Artículos de revistas: "Microalgal bioma"

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Dorrell, Richard G., Alan Kuo, Zoltan Füssy, Elisabeth H. Richardson, Asaf Salamov, Nikola Zarevski, Nastasia J. Freyria et al. "Convergent evolution and horizontal gene transfer in Arctic Ocean microalgae". Life Science Alliance 6, n.º 3 (15 de diciembre de 2022): e202201833. http://dx.doi.org/10.26508/lsa.202201833.

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Microbial communities in the world ocean are affected strongly by oceanic circulation, creating characteristic marine biomes. The high connectivity of most of the ocean makes it difficult to disentangle selective retention of colonizing genotypes (with traits suited to biome specific conditions) from evolutionary selection, which would act on founder genotypes over time. The Arctic Ocean is exceptional with limited exchange with other oceans and ice covered since the last ice age. To test whether Arctic microalgal lineages evolved apart from algae in the global ocean, we sequenced four lineages of microalgae isolated from Arctic waters and sea ice. Here we show convergent evolution and highlight geographically limited HGT as an ecological adaptive force in the form of PFAM complements and horizontal acquisition of key adaptive genes. Notably, ice-binding proteins were acquired and horizontally transferred among Arctic strains. A comparison withTaraOceans metagenomes and metatranscriptomes confirmed mostly Arctic distributions of these IBPs. The phylogeny of Arctic-specific genes indicated that these events were independent of bacterial-sourced HGTs in Antarctic Southern Ocean microalgae.

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Furtado, Mayara Fabiana de Melo y Silvia Maria Mathes Faustino. "Atividade de antimicrobianos sobre o crescimento da microalga (Chlorophyta: Chlorella vulgaris), Beijerinck, 1890". Research, Society and Development 11, n.º 7 (22 de mayo de 2022): e25811729801. http://dx.doi.org/10.33448/rsd-v11i7.29801.

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Os antimicrobianos de uso doméstico, hospitalar, veterinário e na agricultura têm despertado crescente preocupação, devido à presença desses resíduos no ambiente aquático, mesmo em concentrações muito baixas, podem potencialmente interferir no equilíbrio da biota aquática, afetando populações de produtores primários. Dos microrganismos, as microalgas são consideradas umas das mais sensíveis, além de serem mais suscetíveis, por estarem distribuídas por todo o ambiente aquático. O objetivo deste estudo foi avaliar os efeitos de substâncias antibióticas sobre o crescimento da microalga Chlorella vulgaris. Os resultados apontam que os antibióticos, Amoxilina, Ampicilina e Cefalexina monoidratada, pertencentes ao grupo beta-lactâmicos apresenta uma densidade celular superior em relação ao tratamento controle, inibindo o crescimento de C. vulgaris. O estudo sugere a realização de monitoramentos nas matrizes ambientais, principalmente da região norte, por apresentar um baixo percentual no tratamento convencional de esgotos sanitário, evitando assim, riscos sobre a biota aquática e a saúde humana.

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Barra, Lucia, Angela Sardo, Maria Moros, Arianna Smerilli, Pasquale Chiaiese, Isabella Percopo, Elena Cavalletti, Christian Castro-Hinojosa y Sergio Balzano. "Identification of a Green Algal Strain Collected from the Sarno River Mouth (Gulf of Naples, Italy) and Its Exploitation for Heavy Metal Remediation". Microorganisms 10, n.º 12 (10 de diciembre de 2022): 2445. http://dx.doi.org/10.3390/microorganisms10122445.

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Heavy metals (HMs) can induce both chronic and acute harmful effects on marine and freshwater biota. The environmental impact of HMs in freshwater, seawater, soil, and wastewater can be limited using microbes, including microalgae, that are able to remove metals from environmental matrices. Indeed, they can passively adsorb and actively accumulate these persistent pollutants within their organelles, limiting their detrimental effects on cellular metabolism. The Sarno River is a 30 km long freshwater stream located in Southern Italy, polluted by partially untreated municipal, agricultural, and industrial wastewaters. In spite of this, microalgal cultures from Sarno River or Sarno River Mouth have never been established. In the present study, we isolated a green algal strain from the Sarno River Mouth and determined its ability to grow in polluted seawater containing different concentrations of cadmium, lead, or zinc. This strain was found to be able to accumulate these elements within its biomass in a dose-dependent manner. Growth inhibition experiments confirm the relatively low toxicity of Cd and Pb below 50 µM, while algal growth was seriously affected in Zn-amended media. To the best of our knowledge, this is the first study focused on the ability of microalgae from Sarno River Mouth to tolerate and uptake HMs.

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Prambodo, Muhammad Sindhunata, Riche Hariyati y Tri Retnaningsih Soeprobowati. "Spirulina platensis Geitler sebagai Fikoremediator Logam Berat Pb Skala Laboratorium". Bioma : Berkala Ilmiah Biologi 18, n.º 2 (9 de agosto de 2016): 64. http://dx.doi.org/10.14710/bioma.18.2.64-69.

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Industrial waste contributes the heavy metals pollution in the environment, especially in the water. One of the heavy metals that pollute the environment is lead (Pb). Lead is a substance that is harmful to organisms, especially humans, both adults and children. Solutions to tackle Pb pollution isby remediation process. Physical and chemical remediation methods usually costly and ineffective. One of the alternative methods which is used is the bioremediation uses microalgae or called as phycoremediation. One of microalgae which is used as agents of phycoremediation is Spirulina platensis Geitler because it’s easily cultured and it’s abundant in nature. This study aims to assess the population growth and the percentage reduction of Pb after inoculated with the use of Spirulina platensis Geitler. The method which is to cultivate S. platensis Geitler in brackish watermedia with a salinity of 15 ppt which have been added Pb with a concentration of 1 mg, 3 mg, and 5 mg for 8 days and observed the population and the percentage reduction of Pb heavy metals. Environmental factors such as temperature, salinity, pH, light intensity are conditioned to remain stable. After 8 days of research, study was able to reduce Pb. Each treatment has different concentrations decrease. Treatment Pb 1 mg of 0.949 into 0.603 mg / L; Pb 3 mg of 2.894 to 2.46 mg / L; and Pb 5 mg of 4.88 to 4.31 mg / L, with each percentage decline of 36%, 15% and 12%. The Pb 3 mg treatment has higher cell population (129.367 cell / ml) than control (106.600 cell/ml) while 1 mg and 5 mg treatment has 93.700 cell / ml and 93.500 cell / ml. Keywords: Spirulina platensis, phycoremediation, waste, lead.

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Tewal, Fitly, Kurniati Kemer, Joice R. T. S. L. Rimper, Desy M. H. Mantiri, Wilmy E. Pelle y Joppy D. Mudeng. "LAJU PERTUMBUHAN DAN KEPADATAN MIKROALGA Dunaliella sp. PADA PEMBERIAN TIMBAL ASETAT DENGAN KONSENTRASI YANG BERBEDA". JURNAL PESISIR DAN LAUT TROPIS 9, n.º 1 (29 de marzo de 2021): 30. http://dx.doi.org/10.35800/jplt.9.1.2021.33571.

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Microalgae are organisms that contain chlorophyll and other pigments so they can carry out photosynthesis. Microalgae are widespread in nature and can be found in any environment exposed to sunlight. Microalgae are micro-sized biota with a diameter of less than 2 µm. The benefits of microalgae for other living things, especially humans, are numerous, including as a source of food and ingredients in the manufacture of medicines. Dunaliella sp. is a group of green algae that contains protein, fat and carbohydrates as a good source of food. Growth rate and density of microalgae Dunaliella sp. and the effect of lead acetate with different concentrations was observed using a microscope, starting from the lag phase, the logarithmic phase, the stationary phase and the declination phase. Dunaliella sp. Experiencing an exponential phase in the observation before treatment, namely on the 9th day and then doing the treatment. Treatment with lead acetate with concentrations of 10 ppm, 50 ppm and 80 ppm is very influential in the growth of microalgae. The result is that lead acetate contains toxins that can kill microalgae cells in both low and high concentrations.Keywords: Microalgae, Dunaliella sp., Lead Acetate, Concentration

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Telussa, Ivonne, Nikmans Hattu y Arielno Sahalessy. "Morphological Observation, Identification and Isolation of Tropical Marine Microalgae from Ambon Bay, Maluku". Indo. J. Chem. Res. 9, n.º 3 (29 de noviembre de 2021): 137–43. http://dx.doi.org/10.30598//ijcr.2022.9-ivo.

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Microalgae are photosynthetic microorganisms that are widely distributed in waters. They have the potential as an alternative source of pigments, lipids, proteins, and carbohydrates. In this study, identification and isolation of single-cell microalgae from Ambon Bay were carried out by serial dilution method and inoculation of the culture by appearance/spread on the surface of the solidified agar medium. The results showed that the waters of Ambon Bay have physical parameters such as temperature, pH, salinity, and TDS, which are still within the threshold specified in the seawater quality standard for biota. The water conditions at the 10 sampling locations had different salinity, pH, temperature, and TDS. This condition affects the distribution of microalgae in the waters in Ambon Bay. The image from light microscopy shows that there are 27 species of microalgae scattered in the waters of Ambon Bay, which belong to the classes Chlorophyceae, Flagilariophyceae, Bacillariophyceae (diatoms), Coscinodiscophyceae, and Dinophyceae. Microalgae isolation obtained five species (single-cell) including four species from the class Bacillariophyta (Navicula sp, Nitzschia sp, Cyclotella sp) and one species from the class Chlorophyta (Chlorella sp).

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Anggraeni, Vina Juliana, Titis Setyaning Wahyu, Herni Kusriani y Dewi Kurnia. "AKTIVITAS ANTIBAKTERI EKSTRAK MIKROALGA Thalassiosira sp TERHADAP BAKTERI Staphylococcus aureus, Staphylococcus epidermidis dan Propionibacterium Acne". Jurnal Kimia Riset 4, n.º 1 (30 de junio de 2019): 62. http://dx.doi.org/10.20473/jkr.v4i1.13314.

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AbstrakPengembangan obat dan kosmetik dari biota laut kini tengah terjadi di dunia farmasi. Mikroalga Thalassiosira sp merupakan jenis mikroalga yang memiliki kandungan senyawa-senyawa bioaktif. Beberapa penelitian sebelumnya menunjukkan bawa mikroalga memiliki aktivitas antibakteri. Penelitian ini bertujuan untuk mengetahui aktivitas antibakteri dari ekstrak mikroalga Thalassiosira sp terhadap 3 bakteri yaitu staphylococcus aureus, staphylococcus epidermidis dan propionibakterium Acne di fasa n-heksan, etil asetat dan etanol. Ketiga bakteri ini dapat menyebabkan infeksi kulit. Mikroalga Thalassiosira sp dikultivasi menggunakan medium walne dan di panen pada hari ke-6 setelah penanaman. Pemanen mikroalga dilakukan dengan teknik sentrifuga. Ektrak dilakukan dengan cara maserasi bertingkat selama 3 x 24 jam. Pengujian antibakteri dilakukan dengan metode difusi kertas cakram atau metode disc diffusion menurut Kirby-Bauer. Hasil ekstrak mikroalga Thalassiosira sp diperoleh paling banyak pada ekstrak etanol sebanyak 24,24%(b/b), ektrak etil asetat sebanyak 19,75%(b/b) dan paling sedikit adalah ekstrak heksan sebanyak 8,64% (b/b). Hasil uji difusi menunjukkan ekstrak n-heksan, etil asetat dan etanol mikroalga Thalassiosira sp memiliki aktivitas terhadap bakteri staphylococcus aureus, staphylococcus epidermidis dan propionibakterium Acne yang ditunjukan dengan adanya zona bening. Kata kunci: mikroalga, Thalassiosira sp, antibakteri, infeksi kulit, metode difusi Abstract Development drugs and cosmetics from marine biota is now being happened in pharmacy word. Microalgae Thalassiosira sp is a type of microalgae that has a bioactive compounds. Several previous studies have shown the existence of microalgae which have antibacterial activity. This study aimed to study the antibacterial activity of extracts of microalgae Thalassiosira sp against 3 bacteria which is staphylococcus aureus, staphylococcus epidermidis and propionibacterium acne in the n-hexane, ethyl acetate and ethanol phases. These three bacteria can cause skin infections. Microalgae Thalassiosira sp was cultivated using walne medium and harvested on the 7th day after planting. Microalgae harvesters are carried out by centrifuge techniques. The extract is done by multilevel maceration for 3 x 24 hours. Antibacterial testing was carried out by the paper diffusion method or Kirby-Bauer's disc diffusion method. The results of the crude extract of microalgae Thalassiosira sp were obtained at most in ethanol extract as much as 24.24% (w/w), extract of ethyl acetate at 19.75% (w / w) and at least hexane extract at 8.64% (w/w). The diffusion test results for n-hexane, ethyl acetate, and ethanol microalgae Thalassiosira sp extract have activity on staphylococcus aureus, staphylococcus epidermidis and propionibacterium acne which are supported by clear zones. Keywords: mikroalge, Thalassiosira sp, antibacteria, skin infection, diffusion method

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Rahmawati, Novia, Muhammad Zainuri y Hermin Pancasakti Kusumaningrum. "Aplikasi Pakan Kaya Karotenoid Hasil Fusi ProtoplasmIntergenera Dunaliella salina dan Chlorella vulgaris pada Udang Windu (Penaeus monodon F.) Stadia PL-20 Di Desa Asempapan, Pati, Jawa Tengah". Bioma : Berkala Ilmiah Biologi 15, n.º 2 (27 de diciembre de 2013): 46. http://dx.doi.org/10.14710/bioma.15.2.46-52.

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Dunaliella salina and Chlorella vulgaris is a natural feed microalgae with high carotenoid content that can be increased using protoplast fusion technique. Protoplast fusion as one of the application fields of genetic engineering is a method for obtaining recombinant with the desired properties and profitable in a short time. This study aimed to see the effect of the addition of carotenoid-rich feed results from protoplast fusion recombinant D. salina and C. vulgaris on the survival rate and weight of shrimp post larvae. Mixed fusion results feed and artificial feed needed for the growth of post-larval shrimp, moulting and skin pigmentation. The results showed that the recombinant from protoplast fusion intergenera D. salina and C. vulgaris contains carotenoid pigments higher, reaching 124.6 mg / g bks from the second parent, namely D. salina reached 101.83 mg / g bks, while C. vulgaris 97.18 ug / g bks. Feed manufacturing is done by mixing pellets and 80-100x103 cells per 0.0225 g of feed. Application of feed carried on Penaeus monodon F. (tiger prawn) stadia PL-20 for a month. The results of weight measurements showed the highest prawn post larvae reached at artificial feeding plus recombinant protoplast fusion results intergenera D. salina and C. vulgaris and was able to raise the level of post-larval shrimp survival rate reached 88%. Keywords: D. salina, C. vulgaris, Protoplast Fusion, Carotenoid, Penaeus monodon F.

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Tamalonggehe, Joshep, Kurniati Kemer, Darus Sa’adah J. Paransa, Desy MH Mantiri, Nickson J. Kawung y Suzanne L. Undap. "Efek Senyawa Timbal Asetat Terhadap Pertumbuhan Dan Kandungan Pigmen Klorofil Mikroalga Dunaliella sp." JURNAL PESISIR DAN LAUT TROPIS 8, n.º 2 (30 de mayo de 2020): 1. http://dx.doi.org/10.35800/jplt.8.2.2020.28764.

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Microalgae is one of the marine biota that has an important role in the waters because it acts as a supplier of food in the waters. Microalgae is a biological source that needs to be exploited because it is rich in essential compounds. Dunaliella sp. is one of the many micro algae used as research. Utilization of Dunaliella sp. quite diverse and has been marketed in developed countries because of its very attractive economic value. This study aims to determine the effects of lead acetate compounds on growth and content of chlorophyll pigments microalgae Dunaliella sp. The results obtained in this study are the lead acetate compounds can affect the number of cells in the growth of microalgae and analysis results obtained with a spectrophotometer showed that the extraction concentration of control day 5 (Exponential Phase) was higher than the concentration of 15 ppm and 25 ppm, whereas extraction on day 21 (Death Phase) concentration of 15 ppm was higher than 25 ppm.Keywords : Dunalella sp., Lead Acetate, Pigment chlorophyll RingkasanMikroalga adalah salah satu biota laut yang memiliki peran penting di perairan karena berfungsi sebagai pemasok makanan di perairan. Mikroalga adalah sumber biologis yang perlu dieksploitasi karena kaya akan senyawa esensial. Dunaliella sp. adalah salah satu dari banyak mikroalga yang digunakan sebagai penelitian. Pemanfaatan Dunaliella sp. cukup beragam dan telah dipasarkan di negara maju karena nilai ekonominya yang sangat menarik. Penelitian ini bertujuan untuk mengetahui efek senyawa timbal asetat terhadap pertumbuhan dan kandungan pigmen klorofil Dunaliella sp. Hasil yang diperoleh dalam penelitian ini adalah senyawa timbal asetat dapat mempengaruhi jumlah sel dalam pertumbuhan mikroalga, penurunan jumlah sel mengikuti konsentrasi timbal asetat yang diberikan dan hasil analisis yang diperoleh dengan spektrofotometer menunjukkan bahwa konsentrasi ekstraksi kontrol hari 5 (Fase Eksponensial) lebih tinggi daripada konsentrasi 15 ppm dan 25 ppm, sedangkan ekstraksi hari 21 (Fase Kematian) konsentrasi 15 ppm lebih tinggi dari 25 ppm.Kata kunci : Dunaliella sp., Timbal Asetat, Pigmen Klorofil

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Harmoko, Harmoko y Yuni Krisnawati. "Mikroalga Divisi Bacillariophyta yang Ditemukan di Danau Aur Kabupaten Musi Rawas". JURNAL BIOLOGI UNAND 6, n.º 1 (7 de marzo de 2018): 30. http://dx.doi.org/10.25077/jbioua.6.1.30-35.2018.

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Lake Aur has many aquatic biota as well as become one of the mainstay attractions in Musi Rawas Regency. Community activities and lack of awareness of tourists on the cleanliness and importance of maintaining the lake environment have an impact on water pollution. One of the organisms that can be used as an indicator of river water quality is microalgae. The purpose of this study is to determine the types of microalgae Bacillariophyta divisions that exist in the lake Aur, Musi Rawas.The type of research used is survey research. Bacillariophyta Division consists of two classes, 6 orders, 7 families, 8 genera and 11 species. Observed environmental factors: temperature: 290C, pH: 6.7, Brightness: 115 cm and dissolved oxygen amount of: 38 mg / L. Based on the results of research and discussion, we can conclude that: the type of microalgae division bacillariophyta were found in Lake Aur namely: Cylotella sp, Eunotia sp, Eunotia pectinalis, Fragilaria croronensis, Synedra acus, Nitzschia sp, Nitzschia acicularis, Surirella sp, Surirella elegans, Pinnularia sp and Stauroneis sp.

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Devayani, Cantik Sitta, Retno Hartati, Nur Taufiq-Spj, Hadi Endrawati y Suryono Suryono. "Analisis Kelimpahan Mikroalga Epifit Pada Lamun Enhalus acoroides Di Perairan Pulau Karimunjawa, Jepara". Buletin Oseanografi Marina 8, n.º 2 (4 de octubre de 2019): 67. http://dx.doi.org/10.14710/buloma.v8i2.23739.

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Padang lamun berfungsi sebagai daerah asuhan, pemijahan, tempat mencari makan dan habitat bagi biota laut, diantaranya: ikan, meiofauna, maupun mikroalga epifit. Mikroalga epifit dapat digunakan sebagai salah satu unsur indikator dalam ekosistem perairan terkait dengan kesuburan dan pencemaran. Penelitian ini bertujuan untuk mengetahui komposisi dan kelimpahan mikroalga epifit pada daun lamun Enhalus acoroides yang dilakukan pada Oktober 2018 dengan metode diskriptif. Penentuan stasiun penelitian menggunakan metode purposive random sampling dengan tiga stasiun yaitu di perairan Pantai Nyamplungan (Stasiun 1), Pantai Bobi (Stasiun 2) dan Pelabuhan Syahbandar (Stasiun 3). Sampel daun lamun E. acoroides dipotong menjadi tiga bagian, yaitu ujung (UA dan UB), tengah (TA dan TB) dan pangkal (PA dan PB) daun. Untuk mendapatkan sampel mikroalga epifit dilakukan dengan metode pengerikan. Hasil penelitian di semua stasiun ditemukan tiga kelas yakni Bacillariophyceae, Dinophyceae dan Cyanophyceae. Genus yang paling banyak ditemukan adalah Navicula, Rhizosolenia, Oscillatoria, Gonyaulax dan Prorocentrum. Kelimpahan total mikroalga epifit tertinggi terdapat pada Stasiun 3 (11.234 sel/cm2) dan terendah pada Stasiun 2 (6.717 sel/cm2). Kelimpahan mikroalga epifit pada ujung daun bagian permukaan atas (UA) menghasilkan jumlah tertinggi yakni 5.682 sel/cm² dan bagian yang terendah terdapat pada posisi tengah daun bagian permukaan bawah (TB) sebanyak 3.292 sel/cm². Posisi menempel pada bagian lamun berpengaruh terhadap kelimpahan mikro alga epifit. Seagrass bed has a function as nursery, spawning, and feeding ground, as well as a habitat for marine biota such as fish, meiofauna, and epiphytic microalgae. Epiphytic microalgae can be used as one of the indicators in aquatic ecosystems related to productivity and pollution. The aims of this study were to know the composition and abundance of epiphytic microalgae on Enhalus acoroides leaves. This research was done on October 2018 by using descriptive method. The sample was taken from three stations, ie. Nyamplungan (Station 1), Bobi Beach (Station 2) and Syahbandar Port (Station 3). The seagrass samples of Enhalus acoroides leaves were cut into three parts i.e. tip (UA & UB), middle (TA & TB) and base (PA & PB) part of the leaves to obtain the samples of epiphytic microalgae by using scratching method. The results of the study found three classes, i.e. Bacillariophyceae, Dinophyceae and Cyanophyceae. The genus most commonly found were Navicula, Rhizosolenia, Oscillatoria, Gonyaulax and Prorocentrum. The highest total abundance of epiphytic microalgae was at Station 3 (11.234 sel/cm2) and the lowest at Station 2 (6.717 sel/cm2). The abundance of epiphytic microalgae based on different part of seagrass leaves showed that the upper surface of the leaf tip (UA) has highest abundance (5.682 cell/cm²) and the bottom surface of the middle leaf (TB) has the lowest abundance (3.292 cell/cm²). The posisiton of attachment affect on the abundance of epiphyte microalgae.

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Mariano, Stefania, Elisa Panzarini, Maria D. Inverno, Nick Voulvoulis y Luciana Dini. "Toxicity, Bioaccumulation and Biotransformation of Glucose-Capped Silver Nanoparticles in Green Microalgae Chlorella vulgaris". Nanomaterials 10, n.º 7 (15 de julio de 2020): 1377. http://dx.doi.org/10.3390/nano10071377.

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Silver nanoparticles (AgNPs) are one of the most widely used nanomaterials in consumer products. When discharged into the aquatic environment AgNPs can cause toxicity to aquatic biota, through mechanisms that are still under debate, thus rendering the nanoparticles (NPs) effects evaluation a necessary step. Different aquatic organism models, i.e., microalgae, mussels, Daphnia magna, sea urchins and Danio rerio, etc. have been largely exploited for NPs toxicity assessment. On the other hand, alternative biological microorganisms abundantly present in nature, i.e., microalgae, are nowadays exploited as a potential sink for removal of toxic substances from the environment. Indeed, the green microalgae Chlorella vulgaris is one of the most used microorganisms for waste treatment. With the aim to verify the possible involvement of C. vulgaris not only as a model microorganism of NPs toxicity but also for the protection toward NPs pollution, we used these microalgae to measure the AgNPs biotoxicity and bioaccumulation. In particular, to exclude any toxicity derived by Ag+ ions release, green chemistry-synthesised and glucose-coated AgNPs (AgNPs-G) were used. C. vulgaris actively internalised AgNPs-G whose amount increases in a time- and dose-dependent manner. The internalised NPs, found inside large vacuoles, were not released back into the medium, even after 1 week, and did not undergo biotransformation since AgNPs-G maintained their crystalline nature. Biotoxicity of AgNPs-G causes an exposure time and AgNPs-G dose-dependent growth reduction and a decrease in chlorophyll-a amount. These results confirm C. vulgaris as a bioaccumulating microalgae for possible use in environmental protection.

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Rismiarti, Asih, Hermin Pancasakti Kusumaningrum y Muhammad Zainuri. "Karakterisasi Dan Identifikasi Molekuler Fusan Hasil Fusi Protoplas Interspesies Chlorella pyrenoidosa dan Chlorella vulgaris Menggunakan 18SrDNA". Bioma : Berkala Ilmiah Biologi 18, n.º 2 (8 de agosto de 2016): 30. http://dx.doi.org/10.14710/bioma.18.2.30-40.

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Chlorella pyrenoidosa is a unicellular green algae that grows in fresh water with carotenoids consisting of β-carotene, α-carotene, anthaxanthin, neoxanthin, zeaxanthin and lutein. C. vulgaris usually it lives in sea water with carotenoids, chlorophyll, tocopherol, ubiquinone and proteins. The quality of them is improved by protoplast fusion and identified further using moleculer analysis. This study aims to find out the characterization and identification of molecular fusan that is obtained from interspecies C. pyrenoidosa and C. vulgaris protoplast fusion process using 18SrDNA. Both C. pyrenoidosa and C. vulgaris are combined by protoplast fusion and then they were performed the isolation of DNA with CTAB modification method, followed by PCR gradient using primers 18S Chlorella and performed DNA sequencing. The result show that there are different characters between masterplan and fusan based on growth of fresh water and sea water medium. The success frequency of fusan as a result from protoplast fusion in the fresh water media is 21% and 6% for sea water medium. The results of the alignment between fresh water fusan and C. vulgaris masterplan from GeneBank shows that the base sequence homology is 93% C. pyrenoidosa masterplan from GeneBank is 90%. The result of molecular identification towards the sequence of fresh water fusan bases shows that there is a kinship relationship with the masterplan of C. pyrenoidosa 18S Chlorella and Chlorosphaera klebsii microalgae compared with some other species from Chlorophyta group with similarity value as many as 91%. It shows that the high variety genetic is based on variations of the base sequence and has a kinship with other species in the Chlorophyta group. Keywords : Chlorella pyrenoidosa, Chlorella vulgaris, Protoplast Fusion, DNA Sequensing, 18SrDNA.

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Vukosav, Petra, Lea Pašalić, Danijela Bakarić, Darija Domazet Jurašin y Tea Mišić Radić. "Interaction of Silica Nanoparticles with Microalgal Extracellular Polymers". Water 15, n.º 3 (28 de enero de 2023): 519. http://dx.doi.org/10.3390/w15030519.

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The properties of engineered nanoparticles (NPs) in the marine environment are influenced not only by the high ionic strength of seawater but also by the interaction of NPs with naturally occurring components of seawater, especially natural organic matter. The aim of this study was to investigate the interaction of engineered silica nanoparticles (SiO2 NPs, diameter of 12 nm) with microalgal extracellular polymers (EPS) released by the marine diatom Cylindrotheca closterium. Dissolved organic carbon (DOC) content of the prepared EPS suspension (200 μg mL−1) used throughout the study was 3.44 mg C L−1. The incorporation of individual SiO2 NPs (height range 10–15 nm) and their nanoscale aggregates (height up to 25 nm, length up to 600 nm) into the EPS network was visualized by atomic force microscopy (AFM), whereas their molecular-level interaction was unraveled by the change in the signal of the Si-O group in their FTIR spectra. AFM imaging of C. closterium cells taken directly from the culture spiked with SiO2 NPs (10 μg mL−1) revealed that the latter are bound to the EPS released around the cells, predominantly as single NPs (height range 10–15 nm). Since AFM and dynamic and electrophoretic light scattering results demonstrated that SiO2 NPs dispersed in seawater without EPS showed enhanced aggregation (aggregate diameter of 990 ± 170 nm) and a 2.7-fold lower absolute zeta potential value compared to that measured in ultrapure water, our findings suggest that the presence of EPS biopolymers alters the aggregation affinity of SiO2 NPs in the marine environment. This might be of outmost importance during microalgal blooms when increased EPS production is expected because EPS, by scavenging and stabilizing SiO2 NPs, could prolong the presence of NPs in the water column and pose a threat to marine biota.

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Ahmed, Ishtiaq, Muhammad Asgher, Farooq Sher, Syed Hussain, Nadia Nazish, Navneet Joshi, Ashutosh Sharma, Roberto Parra-Saldívar, Muhammad Bilal y Hafiz Iqbal. "Exploring Marine as a Rich Source of Bioactive Peptides: Challenges and Opportunities from Marine Pharmacology". Marine Drugs 20, n.º 3 (13 de marzo de 2022): 208. http://dx.doi.org/10.3390/md20030208.

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This review highlights the underexplored potential and promises of marine bioactive peptides (MBPs) with unique structural, physicochemical, and biological activities to fight against the current and future human pathologies. A particular focus is given to the marine environment as a significant source to obtain or extract high-value MBPs from touched/untouched sources. For instance, marine microorganisms, including microalgae, bacteria, fungi, and marine polysaccharides, are considered prolific sources of amino acids at large, and peptides/polypeptides in particular, with fundamental structural sequence and functional entities of a carboxyl group, amine, hydrogen, and a variety of R groups. Thus, MBPs with tunable features, both structural and functional entities, along with bioactive traits of clinical and therapeutic value, are of ultimate interest to reinforce biomedical settings in the 21st century. On the other front, as the largest biome globally, the marine biome is the so-called “epitome of untouched or underexploited natural resources” and a considerable source with significant potentialities. Therefore, considering their biological and biomedical importance, researchers around the globe are redirecting and/or regaining their interests in valorizing the marine biome-based MBPs. This review focuses on the widespread bioactivities of MBPs, FDA-approved MBPs in the market, sustainable development goals (SDGs), and legislation to valorize marine biome to underlying the impact role of bioactive elements with the related pathways. Finally, a detailed overview of current challenges, conclusions, and future perspectives is also given to satisfy the stimulating demands of the pharmaceutical sector of the modern world.

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Fritsen, Christian H., Susan L. Coale, Diann R. Neenan, Angela H. Gibson y David L. Garrison. "Biomass, production and microhabitat characteristics near the freeboard of ice floes in the Ross Sea, Antarctica, during the austral summer". Annals of Glaciology 33 (2001): 280–86. http://dx.doi.org/10.3189/172756401781818653.

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AbstractThe physical, chemical and biological characteristics of surface and freeboard habitats in the summer pack ice in the eastern Ross Sea, Antarctica, were documented in a continuing effort to determine the factors controlling the distribution, production and succession of sea-ice biota. Three longitudinal transects from approximately 65° to 74° S in the western Ross Sea along 135°, 150° and 165° W were visited where samples of slush and slush interstitial water from surface and freeboard habitats as well as sea water were collected at every degree of latitude. Freeboard and surface habitats, found at all stations in the pack ice, contained a large range (five orders of magnitude) of microalgal biomass (measured as chlorophyll a concentrations) and nutrients ranging from below levels of detection to those of the surrounding sea water. The geophysical attributes of the freeboard habitat (i.e. a layer of semi-consolidated ice overlying a layer containing unconsolidated ice crystals and sea water) are consistent with previous descriptions of this environment. However, additional information is presented on the range of biomass concentrations as well as the small-scale distributions of the habitat and biota.

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Kosarev, A. V., D. E. Ivanov y A. F. Kamenets. "The effect of manganese ions (II) on representatives of aquatic biota". IOP Conference Series: Earth and Environmental Science 949, n.º 1 (1 de enero de 2022): 012013. http://dx.doi.org/10.1088/1755-1315/949/1/012013.

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Abstract The work is devoted to the consideration of the peculiarities of the impact of manganese (II) on representatives of freshwater biota. Manganese plays an important role in the aquatic environment, since it determines the course of the most important metabolic processes in hydrobiont organisms of varying degrees of organization. The analysis of processes involving manganese has shown that the main chemical factors affecting the accumulation of manganese in the aquatic environment are anaerobic biochemical processes caused by active silting of the riverbed due to the washout of organic substances from agricultural fields. The use of various physiological endpoints in daphnids is considered as an inexpensive and simple alternative, the criterion of which corresponds to the rule “replacement, reduction, refinement”. It has been shown that manganese (II) ions in the concentration range of 0.1-1000 LOCvr do not have an acute toxic effect on D. magna crustaceans, chronic toxicity is manifested in samples with concentrations of more than 10 LOCvr. The acute toxicity of solutions of manganese (II) salts in relation to S. Quadricauda was revealed by the change in the fluorescence level of microalgae at a concentration of Mn2+ from 0.05 mg/l.

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18

Ferraz Sena, Camilla, Kelly Vieira Silva, Jorge Rêgo Figueiredo, Matheus Santos dos Anjos, Deivson Araújo Brandão, Mariane Amorim Rocha, Patrícia Belini Nishiyama, Ricardo Evangelista Fraga, Helen Michelle De Jesus Affe y Márcio Borba da Silva. "Diversidade de Euglenophyceae do Pantanal dos Marimbus (Bahia, Brasil)". Heringeriana 16 (12 de enero de 2022): e917959. http://dx.doi.org/10.17648/heringeriana.v16i1.917959.

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A classe Euglenophyceae inclui flagelados unicelulares, autotróficos, mixotróficos e heterotróficos, com morfologia variável e ampla distribuição em ecossistemas aquáticos continentais. O presente estudo teve como objetivo realizar um levantamento florístico de Euglenophyceae no Pantanal dos Marimbus, uma planície de inundação no bioma Caatinga, localizada no Parque Nacional da Chapada Diamantina. A região sofre inundações periódicas; as amostras foram realizadas a partir de uma grande área de lagoas interligadas durante maio e setembro de 2014, abril de 2015 e agosto de 2016, durante os períodos de menor precipitação antes da estação seca, quando as lagoas estavam isoladas umas das outras. Um total de 38 táxons foram identificados; 35 táxons são novas ocorrências para a Bahia, 25 para a região Nordeste e 2 para o Brasil. Os dados coletados aumentam nosso conhecimento sobre a distribuição deste grupo taxonômico nos ambientes aquáticos brasileiros e mostram a considerável diversidade de microalgas no Pantanal dos Marimbus.

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Djearamane, Sinouvassane, Yang Mooi Lim, Ling Shing Wong y Poh Foong Lee. "Cellular accumulation and cytotoxic effects of zinc oxide nanoparticles in microalga Haematococcus pluvialis". PeerJ 7 (25 de septiembre de 2019): e7582. http://dx.doi.org/10.7717/peerj.7582.

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Background Zinc oxide nanoparticles (ZnO NPs) are widely used in household and cosmetic products which imply an increased releasing of these particles into the environment, especially aquatic ecosystems, resulting in the need of assessing the potential toxic effects of ZnO NPS on the aquatic organisms, particularly on microalgae which form the base for food chain of aquatic biota. The present study has investigated the dose- and time-dependent cellular accumulation and the corresponding cytotoxic effects of increasing concentrations of ZnO NPs from 10–200 μg/mL on microalga Haematococcus pluvialis at an interval of 24 h for 96 h. Methods The scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) was used to qualitatively detect the cellular accumulation of ZnO NPs in algal cells, while inductively coupled plasma optical emission spectrometry (ICP OES) was performed to quantify the cell associated-zinc in algal cells. The percentage of cell death, reduction in algal biomass, and loss in photosynthetic pigments were measured to investigate the cytotoxic effects of ZnO NPs on H. pluvialis. Extracellular and intracellular changes in algal cells resulted from the treatment of ZnO NPs were demonstrated through optical, scanning, and transmission electron microscopic studies. Results SEM-EDX spectrum evidenced the accumulation of ZnO NPs in algal biomass and ICP OES results reported a significant (p < 0.05) dose- and time-dependent accumulation of zinc in algal cells from 24 h for all the tested concentrations of ZnO NPs (10–200 μg/mL). Further, the study showed a significant (p < 0.05) dose- and time-dependent growth inhibition of H. pluvialis from 72 h at 10–200 μg/mL of ZnO NPs. The morphological examinations revealed substantial surface and intracellular damages in algal cells due to the treatment of ZnO NPs. Discussion The present study reported the significant cellular accumulation of ZnO NPs in algal cells and the corresponding cytotoxic effects of ZnO NPs on H. pluvialis through the considerable reduction in algal cell viability, biomass, and photosynthetic pigments together with surface and intracellular damages.

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20

Hotos, George N. "A Preliminary Survey on the Planktonic Biota in a Hypersaline Pond of Messolonghi Saltworks (W. Greece)". Diversity 13, n.º 6 (15 de junio de 2021): 270. http://dx.doi.org/10.3390/d13060270.

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During a survey in 2015, an impressive assemblage of organisms was found in a hypersaline pond of the Messolonghi saltworks. The salinity ranged between 50 and 180 ppt, and the organisms that were found fell into the categories of Cyanobacteria (17 species), Chlorophytes (4 species), Diatoms (23 species), Dinoflagellates (1 species), Protozoa (40 species), Rotifers (8 species), Copepods (1 species), Artemia sp., one nematode and Alternaria sp. (Fungi). Fabrea salina was the most prominent protist among all samples and salinities. This ciliate has the potential to be a live food candidate for marine fish larvae. Asteromonas gracilis proved to be a sturdy microalga, performing well in a broad spectrum of culture salinities. Most of the specimens were identified to the genus level only. Based on their morphology, as there are no relevant records in Greece, there is a possibility for some to be either new species or strikingly different strains of certain species recorded elsewhere.

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Liwarska-Bizukojc, Ewa. "Evaluation of Ecotoxicity of Wastewater from the Full-Scale Treatment Plants". Water 14, n.º 20 (21 de octubre de 2022): 3345. http://dx.doi.org/10.3390/w14203345.

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In this work, the influence of wastewater from full-scale wastewater treatment plants (WWTPs) on aquatic and soil biota was reviewed and presented. Moreover, the methods and model organisms used in testing the ecotoxicity of wastewater were shown. It was found that wastewater usually affected the biochemical activity and growth of organisms such as bacteria, algae and protozoa. They contributed to the immobilization and death of inter alia crustaceans and fishes. The values of degree of inhibition or lethality widely varied dependent on the type of wastewater, the sampling point (influent or effluent) and the model organisms applied in the biotests. Thus, a battery of ecotoxicity tests using model organisms of different sensitivities should be employed. So far, bacteria (e.g., Vibrio fischeri), green microalgae (e.g., Raphidocelis subcapitata) and crustaceans (Daphnia magna) have been frequently used organisms in the biological assessment of wastewater. They were applied in almost half (bacteria) or more than half (microalgae, crustaceans) of papers analyzed in this study. In almost all studies, the reduction of wastewater toxicity after treatment processes was found. It was proven that the conventional activated sludge systems were efficient in the removal of wastewater toxicity from both municipal and industrial wastewater, while the tertiary stage of treatment, in particular chlorination or ozonation, contributed to the increase in wastewater toxicity.

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James, Kimberley R., Belinda Cant y Tom Ryan. "Responses of freshwater biota to rising salinity levels and implications for saline water management: a review". Australian Journal of Botany 51, n.º 6 (2003): 703. http://dx.doi.org/10.1071/bt02110.

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All of the plants and animals that make up freshwater aquatic communities are affected by salinity. Many taxa possess morphological, physiological and life-history characteristics that provide some capacity for tolerance, acclimatisation or avoidance. These characteristics impart a level of resilience to freshwater communities.To maintain biodiversity in aquatic systems it is important to manage the rate, timing, pattern, frequency and duration of increases in salinity in terms of lethal and sublethal effects, sensitive life stages, the capacity of freshwater biota to acclimatise to salinity and long-term impacts on community structure.We have limited understanding of the impacts of saline water management on species interactions, food-web structures and how elevated salinity levels affect the integrity of communities. Little is known about the effect of salinity on complex ecosystem processes involving microbes and microalgae, or the salinity thresholds that prevent semi-aquatic and terrestrial species from using aquatic resources. Compounding effects of salinity and other stressors are also poorly understood.Our current understanding needs to be reinterpreted in a form that is accessible and useful for water managers. Because of their complexity, many of the remaining knowledge gaps can only be addressed through a multidisciplinary approach carried out in an adaptive management framework, utilising decision-making and ecological risk assessment tools.

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23

Bergami, Elisa, Emilia Rota, Tancredi Caruso, Giovanni Birarda, Lisa Vaccari y Ilaria Corsi. "Plastics everywhere: first evidence of polystyrene fragments inside the common Antarctic collembolan Cryptopygus antarcticus". Biology Letters 16, n.º 6 (junio de 2020): 20200093. http://dx.doi.org/10.1098/rsbl.2020.0093.

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There is evidence and serious concern that microplastics have reached the most remote regions of the planet, but how far have they travelled in terrestrial ecosystems? This study presents the first field-based evidence of plastic ingestion by a common and central component of Antarctic terrestrial food webs, the collembolan Cryptopygus antarcticus . A large piece of polystyrene (PS) foam (34 × 31 × 5 cm) covered by microalgae, moss, lichens and microfauna was found in a fellfield along the shores of the Fildes Peninsula (King George Island). The application of an improved enzymatic digestion coupled with Fourier transform infrared microscopy (µ-FTIR), unequivocally detected traces of PS (less than 100 µm) in the gut of the collembolans associated with the PS foam and documented their ability to ingest plastic. Plastics are thus entering the short Antarctic terrestrial food webs and represent a new potential stressor to polar ecosystems already facing climate change and increasing human activities. Future research should explore the effects of plastics on the composition, structure and functions of polar terrestrial biota.

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Sosa-Hernández, Juan Eduardo, Zamantha Escobedo-Avellaneda, Hafiz M. N. Iqbal y Jorge Welti-Chanes. "State-of-the-Art Extraction Methodologies for Bioactive Compounds from Algal Biome to Meet Bio-Economy Challenges and Opportunities". Molecules 23, n.º 11 (12 de noviembre de 2018): 2953. http://dx.doi.org/10.3390/molecules23112953.

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Over the years, significant research efforts have been made to extract bioactive compounds by applying different methodologies for various applications. For instance, the use of bioactive compounds in several commercial sectors such as biomedical, pharmaceutical, cosmeceutical, nutraceutical and chemical industries, has promoted the need of the most suitable and standardized methods to extract these bioactive constituents in a sophisticated and cost-effective manner. In practice, several conventional extraction methods have numerous limitations, e.g., lower efficacy, high energy cost, low yield, etc., thus urges for new state-of-the-art extraction methodologies. Thus, the optimization along with the integration of efficient pretreatment strategies followed by traditional extraction and purification processes, have been the primary goal of current research and development studies. Among different sources, algal biome has been found as a promising and feasible source to extract a broader spectrum of bioactive compounds with point-of-care application potentialities. As evident from the literature, algal bio-products includes biofuels, lipids, polyunsaturated fatty acids, pigments, enzymes, polysaccharides, and proteins. The recovery of products from algal biomass is a matter of constant development and progress. This review covers recent advancements in the extraction methodologies such as enzyme-assisted extraction (EAE), supercritical-fluid extraction (SFE), microwave-assisted extraction (MAE) and pressurized-liquid extraction (PLF) along with their working mechanism for extracting bioactive compounds from algal-based sources to meet bio-economy challenges and opportunities. A particular focus has been given to design characteristics, performance evaluation, and point-of-care applications of different bioactive compounds of microalgae. The previous and recent studies on the anticancer, antibacterial, and antiviral potentialities of algal-based bioactive compounds have also been discussed with particular reference to the mechanism underlying the effects of these active constituents with the related pathways. Towards the end, the information is also given on the possible research gaps, future perspectives and concluding remarks.

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Djunaedi, Ali, Chrisna Adi Suryono y Sardjito Sardjito. "Kandungan Pigmen Polar Dan Biomassa Pada Mikroalga Dunaliella Salina Dengan Salinitas Berbeda". Jurnal Kelautan Tropis 20, n.º 1 (19 de julio de 2017): 1. http://dx.doi.org/10.14710/jkt.v20i1.1347.

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Polar pigments content and biomass of Dunaliella salina are affected by salinity related to osmotic pressure and density of media. This study was to determine the effect of salinity on pigment contents and dried biomass of microalgae D. salina. The cultivation used microalgae derived from Balai Besar Pengembangan Budidaya Air Payau (BBPBAP), Jepara. Research method was the Laboratory study with a Completely Randomized Design (CRD). Consisting of one treatment with five stages of salinity treatments: 20 ppt, 25 ppt, 30 ppt, 35 ppt, and 40 ppt and using three times of repetition. Analysis of pigments used UV-Vis spectrophotometric extracted with acetone as the solvent. Harvesting time was when it reached at the stationair phase using flocculation method. The results showed that salinity had the significant effect (P <0.05) on polar pigment and dry biomass. The treatments of 35 ppt showed that the highest content phycocyanin and allophycocyanin pigments were 11.341 mg/gram and 9.644 mg/gram respectively. The highest dry biomass was achieved at 35 ppt salinity treatment at 0.789 gram/L. Keywords: Dunaliella salina, salinity, Polar pigment, Biomass. Kandungan pigmen polar dan biomassa Dunaliella salina dipengaruhi oleh salinitas yang berkaitan dengan tekanan osmotik dan densitas media. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh salinitas terhadap kandungan pigmen polar dan biomassa kering D. salina. Biota uji diperoleh dari Balai Besar Pengembangan Budidaya Air Payau (BBPBAP), Jepara. Metode penelitian adalah eksperimen laboratoris dengan Rancangan Acak Lengkap (RAL) yang terdiri dari 1 perlakuan dengan 5 taraf perlakuan salinitas, yaitu: 20 ppt, 25 ppt, 30 ppt, 35 ppt, dan 40 ppt dengan pengulangan sebanyak 3 kali. Analisis pigmen dengan metode spektrofotometer UV-Vis yang diekstraksi menggunakan larutan aseton. Pemanenan biomassa pada fase stasioner dengan menggunakan metode flokulasi. Hasil penelitian menunjukkan bahwa salinitas berpengaruh terhadap kandungan pigmen dan biomassa kering Dunaliella salina. Perlakuan salinitas 35 ppt menghasilkan kadar pigmen fikosianin dan allofikosianin tertinggi, yaitu 11,341 mg/gram, dan 9,644 mg/gram, serta menghasilkan biomassa kering tertinggi, yaitu 0,789 gram/L. Kata Kunci : Dunaliella salina, Salinitas, Pigmen polar, Biomassa

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Djunaedi, Ali, Sunaryo Sunaryo, Chrisna Adi Suryono y Adi Santosa. "Kandungan Pigmen Fikobiliprotein dan Biomassa Mikroalga Chlorella vulgaris pada media dengan Salinitas Berbeda". Jurnal Kelautan Tropis 20, n.º 2 (22 de noviembre de 2017): 112. http://dx.doi.org/10.14710/jkt.v20i2.1736.

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Phyobilliprotein (phycocyanin and allophycocyanin) pigments content and biomass of Chlorella vulgarisare affected by salinity related to osmotic pressure and density of media. This study was to determine the effect of salinity on phycobiliproteins pigment contents and biomass of microalgae Chlorella vulgaris. The cultivation used microalgae derived from Balai Besar Pengembangan Budidaya Air Payau (BBPBAP), Jepara. Research method was the Laboratory study with a Completely Randomized Design (CRD). Consisting of one treatment with five stages of salinity treatments: 20, 25, 30, 35, and 40 ppt and using three times of repetition. Analysis of pigments used UV-Vis spectrophotometric extracted with acetone as the solvent. Harvesting time was when it reached at the stationair phase using flocculation method. The results showed that salinity had the significant effect (p <0.05) on Phycobilliprotein pigment and biomass. The treatments of 35 ppt showed that the highest content of phycocyanin and allophycocyanin pigments 1,4426 mg/gram and 1,254 mg/gram and biomass were 0,648 g/L respectively.Keywords: Chlorella vulgaris, salinity, Phycobilliprotein pigment, biomass. Kandungan pigmen fikobiliprotein (fikosianin dan allofikosianin)dan biomasa Chlorella vulgaris dipengaruhi oleh salinitas yang berkaitan dengan tekanan osmotik dan densitas media. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh salinitas terhadap kandungan pigmen fikobiliproteindan laju pertumbuhan Chlorella vulgaris. Biota uji diperoleh dari Balai Besar Pengembangan Budidaya Air Payau (BBPBAP), Jepara. Metode penelitian adalah eksperimen laboratoris dengan Rancangan Acak Lengkap (RAL) yang terdiri dari 5 taraf perlakuan salinitas, yaitu: 20, 25, 30, 35, dan 40 ppt dengan pengulangan sebanyak 3 kali. Analisis pigmen dengan metode spektrofotometer UV-Vis yang diekstraksi menggunakan larutan aseton. Pemanenan biomassa pada fase stasioner dengan menggunakan metode flokulasi. Hasil penelitian menunjukkan bahwa salinitas berpengaruh nyata (p<0.05) terhadap kandungan pigmen fikobiliprotein dan biomasa Chlorella vulgaris. Perlakuan salinitas 35 ppt menghasilkan kadar pigmen fikosianin dan allofikosianin tertinggi, yaitu 1,4426 mg/gram, dan 1,254 mg/gram dan biomassa tertinggi yaitu 0,648 gr/L. Kata Kunci : Chlorella vulgaris, salinitas, pigmen fikobiliprotein, biomasa

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Levy, Jacqueline L., Jenny L. Stauber, Steven A. Wakelin y Dianne F. Jolley. "The effect of field-collected biofilms on the toxicity of copper to a marine microalga (Tetraselmis sp.) in laboratory bioassays". Marine and Freshwater Research 62, n.º 12 (2011): 1362. http://dx.doi.org/10.1071/mf10313.

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Standard algal growth rate inhibition bioassays can lack environmental realism and may over- or underestimate metal bioavailability in natural systems. In aquatic environments, algal species interact with other biota, including other algae, bacteria and biofilms. In this work, the feasibility of incorporating marine biofilms into 72 h algal growth inhibition toxicity tests was explored. The effects of copper on Tetraselmis sp. were tested in the absence and presence of characterised field-collected biofilms. We hypothesised that the addition of biofilm would prevent copper toxicity to the alga primarily through interactions of the metal with other cells and biofilm exudates. The sensitivity of Tetraselmis sp. to copper (based on 72 h IC50 values; the copper concentration to inhibit population growth by 50%) in the presence of a blended biofilm inoculum varied 2-fold and was independent of the amount of biofilm added. However, increases in IC10 and IC20 values indicated some amelioration of copper toxicity. When intact biofilms were added to the bioassays, amelioration of toxicity was more consistent, probably due to increased binding of copper to cell surfaces or exudates. Difficulties in characterising biofilms and distinguishing that material from the test alga need to be overcome before biofilms can be routinely incorporated into laboratory bioassays.

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Agić, Heda, Małgorzata Moczydłowska y Lei-Ming Yin. "Affinity, life cycle, and intracellular complexity of organic-walled microfossils from the Mesoproterozoic of Shanxi, China". Journal of Paleontology 89, n.º 1 (enero de 2015): 28–50. http://dx.doi.org/10.1017/jpa.2014.4.

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AbstractLight microscope and scanning electron microscope observations on new material of unicellular microfossilsDictyosphaera macroreticulataandShuiyousphaeridium macroreticulatum,from the Mesoproterozoic Ruyang Group in China, provide insights into the microorganisms’ biological affinity, life cycle and cellular complexity.Gigantosphaeridium fibratumn. gen. et sp., is described and is one of the largest Mesoproterozoic microfossils recorded. Phenotypic characters of vesicle ornamentation and excystment structures, properties of resistance and cell wall structure inDictyosphaeraandShuiyousphaeridiumare all diagnostic of microalgal cysts. The wide size ranges of the various morphotypes indicate growth phases compatible with the development of reproductive cysts. Conspecific biologically, each morphotype represents an asexual (resting cyst) or sexual (zygotic cyst) stage in the life cycle, respectively. We reconstruct this hypothetical life cycle and infer that the organism demonstrates a reproductive strategy of alternation of heteromorphic generations. Similarly inGigantosphaeridium,a metabolically expensive vesicle with processes suggests its protective role as a zygotic cyst. In combination with all these characters and from the resemblance to extant green algae, we propose the placement of these ancient microorganisms in the stem group of Chloroplastida (Viridiplantae). A cell wall composed of primary and secondary layers inDictyosphaeraandShuiyouisphaeridiumrequired a high cellular complexity for their synthesis and the presence of an endomembrane system and the Golgi apparatus. The plastid was also present, accepting the organism was photosynthetic. The biota reveals a high degree of morphological and cell structural complexity, and provides an insight into ongoing eukaryotic evolution and the development of complex life cycles with sexual reproduction by 1200 Ma.

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MACHADO DE LIMA, NÁTHALI MARIA y LUIS H. Z. BRANCO. "Biological soil crusts: new genera and species of Cyanobacteria from Brazilian semi-arid regions". Phytotaxa 470, n.º 4 (9 de noviembre de 2020): 263–81. http://dx.doi.org/10.11646/phytotaxa.470.4.1.

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In the uppermost millimeters of soils is commonly found a thin layer of cryptobiotic organisms, including cyanobacteria, microalgae, lichens, mosses, fungi, bacteria and archaea. These communities are called Biological Soil Crusts (BSCs) or biocrusts and perform important ecological functions, mainly attributed to their capacity of providing soil stability and incorporate nutrients through nitrogen and carbon fixation. Among all the organisms found in the biocrusts, the filamentous cyanobacteria Microcoleus vaginatus and M. steenstrupii are the best studied soil colonizers. The genus Microcoleus is considered complex and has been showing close relation with some species of Phormidium. The poor understanding about these two genera is a limit to the description of the real composition of biocrusts and can generate underestimations in the diversity community and the use of wrong organisms in applied projects (e.g. environmental restoration). This work studied eight cyanobacterial populations from Brazilian BSCs sampled in the Caatinga biome. The populations presented Microcoleus-like and Phormidium-like morphologies, but the phylogenetic analyses based on 16S rRNA gene sequences showed that they represent three new genera and six new species of filamentous cyanobacteria associated to the cryptic genera, they are Pycnacronema caatingensis sp. nov., Pycnacronema edaphica sp. nov., Gracilinea arenicola gen. et sp. nov., Marmoreocelis xerophila gen. et sp. nov., Konicacronema caatinguensis gen. et sp. nov. and Trichocoleus caatingensis sp. nov. The generic name and specific epithets of the new taxa are proposed according to the provisions of the International Code of Nomenclature of algae, fungi, and plants.

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Kovaleva, G. V. y I. Yu Gavrilova. "CHANGES IN THE DOMINANT SPECIES AND SIZE STRUCTURE OF DIATOMS FROM THE SURFACE BOTTOM SEDIMENTS OF THE SEA OF AZOV OVER THE PAST 20 YEARS". Ecology. Economy. Informatics.System analysis and mathematical modeling of ecological and economic systems 1, n.º 6 (2021): 96–103. http://dx.doi.org/10.23885/2500-395x-2021-1-6-96-103.

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The paper presents the results of diatom analysis of surface bottom sediments selected with a range of 20 years. Samples of surface sediments of the Sea of Azov collected in 1998 (before the salinization period) and in 2019 were studied. The results of the diatom analysis of the bottom sediments showed that the sediments were dominated by spores of diatoms from the genus Chaetoceros and stomatocysts of golden algae. In addition to spores and stomatocysts, diatoms from the genus Thalassiosira sp., Coscinodiscus sp., Ditylum brightwellii, Pseudosolenia calcar-avis and Thalassionema nitzschioides were often found in the surface soils of 1998. In the sediments selected in 2019, medium – and large-sized taxa (Actinoptychus senarius, Actinocyclus octonarius, Thalassiosira sp., Coscinodiscus sp.) began to predominate in frequency of occurrence and abundance. The appearance of these species can be associated with an increase in the average salinity of the waters of the Sea of Azov, since most of the representatives of the above taxa belong to marine and brackish-water-marine species. A decrease in freshwater runoff and an increase in salinity in the Sea of Azov can lead not only to a radical transformation of the native microalgae community, but also increases the risk of alien marine species of plankton and benthos. Large-sized diatoms are less attractive as a food base for zooplankton, which can also lead to changes in the native biota of the Sea of Azov. In general, these dangerous transformations can lead to a sharp decrease in the stability of the ecosystem of the Sea of Azov and irreversible consequences.

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Endang Dewi Masithah, Khilyatun Nisak, Boedi Setya Rahardja,. "Studi Perbandingan Kemampuan Nannochloropsis sp. Dan Spirulina sp. Sebagai Agen Bioremediasi Terhadap Logam Berat Timbal (Pb) [Comparative Study Of Ability Nannochloropsis sp. And Spirulina sp. As Agent Bioremediation Of Heavy Metal Plumbum (Pb) ]". Jurnal Ilmiah Perikanan dan Kelautan 5, n.º 2 (19 de enero de 2019): 175. http://dx.doi.org/10.20473/jipk.v5i2.11405.

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Abstract Microalgae species Nannochloropsis sp. can used as heavy metal biosorben because of it’s adsorption capability that caused by the active cluster which contained in that species (Sembiring et al., 2008). Chlorella sp. is one of phytoplankton species that has the bioaccumulation ability of heavy metals and easily cultivated (Arifin, 1997). Lead (Pb) is a mineral belonging to microelements, is a heavy metal and is a potentially toxic material. Water bodies that have been polluted by compounds or ions Pb because can lead to the death of aquatic biota, the number of Lead (Pb) present in water bodies exceeding the proper concentration (Palar, 2004). One way to anticipate the increasing heavy metal pollution in the water is to bioremediation. The research using experimentally, the research design used was completely randomized design (CRD) consisting of four treatments with five replications. The concentrations of heavy metals Plumbum (Pb) used is 0 ppm and 0.9 ppm. The main parameters in this study is the ability of bioremediation Plumbum (Pb) by Nannochloropsis sp. and Chlorella sp. SPSS analytics normality test results and test the ability of T 95% in Nannochloropsis sp. and Chlorella sp. in absorbing heavy metals Plumbum (Pb) concentrations of 0 ppm and 0.9 ppm indicate that the data is normal and the results obtained were significantly different / significant. While the analysis of SPSS test T on heavy metal absorption capability comparison Plumbum (Pb) concentration of 0 ppm and 0.9 ppm by Nannochloropsis sp. and Chlorella sp. showed that the results were not significantly different / non significant. On average results obtained, Nannochloropsis sp. have a higher capacity than Chlorella sp. in the bioremediation process of heavy metals Plumbum (Pb).

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ADESALU, Taofikat Abosede, Olakunbi Anike KUNRUNMI y Muyideen Owonire LAWAL. "Plankton and Macrobiota Composition and Diversity of Three Tropical Freshwaters Rivers in Ogun and Ondo States, Southwest Nigeria". Notulae Scientia Biologicae 8, n.º 2 (17 de junio de 2016): 246–55. http://dx.doi.org/10.15835/nsb829792.

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Three different rivers in Ogun and Ondo states were investigated for both micro and macro-biota of the water bodies. Several physical and chemical properties of these rivers were determined. The pH value of the studied water bodies was essentially neutral with salinity values between 0.02 - 4.0‰. Microalgae communities were represented by three divisions: Cyanophyta, Bacillariophyta and Chlorophyta at Oluwa and Ifara Rivers (Ondo state), while at Ibefun River (Ogun state), five divisions: Cyanophyta, Bacillariophyta, Chlorophyta, Euglenophyta and Pyrrhophyta were identified. Diatoms dominated these water bodies, with Navicula radiosa Kutz. at Ifara River, Fragilaria sp. in Oluwa River, while out of 90 algal taxa identified in Ibefun river, 64 were diatoms species belonging to 26 genera, with Melosira sp. and Synedra sp. recording the highest numbers of cell count. Dinoflagellates recorded only Peridinium sp. while Phacus orbicularis Hubner and Trachelomonas sp. dominated the euglenoids. For the zooplankton composition at Ibefun, rotifers (75.95%) were represented by Brachionus sp., which recorded 62.03%, and Gastropus sp. with 13.92% of the total zooplankton, thus dominated the spectrum, while the copepod recorded 22.78% of the total organisms, with Copilia sp. and Euchirella sp. having 8.86% each. The macrobenthic invertebrates were represented by 3 taxa, belonging to 3 groups, with the dominant group Insecta accounted for 57% of the total individuals (7 individuals/m2), while Oligochaeta and Hirudinea accounted for 29% and 14% respectively of the total individuals at Oluwa and Ifara Rivers. At Ibefun River, the macrobenthic invertebrates were represented by 5 taxa, belonging to 3 groups, Bivalves, Oligochaeta and Insecta, with bivalves being the dominant group (51.7% of the total individuals, as 64 individuals/m2), while Oligochaeta and Insecta accounted for 26.6% and 21.9% respectively of the total individuals. The dominant taxon, Macoma cumana, accounted for 42.2%. A total of seventeen (17) finfish and shellfish species comprised of thirteen (13) finfish and four (4) shellfish species were recorded, being representative of freshwater and brackish water species; Clarias anguillaris (Clariidae), Tilapia zilli (Cichlidae), Chrysichthys nigrodigitatus (Bagridae), Alestes spp. and Macrobrachium vollenhovenii (Palaemonidae) were the most common species observed.

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Deng, Yunyan, Kui Wang, Zhangxi Hu, Qiang Hu y Yingzhong Tang. "Different Geographic Strains of Dinoflagellate Karlodinium veneficum Host Highly Diverse Fungal Community and Potentially Serve as Possible Niche for Colonization of Fungal Endophytes". International Journal of Molecular Sciences 24, n.º 2 (14 de enero de 2023): 1672. http://dx.doi.org/10.3390/ijms24021672.

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In numerous studies, researchers have explored the interactions between fungi and their hosting biota in terrestrial systems, while much less attention has been paid to the counterpart interactions in aquatic, and particularly marine, ecosystems. Despite the growing recognition of the potential functions of fungi in structuring phytoplankton communities, the current insights were mostly derived from phytoplankton hosts, such as diatoms, green microalgae, and cyanobacteria. Dinoflagellates are the second most abundant group of phytoplankton in coastal marine ecosystems, and they are notorious for causing harmful algal blooms (HABs). In this study, we used high-throughput amplicon sequencing to capture global snapshots of specific fungal assemblages associated with laboratory-cultured marine dinoflagellate. We investigated a total of 13 clonal cultures of the dinoflagellate Karlodinium veneficum that were previously isolated from 5 geographic origins and have been maintained in our laboratory from several months to more than 14 years. The total recovered fungal microbiome, which consisted of 349 ASVs (amplicon sequencing variants, sequences clustered at a 100% sequence identity), could be assigned to 4 phyla, 18 classes, 37 orders, 65 families, 97 genera, and 131 species. The fungal consortium displayed high diversity and was dominated by filamentous fungi and ascomycetous and basidiomycetous yeasts. A core set of three genera among all the detected fungi was constitutively present in the K. veneficum strains isolated from geographically distant regions, with the top two most abundant genera, Thyridium and Pseudeurotium, capable of using hydrocarbons as the sole or major source of carbon and energy. In addition, fungal taxa previously documented as endophytes in other hosts were also found in all tested strains of K. veneficum. Because host–endophyte interactions are highly variable and strongly case-dependent, these fungal taxa were not necessarily genuine endosymbionts of K. veneficum; instead, it raised the possibility that dinoflagellates could potentially serve as an alternative ecological niche for the colonization of fungal endophytes. Our findings lay the foundation for further investigations into the potential roles or functions of fungi in the regulation of the growth dynamics and HABs of marine dinoflagellates in the field.

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Djearamane, Sinouvassane, Yang Mooi Lim, Ling Shing Wong y Poh Foong Lee. "Cytotoxic effects of zinc oxide nanoparticles on cyanobacteriumSpirulina (Arthrospira) platensis". PeerJ 6 (1 de junio de 2018): e4682. http://dx.doi.org/10.7717/peerj.4682.

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BackgroundThe extensive usage of zinc oxide nanoparticles (ZnO NPs) in industrial and consumer products raises the risk of releasing their residues into the aquatic environment. The presence of ZnO NPs in the aquatic environment could potentially cause cytotoxic effects on aquatic organisms. Thus, investigating the cytotoxic effects of ZnO NPs on microalgae, which form the base for the food web of aquatic biota, is essential to gain information regarding the ecotoxicological effects of metallic oxide nanoparticles in the aquatic ecosystem. Therefore, the present study has investigated in detail the assorted cytotoxic effects of ZnO NPs onS. platensisusing various concentrations of ZnO NPs (10–200 mg/L) from 6 to 96 h to explore the dose- and time-dependent cytotoxic effects.MethodsThe cytotoxic effects were all assessed through quantification of loss in cell viability, reduction in biomass and decrease in photosynthetic pigments such as chlorophyll-a, carotenoids and phycocyanin. The surface interactions of nanoparticles and the subsequent morphological alterations on algal cells were examined by optical and scanning electron microscopy (SEM). The intracellular alterations of algal cells were studied using transmission electron microscopy. Furthermore, Fourier transformed infrared (FTIR) spectrum was obtained to investigate the involvement of algal surface biomolecules in surface binding of ZnO NPs on algal cells.ResultsThe treatment of ZnO NPs onS. platensisexhibited a typical concentration- and time-dependent cytotoxicity. Results showed a significant (p < 0.05) cytotoxicity from 24 h onwards for all tested concentrations of ZnO NPs. The maximum cytotoxicity on algal cells was achieved at 96 h of exposure to ZnO NPs. In comparison with control, the algal cells that interacted with 200 mg/L of ZnO NPs for 96 h showed 87.3 ± 1% loss in cell viability, 76.1 ± 1.7% reduction in algal biomass, 92.5 ± 2.2%, 76.2 ± 2.2% and 74.1 ± 3.4% decrease in chlorophyll-a, carotenoids and phycocyanin contents respectively. Our study confirmed the cytotoxicity of ZnO NPs through the algal growth inhibition with 72 h EC10and EC50values of 1.29 and 31.56 mg/L, respectively. The microscopic examinations of the algal cells that interacted with ZnO NPs showed severe cell membrane and intracellular damage. The SEM EDX spectrum of ZnO NPs treated algal biomass evidenced the surface accumulation of zinc in the biomass. Finally, the FTIR spectrum confirmed the involvement of amino, hydroxyl and carboxylic groups of algal cell wall in the surface interaction of ZnO NPs on the algal cells.DiscussionThe results showed that the treatment of ZnO NPs onS. platensistriggered substantial cytotoxicity and caused cell death. Hence,S. platensiscould be potentially used as a bioindicator for testing toxicity of ZnO NPs in aquatic environment.

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Kochergina, A. V. y T. Y. Markina. "Ecological assemblages of corticulous myxomycetes in forest communities of the North-East Ukraine". Biosystems Diversity 29, n.º 2 (11 de febrero de 2021): 94–101. http://dx.doi.org/10.15421/012113.

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Corticulous myxomycetes remain one of the least surveyed ecological groups of terrestrial protists. These organisms develop on the bark of trees, mostly feeding on bacteria and microalgae. Their microscopic size and fast developmental cycle (3–5 days) complicate the study of these organisms, and therefore data their on ecological relationships and patterns of biodiversity corticulous myxomycetes remain controversial. On the territory of the southwest spurs of the Central Russian Upland (Northeast Ukraine), no special studies on these organisms have been conducted. During 2017–2020, in nine forest sites located in this territory, we collected samples of bark of 16 species of tree plants, on which sporulating myxomycetes were then identified using the moist chamber technique in laboratory conditions. A total of 434 moist chambers was prepared, and 267 (61.5%) of which were found to contain myxomycete fruiting bodies. In total, we made 535 observations, finding 20,211 sporocarps. As a result, in the surveyed territory, we found 38 species of corticulous myxomycetes, belonging to 18 genera, 10 families, 7 orders, and 2 subclasses of Myxomycetes. Among the species of corticulous myxomycetes, the most abundant were Echinostelium minutum, Arcyria pomiformis, Macbrideola cornea, Perichaena chrysosperma, Licea kleistobolus, Paradiacheopsis fimbriata, Cribraria violacea, Enerthenema papillatum, A. cinerea, and L. operculata. The greatest species richness in the examined biota was observed for genera Comatricha, Licea, Paradiacheopsis and Perichaena, families Amaurochaetaceae and Trichiaceae, orders Stemonitidales, Trichiales and Physarales. By species diversity, dark-spored myxomycetes (Collumellomycetidae) somewhat exceeded bright-spored myxomycetes (Lucisporomycetidae). Badhamia versicolor, Didymium dubium, D. sturgisii, Macbrideola decapillata, and Perichaena luteola are new species for the surveyed area. Four species of myxomycetes were collected in Ukraine for the first time: Hemitrichia pardina, Licea floriformis, L. pygmea, and Macbrideola argentea. Quantitative and qualitative structure of myxomycete consortia developing on different species of substrate-forming plants demonstrated significant differences. The highest level of similarity was demonstrated by Fraxinus excelsior and Acer platanoides, and a relatively strong relationship was seen between Pinus sylvestris and Tilia cordata. The central cluster comprised F. excelsior, A. platanoides and P. sylvestris. By the sum of values of Bray-Curtis coefficient, Quercus robur appeared to be most distinctive plant species by quantitative composition of myxomycete consortia. F. excelsior and T. cordata are the most favourable for the development of corticulous myxomycetes. In all the analyzed consortia, the dominant species belonged to the Stemonitidales and Trichiales orders, while the remaining orders were represented by notably fewer species. Relative species richness of Stemonitidales was the highest in consortia of P. sylvestris, the contribution of Liceales was the greatest in A. platanoides and P. sylvestris, the percentage of Echinosteliales and Physarales was the highest on F. excelsior, the share of Cribrariales was especially large on A. platanoides. Trichiales were represented on all the analyzed substrates to almost the same extent. Representatives of Cribrariales and Physarales were completely absent on P. sylvestris, the species of Clastodermatales – on all species of plants, except Q. robur. Prevalence of bright-spored myxomycetes was determined for consortia of Acer platanoides, the dominance of dark-spored myxomycetes – for F. excelsior, P. sylvestris and Q. robur. The obtained data indicate the presence of stable complexes of corticulous myxomycetes, associated with different species of trees in the forest ecosystems of Northeast Ukraine. This encourages further study of the structure of myxomycete consortia with tree species that were not included in this study and determining the influence of physical-chemical properties of the bark of different plant species on the discovered peculiarities of myxomycete communities.

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Novosel, N., T. Mišić Radić, M. Levak Zorinc, J. Zemla, M. Lekka, I. Vrana, B. Gašparović et al. "Salinity-induced chemical, mechanical, and behavioral changes in marine microalgae". Journal of Applied Phycology, 7 de abril de 2022. http://dx.doi.org/10.1007/s10811-022-02734-x.

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AbstractThis study examines how salinity reduction triggers the response of three marine microalgae at the molecular and unicellular levels in terms of chemical, mechanical, and behavioral changes. At the lowest salinity, all microalgal species exhibited an increase in membrane sterols and behaved stiffer. The glycocalyx-coated species Dunaliella tertiolecta was surrounded by a thick actin layer and showed the highest physiological activity, negatively affecting cell motility and indicating the formation of the palmella stage. The lipid content of membrane and the hydrophobicity of cell were largely preserved over a wide range of salinity, confirming the euryhaline nature of Dunaliella. The species with calcite-encrusted theca Tetraselmis suecica exhibited the highest hydrophobicity at the lowest salinity of all cells examined. At salinity of 19, the cells of T. suecica showed the lowest growth, flagellar detachment and the lowest cell speed, the highest physiological activity associated with a dense network of extracellular polymeric substances, and a decrease in membrane lipids, which could indicate develepment of cyst stage. The organosilicate encrusted species Cylindrotheca closterium appeared to be salinity tolerant. It behaved hydrophobically at lower salinity, whereas becoming hydrophilic at higher salinity, which might be related to a molecular change in the released biopolymers. This study highlighted the interplay between chemistry and mechanics that determines functional cell behavior and shows that cell surface properties and behavior could serve as stress markers for marine biota under climate change. Graphical Abstract

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van den Berg, M. F., A. M. Botha, A. Bierman y P. Oberholster. "Determining biota succession in a domestic wastewater pond system after treatment with a specific consortium microalgae". Journal of Environmental Health Science and Engineering, 26 de octubre de 2022. http://dx.doi.org/10.1007/s40201-022-00840-z.

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Deb, Jiban Chandra y Sarah A. Bailey. "Arctic marine ecosystems face increasing climate stress". Environmental Reviews, 1 de febrero de 2023. http://dx.doi.org/10.1139/er-2022-0101.

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Arctic warming is occurring at a much faster rate than in other parts of the globe, with potentially devastating consequences for the diverse array of species within ecologically and biologically sensitive areas in the Arctic marine region. However, climate change research in this region is sparse compared to other biomes, hindering conservation efforts. In this article, we review and synthesize the available literature to understand the observed and potential impacts of climate change on different species and ecosystems in the Arctic marine region. We reviewed 253 articles reporting changes in species and ecosystems in the Arctic marine region in response to climate change (225 studies documenting observed impacts and 28 reporting predicted impacts). The review revealed that most research effort has been concentrated in only a subset of Arctic Large Marine Ecosystems (LMEs) (5/18 LMEs), with the majority of Arctic LMEs being poorly studied. The majority of the reviewed papers focused on marine mammals (19%) followed by microalgae (17%). A number of studies documented variability in planktonic communities (microalgae, macroalgae, zooplankton), resulting in alteration in ecosystem structure and function. Reproductive failure, decline in populations, and changes in diet composition, behavior and breeding biology were reported for sea birds and mammals. Further, shifts in spatial distribution of fishes were observed by several studies. This review provides persuasive evidence that multiple climate change indices in the Arctic region are changing, with impacts on almost all components of marine biotic ecosystems (from plankton to top predators). We identify a number of gaps (such as limited inventory of biota, robustness of data supporting climate change indices on an Arctic Ocean scale, and climate suitability assessment for all species) in climate change research in Arctic marine ecosystems where future studies can help to quantify the impacts of climate change on species and ecosystems and advance understanding for their adaptive management.

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Abdel-Aal, Eman I., Amany M. Haroon, Shaimaa M. Ibrahim, Ghada S. Abd El-Aziz, Soaad A. Sabae, Khadiga M. Gaber y Mohamed E. Goher. "Ecological status of Lake Nasser Khors, Egypt, before operating the Grand Ethiopian Renaissance Dam". Stochastic Environmental Research and Risk Assessment, 18 de noviembre de 2022. http://dx.doi.org/10.1007/s00477-022-02329-5.

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AbstractLake Nasser is an artificial reservoir that represents the national freshwater reserve of Egypt and has a number of khors (side extensions) along its eastern and western banks. These khors covered approximately 79% of the lake’s total surface area and have an important effect on water quality and fish production in the lake. This study aimed to monitor and assess the water quality, distribution, and structure of the biotic community, including phytoplankton, zooplankton, macrophytes, epiphytes, and macrobenthos in two main khors (Tushka West and Dahmeit) during postflood and preflood periods. There was urgency associated with the study, as it was the last opportunity before the storing of the water behind the Grand Ethiopian Renaissance Dam (GERD), which had begun to fill in July 2020. Although the study confirmed that the water quality of Lake Nasser was good, it is classified as a eutrophic lake (depending on the levels of Chlorophyll-a and nutrients). This study found that pH, NO2, SiO4, NH4, PO4, and temperature were the factors with the greatest effect on the biota community, especially in Dahmeit Khor. In contrast to the phytoplankton and macrobenthos, the highest total density of zooplankton and epiphytic microalgae were detected during the postflood period. This study could be useful in monitoring possible changes in the Lake Nasser environment after the complete filling of the GERD reservoir.

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Vopel, Kay, Alexis Marshall, Shelly Brandt, Adam Hartland, Charles K. Lee, S. Craig Cary y Conrad A. Pilditch. "Biogeochemical feedbacks to ocean acidification in a cohesive photosynthetic sediment". Scientific Reports 11, n.º 1 (24 de noviembre de 2021). http://dx.doi.org/10.1038/s41598-021-02314-y.

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AbstractEcosystem feedbacks in response to ocean acidification can amplify or diminish diel pH oscillations in productive coastal waters. Benthic microalgae generate such oscillations in sediment porewater and here we ask how CO2 enrichment (acidification) of the overlying seawater alters these in the absence and presence of biogenic calcite. We placed a 1-mm layer of ground oyster shells, mimicking the arrival of dead calcifying biota (+Calcite), or sand (Control) onto intact silt sediment cores, and then gradually increased the pCO2 in the seawater above half of +Calcite and Control cores from 472 to 1216 μatm (pH 8.0 to 7.6, CO2:HCO3− from 4.8 to 9.6 × 10−4). Porewater [O2] and [H+] microprofiles measured 16 d later showed that this enrichment had decreased the O2 penetration depth (O2-pd) in +Calcite and Control, indicating a metabolic response. In CO2-enriched seawater: (1) sediment biogeochemical processes respectively added and removed more H+ to and from the sediment porewater in darkness and light, than in ambient seawater increasing the amplitude of the diel porewater [H+] oscillations, and (2) in darkness, calcite dissolution in +Calcite sediment decreased the porewater [H+] below that in overlying seawater, reversing the sediment–seawater H+ flux and decreasing the amplitude of diel [H+] oscillations. This dissolution did not, however, counter the negative effect of CO2 enrichment on O2-pd. We now hypothesise that feedback to CO2 enrichment—an increase in the microbial reoxidation of reduced solutes with O2—decreased the sediment O2-pd and contributed to the enhanced porewater acidification.

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