Comparative Genomics and Physiological Investigation of a New Arthrospira/Limnospira Strain O9.13F Isolated from an Alkaline, Winter Freezing, Siberian Lake.

Cyanobacteria from the genus Arthrospira/Limnospira are considered haloalkalotolerant organisms with optimal growth temperatures around 35 °C. They are most abundant in soda lakes in tropical and subtropical regions. Here, we report the comprehensive genome-based characterisation and physiological investigation of the new strain O9.13F that was isolated in a temperate climate zone from the winter freezing Solenoye Lake in Western Siberia. Based on genomic analyses, the Siberian strain belongs to the Arthrospira/Limnospira genus. The described strain O9.13F showed the highest relative growth index upon cultivation at 20 °C, lower than the temperature 35 °C reported as optimal for the Arthrospira/Limnospira strains. We assessed the composition of fatty acids, proteins and photosynthetic pigments in the biomass of strain O9.13F grown at different temperatures, showing its potential suitability for cultivation in a temperate climate zone. We observed a decrease of gamma-linolenic acid favouring palmitic acid in the case of strain O9.13F compared to tropical strains. Comparative genomics showed no unique genes had been found for the Siberian strain related to its tolerance to low temperatures. In addition, this strain does not possess a different set of genes associated with the salinity stress response from those typically found in tropical strains. We confirmed the absence of plasmids and functional prophage sequences. The genome consists of a 4.94 Mbp with a GC% of 44.47% and 5355 encoded proteins. The Arthrospira/Limnospira strain O9.13F presented in this work is the first representative of a new clade III based on the 16S rRNA gene, for which a genomic sequence is available in public databases (PKGD00000000).

Arthrospiribacter ruber gen. nov., sp. nov., a novel bacterium isolated from Arthrospira cultures.

Polyphasic analysis of ten isolates of the red-pigmented bacteria isolated from ten Arthrospira cultures originating from different parts of the world is described. The 16S rRNA analysis showed <95 % identity with the known bacteria on public databases, therefore, additional analyses of fatty acids profiles, MALDI-TOF/MS, genome sequencing of the chosen isolate and following phylogenomic analyses were performed. Gram-stain-negative, strictly aerobic rods were positive for catalase, negative for oxidase, proteolytic and urease activity. Major fatty acids were 15 : 0 iso, 17:0 iso 3 OH and 17:1 iso w9c/16:0 10-methyl. The whole phylogenomic analyses revealed that the genomic sequence of newly isolated strain DPMB0001 was most closely related to members of Cyclobacteriaceae family and clearly indicated distinctiveness of newly isolated bacteria. The average nucleotide identity and in silico DNA-DNA hybridisation values were calculated between representative of the novel strains DPMB0001 and its phylogenetically closest species, Indibacter alkaliphilus CCUG57479 (LW1)T (ANI 69.2 % is DDH 17.2 %) and Mariniradius saccharolyticus AK6T (ANI 80.02 % isDDH 26.1 %), and were significantly below the established cut-off <94 % (ANI) and <70 % (isDDH) for species and genus delineation. The obtained results showed that the analysed isolates represent novel genus and species, for which names Arthrospiribacter gen nov. and Arthrospiribacter ruber sp. nov. (type strain DPMB0001=LMG 31078=PCM 3008) is proposed.

Pectobacterium polonicum sp. nov. isolated from vegetable fields.

Gram-stain-negative, rod-shaped pectinolytic bacteria strains designated as DPMP315T, DPMP316, DPMP317 and DPMP318 isolated from groundwater sampled from a vegetable field in the North of Poland, were subjected to the polyphasic analyses. Multilocus sequence analyses based on five housekeeping genes (gyrA, recA, recN, rpoA and rpoS) revealed their distinctiveness from the other species of the genus, simultaneously indicating that the newly described species, Pectobacterium punjabense, as well as Pectobacterium parmentieri and P. wasabiae, to be the closest relatives. In silico DNA-DNA hybridization (<43.1 %) and average nucleotide identity (<92.5 %) values of strain DPMP315T with other type strains of species of the genus Pectobacterium supported the delineation of the novel strain as representing a novel species. The phenotypic comparisons, fatty acid methyl esters compositions, genetic rep PCR fingerprint and detailed whole-cell MALDI-TOF mass spectrometry proteomic profiles permitted the differentiation of Polish strains from the type strains of all other known species of the genus Pectobacterium. The results of polyphasic analyses performed for four Polish strains are the basis for the distinction of the novel species. Here, we propose to establish DPMP315T as a type strain (=PCM3006T=LMG 31077T) with the name Pectobacterium polonicum sp. nov.

Edible Cyanobacterial Genus Arthrospira: Actual State of the Art in Cultivation Methods, Genetics, and Application in Medicine.

The cyanobacterial genus Arthrospira appears very conserved and has been divided into five main genetic clusters on the basis of molecular taxonomy markers. Genetic studies of seven Arthrospira strains, including genome sequencing, have enabled a better understanding of those photosynthetic prokaryotes. Even though genetic manipulations have not yet been performed with success, many genomic and proteomic features such as stress adaptation, nitrogen fixation, or biofuel production have been characterized. Many of above-mentioned studies aimed to optimize the cultivation conditions. Factors like the light intensity and quality, the nitrogen source, or different modes of growth (auto-, hetero-, or mixotrophic) have been studied in detail. The scaling-up of the biomass production using photobioreactors, either closed or open, was also investigated to increase the production of useful compounds. The richness of nutrients contained in the genus Arthrospira can be used for promising applications in the biomedical domain. Ingredients such as the calcium spirulan, immulina, C-phycocyanin, and γ-linolenic acid (GLA) show a strong biological activity. Recently, its use in the fight against cancer cells was documented in many publications. The health-promoting action of "Spirulina" has been demonstrated in the case of cardiovascular diseases and age-related conditions. Some compounds also have potent immunomodulatory properties, promoting the growth of beneficial gut microflora, acting as antimicrobial and antiviral. Products derived from Arthrospira were shown to successfully replace biomaterial scaffolds in regenerative medicine. Supplementation with the cyanobacterium also improves the health of livestock and quality of the products of animal origin. They were also used in cosmetic preparations.