercial feed and U. lactuca groups. The highest capsule productivity, yielding 79–82 capsules in 4 weeks, occurred at 15‰-20‰ salinity for diatom-fed adults. Embryos thrived at 0‰ but didn't hatch; hatching required salinities above 0‰, highlighting saline necessity. In addition, acute salinity changes (0‰ to 30‰) can deform embryo. Embryonic development at 15‰–20‰ salinity lasted 13.56–14.33 days with 100% larval hatching. However, larvae hatched at >20‰ salinity exhibit improved the percentage of survival without feeding (longer median lethal times). I. galbana-fed larvae survived 68 days with a 75% rate, outlasting C. muelleri-fed larvae which perished within 28 days. I. galbana-fed larvae, raised for 68 days at 25‰ salinity, showed 100% survival, 44.44% metamorphosis, and a 3.1 times growth increase. Metamorphosis rates were highest at 25‰ salinity with I. galbana, exceeding the 20‰ group by 3.2 times. Mucus of C. diadema boosts larval metamorphosis to 50.00%, 9 times higher than without inducers. Based on previous results, we developed an artificial propagation and breeding method for C. diadema. Artificially propagating C. diadema in large quantities could reduce the need for wild harvesting, thereby mitigating negative ecological impacts from excessive collection.

Effects of Dietary Microalgae Inclusion on Feed Utilization, Morphological and Chemical Characteristics and Body Health in Fish: Advantages and Disadvantages

Background: Dietary microalgae inclusion in small or large amounts to fish species is considered one of the sources for improving nutritional values and productive performances throughout the world. Methods: The microalgae are classified through light and electron microscopes into four groups: blue-green, green, golden and diatoms algae. The microalgae can be cultured in the laboratory under controlled conditions. Hence, the grown microalgae biochemical analysis of pigments, proteins and carbohydrates were differed over controlled conditions. Moreover, molecular biology concerning genes and genomes enabled to study ecology, evolution and physiology of microalgae. The fascinating field of microalgae genetic engineering was applied to produce invaluable microalgae compounds as omega-3 fatty acids. The microalgae and their purified compounds were used as direct nutritional sources or as indirect contributors through improvement of water quality and reduction of stress. Result: The chemical composition of microalgae differed depending on nutrient availability for production and microalgae species. The microalgae invaluable compounds include “proteins, lipids, polysaccharides, polyunsaturated fatty acids, pigments, vitamins and other bioactive constituents”. The dietary microalgae and their purified compounds have been shown to provide beneficial effects in growth performance and body health. The roles of microalgae and their constituents as antioxidant, antibacterial, antiviral and anti-tumour materials have been well-established versus challenging problems. In this context, this review is designed to compile and discuss the advantages and disadvantages effects of microalgae on feed utilization, reproductive and therapeutic performances in fish.

Potential Benefits of a Cosmetic Ingredient Combining Thermal Spring Water and Diatom Algae Extract

The development of cosmetic ingredients improving the management of skin with irritation proclivity is an actual need. However, medical recommendations in specific cases, such as sensitive skin, include the use of as few and low-reactive ingredients as possible. In this context, we here describe the development of a new ingredient consisting of a mixture of thermal water and a diatom algae extract. First, we characterized a thermal spring water (La Solia, LS-TSW). Attending to its chemical composition, LS-TSW displayed an exclusive combination of different inorganic elements, with interesting potential properties when compared with other commercial spring waters. Then, LS-TSW hydrobiome was studied, and after finding specimens of Phaeodactylum-like sp., we proposed potentiating LS-TSW benefits with its combination with an oil extract of Phaeodactylum tricornutum (PtOE). Finally, we assessed the potential of the mixture during pro-inflammatory stimulation, in the first instance using an immune cell model, and then in an in vitro system mimicking keratinocytes under skin irritation. In the last-mentioned model, the ingredient of interest effectively attenuated the induced levels of different pro-inflammatory mediators (IL-6, IL-1, TNFα, NF-κB, and CCL1), at the level of gene expression. Thus, our results highlight the potential benefits of this combination in the context of skin irritation, opening roads for its use in new skincare regimens, and addressing an important dermatological concern.

Distribution, taxonomic diversity and ecology of paleogene <i>Bacillariophyta</i> in Ukraine

The geographic distribution, level of taxonomic diversity, and ecological preferences of Bacillariophyta complexes extracted from Paleogene deposits in various regions of Ukraine are characterized. The stratigraphic sequence of diatom assemblages, the relationship of the conditions of their formation to paleoceanological events in sedimentation basins, and the biostratigraphic significance are traced. The most taxonomically diverse (up to 250 species) associations of marine diatoms and silicoflagellates are found in the Middle to Upper Eocene deposits of the northeast margin of the Dnieper-Donetsk Depression, the northwest margins of the Donbas, and the slopes of the Voronezh Uplift. In Eocene-Oligocene deposits of the Ukrainian Shield, diatom complexes consist of over 60 marine and brackish taxa. Early Oligocene marine associations, widespread in the Sambir Carpathians and the eastern part of the Azov region, include over 130 species-level taxa. Changes in the proportion of ecological groups of diatom algae indicate their formation under different facies conditions and the transition from marine warm to more cold-water coastal-marine environments during the Eocene, with episodes of freshwater input in the Oligocene.

Marine diatom algae cultivation in simulated dairy wastewater and biomass valorization.

Liquid byproducts and organic wastes generated from dairy processing units contribute as the largest source of industrial food wastewater. Though bacteria-mediated treatment strategies are largely implemented, a more effective and innovative management system is needed of the hour. Thus, the current study involves the cultivation of centric diatoms, Chaetoceros gracilis, and Thalassiosira weissflogii in simulated dairy wastewater (SDWW) formulated using varying amounts of milk powder with artificial seawater f/2 media (ASW). The results revealed that cell density and biomass productivity were highest in the 2.5% SDWW treatment cultures of both the strains, the maximum being in C. gracilis (7.5 × 106 cells mL - 1; 21.1mg L-1day-1). Conversely, the total carotenoid, chrysolaminarin, and phenol content were negatively impacted by SDWW. However, a considerable enhancement in the total lipid content was reported in the 2.5% SDWW culture of both species. Furthermore, the fatty acid profiling revealed that though the total polyunsaturated fatty acid (PUFA) content was highest in the control setups, the total mono polyunsaturated fatty acid (MUFA) content was higher in the 5% SDWW setups (30.66% in C. gracilis and 33.21% in T. weissflogii). In addition to it, in the cultures utilizing energy from external carbon sources provided by SDWW, the biodiesel produced was also enhanced owing to the heightened cetane number. Thus, the current study evidently highlights the organic carbon acquisition potential of marine diatoms with the scope of providing sustainable biorefinery.

Ecological and Physiological Characteristics and Biotechnological Potential of Diatom Algae Nitzschia amabilis H. Suzuki

Ecological and Physiological Characteristics and Biotechnological Potential of Diatom Algae Nitzschia amabilis H. Suzuki

Ecological and Physiological Characteristics and Biotechnological Potential of Diatom Algae Nitzschia amabilis H. Suzuki

The study is focused on the ecological and physiological properties, production, and biochemical characteristics of the diatom Nitzschia amabilis. The optimum salinity (35‒36‰), illumination (2.95 klx), and photoperiod (14 h) at which the highest specific cell growth rate is achieved was determined. The coefficient of light saturation (Ik) was calculated and turned out to be lower than one, which indicates the high energy efficiency of photosynthesis. The results of experiments on salinity showed the ability of the alga to grow in the range of 4–68‰, indicating its relatively broad euryhalinity. The biochemical composition of N. amabilis during acumulative cultivation was studied. In general, polyunsaturated fatty acids predominated in the studied strain; eicosapentaenoic, arachidonic, and docosahexaenoic acids were dominant. The main share of saturated fatty acids consisted of palmitic acid. The productivity indicators of N. amabilis in relation to lipids, fucoxanthin, and PUFAs, which were 2.5–3 times higher in the flow cultivation mode than in the cumulative mode, have been established.

Fluorescein-based vital dye for silicifying organisms

A method for the synthesis of a new amine-containing dye based on fluorescein (Flunet) was developed. The new dye exhibits pH-independent fluorescence in aqueous media and is able to penetrate living cells. Flunet can accumulate in the siliceous valve of diatom algae and cause cell death at a concentration of 0.5 μM, accompanied by chloroplast destruction. Flunet is nontoxic to yeasts and photosynthesizing dinoflagellates, but suppresses the growth of sponge primmorphs. Turning off the fluorescence of Flunet using a fluorescein shield protects diatom algae from death. Flunet, unlike other biosilica vital dyes, has emission in the red region (650–700 nm), which corresponds to the absorption band of chlorophyll. We suppose that once a significant amount of Flunet enters the siliceous valve of a diatom alga, it begins to convert blue light into green and red light, leading to the destruction of chloroplasts located very close (at the micrometer level) to the valve. Siliceous sponges can be suppressed in a similar way: light emitted by growing spicules destroys photosynthesizing sponge symbionts. Our findings open up a new way to influence silica-containing organisms by introducing different fluorescent dyes into the silica structures. This effect can be both positive (increased photosynthesis due to light tuning) and negative, leading to phototoxicity. Considering the main role of diatoms in biofouling of ships and other surfaces, the use of silica-penetrating dyes is a promising environmentally friendly way of antifouling protection.

Gas Chromatography-Mass Spectrometric Study of Low-Molecular-Weight Exogenous Metabolites of Algae-Bacterial Communities in the Laboratory Accumulative Culture

The study of exogenous metabolites of algae-bacterial communities in the laboratory accumulative culture obtained from natural river water was conducted using gas chromatography-mass spectrometry. Exometabolites of the algae-bacterial community (including microalgae and cyanobacteria) in the culture medium were represented by saturated, unsaturated, and aromatic hydrocarbons, carboxylic acids, phenolic, and terpene compounds and their derivatives. Possible biological activities of the discovered exometabolites are considered. The study has demonstrated that an increase in the number of main groups of microorganisms, along with changes in the composition of algae and cyanobacteria, are responsible for the increase in the composition and concentration of metabolites in the microecosystem’s culture medium after one month of cultivation. The presence of octacosane in high concentration (0.0603 mg/L; 23.78% of the total content of low molecular weight organic compounds) by the end of exposure accumulative culture is associated with the strong development of the cyanobacterium Gloeocapsa sp. in the presence of diatom algae of the genus Navicula and green algae of the genera Chlorella and Scenedesmus. Due to the need to comprehend the ecological and biochemical mechanisms of the formation and functioning of algae-bacterial communities, as well as to predict potential paths of transformation and evolution of aquatic ecosystems, the specificity of exometabolite complexes of algae and microorganisms, as well as their allelopathic and other biochemical interactions in freshwater ecosystems, requires further serious study.

Characterization of diatom silica exoskeletons using atomic force microscopy: Topography and mechanical properties

Hierarchically structured natural objects provide a promising base for developing advanced hybrid materials and devices for a wide range of applications. Particularly high level of interest has recently been placed on diatom algae, eukaryotic unicellular microorganisms that represent a potential solution to the fundamental problems of bionics, specifically, the effective application of exoskeleton building principles to high efficiency engineering device fabrication. Developing hull engineering structures, in particular, requires a thorough understanding of the structural and mechanical characteristics of diatom frustules. The present study investigated the morphology, topography and mechanical properties of Coscinodiscus oculus-iridis diatom frustules using atomic force microscopy and scanning electron microscopy. The Young’s modulus showed a decrease from the side to the center of the frustule, with the variance up to fivefold, demonstrating the deformation of the structure. Nanostructured siliceous exoskeletons (frustules) offer unique guidance for developing a new generation of nano- and microdevices for electronic, electromechanical, photonic, and other uses by revealing the underlying relationship in the structure-properties-function chain.

Crushing performance and optimization of bio-inspired multi-cell columns

Abstract Multi-cell columns inspired by diatom algae have been examined regarding crashworthiness. Crushing simulations have been conducted for AA2024-T351, B1500HS-O25, and a combination of these materials. The highest specific energy absorption and lowest peak crushing force value were obtained with a homogenous AA2024-T351 column. Single and multi-objective optimization studies have been conducted with this column to find the best design. This design could be used in crash-box-like structures in automotive design.

Broadening the Taxonomic Composition of Diatoms (Bacillariophyta) in Tundra Water Bodies of Adjacent Territories of the Lena Delta Wildlife Reserve (Yakutia, Russia) Using Electron Microscopy<sup>1</sup>

Using the electron microscopy, 435 diatom algae from 78 genera of 14 different types of tundra water bodies located in the vicinity of the Ust-Lensky State Reserve, north of the Arctic Circle, on the northern exposure of the slope of the Primorsky Ridge (the eastern spur of the Kharaulakh Range of the Verkhoyansk Mountain system) 435 diatom algae from 78 genera were revealed. Among them, 24 taxa of the species rank and 1 of the generic rank are new to the flora of Russia. Most of the identified species, which are new to the flora of Russia, are found in Europe and are characteristic of oligotrophic water bodies and watercourses. Of all the species under study, 66 species belonging to 28 genera have been identified to the genus, with the largest number of them belonging to the genera Planothidium (7) and Gomphonema (10).

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.

Diversity of Diatom Algae in the Lena Delta Nature Reserve and the Adjacent Territory in the Specific Ecological Factors of the Arctic

A total of 413 diatom taxa were known for aquatic habitats of the Lena Delta Nature Reserve. We identified 385 taxa in 14 small tundra lakes near the reserve that significantly enriched the diatom diversity of the region (666 taxa including definitions to the genus level). Thus, the species composition of diatoms in the reserve and adjacent territories was increased by 278 species. We showed that the species of the genera Pinnularia (57) and Eunotia (51) have predominance at the family and generic levels. The index of intraspecific variability Ssp./Sp. for the lakes of the reserve was 1.11, and that for the lakes of the Tiksi region 1.14, which is typical for high-latitude and high-mountain communities. The number of rare or endangered species varied in different lakes from 1 to 10, totaling 42 species for the entire study area. Bioindication has shown that potentially threatened species prefer moderate temperatures, and slightly acidic or neutral environments free from organic pollution. A comparative analysis of the species composition of diatoms in the vicinity of the Lena Delta and other northern water bodies of Yakutia and the Arctic Islands showed that the species composition of each lake in the Arctic has a discernably different species distribution. The indicator characteristics show a certain response of the species composition of diatoms to changes in salinity, pH, and organic pollution. Regularities in the spatial distribution of diatoms in the study area were revealed in connection with the environmental variables of their habitat. Statistical mapping of diatom diversity data and bioindicators revealed a pronounced response to point pollution, and also let us assume the influence of summer northeast winds on species composition of the studied lake communities. We suggest that the high diversity inherent in the diatom lakes of the Tiksi coastal zone, which can even be updated in further studies, can be considered as a property of coastal biota inherent in ecotones. Since it is in the coastal Tiksi region that a surge in the number of species is observed, this region can be considered not only an ecotone, but also a hotspot of diatom diversity. The results of the study are important for developing the basis for monitoring biodiversity under the conditions of anthropogenic and climatic changes in the Arctic.

Colonization of diatoms in and on porcine bone substrate and considerations of diatom ecology for forensic science.

The presence of diatom algae in bone marrow has been used as forensic evidence of drowning for several decades; however, these studies are based on known or suspected recent drowning events. This study addresses the potential for diatoms to enter the bone marrow of skeletal remains, that is, de-fleshed long bones post-mortem. In laboratory and field experiments, bones were either inflicted with two access points by a cut and acid pitting or left intact. The bones were submerged in water for at least 1 week and up to 3 months. Samples of the bone surface and marrow were inspected for diatoms. The analysis considered the time required for diatoms to enter marrow and whether genus characteristics like size or mobility affect entry. The presence of an access point influenced diatom entry in that bones without an introduced access point had zero to one diatom present in the marrow, whereas a bone with an access point had >150 diatoms present in the marrow. The results of both laboratory and field phases suggest that diatoms will reliably colonize bone in as quickly as 1 week, establishing and maintaining communities for at least 3 months. However, the bone surface assemblages differ from the source community. Bone marrow displayed even more restrictive access to diatom colonization, resulting in communities dominated by small raphid diatoms. Based on these findings, we suggest some caveats on the use of diatoms as trace evidence in forensic science with recommendations for future avenues of research.

Diatom Algae of Reservoirs of Different Types in the Middle Urals (Sverdlovsk Oblast, Russia)

Diatom Algae of Reservoirs of Different Types in the Middle Urals (Sverdlovsk Oblast, Russia)

Diatom Algae of Different Types of Middle Ural Reservoirs (Sverdlovsk Region, Russia)

For the first time, diatoms from the Beloyarskoe, Chernoistochinskoe and Nizhnetagilskoe reservoirs of the Sverdlovsk region are studies using electron microscopy. The data on the species composition of Bacillariophyta of the Chernoistochinskoe Reservoir are significantly supplemented. A total of 216 taxa of species and intraspecific rank from 63 genera are identified in these three reservoirs. Among them 17 taxa are new to the flora of Russia, 14 forms from 11 genera are identified only to the genus. The maximum taxonomic diversity is recorded in the Nizhnetagilskoe reservoir (179).