Search Results (7)

As belonging to one of the most isolated continents on our planet, the microbial composition of different environments in Antarctica could hold a plethora of undiscovered species with the potential for biotechnological applications. This manuscript delineates our discoveries after an expedition to the Bulgarian Antarctic Base “St. Kliment Ohridski” situated on Livingston Island, Antarctica. Amplicon-based metagenomics targeting the 16S rRNA genes and ITS2 region were employed to assess the metagenomes of the bacterial, fungal, and archaeal communities across diverse sites within and proximal to the research station. The predominant bacterial assemblages identified included Oxyphotobacteria, Bacteroidia, Gammaprotobacteria, and Alphaprotobacteria. A substantial proportion of cyanobacteria reads were attributed to a singular uncultured taxon within the family Leptolyngbyaceae. The bacterial profile of a lagoon near the base exhibited indications of penguin activity, characterized by a higher abundance of Clostridia, similar to lithotelm samples from Hannah Pt. Although most fungal reads in the samples could not be identified at the species level, noteworthy genera, namely Betamyces and Tetracladium, were identified. Archaeal abundance was negligible, with prevalent groups including Woesearchaeales, Nitrosarchaeum, Candidatus Nitrosopumilus, and Marine Group II. Full article

Cyanobacteria can cope with various environmental stressors, due to the excretion of exopolysaccharides (EPS). However, little is known about how the composition of these polymers may change according to water availability. This work aimed at characterizing the EPS of Phormidium ambiguum (Oscillatoriales; Oscillatoriaceae) and Leptolyngbya ohadii (Pseudanabaenales; Leptolyngbyaceae), when grown as biocrusts and biofilms, subject to water deprivation. The following EPS fractions were quantified and characterized: soluble (loosely bound, LB) and condensed (tightly bound, TB) for biocrusts, released (RPS), and sheathed in P. ambiguum and glycocalyx (G-EPS) in L. ohadii for biofilms. For both cyanobacteria upon water deprivation, glucose was the main monosaccharide present and the amount of TB-EPS resulted was significantly higher, confirming its importance in these soil-based formations. Different profiles of monosaccharides composing the EPSs were observed, as for example the higher concentration of deoxysugars observed in biocrusts compared to biofilms, demonstrating the plasticity of the cells to modify EPS composition as a response to different stresses. For both cyanobacteria, both in biofilms and biocrusts, water deprivation induced the production of simpler carbohydrates, with an increased dominance index of the composing monosaccharides. The results obtained are useful in understanding how these very relevant cyanobacterial species are sensitively modifying the EPS secreted when subject to water deprivation and could lead to consider them as suitable inoculants in degraded soils. Full article

A novel cyanobacterial strain (CSML-F035) here described as Stenomitos nagquensis sp. nov. was isolated from a plateau meadow wetland habitat in the Tibet Autonomous Region. The novel strain was studied based on a polyphasic approach by combining characteristics of cell morphology and evidence from molecular data and ecology. Phylogenetic analyses based on the 16S rRNA and rbcL genes indicated that the novel strain is a member of the genus Stenomitos (Leptolyngbyaceae) but is positioned in a unique clade, with strongly supported values from BI, ML, and NJ methods. The percentage similarity of the 16S rRNA gene sequence of CSML-F035 compared with known strains of Stenomitos was >97%. Morphologically, S. nagquensis sp. nov. possesses overlapping morphological characteristics with other Stenomitos species, with thin trichomes enclosed in a firm, colorless, hyaline, persistent mucilage. However, the strain appeared to have slightly smaller cells compared to most known species of Stenomitos. Further analyses of the 16S–23S ITS region showed dissimilarity at 11.2–22.8% compared to known species of Stenomitos. The secondary helices—including D1–D1, V2, Box–B, and V3—that were predicted based on the 16S–23S ITS region for Stenomitos nagquensis sp. nov. were also distinct, thereby providing strong additional support for the separation of this species. This study highlights the importance of unexplored habitats in the Tibet region in which cyanobacterial diversity can be deemed high, with many potential new species that remain poorly explored. Full article

The strains of Drouetiella species (Cyanobacteria, Oculatellaceae) from a terrestrial biotope were isolated and characterized using an integrative approach including molecular, morphological, and ecological information. The specimens were collected from the Arctic and Subarctic areas of European Russia. Drouetiella species possess morphological plasticity and can be confused with similar species of Oculatellaceae or Leptolyngbyaceae. The 16S rRNA gene phylogeny supported the strong monophyly of the genus Drouetiella with the separation of four linages corresponding to three known species and one to new taxon. The 16S-23S ITS rRNA sequences of the analyzed Drouetiella strains differ in length and nucleotide composition, which has had an effect on the hypothetical secondary structures of the D1–D1′, Box-B, V2, and V3 helices. As a result of complex study of the genus Drouetiella, a new species—Drouetiella ramosa sp. nov.—is described from the Subarctic of European Russia. Full article

Thin filamentous cyanobacteria isolated from three collection sites in the Republic of Korea were suggested as three new species belonging to the genus Plectolyngbya, mainly according to their molecular characteristics. The species of Plectolyngbya, including the type species of P. hodgsonii, were cryptic species that were difficult to distinguish morphologically from each other, and had appeared in ecologically diverse habitats. P. terrestris and P. koreana were subaerophytes collected from certain black spots and soils between stone walls in Seoul, Republic of Korea. In addition, hypersaline species collected from a saltern, P. salina, shared the same halophytic feature as the P. hodgsonii from the littoral zone of a coastal lake in the Antarctic. The 16S rRNA gene phylogeny supported the monophyly of Plectolyngbya with solid support, 99% Maximum Likelihood, 98% Neighbor-Joining bootstrap support values, and 1.0 Bayesian posterior probability. The ITS sequences of P. terrestris, P. koreana, and P. salina were unique in length and nucleotide composition, with different secondary structures of D1–D1ʹ and Box-B helices, compared with those of P. hodgsonii. These results demonstrate that the proposed new Plectolyngbya species were unique in their molecular traits. Therefore, we suggest them as new species belonging to the genus Plectolyngbya with the names P. terrestris sp. nov., P. koreana sp. nov., and P. salina sp. nov. Full article

Cyanobacteria are crucial components of biological soil crusts of polar landscapes and carry out many functions in subaerial environments. Simple untapered filamentous cyanobacteria are typically in the terrestrial biotopes. They appear to be a group with an abundance of cryptic taxa. We isolated 23 strains of cyanobacteria from the different habitats of the Arctic and temperate zone, from 10 locations in order to characterize their morphological and genotypic diversity. Phylogenetic analyses were conducted on the 16S and 16S–23S ITS rRNA gene regions using Bayesian inference and maximum likelihood. A morphological comparison of the isolated strains with similar known species, as well as its phylogenetic analyses, revealed that they belong to three species of the genus Phormidesmis (P. nigrescens, P. pristley, and P. communis)—and to the previously unknown genus of Leptolyngbyaceae. Using an integrative approach, we provide here a description of a new taxon Apatinema gen. nov. Full article

(1) Background: Microbial communities in terrestrial, calcifying high-alkaline springs are not well understood. In this study, we investigate the structure and composition of microbial mats in ultrabasic (pH 10–12) serpentinite springs of the Voltri Massif (Italy). (2) Methods: Along with analysis of chemical and mineralogical parameters, environmental DNA was extracted and subjected to analysis of microbial communities based upon next-generation sequencing. (3) Results: Mineral precipitation and microbialite formation occurred, along with mat formation. Analysis of the serpentinite spring microbial community, based on Illumina sequencing of 16S rRNA amplicons, point to the relevance of alkaliphilic cyanobacteria, colonizing carbonate buildups. Cyanobacterial groups accounted for up to 45% of all retrieved sequences; 3–4 taxa were dominant, belonging to the filamentous groups of Leptolyngbyaceae, Oscillatoriales, and Pseudanabaenaceae. The cyanobacterial community found at these sites is clearly distinct from creek water sediment, highlighting their specific adaptation to these environments. Full article