Daniel Guzmán

The strain Limnospira platensis LEGE 231238, isolated from the saline Alalay Lake in Bolivia, was identified through a polyphasic approach. The biochemical characterization revealed that the dry biomass presented (% of dry weight) protein (45.40 ± 0.54), carbohydrates (27.84 ± 0.25), ash (19.90 ± 0.32), lipids (6.86 ± 0.18), and C:N ratio (5.54 ± 0.17). Lipid extracts revealed 46.23 ± 0.60% polyunsaturated fatty acids (FA), 41.24 ± 0.72% saturated FA, with palmitic acid (FA 16:0) accounting for 39.05 ± 0.66% and γ-linolenic acid (FA 18:3 n–6) for 31.32 ± 0.30%. Nutritional quality indices included atherogenic (0.75 ± 0.03%), thrombogenic (1.32 ± 0.04%), and hypocholesterolemic/hypercholesterolemic index (0.45 ± 0.03%). Acetonic extracts contained 78.66% chlorophyll-a, 16.18% total carotenes, and 5.11% xanthophylls. The aqueous extract showed the following contents (µg mg⁻¹): phenolics with 15.64 ± 1.76 as gallic acid equivalents, sugars with 7.19 ± 0.75 of glucose equivalents, chlorophyll-a with 5.84 ± 1.87 mg g⁻¹ of dry extract, and total chlorophylls with 10.02 ± 2.06 mg g⁻¹ of dry extract. Phycobiliprotein content revealed concentrations of phycocyanin, allophycocyanin, and phycoerythrin at 84.88 ± 8.29, 53.11 ± 6.21, and 20.25 ± 3.12 µg mg⁻¹ of dry extract, respectively. The nutritional profile of LEGE 231238 is comparable to that of other Spirulina strains currently available on the market, supporting its suitability as a food supplement. This work represents the first published report of an L. platensis isolate from Bolivia and underscores its strong potential for commercial exploitation.

This article describes a new genus and species of cyanobacteria isolated from Laguna Pastos Grandes in the Bolivian Altiplano. This discovery marks the first described species of this phylum from this extreme environment. Additionally, the phylogenetic status of the genus Capilliphycus is reassessed. The analyses are based on 16S rRNA gene maximum likelihood and Bayesian phylogenies, identity (p-distance), morphology and habitat comparisons. The new genus is a Lyngbya-like type from a mat at the margin of a brackish–alkaline lake with borax. It is phylogenetically close to Dapis, Tenebriella and Okeania, but compared to these genera, the maximum 16S rRNA gene identity values reached only 90.9%, 91.1% and 92.5%, respectively. The genus Capilliphycus was found to be polyphyletic. The type species Capilliphycus salinus is clustered with C. guerandensis. However, “C. tropicalis” and “C. flaviceps” form a distinct clade, distant from the Capilliphycus type species. Between the two “Capilliphycus” clades, Sirenicapillaria and Limnoraphis are found.

Ultraviolet (UV) radiation responses of extremophilic and archaeal microorganisms are of interest from evolutionary, physiological, and astrobiological perspectives. Previous studies determined that the halophilic archaeon, Halobacterium sp. NRC-1, which survives in multiple extremes, is highly tolerant of UV radiation. Here, Halobacterium sp. NRC-1 UV tolerance was compared to taxonomically diverse Haloarchaea isolated from high-elevation salt flats, surface warm and cold hypersaline lakes, and subsurface Permian halite deposits. Haloterrigena/Natrinema spp. from subsurface halite deposits were the least tolerant after exposure to photoreactivating light. This finding was attributed to deviation of amino acid residues in key positions in the DNA photolyase enzyme or to the complete absence of the photolyase gene. Several Halobacterium, Halorubrum and Salarchaeum species from surface environments exposed to high solar irradiance were found to be the most UV tolerant, and Halorubrum lacusprofundi from lake sediment was of intermediate character. These results indicate that high UV tolerance is not a uniform character trait of Haloarchaea and is likely reflective of UV exposure experienced in their environment. This is the first report correlating natural UV tolerance to photolyase gene functionality among Haloarchaea and provides insights into their survival in ancient halite deposits and potentially on the surface of Mars.

Salar de Uyuni is a vast, high-altitude salt flat in Bolivia with extreme physico-geochemical properties approaching multiple limits of life. Evidence for diverse halophilic bacteria and archaea was found in its surface and near-surface salt crust using 16S amplicon analysis, providing a snapshot of prokaryotic life.

Two extremely halophilic archaea, namely, Natrinema versiforme BOL5-4 and Natrinema pallidum BOL6-1, were isolated from a Bolivian salt mine and their genomes sequenced using single-molecule real-time sequencing. The GC-rich genomes of BOL5-4 and BOL6-1 were 4.6 and 3.8 Mbp, respectively, with large chromosomes and multiple megaplasmids. Genome annotation was incorporated into HaloWeb and methylation patterns incorporated into REBASE.

Halorubrum sp. strain BOL3-1 was isolated from Salar de Uyuni, Bolivia, and sequenced using single-molecule real-time sequencing. Its 3.7-Mbp genome was analyzed for gene content and methylation patterns and incorporated into the Haloarchaeal Genomes Database ( http://halo.umbc.edu ).

A Gram-stain-positive, coccoid-shaped, halophilic bacterium, strain SR-1^T, was isolated from a salt crystal obtained from a mine located in Tarija, Bolivia. The strain was investigated using a polyphasic approach. The optimum conditions for growth of strain SR-1^T were reached at 5 % (w/v) NaCl, pH 7.6 and 37–40 °C. The peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. The isoprenoid quinone was MK-7. The major cellular fatty acids of strain SR-1^T were anteiso-C_15 : 0, anteiso-C_17 : 0 and iso-C_16 : 0. The DNA G+C content of strain SR-1^T was 48.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed a close relationship between strain SR-1^T and Marinococcus halophilus JCM 2479^T (99.7 % 16S rRNA gene sequence similarity), Marinococcus halotolerans KCTC 19045^T (99.4 %) and Marinococcus luteus KCTC 13214^T (99.8 %). However, strain SR-1^T also showed low levels of DNA–DNA relatedness with these reference strains (47, 61 and 58 %, respectively). On the basis of phenotypic differences and DNA–DNA hybridization results, strain SR-1^T is considered to represent a novel species of the genus Marinococcus , for which the name Marinococcus tarijensis sp. nov. is proposed. The type strain is SR-1^T ( = LMG 26930^T = CECT 8130^T).

Background: Halomonas boliviensis is a halophilic bacterium that is included in the γ-Proteobacteria sub-group, and is able to assimilate different types of carbohydrates. H. boliviensis is also able to produce poly(3-hydroxybutyrate) (PHB) in high yields using glucose as the carbon precursor. Accumulation of PHB by microorganisms is induced by excess of intracellular NADH. The genome sequences and organization in microorganisms should be the result of evolution and adaptation influenced by mutation, gene duplication, horizontal gen transfer (HGT) and recombination. Furthermore, the nearly neutral theory of evolution sustains that genetic modification of DNA could be neutral or selected, albeit most mutations should be at the border between neutrality and selection, i.e. slightly deleterious base substitutions in DNA are followed by a slightly advantageous substitutions. Results: This article reports the genome sequence of H. boliviensis. The chromosome size of H. boliviensis was 4 119 979 bp, and contained 3 863 genes. A total of 160 genes of H. boliviensis were related to carbohydrate transport and metabolism, and were organized as: 70 genes for metabolism of carbohydrates; 47 genes for ABC transport systems and 43 genes for TRAP-type C4-dicarboxylate transport systems. Protein sequences of H. boliviensis related to carbohydrate transport and metabolism were selected from clusters of orthologous proteins (COGs). Similar proteins derived from the genome sequences of other 41 archaea and 59 bacteria were used as reference. We found that most of the 160 genes in H. boliviensis, c.a. 44%, were obtained from other bacteria by horizontal gene transfer, while 13% of the genes were acquired from haloarchaea and thermophilic archaea, only 34% of the genes evolved among Proteobacteria and the remaining genes encoded proteins that did not cluster with any of the proteins obtained from the reference strains. Furthermore, the diversity of the enzymes derived from these genes led to polymorphism in glycolysis and gluconeogenesis. We found further that an optimum ratio of glucose and sucrose in the culture medium of H. boliviensis favored cell growth and PHB production. Conclusions: Results obtained in this article depict that most genetic modifications and enzyme polymorphism in the genome of H. boliviensis were mainly influenced by HGT rather than nearly neutral mutations. Molecular adaptation and evolution experienced by H. boliviensis were also a response to environmental conditions such as the type and amount of carbohydrates in its ecological niche. Consequently, the genome evolution of H. boliviensis showed to be strongly influenced by the type of microorganisms, genetic interaction among microbial species and its environment. Such trend should also be experienced by other prokaryotes. A system for PHB production by H. boliviensis that takes into account the evolutionary adaptation of this bacterium to the assimilation of combinations of carbohydrates suggests the feasibility of a bioprocess economically viable and environmentally friendly.

Scaffolds made from poly(3-hydroxybutyrate) were prepared by thermally induced phase separation from solutions in dioxane at temperatures above (23°C) or below the freezing point of the solvent. At 23°C, gelation occured with nano-fibrous network formation. The scaffolds prepared at —12°C and —25°C exhibited a highly porous morphology, with pores in the range of 3—25 μm, caused by freezing of dioxane. The macroporous scaffolds, prepared at —12°C, were treated with lipase to generate functional groups to which gelatin and glucosamine, respectively, were chemically coupled. The modified scaffolds had lower molecular weight, higher water content, lower melting temperature, and enthalpy. Cultivation of human embryonic fibroblasts on the macroporous scaffolds confirmed that the cells proliferated and adhered to the materials.