Diatom Cultures Research Articles

Investigating the interaction of uranium(VI) with diatoms and their bacterial community: A microscopic and spectroscopic study

Diatoms and bacteria play a vital role in investigating the ecological effects of heavy metals in the environment. Despite separate studies on metal interactions with diatoms and bacteria, there is a significant gap in research regarding heavy metal interactions within a diatom-bacterium system, which closely mirrors natural conditions. In this study, we aim to address this gap by examining the interaction of uranium(VI) (U(VI)) with Achnanthidium saprophilum freshwater diatoms and their natural bacterial community, primarily consisting of four successfully isolated bacterial strains (Acidovorax facilis, Agrobacterium fabrum, Brevundimonas mediterranea, and Pseudomonas peli) from the diatom culture. Uranium (U) bio-association experiments were performed both on the xenic A. saprophilum culture and on the four bacterial isolates. Scanning electron microscopy and transmission electron microscopy coupled with spectrum imaging analysis based on energy-dispersive X-ray spectroscopy revealed a clear co-localization of U and phosphorus both on the surface and inside A. saprophilum diatoms and the associated bacterial cells. Time-resolved laser-induced fluorescence spectroscopy with parallel factor analysis identified similar U(VI) binding motifs both on A. saprophilum diatoms and the four bacterial isolates. This is the first work providing valuable microscopic and spectroscopic data on U localization and speciation within a diatom-bacterium system, demonstrating the contribution of the co-occurring bacteria to the overall interaction with U, a factor non-negligible for future modeling and assessment of radiological effects on living microorganisms.

STUDY OF SPECIES COMPOSITION OF ALGOFLORA FROM NATURAL THERAPEUTIC MUD IN ZHANAKORGAN DISTRICT

There is currently a global increase in interest in the use of natural therapeutic muds. Therapeutic mud is a natural product that has a beneficial therapeutic effect on the skin and a lower incidence of adverse effects on the human body. The object of the study was water from two wells and a medicinal swamp in the settlement of Zhanakorgan district of Kyzylorda region. The present study examined the species composition of microalgae and cyanobacteria in two wells and in therapeutic swamps within the settlement of Zhanakorgan district. The objective of this study was to examine the species diversity, morphological and cultural characteristics of cyanobacteria, green and diatom algae in the Zhanakorgan district settlement, and to introduce them into axenic cultures for storage in a collection for potential utilization in industrial biotechnology, in the pharmaceutics, as well as in textile and food industry due to their rich chemical composition. The study yielded seven new axenic cultures of cyanobacteria, green algae, and diatoms, which were identified as Dunaliella salina, Chlamydomonas sp., Scenedesmus sp., Trichormus variabilis, Calothrix epiphytica, Nostoc oryzae, Navicula sp.

An integrated process for enhanced production and purification of fucoxanthin and sulfated polysaccharides in diatom Hyalosynedra toxoneides cultures

BackgroundThis study explores the efficient production and purification of health-promoting compounds, fucoxanthin and sulfated polysaccharides, from the diatom Hyalosynedra toxoneides, contributing to the growing demand for sustainable bioactive compounds. MethodsSemi-continuous cultivation of H. toxoneides (AQ9) in three medium concentrations (2.5f, 5f, 10f) was conducted in a custom-made photobioreactor. Fucoxanthin was extracted using 95 % ethanol, purified through silica gel chromatography, and characterized via high-performance liquid chromatography. Crude polysaccharides were obtained, purified using DEAE-Sephacel resins, and characterized for uronic acid and sulfate content. Significant findingsHigher culture medium concentrations led to increased biomass, fucoxanthin, and polysaccharide yields, providing insights for large-scale cultivation. With a 10f medium in semi-continuous cultures, we achieved the highest yields of approximately 1.18 g/L for cell mass, 4.45 mg/L for fucoxanthin, and 17.20 mg/L for crude polysaccharides, with corresponding productivities of 0.20 g/L/day, 0.74 mg/L/day, and 2.46 mg/L/day. Fucoxanthin was purified from crude pigments with 91 % purity and 70 % recovery. Meanwhile, two uncharacterized sulfated polysaccharides were isolated from crude polysaccharides using anion-exchange chromatography. Notably, the culture media influenced sulfated polysaccharide distribution. This integrated approach contributes to efficient production and purification of bioactive compounds from diatom cultures, with potential applications in diverse industries, including nutraceuticals and cosmetics.

Ecophysiological performance of terrestrial diatoms isolated from biocrusts of coastal sand dunes.

Terrestrial diatoms are widespread in a large variety of habitats and are regularly recorded in biocrusts. Although diatoms have long been known to live in terrestrial habitats, only a few studies have focused on their diversity of ecophysiology. Here we present a study on the ecophysiological performance of five terrestrial diatom cultures from biocrusts, which were collected in sand dunes of the German coast of the Baltic Sea. The sampling sites were selected along a gradient of human impacts on the dunes. The richness of diatom species, roughly estimated from permanent slides, was around 30 species per sampling site. The species abundance was calculated in the same way revealing a high proportion of broken diatom frustules. All diatom cultures established in the laboratory showed no photoinhibition and high oxygen production along a light gradient. The desiccation tolerance differed among the strains, with high recovery observed for Hantzschia abundans and Achnanthes coarctata and low to no recovery for Pinnularia borealis and Pinnularia intermedia. The maximum growth rate for most strains was between 25 and 30°C. These temperatures can be easily reached in their natural environments. Nevertheless, during short-term exposure to elevated temperatures, oxygen production was recorded up to 35°C. Interestingly, two of five diatom cultures (Hantzschia abundans and Pinnularia borealis) produced mycosporine-like amino acids. These UV-protective substances are known from marine diatoms but not previously reported in terrestrial diatoms.

Mitochondrial genome sequence of the protist Ancyromonas sigmoides Kent, 1881 (Ancyromonadida) from the Sugluk Inlet, Hudson Strait, Nunavik, Québec.

There is little information on evolutionarily ancient eukaryotes, which are often referred to as basal eukaryotes, in Arctic waters. Despite earlier studies being conducted in the Russian White Sea, only few have been reported. Following a shotgun sequence survey of diatom cultures from Sugluk Inlet off the Hudson Strait in Northern Québec, we obtained the complete mitochondrial genome and the operon of nuclear ribosomal RNA genes from a strain that matches that of Ancyromonas sigmoides (Kent, 1881). The sequence of the mitogenome retrieved was 41,889 bp in length and encoded 38 protein-coding genes, 5 non-conserved open-reading frames, and 2 rRNA and 24 tRNA genes. The mitogenome has retained sdh2 and sdh3, two genes of the succinate dehydrogenase complex, which are sometimes found among basal eukaryotes but seemingly missing among the Malawimonadidae, a lineage sister to Ancyromonadida in some phylogenies. The phylogeny inferred from the 18S rRNA gene associated A. sigmoides from Sugluk Inlet with several other strains originating from the Arctic. The study also unveiled the presence of a metagenomic sequence ascribed to bacteria in GenBank, but it was clearly a mitochondrial genome with a gene content highly similar to that of A. sigmoides, including the non-conserved open-reading frames. After re-annotation, a phylogeny was inferred from mitochondrial protein sequences, and it strongly associated A. sigmoides with the misidentified organism, with the two being possibly conspecific or sibling species as they are more similar to one another than to species of the genus Malawimonas. Overall our phylogeny showed that the ice associated ancryomonads were clearly distinct from more southerly strains.

Evaluation of the antioxidative response of diatoms grown on emerging steroidal contaminants.

With increasing anthropic activities, a myriad of typical contaminants from industries, hospitals, and municipal discharges have been found which fail to be categorized under regulatory standards and are hence considered contaminants of "emerging concern". Since these pollutants are not removed effectively even by the conventional treatment systems, they tend to inflict potential threats to both human and aquatic life. However, microalgae-mediated remediation strategies have recently gained worldwide importance owing to their role in carbon fixation, low operational cost, and production of high-value products. In this study, centric diatom Chaetoceros neogracilis was exposed to different concentrations of estradiol (E2)-induced synthetic media ranging from 0 to 2mg L-1, and its impact on the antioxidative system of algae was investigated. The results demonstrate that the nutrient stress caused a strong oxidative response elevating the superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in the 2mg L-1 E2-treated diatom cultures. However, the specific activity of the H2O2 radical scavenging enzymes like catalase (CAT) was inhibited by the E2 treatment, while that of ascorbate peroxidase (APX) remained comparable to the control (0mg L-1 of E2). Thus, the study reveals the scope of diatoms as potential indicators of environmental stress even under the varying concentration of a single contaminant (E2).

Mass Cultivation of Microalgae: II. A Large Species Pulsing Blue Light Concept.

If mass cultivation of photoautotrophic microalgae is to gain momentum and find its place in the new "green future", exceptional optimizations to reduce production costs must be implemented. Issues related to illumination should therefore constitute the main focus, since it is the availability of photons in time and space that drives synthesis of biomass. Further, artificial illumination (e.g., LEDs) is needed to transport enough photons into dense algae cultures contained in large photobioreactors. In the present research project, we employed short-term O2 production and 7-day batch cultivation experiments to evaluate the potential to reduce illumination light energy by applying blue flashing light to cultures of large and small diatoms. Our results show that large diatom cells allow more light penetration for growth compared to smaller cells. PAR (400-700 nm) scans yielded twice as much biovolume-specific absorbance for small biovolume (avg. 7070 μm3) than for large biovolume (avg. 18,703 μm3) cells. The dry weight (DW) to biovolume ratio was 17% lower for large than small cells, resulting in a DW specific absorbance that was 1.75 times higher for small cells compared to large cells. Blue 100 Hz square flashing light yielded the same biovolume production as blue linear light in both the O2 production and batch experiments at the same maximum light intensities. We therefore suggest that, in the future, more focus should be placed on researching optical issues in photobioreactors, and that cell size and flashing blue light should be central in this.

Infection strategies of different chytrids in a diatom spring bloom

Abstract Diatom blooms are often accompanied by an increase in parasitic chytrids that kill the host cells, which they are infecting, and can contribute to the decline of the bloom. However, host specificity and range of these chytrids are currently poorly understood. Low host specificity would enable the parasites to opportunistically infect any diatom species, while specialisation on infecting specific high‐biomass species could result in high prevalence and rapid spread of infection. We investigated such host–parasite interactions by monitoring the diverse diatom spring bloom in lake Erken using amplicon sequencing. We also performed infection experiments with two different, newly isolated chytrid species and several diatom cultures from the bloom. Chytridiomycota displayed the highest relative abundance of all parasitic lineages and were probably physically attached to larger organisms. Since the chytrids reached maximum abundance shortly after a peak in diatom reads, they were probably infecting these important primary producers. Phylogenetic analyses of the isolated chytrid strains identified them as members of the classes Rhizophydiales and Lobulomycetales. The infection experiments revealed high host specificity in these two chytrids targeting different diatom species. The experimental results supported statistical analyses of the environmental sequencing data, which suggested the presence of two different infection strategies: the most abundant chytrid species were specialised on infecting dominant diatom genera (i.e. Stephanodiscus, Aulacoseira, Asterionella), while rarer chytid species infected a range of less abundant diatoms.

Fabrication of SiO2 Materials used in Diatom Culture

Diatoms are one of the microalgae species commonly used as food for many aquatic organisms during the hatchery stage. The culture of diatoms usually uses silicon from Na2SiO3, but this salt compound easily causes the precipitation of trace ions in the culture medium. This study is to fabricate SiO2 material particles used to replace Na2SiO3 in the period of diatom proliferation and application in aquiculture. The material particles were synthesized based on the Stober method using the surfactant compound CTAB with a spherical particle structure with the particle size of about 700 nm. Testing using SiO2 material particles showed faster growth of diatoms compared with conventional culture media using Na2SiO3.

Characterization and in vitro anticancer potential of exopolysaccharide extracted from a freshwater diatom Nitzschia palea (Kütz.) W.Sm. 1856

Diatoms are photoautotrophic microalgae classified under class Bacillariophyceae, engulfed by hard silicate frustules, which give mechanical support and protection from bacterial infections. They exude polysaccharides extracellularly that help them with their gliding motion (locomotion). However, the bioactivity of such compounds was least explored from freshwater diatoms. In the present study, a single species of pennate diatom identified as Nitzschia palea was isolated and molecularly characterized by 18S rRNA smaller subunit gene (partial) sequencing and submitted to GenBank NCBI and accession number retrieved as ON360983. Based on logarithmic growth curve analysis, the exponential phase was obtained from 3rd to 4th day of diatom culture. The exopolysaccharide was extracted by the hot-water extraction method, and characterized by FT-IR. The total yield of exopolysaccharide from Nitzschia palea was estimated as 1.56 mg in 100 mL of culture after 7 days of incubation. The estimated carbohydrate content was 51.35 µg/100 µL. The monosaccharide constituents were determined by acid hydrolysis of exopolysaccharide, silylation (derivatization), followed by GC–MS analysis and tabulated. The extracted exopolysaccharide was evaluated for its anti-cancer potential against the Human Adenocarcinoma lung cancer cell line (A549) and the estimated IC50 value was 62.64 µg/mL. Acridine orange staining assay and DNA fragmentation assay also confirmed the apoptotic activity of exopolysaccharide derived from the diatom Nitzschia palea.

Vertical and temporal distribution of chytrids infecting diatoms in the Gulf of Naples (Italy, Mediterranean Sea)

AbstractThe presence of phytoplankton parasites along the water column was explored at the Long‐Term Ecological Station MareChiara (LTER‐MC) in the Gulf of Naples (Mediterranean Sea) in October 2019. Microscopy analyses showed diatoms dominating the phytoplankton community in the upper layers (0–20 m). Metabarcoding data from the water column showed the presence of Chytridiomycota predominantly in the upper layers coinciding with the vertical distribution of diatoms. Laboratory incubations of natural samples enriched with different diatom cultures confirmed parasitic interactions of some of those chytrids—including members of Kappamyces—with diatom taxa. The temporal dynamics of diatoms and chytrids was also explored in a 3‐year metabarcoding time‐series (2011–2013) from surface waters of the study area and in sediment samples. Chytrids were recurrently present at low relative abundances, and some taxa found to infect diatoms in the incubation experiments were also identified in the ASV time‐series. However, co‐occurrence analyses did not show any clear or recurrent pairing patterns for chytrid and diatom taxa along the 3 years. The chytrid community in the sediments showed a clearly different species composition compared with that recorded in the water column samples, with higher diversity and relative abundance. The combination of observations, incubations, and metabarcoding confirmed that parasites are a common component of marine protist communities at LTER‐MC. Host–parasite interactions must be determined and quantified to understand their role and the impact they have on phytoplankton dynamics.

Exploring diatom diversity through cultures - a case study from the Bow River, Canada

Diatom cultures can help answer taxonomic, biogeographic and ecological questions on a local and global scale. Unialgal cultures are derived from a single cell and provide abundant material for morphological and molecular analyses. The link between the historic morphological species concept and the molecular data is becoming increasingly important with the use of eDNA metabarcoding. Additionally, cultures provide insights into the life cycle of diatoms and thereby complement taxonomy and species ecology. In this study, we present an approach to extract benthic diatoms from an environmental sample to generate unialgal cultures. We explored diatom diversity in preserved assemblages and by culturing as many different taxa as possible from benthic freshwater samples taken on the same day from the Bow River in Calgary, Canada. With both methods we found a total of 221 different benthic diatom taxa, of which 182 were identified in the preserved diatom assemblages. Interestingly, an additional 39 taxa only appeared in the cultures. In total 129 strains were cultivated representing 71 different taxa. This study includes pictures of living cells demonstrating the additional merits of unialgal cultures, as they provide information on plastid details, auxospores and endosymbionts. Both, the identification of the diatom assemblages and the generation and identification of strains provide the foundation for additional water quality assessment tools, taxonomic insights and molecular references libraries.

Extending the Monod model of microbal growth with memory

Monod’s model describes the growth of microorganisms using a hyperbolic function of extracellular resource concentration. Under fluctuating or limited resource concentrations this model performs poorly against experimental data, motivating the more complex Droop model with a time-varying internal storage pool. We extend the Monod model to incorporate memory of past conditions, adding a single parameter motivated by a fractional calculus analysis. We show how to interpret the memory element in a biological context and describe its connection to a resource storage pool. Under nitrogen starvation at non-equilibrium conditions, we validate the model with simulations and empirical data obtained from lab cultures of diatoms (T. pseudonana and T. weissflogii) and prasinophytes (Micromonas sp. and O. tauri), globally influential phytoplankton taxa. Using statistical analysis, we show that our Monod-memory model estimates the growth rate, cell density and resource concentration as well as the Droop model, while requiring one less state variable. Our simple model may improve descriptions of phytoplankton dynamics in complex earth system models at a lower computational cost than is presently achievable.

Flavobacterial exudates disrupt cell cycle progression and metabolism of the diatom Thalassiosira pseudonana

Phytoplankton and bacteria form the base of marine ecosystems and their interactions drive global biogeochemical cycles. The effects of bacteria and bacteria-produced compounds on diatoms range from synergistic to pathogenic and can affect the physiology and transcriptional patterns of the interacting diatom. Here, we investigate physiological and transcriptional changes in the marine diatom Thalassiosira pseudonana induced by extracellular metabolites of a known antagonistic bacterium Croceibacter atlanticus. Mono-cultures of C. atlanticus released compounds that inhibited diatom cell division and elicited a distinctive morphology of enlarged cells with increased chloroplast content and enlarged nuclei, similar to what was previously observed when the diatom was co-cultured with live bacteria. The extracellular C. atlanticus metabolites induced transcriptional changes in diatom pathways that include recognition and signaling pathways, cell cycle regulation, carbohydrate and amino acid production, as well as cell wall stability. Phenotypic analysis showed a disruption in the diatom cell cycle progression and an increase in both intra- and extracellular carbohydrates in diatom cultures after bacterial exudate treatment. The transcriptional changes and corresponding phenotypes suggest that extracellular bacterial metabolites, produced independently of direct bacterial-diatom interaction, may modulate diatom metabolism in ways that support bacterial growth.

More than just hitchhikers: a survey of bacterial communities associated with diatoms originating from sea turtles.

Diatoms and bacteria are known for being the first colonizers of submerged surfaces including the skin of marine reptiles. Sea turtle carapace and skin harbor diverse prokaryotic and eukaryotic microbes, including several epizoic diatoms. However, the importance of diatom-bacteria associations is hardly investigated in biofilms associated with animal hosts. This study provides an inventory of diatoms, bacteria and diatom-associated bacteria originating from loggerhead sea turtles using both metabarcoding and culturing approaches. Amplicon sequencing of the carapace and skin samples chloroplast gene rbcL and 16S rRNA gene detected, in total, 634 diatom amplicon sequence variants (ASVs) and 3661 bacterial ASVs, indicating high diversity. Cultures of putative epizoic and non-epizoic diatoms contained 458 bacterial ASVs and their bacterial assemblages reflected those of their host. Diatom strains allowed for enrichment and isolation of bacterial families rarely observed on turtles, such as Marinobacteraceae, Alteromonadaceae and Alcanivoracaceae. When accounting for phylogenetic relationships between bacterial ASVs, we observed that related diatom genera might retain similar microbial taxa in culture, regardless of the turtle's skin or carapace source. These data provide deeper insights into the sea turtle-associated microbial communities, and reveal the potential of epizoic biofilms as a source of novel microbes and possibly important diatom-bacteria associations.

Selective utilization of phosphorus compounds by Chaetoceros tenuissimus (Bacillariophyceae): Approach using 31P nuclear magnetic resonance analysis

SUMMARYSeveral diatom species can utilize various forms of organic phosphorus via enzymatic hydrolysis. The present study identified which phosphorus compounds are preferentially utilized by planktonic diatom Chaetoceros tenuissimus cultures using a 31P nuclear magnetic resonance (NMR)‐based method. Our 31P NMR analysis, which involves a sample extraction procedure using DIAION™ CR11, detected and quantified phosphorus compounds present at concentrations of at least 7.5 μM in the seawater‐based media, including orthophosphate, phosphate monoester, phosphate diester, phosphonate, and other compounds. Based on this analysis, we examined the temporal variations of phosphorus compounds in C. tenuissimus cultures in which orthophosphate, phosphate monoester, phosphate diester, and phosphonate compounds were present simultaneously. Cells pre‐grown under phosphorus‐replete conditions utilized orthophosphate as the preferential phosphorus source and switched to phosphate monoester after exhausting orthophosphate. Enzymatic activity for phosphate monoester hydrolysis, namely phosphomonoesterase (synonym to alkaline phosphatase) activity, appeared when C. tenuissimus began to utilize phosphate monoester. In contrast, C. tenuissimus pre‐grown on phosphorus‐depleted media simultaneously hydrolyzed phosphate monoester and phosphate diester compounds, released orthophosphate from these compounds, and utilized the released orthophosphate and original orthophosphate without discrimination. Overall, we demonstrated that 31P NMR‐based method can comprehensively analyze the variations of dissolved phosphorus compounds in diatom cultures. Our results showed selective utilization of phosphorus compounds by C. tenuissimus and suggested that phosphate monoester and phosphate diester compounds were important phosphorus sources for this diatom in orthophosphate‐depleted coastal waters.

Selection constrains lottery assembly in the microbiomes of closely related diatom species

It is generally recognised that interactions between microalgae and bacteria play an important role in the functioning of marine ecosystems. In this context, increasing attention is paid to the processes that shape microalga-associated microbiomes. In recent years, conflicting evidence has been reported with respect to the relative importance of selective vs neutral processes in the assembly process. Whereas some studies report strong selection imposed by the host, others propose a more neutral, lottery-like assembly model according to which the chance of bacteria becoming part of the microbiome is proportional to their abundance in the environment and not driven by the selectional pressure created by the host. In the present study, we investigated to what degree selective vs neutral assembly processes constrain taxonomic, phylogenetic and functional variation within and between microbiomes associated with 69 isolates belonging to the Cylindrotheca closterium benthic marine diatom complex. The diatom cultures were initiated from non-axenic clonal isolates from different marine environments and geographic locations, and were then reared in a common garden (lab) environment. An important environmental imprint, likely due to in situ lottery dynamics, was apparent in the diatom microbiomes. However, microbiome assembly was also phylogenetically and functionally constrained through selective filtering related to the host microhabitat. Randomised microbiome assembly simulations revealed evidence for phylogenetic overdispersion in the observed microbiomes, reflecting an important role in the assembly process for competition between bacteria on the one hand and predominantly genetically driven differences between the hosts on the other hand. Our study thus shows that even between closely related diatom strains, host selection affects microbiome assembly, superimposing the predominantly stochastically driven recruitment process.

Photonic tools for evaluating the growth of diatom colonies during long-term batch cultivation

Diatoms are unicellular photosynthetic microalgae with a nanostructured silica cell wall – frustule. Diatoms, considered one of the most abundant and ecologically important phytoplankton groups, can also be easily grown in the laboratory and used for different applications. With long-term cultivation, it is essential to monitor their growth properly; therefore, we proposed new, fast and easy-to-use methods based on the absorption and fluorescence of diatom chromophores. The average radiant efficiency of diatom culture Achnanthidium sibiricum obtained using the IVIS SpectrumCT In vivo Imaging system increased up to 45 days of cultivation, after which we observed steady decrease. The highest photoacoustic signal of diatoms mixed with an agarose gel excited by a 532 nm laser was also recorded after 45 days of cultivation. The results obtained are in good agreement with the obtained spectra during the 100-day cultivation period. Thus, photonic methods have proven to be effective for monitoring the growth of diatoms during long-term cultivation, expanding the possibilities of growing and collecting diatoms for various purposes.

Pesticide toxicity towards microalgae increases with environmental mixture complexity.

Effect-directed analysis (EDA) aims at identifying the compound(s) responsible for toxicity in a complex environmental sample where several dozens of contaminants can be present. In this study, we used an environmental mixture extracted from the Polar Organic Chemical Integrative Sampler (POCIS) previously immersed downstream a landfill (River Ponteils, South West France), to perform an EDA approach using a microalgal bioassay based on the photosynthetic capacities of diatom (Nitzschia palea) cultures. Adverse effects on photosynthetic capacities were recorded when algae were exposed to the entire POCIS extract (> 85% inhibition at the highest concentration tested). This result was coherent with the detection of diuron and isoproturon, which were the 2 most concentrated herbicides in the extract. However, the EDA process did not allow pointing out the specific compound(s) responsible for the observed toxicity but rather suggested that multiple compounds were involved in the overall toxicity and caused mixture effects.

Collection of living diatom cultures of Limnological Institute: Trends and use potential

Abstract. Microalgae culture collections enable the practical use of the products of their metabolism and provide an overview of the morphological, genetic and physiological diversity known in nature. However, despite the fact that diatoms are a unique object, a little number of species is maintained in culture in world collections compared to their huge diversity. The Department of Cell Ultrastructure of the Limnological Institute of the Siberian Branch of the Russian Academy of Sciences (LIN SB RAS) has created a collection of monoclonal cultures of diatoms isolated from different regions of Lake Baikal and other water bodies. Currently, the collection is represented by 144 strains of planktonic and benthic diatoms belonging to 20 species. Regularly reseeded cultures are used to solve a number of problems related to ecology, taxonomy, cell biology, molecular genetic research, as well as for use in biotechnology.