Frondihabitans cladoniiphilus sp. nov., an actinobacterium of the family Microbacteriaceae isolated from lichen, and emended description of the genus Frondihabitans

Ruicaihuangia caeni gen. nov., sp. nov., a novel taxon within the family Microbacteriaceae isolated from sludge

A Gram-stain-positive bacterium, designated YN-L-19T, was isolated from a sludge sample collected from a pesticide-manufacturing plant. Cells of YN-L-19T were strictly aerobic, non-spore-forming, non-motile and ovoid-shaped. Colonies were small, smooth and yellow. Growth occurred at 10-37 °C (optimum, 30 °C), pH 5.0-9.0 (optimum, 7.0) and 0-3.0 % (w/v) NaCl (optimum 0.5 %). Phylogenetic analysis based on genome and 16S rRNA gene sequences indicated that YN-L-19T was affiliated to the family Microbacteriaceae and most closely related to Diaminobutyricimonas aenilata, Terrimesophilobacter mesophilus, Planctomonas deserti and Curtobacterium luteum. The major cellular fatty acids of YN-L-19T were anteiso-C15 : 0, anteiso-C17 : 0, iso-C16 : 0 and C16 : 0. The predominant menaquinone was MK-7. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, glycolipid and one unidentified lipid. The average amino acid identity values between strain YN-L-19T and the related strains were 57.9-61.9 %, which were below the genus boundary (70 %). On the basis of the evidence presented in this study, strain YN-L-19T represents a novel species of a new genus in the family Microbacteriaceae, for which the name Ruicaihuangia caeni gen. nov., sp. nov. (type strain YN-L-19T=CCTCC AB 2022401T= KCTC 49935T) is proposed.

Antiquaquibacter oligotrophicus gen. nov., sp. nov., a novel oligotrophic bacterium from groundwater

In this study, a Gram-stain-positive, non-motile, oxidase- and catalase-negative, rod-shaped, bacterial strain (SG_E_30_P1T) that formed light yellow colonies was isolated from a groundwater sample of Sztaravoda spring, Hungary. Based on 16S rRNA phylogenetic and phylogenomic analyses, the strain was found to form a distinct linage within the family Microbacteriaceae. Its closest relatives in terms of near full-length 16S rRNA gene sequences are Salinibacterium hongtaonis MH299814 (97.72 % sequence similarity) and Leifsonia psychrotolerans GQ406810 (97.57 %). The novel strain grows optimally at 20-28 °C, at neutral pH and in the presence of NaCl (1-2 w/v%). Strain SG_E_30_P1T contains MK-7 and B-type peptidoglycan with diaminobutyrate as the diagnostic amino acid. The major cellular fatty acids are anteiso-C15 : 0, iso-C16 : 0 and iso-C14 : 0, and the polar lipid profile is composed of diphosphatidylglycerol and phosphatidylglycerol, as well as an unidentified aminoglycolipid, aminophospholipid and some unidentified phospholipids. The assembled draft genome is a contig with a total length of 2 897 968 bp and a DNA G+C content of 65.5 mol%. Amino acid identity values with it closest relatives with sequenced genomes of <62.54 %, as well as other genome distance results, indicate that this bacterium represents a novel genus within the family Microbacteriaceae. We suggest that SG_E_30_P1T (=DSM 111415T=NCAIM B.02656T) represents the type strain of a novel genus and species for which the name Antiquaquibacter oligotrophicus gen. nov., sp. nov. is proposed.

Lichen-Derived Actinomycetota: Novel Taxa and Bioactive Metabolites

Actinomycetes are essential sources of numerous bioactive secondary metabolites with diverse chemical and bioactive properties. Lichen ecosystems have piqued the interest of the research community due to their distinct characteristics. Lichen is a symbiont of fungi and algae or cyanobacteria. This review focuses on the novel taxa and diverse bioactive secondary metabolites identified between 1995 and 2022 from cultivable actinomycetota associated with lichens. A total of 25 novel actinomycetota species were reported following studies of lichens. The chemical structures and biological activities of 114 compounds derived from the lichen-associated actinomycetota are also summarized. These secondary metabolites were classified into aromatic amides and amines, diketopiperazines, furanones, indole, isoflavonoids, linear esters and macrolides, peptides, phenolic derivatives, pyridine derivatives, pyrrole derivatives, quinones, and sterols. Their biological activities included anti-inflammatory, antimicrobial, anticancer, cytotoxic, and enzyme-inhibitory actions. In addition, the biosynthetic pathways of several potent bioactive compounds are summarized. Thus, lichen actinomycetes demonstrate exceptional abilities in the discovery of new drug candidates.

Chronicle of Research into Lichen-Associated Bacteria

Lichens are mutually symbiotic systems consisting of fungal and algal symbionts. While diverse lichen-forming fungal species are known, limited species of algae form lichens. Plasticity in the combination of fungal and algal species with different eco-physiological properties may contribute to the worldwide distribution of lichens, even in extreme habitats. Lichens have been studied systematically for more than 200 years; however, plasticity in fungal-algal/cyanobacterial symbiotic combinations is still unclear. In addition, the association between non-cyanobacterial bacteria and lichens has attracted attention in recent years. The types, diversity, and functions of lichen-associated bacteria have been studied using both culture-based and culture-independent methods. This review summarizes the history of systematic research on lichens and lichen-associated bacteria and provides insights into the current status of research in this field.

Microbial Diversity of Psychrotolerant Bacteria Isolated from Wild Flora of Andes Mountains and Patagonia of Chile towards the Selection of Plant Growth-Promoting Bacterial Consortia to Alleviate Cold Stress in Plants

Cold stress decreases the growth and productivity of agricultural crops. Psychrotolerant plant growth-promoting bacteria (PGPB) may protect and promote plant growth at low temperatures. The aims of this study were to isolate and characterize psychrotolerant PGPB from wild flora of Andes Mountains and Patagonia of Chile and to formulate PGPB consortia. Psychrotolerant strains were isolated from 11 wild plants (rhizosphere and phyllosphere) during winter of 2015. For the first time, bacteria associated with Calycera, Orites, and Chusquea plant genera were reported. More than 50% of the 130 isolates showed ≥33% bacterial cell survival at temperatures below zero. Seventy strains of Pseudomonas, Curtobacterium, Janthinobacterium, Stenotrophomonas, Serratia, Brevundimonas, Xanthomonas, Frondihabitans, Arthrobacter, Pseudarthrobacter, Paenarthrobacter, Brachybacterium, Clavibacter, Sporosarcina, Bacillus, Solibacillus, Flavobacterium, and Pedobacter genera were identified by 16S rRNA gene sequence analyses. Ten strains were selected based on psychrotolerance, auxin production, phosphate solubilization, presence of nifH (nitrogenase reductase) and acdS (1-aminocyclopropane-1-carboxylate (ACC) deaminase) genes, and anti-phytopathogenic activities. Two of the three bacterial consortia formulated promoted tomato plant growth under normal and cold stress conditions. The bacterial consortium composed of Pseudomonas sp. TmR5a & Curtobacterium sp. BmP22c that possesses ACC deaminase and ice recrystallization inhibition activities is a promising candidate for future cold stress studies.

3D biofilms: in search of the polysaccharides holding together lichen symbioses

Stable, long-term interactions between fungi and algae or cyanobacteria, collectively known as lichens, have repeatedly evolved complex architectures with little resemblance to their component parts. Lacking any central scaffold, the shapes they assume are casts of secreted polymers that cement cells into place, determine the angle of phototropic exposure and regulate water relations. A growing body of evidence suggests that many lichen extracellular polymer matrices harbor unicellular, non-photosynthesizing organisms (UNPOs) not traditionally recognized as lichen symbionts. Understanding organismal input and uptake in this layer is key to interpreting the role UNPOs play in lichen biology. Here, we review both polysaccharide composition determined from whole, pulverized lichens and UNPOs reported from lichens to date. Most reported polysaccharides are thought to be structural cell wall components. The composition of the extracellular matrix is not definitively known. Several lines of evidence suggest some acidic polysaccharides have evaded detection in routine analysis of neutral sugars and may be involved in the extracellular matrix. UNPOs reported from lichens include diverse bacteria and yeasts for which secreted polysaccharides play important biological roles. We conclude by proposing testable hypotheses on the role that symbiont give-and-take in this layer could play in determining or modifying lichen symbiotic outcomes.

Lichenibacterium ramalinae gen. nov, sp. nov., Lichenibacterium minor sp. nov., the first endophytic, beta-carotene producing bacterial representatives from lichen thalli and the proposal of the new family Lichenibacteriaceae within the order Rhizobiales

This study of lichens in the subarctic zone of the northern hemisphere has resulted in the detection of new representatives of the order Rhizobiales. The16S rRNA gene sequence phylogeny placed the strains as a separate branch inside the Rhizobiales clade. Strain RmlP001^T exhibits 91.85% similarity to Roseiarcus fermentans strain Pf56^T and 91.76% to Beijerinckia doebereinerae strain LMG 2819^T, whilst strain RmlP026^T is closely related to B. doebereinerae strain LMG 2819^T (91.85%) and Microvirga pakistanensis strain NCCP-1258^T (91.39%). A whole-genome phylogeny of the strains confirmed their taxonomic positions. The cells of both strains were observed to be Gram-negative, motile rods that multiplied by binary fission. The cells were found to contain poly-β-hydroxybutyrate and polyphosphate, to grow at pH 3.5-8.0 and 10-30 °C, and could not fix atmospheric nitrogen. Their major cellular fatty acid identified was C_18:1ω7c (68-71%) and their DNA G + C contents determined to be 70.5-70.8%. Beta-carotene was identified as their major carotenoid pigment; Q-10 was the only ubiquinone detected. Strains RmlP001^T and RmlP026^T are distinguishable from related species by the presence of β-carotene, the absence of C1 metabolism and the ability to grow in the presence of 3.5% NaCl. Based on their phylogenetic, phenotypic and chemotaxonomic features, we propose a novel genus Lichenibacterium and two novel species, Lichenibacterium ramalinae (the type species of the genus) and Lichenibacterium minor, to accommodate these bacteria within the family Lichenibacteriaceae fam. nov. of the order Rhizobiales. The L. ramalinae type strain is RmlP001^T (= KCTC 72076^T = VKM B-3263^T) and the L. minor type strain is RmlP026^T (= KCTC 72077^T = VKM B-3277^T).

Lacisediminihabitans profunda gen. nov., sp. nov., a member of the family Microbacteriaceae isolated from freshwater sediment

A novel Gram-stain-positive bacterial strain, CHu50b-6-2^T, was isolated from a 67-cm-long sediment core collected from the Daechung Reservoir at a water depth of 17 m, Daejeon, Republic of Korea. The cells of strain CHu50b-6-2^T were aerobic non-motile and formed yellow colonies on R2A agar. The phylogenetic analysis based on 16S rRNA gene sequencing indicated that the strain formed a separate lineage within the family Microbacteriaceae, exhibiting 98.0%, 97.7% and 97.6% 16S rRNA gene sequence similarities to Glaciihabitans tibetensis KCTC 29148^T, Frigoribacterium faeni KACC 20509^T and Lysinibacter cavernae DSM 27960^T, respectively. The phylogenetic trees revealed that strain CHu50b-6-2^T did not show a clear affiliation to any genus within the family Microbacteriaceae. The chemotaxonomic results showed B1α type peptidoglacan containg 2, 4-diaminobutyric acid (DAB) as the diagnostic diamino acid, MK-10 as the predominant respiratory menaquinone, diphosphatidylglycerol, phosphatidylglycerol, and an unidentified glycolipid as the major polar lipids, anteiso-C_15:0, iso-C_16:0, and anteiso-C_17:0 as the major fatty acids, and a DNA G + C content of 67.3 mol%. The combined genotypic and phenotypic data showed that strain CHu50b-6-2^T could be distinguished from all genera within the family Microbacteriaceae and represents a novel genus, Lacisediminihabitans gen. nov., with the name Lacisediminihabitans profunda sp. nov., in the family Microbacteriaceae. The type strain is CHu50b-6-2^T (= KCTC 49081^T = JCM 32673^T).

Planctomonas deserti gen. nov., sp. nov., a new member of the family Microbacteriaceae isolated from soil of the Taklamakan desert

A Gram-staining-positive, aerobic, irregular coccoid- to ovoid-shaped, non-spore-forming and motile bacterium, designated strain 13S1-3^T, was isolated from a soil sample from the rhizosphere of Tamarix collected in the Taklamakan desert in Xinjiang Uygur Autonomous Region, PR China. The strain was examined by a polyphasic approach to clarify its taxonomic position. Strain 13S1-3^T grew optimally at 28-30 °C, pH 7.0 and with 0-1 % (w/v) NaCl. The cell-wall peptidoglycan was of the B2γ type and contained d-alanine, d-glutamic acid, glycine, d-2,4-diaminobutyric acid and l-2,4-diaminobutyric acid. Ribose, xylose, glucose and galactose were detected as cell-wall sugars. The acyl type of the muramic acid was acetyl. The predominant menaquinones were MK-12, MK-11, MK-13 and MK-10. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, two unidentified glycolipids and one unidentified phospholipid. The major whole-cell fatty acids were anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. The DNA G+C content was 70.4 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that 13S1-3^T represented a member of the family Microbacteriaceae and showed the highest level of 16S rRNA gene sequence similarity with Frondihabitans australicus E1HC-02^T (97.11 %). Phylogenetic trees revealed that 13S1-3^T formed a distinct lineage with respect to closely related genera within the family Microbacteriaceae. On the basis of the results of phylogenetic, phenotypic and chemotaxonomic analyses, 13S1-3^T is distinguishable from phylogenetically related genera in the family Microbacteriaceae, and represents a novel species of a new genus, for which the name Planctomonas deserti gen. nov., sp. nov. is proposed. The type strain is 13S1-3^T (=KCTC 49115^T=CGMCC 1.16554^T).

Diversity, Antimicrobial Activity, and Biosynthetic Potential of Cultivable Actinomycetes Associated with Lichen Symbiosis

Lichens are structured associations of a fungus with a cyanobacteria and/or green algae in a symbiotic relationship, which provide specific habitats for diverse bacterial communities, including actinomycetes. However, few studies have been performed on the phylogenetic relationships and biosynthetic potential of actinomycetes across lichen species. In the present study, a total of 213 actinomycetes strains were isolated from 35 lichen samples (22 lichen genera) collected in Yunnan Province, China. 16S rRNA gene sequence analysis revealed an unexpected level of diversity among these isolates, which were distributed into 38 genera, 19 families, and 9 orders within the Actinobacteria phylum. The detailed taxa of isolates had no clear relationship to the taxonomic affiliations of the associated lichens. To the best of our knowledge, this is the first report to describe the isolation of Actinophytocola, Angustibacter, Herbiconiux, Kibdelosporangium, Kineosporia, Kitasatospora, Nakamurella, Nonomuraea, Labedella, Lechevalieria, Lentzea, Schumannella, and Umezawaea species from lichens. At least 40 isolates (18.78%) are likely to represent novel actinomycetes taxa within 15 genera. In addition, all 213 isolates were tested for antimicrobial activity and screened for genes associated with secondary metabolite production to evaluate their biosynthetic potential. These results demonstrate that the lichens of Yunnan Province represent an extremely rich reservoir for the isolation of a significant diversity of actinomycetes, including novel species, which are potential source for discovering biologically active compounds.

Subtercola lobariae sp. nov., an actinobacterium of the family Microbacteriaceae isolated from the lichen Lobaria retigera

An actinobacterium, designated strain 9583bT, was isolated from the lichen Lobaria retigera collected from Jiaozi Snow Mountain, Yunnan Province, China. Cells of strain 9583bT were Gram-stain-positive, aerobic, catalase-positive and oxidase-negative. The strain have a short rod-shaped, irregular morphology, and could grow at the temperature range of 4 to 28 °C. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 9583bT belonged to the genus Subtercola in the family Microbacteriaceae, and shared highest sequence similarity with the type strains of Subtercola frigoramans and Subtercola boreus (96.8 and 95.6 %, respectively). The peptidoglycan type was B2γ, with diaminobutyric acid as the diagnostic diamino acid. The polar lipids comprised of phosphatidylglycerol, diphosphatidylglycerol, five unidentified glycolipids and three unidentified phospholipids. The respiratory quinone was determined to be MK-10. While the major fatty acids (>5 %) of strain 9583bT were anteiso-C15 : 0, C14 : 0 2-OH and iso-C16 : 0, the 1,1-dimethoxy-alkanes included a-15 : 0 DMA, i-16 : 0 DMA, a-17 : 0 DMA and i-15 : 0 DMA. The genomic DNA G+C content of strain 9583bT was 66.8 mol%. On the basis of the phylogenetic, phenotypic and chemotaxonomic data in this study, strain 9583bT represents a novel species of the genus Subtercola, for which the name Subtercola lobariae sp. nov. is proposed. The type strain is 9583bT (=CGMCC 1.12976T=DSM 103962T).

Schizoxylon as an experimental model for studying interkingdom symbiosis

Experiments to re-synthesise lichens so far focused on co-cultures of fungal and algal partners. However, recent studies have revealed that bacterial communities colonise lichens in a stable and host-specific manner. We were therefore interested in testing how lichenised fungi and algae interact with selected bacteria in an experimental setup. We selected the symbiotic system of Schizoxylon albescens and the algal genera Coccomyxa and Trebouxia as a suitable model. We isolated bacterial strains from the naturally occurring bacterial fraction of freshly collected specimens and established tripartite associations under mixed culture experiments. The bacteria belong to Actinobacteria, Firmicutes and Proteobacteria and corresponded to groups already found associated with fungi including lichens. In mixed cultures with Coccomyxa, the fungus formed a characteristic filamentous matrix and tightly contacted the algae; the bacteria distributed in small patches between the algal cells and attached to the cell walls. In mixed cultures with Trebouxia, the fungus did not develop the filamentous matrix, but bacterial cells were observed to be tightly adhering to the fungal hyphae. Our experiments show that this tripartite fungal-algal-bacterial model system can be maintained in culture and can offer multiple opportunities for functional studies based on experiments under controlled conditions in the laboratory.

Lysinibacter cavernae gen. nov., sp. nov., a new member of the family Microbacteriaceae isolated from a karst cave

A Gram-stain-positive, aerobic, straight or slightly bent rod-shaped, non-motile, non-spore-forming bacterium, designated strain CC5-806T, was isolated from a soil sample collected from a wild karst cave in the Wulong region, Chongqing, PR China and examined using a polyphasic approach to clarify its taxonomic position. This bacterium did not produce substrate mycelium or aerial hyphae, and no diffusible pigments were observed on the media tested. Strain CC5-806T grew optimally without NaCl at 20 °C and at pH 7.0. Phylogenetic analysis, based on 16S rRNA gene sequences, indicated that strain CC5-806T belonged to the family Microbacteriaceae and showed the highest levels of 16S rRNA gene sequence similarities with Frigoribacterium endophyticum EGI 6500707T (97.56 %), Frigoribacterium faeni 801T (97.53 %) and Glaciihabitans tibetensis MP203T (97.42 %). Phylogenetic trees revealed that strain CC5-806T did not show a clear affiliation to any genus within the family Microbacteriaceae. The DNA G+C content of strain CC5-806T was 62.6 mol%. The cell-wall peptidoglycan contained l-lysine as a diagnostic diamino acid. The predominant menaquinones were MK-11, MK-10 and MK-9. Phosphatidylglycerol, diphosphatidylglycerol, an unidentified glycolipid, four unidentified phospholipids and other polar lipids were detected in the polar lipid extracts. The major fatty acids were anteiso-C15 : 0, iso-C16 : 0 and iso-C14 : 0. On the basis of the phylogenetic analysis, and phenotypic and chemotaxonomic characteristics, strain CC5-806T was distinguishable from phylogenetically related genera in the family Microbacteriaceae. It represents a novel species of a novel genus, for which the name Lysinibacter cavernae gen. nov., sp. nov. is proposed. The type strain is CC5-806T ( = DSM 27960T = CGMCC 1.14983T).

Complete genome sequence of Frondihabitans sp. strain PAMC28766, a novel carotenoid-producing and radiation-resistant strain isolated from an Antarctic lichen

Here, we report the first complete genome sequence of Frondihabitans sp. strain PAMC28766, which was found to consist of three plasmids, one chromosome (4,345,897bp), and a series of genes involved in carotenoid biosynthesis and nucleotide excision repair. An analysis of the Frondihabitans sp. PAMC28766 genome will improve our understanding of the carotenoid biosynthesis pathway. Furthermore, the sequence data will provide novel insight into UV radiation-resistance in extremely cold environments.

Lichens as natural sources of biotechnologically relevant bacteria

The search for microorganisms from novel sources and in particular microbial symbioses represents a promising approach in biotechnology. In this context, lichens have increasingly become a subject of research in microbial biotechnology, particularly after the recognition that a diverse community of bacteria other than cyanobacteria is an additional partner to the traditionally recognized algae-fungus mutualism. Here, we review recent studies using culture-dependent as well as culture-independent approaches showing that lichens can harbor diverse bacterial families known for the production of compounds of biotechnological interest and that several microorganisms isolated from lichens, in particular Actinobacteria and Cyanobacteria, can produce a number of bioactive compounds, many of them with biotechnological potential.

Deciphering microbial landscapes of fish eggs to mitigate emerging diseases

Animals and plants are increasingly suffering from diseases caused by fungi and oomycetes. These emerging pathogens are now recognized as a global threat to biodiversity and food security. Among oomycetes, Saprolegnia species cause significant declines in fish and amphibian populations. Fish eggs have an immature adaptive immune system and depend on nonspecific innate defences to ward off pathogens. Here, meta-taxonomic analyses revealed that Atlantic salmon eggs are home to diverse fungal, oomycete and bacterial communities. Although virulent Saprolegnia isolates were found in all salmon egg samples, a low incidence of Saprolegniosis was strongly correlated with a high richness and abundance of specific commensal Actinobacteria, with the genus Frondihabitans (Microbacteriaceae) effectively inhibiting attachment of Saprolegniato salmon eggs. These results highlight that fundamental insights into microbial landscapes of fish eggs may provide new sustainable means to mitigate emerging diseases.

Glaciihabitans tibetensis gen. nov., sp. nov., a psychrotolerant bacterium of the family Microbacteriaceae, isolated from glacier ice water

A Gram-stain-positive, aerobic, non-spore-forming, short-rod-shaped bacterium, designated strain MP203T, was isolated from ice water of Midui Glacier in Tibet Autonomous Region, China. The strain was psychrotolerant, growing at 0–25 °C. 16S rRNA gene sequence analysis showed that strain MP203T was most similar to Frigoribacterium faeni NBRC 103066T, Compostimonas suwonensis KACC 13354T, Frigoribacterium mesophilum KCTC 19311T, Marisediminicola antarctica CCTCC AB 209077T and Alpinimonas psychrophila JCM 18951T, with similarities of 97.4, 97.2, 97.2, 97.1 and 97.1 %, respectively. The maximum-likelihood phylogenetic tree indicated that strain MP203T clustered with nine genera of the family Microbacteriaceae , namely Frigoribacterium , Compostimonas , Marisediminicola , Alpinimonas , Frondihabitans , Clavibacter , Subtercola , Klugiella and Agreia . However, bootstrap analysis showed that there was no significance in the branching pattern of the linage comprising strain MP203T and any existing generic lineage of the family Microbacteriaceae . DNA–DNA hybridization results indicated levels of relatedness between strain MP203T and Marisediminicola antarctica CCTCC AB 209077T, Frigoribacterium faeni NBRC 103066T, Frigoribacterium mesophilum KCTC 19311T, Compostimonas suwonensis KACC 13354T and Alpinimonas psychrophila JCM 18951T were 25.8±7.3, 29.6±7.6, 19.7±6.7, 16.0±4.2 and 12.4±5.1 % (mean±sd), respectively. The G+C content of the genomic DNA was 64.1 mol%. Analysis of the cell-wall peptidoglycan revealed that the peptidoglycan structure of strain MP203T was B10 type with Gly[l-Hse]–d-Glu–d-DAB, containing 2, 4-diaminobutyric acid (DAB) as a diagnostic amino acid. The cell-wall sugars were rhamnose, ribose, mannose and glucose. The major fatty acids were anteiso-C15 : 0, iso-C16 : 0 and anteiso A-C15 : 1. An unusual compound identified as anteiso-C15 : 0-DMA (1, 1-dimethoxy-anteiso-pentadecane) was also present in strain MP203T. The predominant menaquinone was MK-10. Diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), one unknown glycolipid and four unknown lipids were detected in the polar lipid extracts. As strain MP203T was distinguishable from phylogenetically related genera in the family Microbacteriaceae in terms of its physiological and chemotaxonomic characteristics and phylogenetic position, it was considered to represent a novel species of a new genus. Thus, the name Glaciihabitans tibetensis gen. nov., sp. nov. is proposed. The type strain of Glaciihabitans tibetensis is MP203T ( = CGMCC 1.12484T = KCTC 29148T).

Description of Galbitalea soli gen. nov., sp. nov., and Frondihabitans sucicola sp. nov

Bacterial strains KIS82-1(T) and GRS42(T) were isolated from soil and from sap of Acer mono, respectively, in the Republic of Korea. Both strains were aerobic, Gram-stain-positive, mesophilic, rod-shaped and motile. Phylogenetically, both strains belonged to the family Microbacteriaceae of the phylum Actinobacteria. The 16S rRNA gene sequence of strain KIS82-1(T) showed the highest similarity to those of Frondihabitans peucedani RS-15(T) (97.6%), Frigoribacterium mesophilum MSL-08(T) (97.2%) and Labedella gwakjiensis KSW2-17(T) (97.0%), while strain GRS42(T) showed the highest 16S rRNA gene sequence similarity to Frondihabitans peucedani RS-15(T) (98.7%), Frondihabitans cladoniiphilus CafT13(T) (98.4%), Frondihabitans australicus E1HC-02(T) (98.2%) and Frigoribacterium faeni 801(T) (97.3%). The 16S rRNA gene sequence similarity between GRS42(T) and KIS82-1(T) was 97.0%. Phylogenetic trees indicated that strain GRS42(T) was firmly grouped into the genus Frondihabitans, while strain KIS82-1(T) did not show a clear affiliation to any genus within the family Microbacteriaceae. Strain KIS82-1(T) showed type B1β peptidoglycan with 2,4-diamino-L-butyric acid as the diamino acid. It had MK-11, MK-10 and MK-12 as respiratory quinones, anteiso-C(15 : 0), iso-C(16: 0) and iso-C(14 : 0) as major cellular fatty acids and diphosphatidylglycerol, phosphatidylglycerol and an unknown glycolipid as predominant polar lipids. The peptidoglycan of strain GRS42(T) was of type B2β with D-ornithine as the diamino acid. The strain contained MK-8, MK-9 and MK-7 as respiratory quinones, summed feature 8 (C(18 : 1)ω6c and/or C(18 : 1)ω7c) as major cellular fatty acid and diphosphatidylglycerol, phosphatidylglycerol and three unknown glycolipids as predominant polar lipids. Strain GRS42(T) revealed low DNA-DNA hybridization (<50% relatedness) with closely related strains. Based on the data obtained in the present polyphasic taxonomic study, we propose that strain KIS82-1(T) represents a novel genus and species and that strain GRS42(T) represents a novel species in the family Microbacteriaceae. The genus Galbitalea gen. nov. is proposed, with strain KIS82-1(T) ( = KACC 15520(T) = NBRC 108727(T)) as the type strain of the type species, Galbitalea soli sp. nov. Strain GRS42(T) ( = KACC 15521(T) = NBRC 108728(T)) is proposed as the type strain of Frondihabitans sucicola sp. nov.

Bacterial epibionts and endolichenic actinobacteria and fungi in the Lower Devonian lichen Chlorolichenomycites salopensis

The charcoalified fragment of the dorsiventrally organized, internally stratified presumed green algal lichen Chlorolichenomycites salopensis from the Lower Devonian Lochkovian strata in the Welsh Borderland carries bacterial colonies on the upper surface, i.e. the cortex, and actinobacterial filaments in the medulla underneath the photobiont layer. Moreover relatively thin hyphae of presumed endolichenic fungi were found. As in extant lichens, which are best regarded as consortia with an unknown number of participants, this internally stratified, fossil thallus fragment of a presumed green algal lichen harbours a diverse microbial community.