Search Results (153)

This study reports the discovery of four novel Pinnularia species—P. latocentra sp. nov., P. rhombocentra sp. nov., P. seouloflexuosa sp. nov., and P. paristriata sp. nov.—from urban freshwater streams in South Korea. Species delimitation was achieved using a polyphasic approach that integrated light and scanning electron microscopy, ecological profiling, and molecular evidence from SSU rRNA and rbcL sequences. Each taxon was confirmed as morphologically and genetically distinct from its closest congeners. Our findings broaden the recognized diversity of Pinnularia in East Asia and demonstrate that urban streams, often regarded as degraded habitats, can harbor hidden diatom diversity and ecological complexity. By clarifying diagnostic traits, validating type material in a recognized repository, and aligning molecular and morphological evidence, this study contributes to a more robust taxonomy of Pinnularia. These results also highlight the importance of polyphasic taxonomy and the strategic inclusion of urban habitats in diatomological surveys and biodiversity assessments. Full article

The current study focuses on the diversity, distribution and toxic potential of cyanobacteria in the waterbodies of Moscow, Russia. The research involves the sampling of natural and artificial water environments situated within the Moscow city agglomeration, including the waterbodies of recreational importance. A total of 20 strains of cyanobacteria, namely representatives of Anabaena, Aphanizomenon, Argonema, Dolichospermum, Microcystis and Woronichinia, are isolated from the collected samples. The morphology of the newly obtained strains is analyzed through light microscopy. The results of morphological identification are compared to the molecular data. The molecular phylogeny of the cyanobacterial strains is assessed on the basis of 16S rRNA sequencing. The detection of cyanotoxin-producing genes through PCR reveals two strains of Microcystis aeruginosa capable of microcystin synthesis. Further analysis using HPLC-HRMS demonstrates that microcystin production includes a high proportion (20–28%) of exceptionally toxic microcystin–leucine arginine compounds. Hereby, we discuss the morphology and phylogeny of the analyzed strains and provide comments on the toxic potential of cyanobacteria within the waterbodies of Moscow. Full article

Our current knowledge of the cyanobacterial diversity in Egypt is still underestimated During our routine study on Egyptian cyanobacteria, two interesting and morphologically cryptic strains were isolated from streams of Bahr Yussef and Qarun Lake, one of the oldest lakes in the world, located at the Faiyum depression, Egypt. We applied the polyphasic approaches, combining the state-of-the-art morphotaxonomy, 16S rRNA gene phylogenies, and ecological preferences to precisely unravel the taxonomic positions of these two cyanobacterial strains. Based on a combination of their morphotaxonomic traits and 16S rRNA phylogenetic assessment, we identified them as Alkalinema pantanalense (Leptolyngbyaceae, Leptolyngbyales) and Roholtiella edaphica (Nostocaceae, Nostocales). Both species are considered new cyanobacterial records for Egypt and the African continent based on the available literature. From an ecological standpoint, both species are eutraphentic, where they could tolerate relatively elevated concentrations of NO₃⁻, NH₄⁺ (in particular for R. edaphica), and silicates, reflecting eutrophication signs in the ecosystems they colonize. This study adds to the limited molecular information available on the Egyptian cyanobacteria, and also highlights the need for re-investigation of Egyptian cyanobacteria, using polyphasic approaches, to better understand their taxonomy and ecology. Full article

The taxonomic status of two bacterial strains, KW56^T and 2063^T, isolated from root nodules of Chamaecytisus albus (Spanish broom), was investigated using a polyphasic approach. Both isolates belong to the genus Phyllobacterium, yet exhibit significant genotypic and phenotypic differences from all currently described species. Whole-genome comparisons revealed that strain KW56^T is most closely related to Phyllobacterium trifolii PETP 02^T, while strain 2063^T is related to Phyllobacterium brassicacearum strains STM 196^T and 29-15. However, digital DNA–DNA hybridization (dDDH) and average nucleotide identity (ANI) values between the new isolates and their closest relatives were below established species delineation thresholds, supporting their recognition as novel species. Phenotypic analyses confirmed morphological and growth characteristics typical for Phyllobacterium, while also revealing several discriminatory physiological traits. Fatty acid profiling showed that cyclopropyl 19:0 was the major fatty acid in both strains, though each exhibited a unique fatty acid composition. Chemotaxonomic markers included 3-OH 14:0, a19:1, and 21:0 for strain KW56^T, and 3-OH 14:0, 3-OH 17:0, and 3-OH 18:0 for strain 2063^T. Based on the genomic, phenotypic, and chemotaxonomic data, we propose that strains KW56^T and 2063^T represent two novel species, for which the names Phyllobacterium chamaecytisi sp. nov. (DSM 113831) and Phyllobacterium lublinensis sp. nov. (DSM 113830) are proposed. Full article

This paper presents a novel analytical approach for the efficient design of a particular class of 2D FIR filters, having a frequency response with an elliptically shaped support in the frequency plane. The filter design is based on a Gaussian shaped prototype filter, which is frequently used in signal and image processing. In order to express the Gaussian prototype frequency response as a trigonometric polynomial, we developed it into a Fourier series up to a specified order, given by the imposed approximation precision. We determined analytically a 1D to 2D frequency transformation, which was applied to the factored frequency response of the prototype, yielding directly the factored frequency response of a directional, elliptically shaped 2D filter, with specified selectivity and an orientation angle. The designed filters have accurate shapes and negligible distortions. We also designed a 2D uniform filter bank of elliptical filters, which was then applied in decomposing a test image into sub-band images, thus proving its usefulness as an analysis filter bank. Then, the original image was accurately reconstructed from its sub-band images. Very selective directional elliptical filters can be used in efficiently extracting straight lines with specified orientations from images, as shown in simulation examples. A computationally efficient implementation at the system level was also discussed, based on a polyphase and block filtering approach. The proposed implementation is illustrated for a smaller size of the filter kernel and input image and is shown to have reduced computational complexity due to its parallel structure, being much more arithmetically efficient compared not only to the direct filtering approach but also with the most recent similar implementations. Full article

Fusarioid fungi, members of the Nectriaceae within the Hypocreales (Ascomycota), exhibit diverse ecological roles and possess complex phylogenetic relationships, including endophytic, saprophytic, and pathogenic lifestyles. Among them, the genera Fusarium and Neocosmospora are particularly significant in agriculture and medicine. However, the boundaries between their species remain taxonomically contentious. In this study, 22 representative isolates from plant, fungal, and insect hosts were subjected to a polyphasic taxonomic approach that integrated morphological characterization, multilocus phylogenetic analyses, and phylogenomic analysis based on 4,941 single-copy orthologous genes. Consequently, five new species (F. dracaenophilum, F. puerense, F. wenshanense, N. alboflava, and N. fungicola) were described, and F. qiannanense and N. solani were recorded from new host species. The resulting phylogenomic tree topology was highly congruent with the multilocus phylogeny, providing robust support for the taxonomic distinction between Fusarium and Neocosmospora. This study provides new insights into the taxonomy of fusarioid fungi and has important implications for plant disease management, biodiversity conservation, and the study of fungal evolution. Full article

ES5-4^T, a Gram-positive, motile, aerobic, and rod-shaped strain, was isolated from the rhizosphere of Galinsoga parviflora growing in the selenium-rich ore area of Enshi, Hubei Province, China. This strain can grow at pH levels of 5.0–10.0 and temperatures of 4–42 °C, with optimal growth at pH 7.0 and 28 °C. It was found to resist NaCl up to 5% (w/v), with an optimal growth condition of 0.5–1.0%. The strain exhibited tolerance to selenite (Se⁴⁺) concentrations up to 5000 mg/L. The major fatty acids of the ES5-4^T strain were anteiso-C_15:0 (46.5%) and C_16:0 (21.7%), its predominant respiratory quinone was MK-7, and its polar lipids included diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and an unidentified phospholipid (PL). The presence of the 16S rRNA gene sequence implies that ES5-4^T belongs to a member of the genus Paenibacillus, with the highest sequence similarity of 98.4% to Paenibacillus pabuli NBRC 13638^T. The bac120 tree also confirmed that the strain is within the genus Paenibacillus. The average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between ES5-4^T and closely related members of the genus Paenibacillus were all below the cutoff levels of 95–96% and 70%, respectively. Based on a polyphasic approach, including phenotypic, chemotaxonomic, and phylogenetic analyses, the ES5-4^T strain is proposed as a novel species of the genus Paenibacillus, for which the name Paenibacillus hubeiensis sp. nov. is proposed. This type strain is designated as ES5-4^T (=GDMCC 1.3540^T = KCTC 43478^T). Full article

In Thailand, mangrove forests form a major component of the Andaman coastal ecosystems in the southern provinces. However, studies on their microbial assemblage largely revolved around groups of bacteria, fungi, and eukaryotic microalgae, while the diversity of cyanobacteria in these regions remains almost unknown. This taxonomic study applied the polyphasic approach to examine seven cyanobacterial strains collected from different mangrove environments (including soil crust, tree bark, wood, and rock surface) across Ranong, Phang-Nga, and Phuket provinces. The comprehensive analysis combining morphology, ecology, 16S rRNA phylogenetic relationships, genetic identity, ITS secondary structure, and ITS dissimilarity resulted in the first records of the genera Picosynechococcus, Allocoleopsis, and Sirenicapillaria in Thailand, and led to the description of a new species, Picosynechococcus mangrovensis sp. nov. This new species was differentiated from the type species P. fontinalis based on the distinct 16S rRNA gene phylogenetic position, low 16S rRNA genetic similarity, its slightly halophilic nature, and ability to form pseudo-filaments with up to 160 cells. Our research significantly expands the documented cyanobacterial diversity of Southeast Asian mangrove ecosystems, establishing a critical foundation for future ecological and biotechnological investigations in these understudied yet vital tropical habitats. Full article

Oculatellaceae is a family of cyanobacteria with orange spots in the apical cells and has a wide distribution in various living environments. The species of this family are widely distributed but relatively few in number. In order to enrich our knowledge of the species diversity of cyanobacteria in China, and further achieve the monophyletic development of modern cyanobacteria classification systems, we studied two algal strains, designated as SXACC0114 and SXACC0117, isolated from China and subjected to taxonomic studies using a multiphase approach. The colony of the strain SXACC0114 is bright blue-green in color and does not form a biofilm. The trichomes are yellow-green to bright blue-green. For the strain SXACC0117, no false branching is observed. It has wider filaments and more distinct sheaths, and lacks swollen cells. Based on 16S rRNA gene phylogenetic analysis, the results showed that these two algal strains clustered in Albertania and Tildeniella evolutionary branches, respectively, with high bootstrap support. In addition, the secondary structures, which are constructed based on the internal transcription spacer (ITS) of 16S-23S rRNA, exhibit differences, and the algal strain has unique D1-D1ʹ, Box-B, and V3 helix structures. These results support the establishment of two new species, described as Albertania yunnanense sp. nov. and Tildeniella yunnanense sp. nov. The discovery of these new species provides a scientific basis for the development and utilization of algae. Full article

During our research on the diversity of diatoms and green microalgae from Egypt, four new-to-science, newly recorded, and poorly known species were retrieved from different Egyptian habitats. The new benthic diatom species Halamphora shaabanii A.A. Saber, El-Sheekh, Levkov, H. Saber et Cantonati sp. nov., which could not be identified using the currently available literature, was described from the high-conductivity, oasis lake Abu Nuss in the El-Farafra Oasis, located in the Western Desert of Egypt, employing both light (LM) and scanning electron (SEM) microscopy observations. A detailed comparison of the biometrically distinctive traits, and ecological preferences, of this new diatom species revealed sufficient differentiations from its morphologically most closely related species: H. atacamana, H. caribaea, H. ectorii, H. gasseae, H. halophila, H. mosensis, H. poianensis, and H. vantushpaensis. Ecologically, Halamphora shaabanii can tolerate relatively high nutrients (N and P) and prefers saline inland environments with NaCl water types. The araphid diatom Pseudostaurosiropsis geocollegarum was observed in the epilithic diatom assemblages of the River Nile Damietta Branch and identified on the basis of LM and SEM. From an ecological standpoint, P. geocollegarum seems to prefer elevated nutrient concentrations (meso-eutraphentic species), reflecting different human influences on the freshwater River Nile Damietta Branch. Based on the available literature, this is the first documentation of this freshwater diatom species for Egypt, and the second record for the African continent. Two green motile microalgae, Chlamydomonas proboscigera and Gonium pectorale, were isolated and identified from the terrestrial biomes of the arid habitat “Wadi El-Atshan” in the Eastern Desert of Egypt. C. proboscigera is reported herein for the first time in the Egyptian algal flora, while G. pectorale is poorly documented in the available literature. In light of our findings, the Egyptian habitats, particularly the isolated desert ecosystems, are interesting biodiversity hotspots and have a richer algal microflora than earlier anticipated. Furthermore, more in-depth taxonomic studies, using a combined polyphasic approach, are needed not only to foster our knowledge of the Egyptian and African algal and cyanobacterial diversity and biogeography, but also to be further used in applied environmental sciences. Full article

Actinomycetes are known to produce a vast array of bioactive secondary metabolites with potential therapeutic applications, including antimicrobials, anticancer agents, and enzyme inhibitors. Among these, members of the genus Nonomuraea have received much attention due to their broad ecological importance in nutrient cycling in soil and their ability to produce new bioactive compounds. A novel actinomycetes, designated strain M3C6^T, was isolated from soil samples collected on Marmara Island, located in the Istanbul province, aiming to explore the microbial diversity of unexplored habitats, and characterized using a polyphasic approach. The isolate showed chemotaxonomic and morphological features consistent with members of the genus Nonomuraea. The 16S rRNA gene sequence analysis revealed that strain M3C6^T shared the highest similarity, at 98.7% sequence identity, to Nonomuraea basaltis 160415^T and Nonomuraea turkmeniaca DSM 43926^T. However, the ANI and dDDH values between strain M3C6^T and these reference strains were fairly low, ranging from 84.0 to 84.6% and 31.8 to 33.7%, respectively, below the generally accepted cutoffs for ANI and DDH that delineate different prokaryotic species. Genomic analysis of strain M3C6^T showed that it had a genome size of 10.38 Mbp and a DNA G+C content of 69.5 mol%. Based on these chemotaxonomic, phenotypic, and genomic data, strain M3C6^T is classified as a novel species within the genus Nonomuraea, for which the name Nonomuraea marmarensis sp. nov. is proposed. The type strain is M3C6^T (= KCTC 49983^T = CGMCC 4.8035^T). Genomic analyses confirmed the high potential of M3C6^T to produce specialized secondary metabolites. Full article

Background: Lake Al-Asfar in KSA was used as a sink for wastewater for decades and suffered from pollution. The lake is a habitat to different microbial species that play important ecological roles, some of which are good, and some are bad and even pathogenic. In a previous investigation, algal-bacteria consortia have proven to be beneficial in bioremediating heavy metals and hydrocarbons in Lake Al-Asfar. The identity of algae was revealed to be Chlorella sp. and Geitlernema sp. in the consortia. The identity of the heterotrophic bacterial partners, on the other hand, awaits investigation and is addressed in the present research. On the other hand, investigating the diversity of Protozoa and parasites is also tackled as they represent indicators of pollution. Some pose serious health risks, but some of them also contribute to reducing some of the pollution levels. Methods: Bacteria associated with algae were isolated in pure form. The polyphasic approach was used to identify bacterial samples, including staining procedures, the use of Vitek technology, and scanning electron microscopy. This information was integrated with structure information such as capsule presence, endospore formation, and wall characteristics indicated by Gram stain. With regard to protists including Protozoa and parasites, Light microscopy and taxonomic books of identification were used to reveal their identity. Results: three main bacterial strains belonging to the following genera were identified: Sphingomonas, Rhizobium, and Enterbacter. The last is potentially pathogenic and poses health risks to Lake goers. Rhizobium, on the other hand, is most likely found in the lake from agricultural wastewater and is a nitrogen fixer that increases the fertility of crops. The first bacterium is associated with special lipid metabolism and is hardly pathogenic. Several diverse microscopic forms of protists, mainly Protozoa and parasites, were identified, which included Entamoeba histolytica, Balantidium coli, Ascaris lumbricoides, Amoeba, Paramecium, Euglena, and Gymnodinium sp. Discussion: The three types of bacteria identified have metabolic activities that are associated with bioremediation. On the other hand, protists, including Protozoa and parasites, are regular members of wastewater communities and help in scavenging solid wastes, but they cause hazards such as secreting toxins, causing disease, and impacting the bioremediation potential by feeding on beneficial bioremediating algae and bacteria. This is part of the wastewater ecosystem dynamics, but efforts must be exerted to minimize, if not completely eliminate, pathogenic parasites in order to maximize the growth of algal consortia. Conclusions: Vitek technology is an emerging less time- and effort-consuming fast technology for identifying bacteria. Bacteria identified have significant ecological bioremediating roles, together with their algal partners, but some pose pathogenic risks. Identifying co-inhabitants like protists and parasites helps to shed light on their impact on one another and pave the way for restoration efforts that minimize the biological hazards and maximize the use of beneficial local microorganisms. Full article

As our comprehension of cyanobacterial classification in diverse ecosystems broadens, it becomes essential to explore the biodiversity of lesser-known areas for a thorough understanding of both global and local diversity. This research, which is part of a larger investigation into soil biocrust algae diversity in the Sanyang Wetland located in Zhejiang Province, China, introduces a novel taxon of non-heterocystous filamentous cyanobacteria employing a polyphasic approach for cyanobacterial classification, integrating morphological, molecular, ecological, and biogeographical considerations. The findings from morphological analysis, 16S rRNA gene sequencing, and the identification of the 16S-23S ITS rRNA region have led to the discovery of a new genus, Paludothrix, which is categorized within the family Coleofasciculaceae. The proposed generic name and specific epithet of these new taxa adhere completely to the guidelines established by the International Code of Nomenclature for algae, fungi, and plants. The modern taxonomic system of cyanobacteria is constantly being updated and improved. The description of new taxa using the polyphasic approach can enrich the relevant knowledge in the field of cyanobacteria classification. The results of this study will increase our understanding of terrestrial cyanobacteria within wetland environments. Full article

Helvella bachu, an ectomycorrhizal fungus, forms a symbiotic relationship with Populus euphratica, a rare and endangered species crucial to desert riparian ecosystems. In this study, endofungal bacteria (EFBs) within the fruiting bodies of H. bachu were confirmed by a polyphasic approach, including genomic sequencing, real-time quantitative PCR targeting the 16S rRNA gene, full-length and next-generation sequencing (NGS) of the 16S rRNA gene, and culture methods. The genera Stenotrophomonas, Variovorax, Acidovorax, and Pedobacter were abundant in the EFBs of fruiting bodies associated with three Populus hosts and were consistently present across different developmental stages. Notably, S. maltophilia and V. paradoxus were detected in high abundance, as revealed by full-length 16S rRNA sequencing, with S. maltophilia also isolated by culture methods. KO-pathway analysis indicated that pathways related to primary, secondary, and energy metabolism were predominantly enriched, suggesting these bacteria may promote H. bachu growth by producing essential compounds, including sugars, proteins, and vitamins, and secondary metabolites. This study confirmed the presence of EFBs in H. bachu and provided the first comprehensive overview of their structure, functional potential, and dynamic changes throughout fruiting body maturation, offering valuable insights for advancing the artificial domestication of this species. Full article

In our large-scale search for antimicrobial-producing bacteria, we isolated an actinomycete strain from rhizospheric soil of Bambusa vulgaris. The strain designated BP-8 showed noticeable antibacterial activity. BP-8 was subjected to a whole-genome analysis via a polyphasic taxonomy approach, and its antibacterial metabolite was identified by HRLS-MS. The results of the physiological and morphological analyses indicated that BP-8 is an aerobic, neutrophilic, mesophilic organism that is tolerant to 8% NaCl and can use a wide range of carbohydrates. It forms curly sporophores with a warty surface. The results of the phylogenetic and average nucleotide identity analyses and in silico DNA–DNA hybridization calculation indicated that BP-8 represents the type strain of a novel Streptomyces species. A comparative in silico analysis of the genome sequences of BP-8 and its closest related strains revealed the presence of genes encoding chemotaxonomic markers characteristic of Streptomyces. The antibacterial compound was identified as amicetin. Genomic mining also revealed more than 10 biosynthetic gene clusters that have not been described previously and may lead to the discovery of new valuable compounds. On the basis of these results, strain BP-8^T (=VKM Ac-3066^T = CCTCC AA 2024094^T) is proposed as the type strain of the novel species Streptomyces sirii sp. nov. Full article