16S-23S rRNA Research Articles

Identification and characteristics of Plesiomonas shigelloides isolated from Mastacembelus armatus

Plesiomonas shigelloides (P. shigelloides), a dominant pathogenic strain identified as YY001, was successfully isolated and characterized from the hepatopancreas of diseased Mastacembelus armatus (M. armatus) for the first time. The strain was identified through a comprehensive approach that included morphological, physiological, and biochemical characterization, as well as 16S rRNA, 23S rRNA, and gyrB gene sequence analysis. Strain YY001 is classified as a Gram-negative bacterium, with optimal growth conditions observed at 28°C and pH 7.0. Results from the bacterium hemolysis test indicated the absence of hemolytic activity in YY001. However, the strain exhibited amplification of nine virulence genes: nanE, waaA, clpP, ssb, actP, aphA, astA, astD, and astB. Drug-resistance testing showed that YY001 displayed resistance only to penicillin G, oxacillin, norfloxacin, and tetracycline, while remaining sensitive to the majority of other antibiotics. Furthermore, nine drug-resistance genes, including emrD, catB, macB, ksgA, tolC, bacA, MdfA, sul1, and DegP, were detected through amplification. Experimental infection demonstrated that YY001 induced symptoms such as abdominal swelling, visceral edema, and hemorrhage, with hepatopancreatic manifestations being particularly severe. The median lethal dosage of strain YY001 in M. armatus was 9.7×108 colony-forming units (CFU)/mL within 48 h, and 4.9×106 CFU/mL within 192 h under the conditions of intraperitoneal injection. The hepatopancreas, gill, and intestine of infected fish showed obvious pathological symptoms, including tissue loosening, hemorrhage, and cell necrosis. The results of this study provided evidence for a more comprehensive understanding of P. shigelloides strain YY001 infection in M. armatus.

Grevenius granulifer (Thulin, 1928) revised: a fresh look at one of the most intensively studied water bears (Eutardigrada: Isohypsibioidea)

AbstractRedescriptions of species established in the incipient stage of tardigrade taxonomy, in the first half of 20th century, have currently become a routine. Especially type species of all genera should undergo an urgent revision to allow more precise diagnoses and unravel species complexes. Herein, an aquatic species Grevenius granulifer is amended based on the topotypic population from a pond in the Botanical Garden of Lund. Detailed qualitative and quantitative characters alongside a full set of standard DNA barcodes (18S rRNA, 28S rRNA, ITS-2, and COI) are provided. This will open a window for systematic works on other representatives of Grevenius and delivers new data on rarely addressed freshwater tardigrades.

PCR Detection of Bartonella spp. and Borreliella spp. DNA in Dry Blood Spot Samples from Human Patients.

Lyme disease is the most commonly reported vector-borne disease in the United States. Bartonella constitute an additional zoonotic pathogen whose public health impact and diversity continue to emerge. Rapid, sensitive, and specific detection of these and other vector-borne pathogens remains challenging, especially for patients with persistent infections. This report describes an approach for DNA extraction and PCR testing for the detection of Bartonella spp. and Borreliella spp. from dry blood spot (DBS) specimens from human patients. The present study included extraction of DNA and PCR testing of DBS samples from 105 patients with poorly defined, chronic symptoms labeled as Lyme-Like Syndromic Illness (LLSI). Bartonella spp. DNA was detected in 20/105 (19%) and Borreliella spp. DNA was detected in 41/105 (39%) patients with LLSI. Neither group of organisms was detected in DBS samples from 42 healthy control subjects. Bartonella spp. 16S-23S rRNA internal transcribed spacer sequences were highly similar to ones previously identified in yellow flies, lone star ticks, a human patient from Florida, mosquitoes in Europe, or B. apihabitans and choladocola strains from honeybees. These human strains may represent new genetic strains or groups of human pathogenic species of Bartonella. The 41 Borreliella spp. flaB gene sequences obtained from human patients suggested the presence of four different species, including B. burgdorferi, B. americana, B. andersonii, and B. bissettiae/carolinensis-like strains. These results suggest that specific aspects of the DBS DNA extraction and PCR approach enabled the detection of Bartonella spp. and Borreliella spp. DNA from very small amounts of human whole blood from some patients, including specimens stored on filter paper for 17 years.

Prevalence and genetic diversity of Bartonella spp. in wild small mammals from South Africa.

Bartonella spp. are intracellular bacteria associated with several re-emerging human diseases. Small mammals play a significant role in the maintenance and spread of Bartonella spp. Despite the high small mammal biodiversity in South Africa, there is limited epidemiological information regarding Bartonella spp. in these mammals. The main aim of this study was to determine the prevalence and genetic diversity of Bartonella spp. from wild small mammals from 15 localities in 8 provinces of South Africa. Small mammals (n = 183) were trapped in the Eastern Cape, Free State, Gauteng, Limpopo, Mpumalanga, Northern Cape, North West, and Western Cape provinces of South Africa between 2010 and 2018. Heart, kidney, liver, lung, and spleen were harvested for Bartonella DNA screening, and prevalence was determined based on the PCR amplification of partial fragments of the 16S-23S rRNA intergenic spacer (ITS) region, gltA, and rpoB genes. Bartonella DNA was detected in Aethomys chrysophilus, Aethomys ineptus, Gerbillurus spp., Lemniscomys rosalia, Mastomys coucha, Micaelamys namaquensis, Rhabdomys pumilio, and Thallomys paedulcus. An overall prevalence of 16.9% (31/183, 95% CI: 12.2%-23%) was observed. Bartonella elizabethae, Bartonella grahamii, and Bartonella tribocorum were the zoonotic species identified, while the remaining sequences were aligned to uncultured Bartonella spp. with unknown zoonotic potential. Phylogenetic analyses confirmed five distinct Bartonella lineages (I-V), with lineage IV displaying strong M. coucha host specificity. Our results confirm that South African wild small mammals are natural reservoirs of a diverse assemblage of Bartonella spp., including some zoonotic species with high genetic diversity, although prevalence was relatively low.IMPORTANCESmall mammals play a significant role in the maintenance and spread of zoonotic pathogens such as Bartonella spp. Despite the high small mammal biodiversity in southern Africa including South Africa, there is limited epidemiological information regarding Bartonella spp. in these mammals across the country. Results from our study showed the liver and spleen had the highest positive cases for Bartonella spp. DNA among the tested organs. Bartonella elizabethae, B. grahamii, and B. tribocorum were the three zoonotic species identified and five distinct Bartonella lineages (I-V) were confirmed through phylogenetic analyses. To the best of our knowledge, this study presents the first extensive nuclear diversity investigation of Bartonella spp. in South African small mammals in South Africa.

The description of a novel Gloeothece species (Chroococcales, Cyanobacteria) from China, based on a polyphasic approach

Cyanobacteria, with strong adaptability, occupied an important position on the earth all the time. In this study, the strain of coccoid cyanobacteria (CHAB 5847) was isolated and purified from Guizhou Province, China. The phylogenetic and taxonomic characteristics of CHAB 5847 were studied using polyphasic approach combining morphological, ecological and molecular data. Based on phylogenetic analysis of 16S rRNA gene sequence, the studied strain occupied a unique position, and clustered in Gloeothece clade. The 16S rRNA gene sequences of two clones of the studied strain shared 93.1%–98.1% similarity to other Gloeothece species, which supports well it to be a new member of Gloeothece genus. Furthermore, the unique pattern of D1-D1′, Box-B and V3 helix of the 16S–23S rRNA internal transcribed spacer (ITS) secondary structure revealed that the strain represented a novel species. These results support the establishment of a new species of Gloeothece genus with the name G. guizhouensis sp. nov.

Integrative taxonomy reveals exceptional species diversity of Lucasioides from China (Isopoda: Oniscidea: Agnaridae)

The genus Lucasioides Kwon, 1993 (Isopoda: Oniscidea: Agnaridae) occurs in Asia, but confined only to China, Japan, Korea, and Russian Siberia. The ambiguously morphological differences among some members of the genus make a dilemma: the species recognition, whether morphologically similar or different, is uncertain. In this paper, we present first morphometric and molecular data for the genus from a broad sample. DNA sequences (mitochondrial COI, nuclear 18S rRNA, 28S rRNA, and NaK) were generated and integrated with morphological evidence to reveal the cryptic species and delimit the new species within the genus. Seven species are described as new to science: Lucasioides digitatussp. nov., L. dissectussp. nov., L. dianensissp. nov., L. formosussp. nov., L. gracilentussp. nov., L. schmidtisp. nov. and L. subcurvatussp. nov. To date, Lucasioides species from China are 44.4% as many as all the known congeners worldwide, showing the exceptional species diversity of Lucasioides species from China. The results demonstrate that the integrative taxonomy is especially important to reveal the cryptic species among the high morphological similarity of taxa, as well as providing an effective way for species identification to accelerate the exploration of woodlice biodiversity.

Okeanomitos corallinicola gen. and sp. nov. (Nostocales, Cyanobacteria), a new toxic marine heterocyte-forming Cyanobacterium from a coral reef.

Cyanobacterial mats supplanting coral and spreading coral diseases in tropical reefs, intensified by environmental shifts caused by human-induced pressures, nutrient enrichment, and global climate change, pose grave risks to the survival of coral ecosystems. In this study, we characterized Okeanomitos corallinicola gen. and sp. nov., a newly discovered toxic marine heterocyte-forming cyanobacterium isolated from a coral reef ecosystem of the South China Sea. Phylogenetic analysis, based on the 16S rRNA gene and the secondary structure of the 16S-23S rRNA intergenic region, placed this species in a clade distinct from closely related genera, that is, Sphaerospermopsis stricto sensu, Raphidiopsis, and Amphiheterocytum. The O. corallinicola is a marine benthic species lacking gas vesicles, distinguishing it from other members of the Aphanizomenonaceae family. The genome of O. corallinicola is large and exhibits diverse functional capabilities, potentially contributing to the resilience and adaptability of coral reef ecosystems. Invitro assays revealed that O. corallinicola demonstrates notable cytotoxic activity against various cancer cell lines, suggesting its potential as a source of novel anticancer compounds. Furthermore, the identification of residual saxitoxin biosynthesis function in the genome of O. corallinicola, a marine cyanobacteria, supports the theory that saxitoxin genes in cyanobacteria and dinoflagellates may have been horizontally transferred between them or may have originated from a shared ancestor. Overall, the identification and characterization of O. corallinicola provides valuable contributions to cyanobacterial taxonomy, offering novel perspectives on complex interactions within coral reef ecosystems.

Discovery of novel Nodosilinea species (Cyanobacteria, Nodosilineales) isolated from terrestrial habitat in Ryukyus campus, Okinawa, Japan

Terrestrial cyanobacteria are extremely diverse. In urban areas, they can be found as black stains on the surface of building walls, stone monuments, or man-made structures. Many of the terrestrial cyanobacteria are still understudied. To expand knowledge of terrestrial cyanobacterial diversity, a polyphasic characterization was performed to identify 12 strains isolated from campus of University of the Ryukyus, Okinawa, Japan. Multigene phylogenetic analyses based on 16S rRNA gene and 16S-23S rRNA internal transcribed spacer (ITS) region showed that the isolated strains formed two independent subclades within Nodosilinea, and were distantly related to all described Nodosilinea species. The 16S-23S rRNA ITS secondary structures showed variations for D1-D1′ and Box B domain, while V3 domain was almost identical among entire species of Nodosilinea, including the studied strains. In addition, a unique morphological character, i.e. forming nodule or spiral shape, was also observed in certain studied strains. According to polyphasic characterization, Nodosilinea coculeatus sp. nov. and Nodosilinea terrestrialis sp. nov., were proposed as two new species of terrestrial cyanobacteria from Okinawa.

Customized 16S-23S rDNA ITS Amplicon Metagenomics for Acetic Acid Bacteria Species Identification in Vinegars and Kombuchas.

Acetic acid bacteria (AAB) are involved in food and beverage production bioprocesses, like those in vinegar and kombucha. They oxidize sugars and alcohols into various metabolites, resulting in the final products' pleasant taste and aroma. The 16S rDNA amplicon metagenomics using Illumina technology is usually used to follow the microbiological development of these processes. However, the 16S rRNA gene sequences among different species of AAB are very similar, thus not enabling a reliable identification down to the species level but only to the genus. In this study, we have constructed primers for amplifying half of the 16S-23S rRNA gene internal transcribed spacer (ITS) for library construction and further sequencing using Illumina technology. This approach was successfully used to estimate the relative abundance of AAB species in defined consortia. Further application of this method for the analysis of different vinegar and kombucha samples proves it suitable for assessing the relative abundance of AAB species when these bacteria represent a predominant part of a microbial community.

Polyphasic Approach and Potential Cyanotoxin Production by Planktothrix from the Río Grande de Comitán and Montebello Lakes National Park, Southern Mexico.

The development of anthropic activities during recent years has led to an increase in nutrient fluxes in the Río Grande de Comitán and Montebello Lakes National Park, Mexico. In turn, this has modified the dynamics of the biotic community, specifically favoring the presence of cyanobacteria tolerant to contamination. The continual and massive presence of Planktothrix species (spp.) in the system suggests a potential detrimental impact for economic issues and human health. In this study, we identify the morphological and molecular characteristics of Planktothrix populations from seven tropical (1,380-1,740 masl, 23.0-25.5°C) and calcareous lakes and two ponds from a water treatment plant. We also assess the ecological drivers that could be related to the presence of cyanotoxins in the system. The ecological preferences, morphology, 16S rRNA structure, and 16S-23S rRNA internal transcribed spacer found evidence for three species: P. agardhii distributed in neutral to slightly basic water (pH = 7.7-8.7), and P. spiroides and Planktothrix sp. in alkaline waters (pH = 9.1). The presence of the mcyE gene and its validation by liquid chromatography confirmed the presence of two microcystin variants (MC-RR and MC-LR) in at least three populations of P. agardhii. These microcystins put the health of the ecosystem and its inhabitants at risk, a condition that should be addressed and resolved with a water management and detoxification strategy in the basin.

Molecular characterization uncovering a novel genus of tapering-filamentous cyanobacteria from Thailand: Phayaothrix lacustris gen. & sp. nov. (Nostocales, Cyanophyta)

In this study, novel Calothrix-like strains NUACC09 and NUACC10 were isolated from the surfaces of rocks in Phayao Lake, Thailand. Morphological, molecular and ecological comparisons were investigated to characterize the taxonomic status of these novel strains. Under the light microscope, morphological studies indicated that these two strains were morphologically similar to Calothrix but could be differentiated by production of a non-hyaline hair at the terminal end, a low degree of tapering, twisted or loop-forming filaments, a knotted growth form, intertwined trichomes and presenting more than one trichome within the single sheath. In the 16S rRNA and rbcLX gene phylogenetic tree analyses, our strains formed a monophyletic clade with former freshwater/terrestrial Calothrix-like taxa separating distantly from other Calothrix-like genera. Furthermore, low 16S rRNA gene sequence similarity (<94.9%) to the closely related genera and species delimitation analyses (PTP/bPTP, GMYC, ABGD and ASAP methods) indicated that this clade should be considered as a different cyanobacterial lineage. The phylogenetic tree and secondary structures (D1–D1′, V2, Box-B and V3 helix) based on 16S–23S rRNA ITS regions suggested that multiple species might be contained in this clade. Therefore, here, Phayaothrix was proposed as a novel cyanobacterial genus with Phayaothrix lacustris sp. nov. as the type species following the International Code of Nomenclature for algae, fungi and plants.

MOLECULAR PHYLOGENY OF THE LEECH GENUS PONTOBDELLA (HIRUDINIDA: PISCICOLIDAE) WITH NOTES ON PONTOBDELLA CALIFORNIANA AND PONTOBDELLA MACROTHELA.

Leech specimens of the genus Pontobdella (Hirudinida: Piscicolidae) were found off the coast of the state of Oaxaca (Pacific) as well as in Veracruz and Tabasco (Gulf of Mexico), Mexico. Based on the specimens collected in Oaxaca, a redescription of Pontobdella californiana is provided, with emphasis on the differences in the reproductive organs with the original description of the species. In addition, leech cocoons assigned to P. californiana were found attached to items hauled by gillnets and studied using scanning electron microscopy and molecular approaches. Samples of Pontobdella macrothela were found in both Pacific and Atlantic oceans, representing new geographic records. The phylogenetic position of P. californiana is investigated for the first time, and with the addition of Mexican samples of both species, the phylogenetic relationships within Pontobdella are reinvestigated. Parsimony and maximum-likelihood phylogenetic analysis were based on mitochondrial (cytochrome oxidase subunit I [COI] and 12S rRNA) and nuclear (18S rRNA and 28S rRNA) DNA sequences. Based on our results, we confirm the monophyly of Pontobdella and the pantropical distribution of P. macrothela with a new record in the Tropical Eastern Pacific.

Post-mortem detection of hemoplasmas (hemotropic Mycoplasma spp.) in South American fur seal (Arctocephalus australis) sampled in Rio Grande do Sul State, southern Brazil

Hemotropic mycoplasmas are bacteria that attaches to erythrocytes surface, which some species presents zoonotic concerns. In the suborder Pinnipedia, genera Otaria and Arctocephalus are prominent in Brazil. This study investigated the occurrence of hemoplasmas in Arctocephalus sp. and Otaria flavescens found dead along the coast of a Southern Brazilian State. DNA from 135 spleen samples were extracted and subjected to conventional PCR protocols, targeting the 16 S rRNA and 23 S rRNA gene. Three (2.22 %) Arctocephalus australis were positive in the 16 S rRNA gene, and no samples amplified in the 23 S rRNA gene. Samples from this study clustered with Zalophus californianus and Arctocephalus tropicalis mycoplasmas on a Bayesian phylogenetic analysis. Genetic diversity analysis suggested distinct genotypes, indicating A. australis as a new host for hemoplasma, and also a potential putative novel hemoplasma genotype. These findings raises future awareness for pinnipeds conservation, and adds Mycoplasma spp. to be taken into consideration when clinically evaluating rescued animals.

A new parasitic barnacle (Crustacea, Cirripedia, Rhizocephala, Mycetomorpha) from the abyssal zone in the northwestern Pacific

I describe the parasitic barnacle Mycetomorpha abyssalissp. nov. from the crangonid shrimp Sclerocrangon zenkevitchi collected from 3893–3890 m depth off the eastern coast of Iwate, Japan, northwestern Pacific. This is the first Mycetomorpha rhizocephalan from the abyssal zone and the third species in Mycetomorpha. Mycetomorpha abyssalissp. nov. differs from its congeners M. vancouverensis and M. albatrossi in (1) triangular shield lacking, (2) stalk one-quarter of length from posterior end of externa, (3) mantle opening clearly anterior to stalk, (4) different host genus, and (5) depth range much deeper. I determined partial sequences for the mitochondrial cytochrome c oxidase subunit I (COI) and 16S rRNA genes and nuclear 18S rRNA and 28S rRNA genes from M. abyssalissp. nov. for future DNA barcoding and phylogeny. Kimura 2-parameter distances between M. abyssalissp. nov. and M. vancouverensis were 21.2% (16S), 0.6% (18S), and 1.5% (28S).

First Report of Lactococcus petauri in the Pumpkinseed (Lepomis gibbosus) from Candia Lake (Northwestern Italy)

Lactococcus petauri has emerged as a pathogen affecting farmed fish. In this case report, L. petauri was isolated from Lepomis gibbosus captured in Lake Candia, located in Piedmont, Northwestern Italy. Initially identified as L. garvieae using conventional methods like RAPID 32 ID STREP and MALDI-TOF, molecular analysis based on sequencing of the 16S-23S rRNA internal transcribed spacer region (ITS) confirmed it as L. petauri. The study also assessed the isolated strain’s pathogenicity by examining hemolysin and capsule cluster genes, revealing only hemolysin 2 amplicon; notably, the fish exhibited no lesions or pathological alterations. The L. petauri strain from this study displayed resistance to several antibiotics, being sensitive only to ampicillin, amoxicillin, florfenicol, and G-penicillin. This research provides new insights into host range of L. petauri and raises awareness of potential public health implications, particularly concerning zoonotic potential.

Diversity of Flea Species (Siphonaptera) and Their Vector-Borne Pathogens from Bats (Chiroptera) in Lithuania

Bat fleas (Insecta: Siphonaptera: Ischnopsyllidae) are highly host-specific ectoparasites distributed worldwide (except Antarctica). The identification of flea species and the detection of flea-borne pathogens plays a significant role not only in veterinary and public health, but also in providing insights into the ecology, behaviour, and geographical distribution of fleas and flea-associated pathogens. The present study aimed to conduct a morphological and molecular identification of fleas collected from Lithuanian bats, as well as to screen for the presence of vector-borne pathogens. A total of 58 flea specimens were collected from bats in Lithuania. Based on morphological analysis, seven flea species were identified (Ischnopsyllus variabilis, I. octactenus, I. simplex, I. elongatus, I. hexactenus, Nycteridopsylla pentactena, and N. eusarca) and screened for the presence of Anaplasma spp., Borrelia spp., Babesia spp., Bartonella spp., Rickettsia spp., and Mycoplasma spp. Molecular analysis of fleas’ COI and 18S rRNA genes showed that the flea species collected from bats are closely genetically related. Bartonella DNA was detected in bat fleas (41.4%). No DNA of Anaplasma, Borrelia, Babesia, Rickettsia, and Mycoplasma was amplified in the tested samples. The Wolbachia sp. was accidentally found in I. elongatus. The phylogenetic analysis of four Bartonella genes (16S-23S rRNA ITS, gltA, rpoB, and groEL) revealed specificity to bats or bats’ ectoparasites. This is the first report about bat flea species and the pathogens in bat fleas in Lithuania. New host records for bat fleas were also reported. This study extends the knowledge about bat fleas and their role as vectors of different pathogens.

Genetic Diversity of Trypanosomes Infesting Cattle from Savannah District in North of Côte d'Ivoire Using Conserved Genomic Signatures: rRNA, ITS1 and gGAPDH.

The potential danger to livestock from African animal trypanosomiasis is well known. However, the trypanosome species circulating in cattle and their genetics are poorly understood. After different alignments according to three regions (ITS1, gGAPDH and rRNA gene) of the trypanosome genome, phylogenetic analyses were used to show the genetic diversity of the different species that were circulating in the cattle in three regions (Bagoue, Poro and Tchologo) of Côte d'Ivoire. These analyses were performed by alignment of ITS1; by alignment of partial 18S, ITS1, 5.8S, ITS2 and partial 28S rRNA genes; and by alignment of gGAPDH gene with sequences of Trypanosomes found in GenBank. Three species were identified (T. vivax, T. theileri and T. congolense) in the cattle in the three northern regions of Côte d'Ivoire. T. vivax and T. theileri were the most abundant species in the present study. Contrary to the other primers used in this study, the ITS1 primers were not able to amplify T. theileri. We observed mixed infections between T. theileri and the other two species identified (T. vivax and T. congolense). As far as primers are concerned, in some cases, rRNA was able to identify the same species of trypanosomes that the ITS1 and gGAPDH primers were able to identify. Two main distinct groups of T. theileri complex were identified. The T. congolense and T. vivax strains were close to African strains, such as those from Kenya, Nigeria and Cameroon, unlike the T. theileri strain. Three trypanosome species (T. vivax, T. theileri and T. congolense) circulate in cattle in the Savannah district of Côte d'Ivoire. The genetic diversity of the trypanosome species encountered in this study cannot be classified as intraspecies according to geographical area and breed of cattle they infect.

Terrestrial predatory leeches of the genus Orobdella (Hirudinea: Erpobdelliformes: Orobdellidae) endemic to the Southern Russian Far East: a new species of the genus from Primorsky Krai, Russia.

A quadrannulate species, Orobdella ganini sp. nov., is described from the Lazovsky Nature Reserve in Primorsky Krai, the Southern Russian Far East, Russia. Morphological features of O. ghilarovi Nakano & Prozorova, 2019 from the reserve are also provided leading to an amendment of the species diagnosis. Maximum likelihood and Bayesian inference phylogenetic analyses, which were performed using nuclear 18S rRNA, 28S rRNA, and histone H3, and mitochondrial cytochrome c oxidase subunit I, tRNACys, tRNAMet, 12S rRNA, tRNAVal, 16S rRNA, tRNALeu and NADH dehydrogenase subunit 1 markers, show that O. ganini sp. nov., O. ghilarovi and two species endemic to Hokkaido, Japan form a clade, with the new species sister to a lineage composed of the two Japanese species. A partial cytochrome c oxidase subunit I sequence obtained from a cocoon found in the Lazovsky Nature Reserve reveals that Orobdella leeches deposit cocoons somewhat similar to those deposited by terrestrial blood-sucking leeches of Haemadipsidae.

Revealing the Diversity of Thin Filamentous Cyanobacteria, with the Discovery of a Novel Species, Pegethrix qiandaoensis sp. nov. (Oculatellaceae, Oculatellales), in a Freshwater Lake in China

During the study of diversity in filamentous cyanobacteria in China, two strains (WZU0719 and WZU0723) with the form of thin filaments were isolated from the surface of Qiandao Lake, a large freshwater lake in Zhejiang Province, China. A comprehensive analysis was conducted, incorporating morphological, ecological, and molecular data. The morphological examination provided an initial identification as a Leptolyngbya-like cyanobacterium. Genetic characterization was also performed by amplifying the 16S rRNA gene and the 16S-23S rRNA internal transcribed spacer (ITS) region. The phylogenetic grouping based on the 16S rRNA gene demonstrates that the examined strain is unequivocally assigned to the Pegethrix genus. However, it possesses distinct phylogenetic divergence from the six described Pegethrix species. Additionally, discrepancies in habitat further differentiate it from other members of this genus. Employing the polyphasic approach, we present a comprehensive account of the newly discovered taxa: Pegethrix qiandaoensis sp. nov. The novel taxonomic finding in this research significantly contributes to enhancing the comprehension of Pegethrix diversity across various habitats.

Metabolomic and taxonomic characterization of Haloleptolyngbya lusitanica sp. nov. (Cyanobacteria, Synechococcales)

ABSTRACT The morphological plasticity of cyanobacteria and their widespread ecological dominance in a wide range of habitats highlights the need for in-depth taxonomic studies. This work focused on the taxonomical revision of Leptolyngbya (Cyanophyceae) strains deposited in the ESSACC culture collection and their metabolomic characterization. Although the studied ESSACC strains were morphologically identified as Leptolyngbya sp., the 16S rRNA gene and 16S–23S rRNA ITS analysis revealed that two strains (LMECYA 079 and LMECYA 173) belong to Haloleptolyngbya and represent a new taxonomical unit, genetically unique, ecologically plastic and adapted to both freshwater and thermal habitats, here described as Haloleptolyngbya lusitanica sp. nov. To perform a suspect screening of cyanometabolites in these strains, we used a non-targeted liquid chromatography-high resolution mass spectrometry (LC-HRMS) metabolomic approach. Several metabolites were identified in Haloleptolyngbya lusitanica: micropeptin MM978, spumigin 640, oscillatoxin A and anabaenopeptin D. Strains were maintained and grown under the same conditions, revealing the common production of oscillatoxin A by both H. lusitanica strains. Other identified metabolites, however, were strain-specific, such as anabaenoptin D, which was only detected in LMECYA 173. The different cyanometabolite profiles reinforce the notion that cyanobacteria have the ability to adapt to different habitats, which is maintained under long-term culturing conditions.