A Novel Fatty Acid, 12,17-Dimethyloctadecanoic Acid, from the Extremophile Thermogemmatispora sp. (Strain T81)

Reticulibacter mediterranei gen. nov., sp. nov., within the new family Reticulibacteraceae fam. nov., and Ktedonospora formicarum gen. nov., sp. nov., Ktedonobacter robiniae sp. nov., Dictyobacter formicarum sp. nov. and Dictyobacter arantiisoli sp. nov., belonging to the class Ktedonobacteria

The aerobic, Gram-positive, mesophilic Ktedonobacteria strains, Uno17^T, SOSP1-1^T, 1-9^T, 1-30^T and 150040^T, formed mycelia of irregularly branched filaments, produced spores or sporangia, and numerous secondary metabolite biosynthetic gene clusters. The five strains grew at 15-40 °C (optimally at 30 °C) and pH 4.0-8.0 (optimally at pH 6.0-7.0), and had 7.21-12.67 Mb genomes with 49.7-53.7 mol% G+C content. They shared MK9(H₂) as the major menaquinone and C_16 : 1-2OH and iso-C_17 : 0 as the major cellular fatty acids. Phylogenetic and phylogenomic analyses showed that Uno17^T and SOSP1-9^T were most closely related to members of the genus Dictyobacter, with 94.43-96.21 % 16S rRNA gene similarities and 72.16-81.56% genomic average nucleotide identity. The strain most closely related to SOSP1-1^T and SOSP1-30^T was Ktedonobacter racemifer SOSP1-21^T, with 91.33 and 98.84 % 16S rRNA similarities, and 75.13 and 92.35% average nucleotide identities, respectively. Strain 150040^T formed a distinct clade within the order Ktedonobacterales, showing <90.47 % 16S rRNA gene similarity to known species in this order. Based on these results, we propose: strain 150040^T as Reticulibacter mediterranei gen. nov., sp. nov. (type strain 150 040^T=CGMCC 1.17052^T=BCRC 81202^T) within the family Reticulibacteraceae fam. nov. in the order Ktedonobacterales; strain SOSP1-1^T as Ktedonospora formicarum gen. nov., sp. nov. (type strain SOSP1-1^T=CGMCC 1.17205^T=BCRC 81203^T) and strain SOSP1-30^T as Ktedonobacter robiniae sp. nov. (type strain SOSP1-30^T=CGMCC 1.17733^T=BCRC 81205^T) within the family Ktedonobacteraceae; strain Uno17^T as Dictyobacter arantiisoli sp. nov. (type strain Uno17^T=NBRC 113155^T=BCRC 81116^T); and strain SOSP1-9^T as Dictyobacter formicarum sp. nov. (type strain SOSP1-9^T=CGMCC 1.17206^T=BCRC 81204^T) within the family Dictyobacteraceae.

Molecules derived from the extremes of life: a decade later

Covering: Early 2008 until the end of 2019Microorganisms which survive (extreme-tolerant) or even prefer (extremophilic) living at the limits of pH, temperature, salinity and pressure found on earth have proven to be a rich source of novel structures. In this update we summarise the wide variety of new molecules which have been isolated from extremophilic and extreme-tolerant microorganisms since our original 2009 review, highlighting the range of bioactivities these molecules have been reported to possess.

Ktedonoketone and 2'-oxosattabacin, benzenoid metabolites from a thermophilic bacterium Thermosporothrix hazakensis in the phylum Chloroflexi

A thermophilic bacterium Thermosporothrix hazakensis NBRC 105916 which belongs to the class Ktedonobacteria was investigated to explore its biosynthetic potential of secondary metabolites. UV-guided fractionation led to the identification of a new benzenoid metabolite designated ktedonoketone (6) and an α-diketone metabolite 2'-oxosattabacin (7) along with five known compounds. Compound 7 was previously described as a synthetic compound, but this is the first finding as a natural product. Compound 7 induced adipocyte differentiation at 10-20 μM and autophagy at 1-10 μM. Compound 6 showed weak inducing activity of adipocyte differentiation. The biosynthetic origin of hazakacin (3), an acyloin-type compound, was elucidated by ¹³C-labeled precursor-feeding experiments.

Two Chloroflexi classes independently evolved the ability to persist on atmospheric hydrogen and carbon monoxide

Most aerobic bacteria exist in dormant states within natural environments. In these states, they endure adverse environmental conditions such as nutrient starvation by decreasing metabolic expenditure and using alternative energy sources. In this study, we investigated the energy sources that support persistence of two aerobic thermophilic strains of the environmentally widespread but understudied phylum Chloroflexi. A transcriptome study revealed that Thermomicrobium roseum (class Chloroflexia) extensively remodels its respiratory chain upon entry into stationary phase due to nutrient limitation. Whereas primary dehydrogenases associated with heterotrophic respiration were downregulated, putative operons encoding enzymes involved in molecular hydrogen (H₂), carbon monoxide (CO), and sulfur compound oxidation were significantly upregulated. Gas chromatography and microsensor experiments showed that T. roseum aerobically respires H₂ and CO at a range of environmentally relevant concentrations to sub-atmospheric levels. Phylogenetic analysis suggests that the hydrogenases and carbon monoxide dehydrogenases mediating these processes are widely distributed in Chloroflexi genomes and have probably been horizontally acquired on more than one occasion. Consistently, we confirmed that the sporulating isolate Thermogemmatispora sp. T81 (class Ktedonobacteria) also oxidises atmospheric H₂ and CO during persistence, though further studies are required to determine if these findings extend to mesophilic strains. This study provides axenic culture evidence that atmospheric CO supports bacterial persistence and reports the third phylum, following Actinobacteria and Acidobacteria, to be experimentally shown to mediate the biogeochemically and ecologically important process of atmospheric H₂ oxidation. This adds to the growing body of evidence that atmospheric trace gases are dependable energy sources for bacterial persistence.

Analytical Techniques in Lipidomics: State of the Art

Current studies related to lipid identification and determination, or lipidomics in biological samples, are one of the most important issues in modern bioanalytical chemistry. There are many articles dedicated to specific analytical strategies used in lipidomics in various kinds of biological samples. However, in such literature, there is a lack of articles dedicated to a comprehensive review of the actual analytical methodologies used in lipidomics. The aim of this article is to characterize the lipidomics methods used in modern bioanalysis according to the methodological point of view: (1) chromatography/separation methods, (2) spectroscopic methods and (3) mass spectrometry and also hyphenated methods. In the first part, we discussed thin layer chromatography (TLC), high-pressure liquid chromatography (HPLC), gas chromatography (GC) and capillary electrophoresis (CE). The second part includes spectroscopic techniques such as Raman spectroscopy (RS), Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR). The third part is a synthetic review of mass spectrometry, matrix-assisted laser desorption/ionization (MALDI), hyphenated methods, which include liquid chromatography-mass spectrometry (LC-MS), gas chromatography-mass spectrometry (GC-MS) and also multidimensional techniques. Other aspects are the possibilities of the application of the described methods in lipidomics studies. Due to the fact that the exploration of new methods of lipidomics analysis and their applications in clinical and medical studies are still challenging for researchers working in life science, we hope that this review article will be very useful for readers.

Thermosporothrix narukonensis sp. nov., belonging to the class Ktedonobacteria, isolated from fallen leaves on geothermal soil, and emended description of the genus Thermosporothrix

A thermophilic, Gram-stain-positive, spore-forming bacterium that formed branched vegetative and aerial mycelia was isolated from fallen leaves on geothermal soil. This strain, designated F4T, grew at temperatures between 30 and 60 °C; optimum growth temperature was 50 °C, whereas no growth was observed below 28 °C or above 65 °C. The pH range for growth was 4.9-9.5; the pH for optimum growth was 7.0, but no growth was observed at pH below 4.4 or above 10.0. Strain F4T was able to hydrolyse polysaccharides such as cellulose, xylan, chitin and starch. The G+C content in the DNA of strain F4T was 52.5 mol%. The major fatty acid was iso-C17 : 0 and the major menaquinone was MK-9 (H2). The cell wall of strain F4T contained glutamic acid, serine, glycine, alanine and ornithine in a molar ratio of 1.0:1.5:1.4:1.8:0.7. The polar lipids of this strain consisted of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, one unknown phospholipid, three unknown glycolipids and two unknown lipids. The cell-wall sugar was mannose. Detailed phylogenetic analysis based on 16S rRNA gene sequences indicated that strain F4T belongs to the genus Thermosporothrix, and that it was related most closely to Thermosporothrix hazakensis SK20-1T (98.7 % similarity). DNA-DNA hybridization showed relatedness values of less than 15 % with the type strain of Thermosporothrix hazakensis. On the basis of phenotypic features and phylogenetic position, strain F4T is considered to represent a novel species, Thermosporothrix narukonensis sp. nov. The type strain is F4T(=NBRC 111777T=BCCM/LMG 29329T).

Thermorudis pharmacophila sp. nov., a novel member of the class Thermomicrobia isolated from geothermal soil, and emended descriptions of Thermomicrobium roseum, Thermomicrobium carboxidum, Thermorudis peleae and Sphaerobacter thermophilus

An aerobic, thermophilic and cellulolytic bacterium, designated strain WKT50.2T, was isolated from geothermal soil at Waikite, New Zealand. Strain WKT50.2T grew at 53-76 °C and at pH 5.9-8.2. The DNA G+C content was 58.4 mol%. The major fatty acids were 12-methyl C18 : 0 and C18 : 0. Polar lipids were all linked to long-chain 1,2-diols, and comprised 2-acylalkyldiol-1-O-phosphoinositol (diolPI), 2-acylalkyldiol-1-O-phosphoacylmannoside (diolP-acylMan), 2-acylalkyldiol-1-O-phosphoinositol acylmannoside (diolPI-acylMan) and 2-acylalkyldiol-1-O-phosphoinositol mannoside (diolPI-Man). Strain WKT50.2T utilized a range of cellulosic substrates, alcohols and organic acids for growth, but was unable to utilize monosaccharides. Robust growth of WKT50.2T was observed on protein derivatives. WKT50.2T was sensitive to ampicillin, chloramphenicol, kanamycin, neomycin, polymyxin B, streptomycin and vancomycin. Metronidazole, lasalocid A and trimethoprim stimulated growth. Phylogenetic analysis of 16S rRNA gene sequences showed that WKT50.2T belonged to the class Thermomicrobia within the phylum Chloroflexi, and was most closely related to Thermorudis peleae KI4T (99.6% similarity). DNA-DNA hybridization between WKT50.2T and Thermorudis peleae DSM 27169T was 18.0%. Physiological and biochemical tests confirmed the phenotypic and genotypic differentiation of strain WKT50.2T from Thermorudis peleae KI4T and other members of the Thermomicrobia. On the basis of its phylogenetic position and phenotypic characteristics, we propose that strain WKT50.2T represents a novel species, for which the name Thermorudis pharmacophila sp. nov. is proposed, with the type strain WKT50.2T ( = DSM 26011T = ICMP 20042T). Emended descriptions of Thermomicrobium roseum, Thermomicrobium carboxidum, Thermorudis peleae and Sphaerobacter thermophilus are also proposed, and include the description of a novel respiratory quinone, MK-8 2,3-epoxide (23%), in Thermomicrobium roseum.

Description of Thermogemmatispora carboxidivorans sp. nov., a carbon-monoxide-oxidizing member of the class Ktedonobacteria isolated from a geothermally heated biofilm, and analysis of carbon monoxide oxidation by members of the class Ktedonobacteria

A thermophilic, aerobic, Gram-stain-positive bacterium (strain PM5T), which formed mycelia of irregularly branched filaments and produced multiple exospores per cell, was isolated from a geothermally heated biofilm. Strain PM5T grew at 40–65 °C and pH 4.1–8.0, with optimal growth at 55 °C and pH 6.0. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain PM5T belonged to the class Ktedonobacteria , and was related most closely to Thermogemmatispora onikobensis ONI-1T (97.7 % similarity) and Thermogemmatispora foliorum ONI-5T (96.1 %). Morphological features and fatty acid profiles (major fatty acids: iso-C17 : 0, iso-C19 : 0 and 12,17-dimethyl C18 : 0) supported the affiliation of strain PM5T to the genus Thermogemmatispora . Strain PM5T oxidized carbon monoxide [CO; 10±1 nmol h−1 (mg protein)−1], but did not grow with CO as a sole carbon and energy source. Results from analyses of related strains indicated that the capacity for CO uptake occurred commonly among the members of the class Ktedonobacteria ; 13 of 14 strains tested consumed CO or harboured coxL genes that potentially enabled CO oxidation. The results of DNA–DNA hybridization and physiological and biochemical tests allowed the genotypic and phenotypic differentiation of strain PM5T from the two recognized species of the genus Thermogemmatispora . Strain PM5T differed from Thermogemmatispora onikobensis ONI-1T in its production of orange pigment, lower temperature optimum, hydrolysis of casein and starch, inability to grow with mannitol, xylose or rhamnose as sole carbon sources, and utilization of organic acids and amino acids. Strain PM5T is therefore considered to represent a novel species, for which the name Thermogemmatispora carboxidivorans sp. nov. is proposed. The type strain is PM5T ( = DSM 45816T = ATCC BAA-2534T).

Paenibacillus darwinianus sp. nov., isolated from gamma-irradiated Antarctic soil

A novel bacterium, strain Br(T), was isolated from gamma-irradiated soils of the Britannia drift, Lake Wellman Region, Antarctica. This isolate was rod-shaped, endospore forming, Gram-stain-variable, catalase-positive, oxidase-negative and strictly aerobic. Cells possessed a monotrichous flagellum. Optimal growth was observed at 18 °C, pH 7.0 in PYGV or R2A broth. The major cellular fatty acid was anteiso-C15 : 0 (63.4 %). Primary identified lipids included phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol. Total phospholipid was 60 % (w/w) of the total lipid extract. MK-7 was the dominant isoprenoid quinone. The genomic DNA G+C content was 55.6 mol%. Based on 16S rRNA gene sequence similarity, strain Br(T) clusters within the genus Paenibacillus with similarity values ranging from 93.9 to 95.1 %. Phylogenetic analyses by maximum-likelihood, maximum-parsimony and neighbour-joining methods revealed that strain Br(T) clusters with Paenibacillus daejeonensis (AF290916), Paenibacillus tarimensis (EF125184) and Paenibacillus pinihumi (GQ423057), albeit with weak bootstrap support. On the basis of phenotypic, chemotaxonomic and phylogenetic characteristics, we propose that strain Br(T) represents a novel species, Paenibacillus darwinianus sp. nov. The type strain is Br(T) ( = DSM 27245(T) = ICMP 19912(T)).