Blastococcus carthaginiensis sp. nov., isolated from a monument sampled in Carthage, Tunisia

Abstract

A comprehensive polyphasic investigation was conducted to elucidate the taxonomic position of an actinobacterium, designated BMG 814T, which was isolated from the historic ruins of Carthage city in Tunisia. It grew as pink-orange pigmented colonies and displayed versatile growth capabilities, thriving within a temperature range of 20–40 °C, across a pH spectrum ranging from pH 5.5 to 10 and in the presence of up to 4 % NaCl. Chemotaxonomic investigations unveiled specific cell components, including diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, glycophosphatidylinositol, an unidentified aminoglycophospholipid, six unidentified aminolipids, two unidentified phospholipids and one unidentified lipid in its polar lipid profile. Furthermore, galactose, glucose and ribose were identified as the primary cell-wall sugars. Major menaquinones identified were MK-9(H4), MK-9(H2) and MK-9, while major fatty acids comprised iso-C15 : 0, iso-C16 : 0, C17 : 1 ω8c and C18 : 1 ω9c. Through phylogenetic analysis based on the 16S rRNA gene sequence, the strain was positioned within the genus Blastococcus , with Blastococcus capsiensis BMG 804T showing the closest relationship (99.1 %). In light of this, draft genomes for both strains, BMG 814T and BMG 804T, were sequenced in this study, and comparative analysis revealed that strain BMG 814T exhibited digital DNA–DNA hybridization and average nucleotide identity values below the recommended thresholds for demarcating new species with all available genomes of type strains of validly names species. Based on the polyphasic taxonomy assessment, strain BMG 814T (=DSM 46848T=CECT 8878T) was proposed as the type strain of a novel species named Blastococcus carthaginiensis sp. nov.

Blastococcus brunescens sp. nov., a member of the Geodermatophilaceae isolated from sandstone collected from the Sahara Desert in Tunisia

“…The colonies exhibited a pink-orange hue on GYM Streptomyces , showcasing irregularities with a dry surface. A diffusible pink pigment was observed on medium 5322 (ISP7), while a distinctive brown pigment was observed on medium 5006, a characteristic not reported for other Blastococcus type strains [2–10] (Fig. S1A, available in the online version of this article).…”

“…Blastococcus species have been identified as key components in soils facing diverse challenges, including dryness [2][3][4][5][6][7][8][9][10][11], salinity [43], alkalinity [44], exposure to toxins [45], and notably, heavy metal contamination [46][47][48][49][50]. Consequently, the distribution of genes associated with stress response, antibiotic resistance, as well as resistance to heavy metals and toxic compounds, were evaluated within these genomes.…”

“…While their ecological roles in these demanding conditions are still being unravelled, this recognition underscores their potential as valuable assets with significant biotechnological applications. These potential applications encompass various roles such as bioremediation, bioleaching, agriculture, enzyme production, and the generation of bioactive molecules [7,11].…”

“…The genus Blastococcus [1] encompasses 15 species with validly published names sourced from diverse environments. Blastococcus species have been identified in habitats as varied as the seawater of the Baltic Sea ( Blastococcus aggregatus [1]), monument samples (including Blastococcus saxobsidens [2], Blastococcus capsensis [3], Blastococcus colisei [4], Blastococcus xanthinilyticus [5], Blastococcus tunisiensis [6], and Blastococcus carthaginensis [7]), as well as desert soils and sands (with representatives such as Blastococcus aurantiacus [8], Blastococcus haudaquaticus [8], Blastococcus mobilis [8], Blastococcus atacamensis [9], and Blastococcus deserti [10]). While their ecological roles in these demanding conditions are still being unravelled, this recognition underscores their potential as valuable assets with significant biotechnological applications.…”