Blastococcus tunisiensis sp. nov., isolated from limestone collected in Tunisia.

A new actinobacterium strain, designated BMG 823T, was isolated from a limestone sample collected in Tunisia. Its taxonomic position was scrutinized using a polyphasic approach. Colonies of strain BMG 823T were pink orange-coloured, regular and had a moist surface. Cells are Gram-stain-positive, catalase-negative and oxidase-negative. The strain grew at pH 5.5-9, 10-40 °C and in presence of up to 4 % NaCl (w/v). Chemotaxonomically, strain BMG 823T was characterized by cell-wall type III containing meso-diaminopimelic acid as diamino acid, glucose, ribose and rhamnose as whole-cell sugars, MK-9(H4) as predominant menaquinone, and phosphatidylcholine, diphosphadidylglycerol, phosphatidethanolamine, phosphatidylcholine, phosphatidylinositol, unidentified glycolipid, unidentified aminophospholipids and unidentified glycophospholipid as major polar lipids. The fatty acid profile consisted of iso-C16 : 0 and iso-C17 : 1 ω9. Phylogenetic trees based on 16S rRNA gene and genome sequences placed strain BMG 823T within the genus Blastococcus and separated it from all type strains of validly published species. Comparison of 16S rRNA gene sequence similarity, digital DNA-DNA hybridization and average nucleotide identity indicated that strain BMG 823T was most closely related to Blastococcus litoris DSM 106127T and Blastococcus colisei BMG 822T with pairwise values well below the species differentiation thresholds. The distinct phenotypic and genotypic features of strain BMG 823T (=DSM 46838T=CECT 8881T) within the genus Blastococcus warrant its recognition as the type strain for the new species for which we propose the name Blastococcus tunisiensis sp. nov.

Elucidating the ecological networks in stone-dwelling microbiomes.

Stone surfaces are extreme environments that support microbial life. This microbial growth occurs despite unfavourable conditions associated with stone including limited sources of nutrients and water, high pH and exposure to extreme variations in temperature, humidity and irradiation. These stone-dwelling microbes are often resistant to extreme environments including exposure to desiccation, heavy metals, UV and Gamma irradiation. Here, we report on the effects of climate and stone geochemistry on microbiomes of Roman stone ruins in North Africa. Stone microbiomes were dominated by Actinobacteria, Cyanobacteria and Proteobacteria but were heavily impacted by climate variables that influenced water availability. Stone geochemistry also influenced community diversity, particularly through biologically available P, Mn and Zn. Functions associated with photosynthesis and UV protection were enriched in the metagenomes, indicating the significance of these functions for community survival on stones. Core members of the stone microbial communities were also identified and included Geodermatophilaceae, Rubrobacter, Sphingomonas and others. Our research has helped to expand the understanding of stone microbial community structure and functional capacity within the context of varying climates, geochemical properties and stone conditions.

Blastococcus capsensis sp. nov., isolated from an archaeological Roman pool and emended description of the genus Blastococcus, B. aggregatus, B. saxobsidens, B. jejuensis and B. endophyticus.

A novel Gram-reaction-positive actinobacterium, designated BMG 804T, was isolated from an archaeological Roman pool located in Gafsa, Tunisia. The strain grew as dry bright orange colonies at 30 °C and pH 6.0-8.0. It contained meso-diaminopimelic acid in the cell wall. The whole-cell sugars consisted of glucose, rhamnose and ribose. Polar lipids present were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, an unidentified glycolipid and two unidentified phospholipids. MK-9(H4) was the predominant menaquinone. The fatty acid profile contained major amounts (>5 %) of C17 : 1ω8c, C16 : 1ω7c, iso-C15 : 0, iso-C16 : 0 and iso-C16 : 1H. The 16S rRNA gene sequence of BMG 804T showed 99.4 % as highest sequence similarity with Blastococcussaxobsidens. DNA-DNA hybridization between strain BMG 804T and B.saxobsidens DSM 44509T was 48.6±6.6 %. The G+C content of the DNA was 73.7 mol%. On the basis of the phenotypic and genotypic characteristics, including DNA-DNA hybridization results, BMG 804T (=DSM 46835T=CECT 8876T) is proposed as the type strain of a novel species Blastococcuscapsensis sp. nov. Emended descriptions of the genus Blastococcus and the species Blastococcus aggregatus, B. saxobsidens, Blastococcus jejuensis and Blastococcus endophyticus are also proposed.

Root Nodule Microsymbionts of Native Coriaria myrtifolia in Algeria.

Coriaria myrtifolia occurs as natural flora of warm temperate climates of northern Algeria which commonly found in hedges, forest and ravine edges. This actinorhizal species was known to establish a mutualistic symbiosis with members of phylogenetic cluster 2 (including strains associated to Coriaria spp., Ceanothus, Datiscaceae, and Dryadoideae) within the genus Frankia. Attempts to isolate C. myrtifolia microsymbionts from native plants growing in 4 locations in Algeria permitted to only recover asymbiotic Frankia strains (unable to reestablish nodulation and to fix nitrogen) from phylogenetic cluster 4 and several non-Frankia actinobacteria including members of Micrococcus, Micromonospora, Nocardia, Plantactinospora, and Streptomyces genera. The biodiversity of Frankia microsymbionts of C. myrtifolia root nodules was assessed using PCR-amplification followed by partial nucleotide sequencing of glnA1 (glutamine synthetase type 1) gene. On the 12 different glnA1 gene sequences obtained in this study, 9 were detected for the first time, and were mainly closelyrelated to Mediterranean genotypes previously described in the Grand Maghreb countries (Morocco and Tunisia) and in Europe (France) but without clear separations from other cluster 2 genotypes.

Permanent Improved High-Quality Draft Genome Sequence of Nocardia casuarinae Strain BMG51109, an Endophyte of Actinorhizal Root Nodules of Casuarina glauca.

Here, we report the first genome sequence of a Nocardia plant endophyte, N. casuarinae strain BMG51109, isolated from Casuarina glauca root nodules. The improved high-quality draft genome sequence contains 8,787,999 bp with a 68.90% GC content and 7,307 predicted protein-coding genes.

Permanent Draft Genome Sequence of Nocardia sp. BMG111209, an Actinobacterium Isolated from Nodules of Casuarina glauca.

Nocardia sp. strain BMG111209 is a non-Frankia actinobacterium isolated from root nodules of Casuarina glauca in Tunisia. Here, we report the 9.1-Mbp draft genome sequence of Nocardia sp. strain BMG111209 with a G + C content of 69.19% and 8,122 candidate protein-encoding genes.