Yonghaparkia alkaliphila gen. nov., sp. nov., a novel member of the family Microbacteriaceae isolated from an alkaline soil

Aging in soil increases the disturbance of microplastics to the gut microbiota of soil fauna

Microplastics (MPs) in the soil environment inevitably experience aging processes. However, how aging in soil affects MP toxicity to soil fauna remains poorly understood. In this study, two types of widely distributed MPs (polypropylene and tire wear particles) were aged in different soils, and their surface properties, morphology, leaching features of additives, biofilm colonization and toxicity to the typical soil fauna Enchytraeus crypticus were investigated. Results showed that aging in soil slightly changed the surface properties and morphology for both types of MPs, but significantly affected the release of additives, especially for those MPs aged in soil amended with manure. Moreover, a distinct and less diverse microbial community than the surrounding soils was formed on the surface of MPs, and MP type was a determinant of the biofilm microbial community. Exposure experiments indicated that aged MPs, especially those aged in soil with manure significantly affected the reproduction of soil worms with a more obvious disturbance to their gut microbiota, and biofilm features and changes in the leaching properties of MPs during aging were the main factors for these shifts. This study is the first attempt to reveal the role of aging in soil in MP toxicity to soil fauna.

Description of Microcella humidisoli sp. nov. and Microcella daejeonensis sp. nov., isolated from riverside soil, reclassification of Marinisubtilis pacificus as Microcella pacifica comb. nov., and emended description of the genus Microcella

Three Gram-positive, aerobic and rod shaped actinobacteria, designated strains MMS21-STM10T, MMS21-STM12T and MMS21-STM26, were isolated from riverside soil and subjected to polyphasic taxonomic analysis. The strains grew optimally at mesophilic temperatures (25-30 °C) and neutral to slightly alkaline pH (7-8), and NaCl was not required for growth. Best growth was observed on nutrient agar or marine agar media. The strains contained diphosphatidylglycerol, phosphatidylglycerol and a series of unidentified phospholipids, glycolipids and aminolipids, and anteiso-C15 : 0 and iso-C16 : 0 as the main fatty acids in common. The genome sizes ranged between 2.65 and 2.78 Mbp, and the DNA G+C contents between 70.4 and 72.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain MMS21-STM10T showed highest sequence similarity of 98.3 % to Microcella putealis CV-2T, and MMS21-STM12T and MMS21-STM26 of 99.2-99.3 % to Microcella flavibacter WY83T, respectively. In the whole genome-based comparison using the orthologous average nucleotide identity and digital DNA-DNA hybridization, each of strains MMS21-STM10T and MMS21-STM12T could be separated from other species of Microcella. The genome analysis also indicated that both strains contained gene clusters involved in the biosynthesis of alkylresorcinol, microansamycin and carotenoids. The phenotypic characteristics again differentiated the strains from related species, and two new species of Microcella, Microcella humidisoli sp. nov. (type strain, MMS21-STM10T=KCTC 49773T=LMG 32522T) and Microcella daejeonensis sp. nov. (type strain, MMS21-STM12T=KCTC 49750T=LMG 32523T) are proposed accordingly. It was also evident that Marinisubtilis pacificus KN1116T should be reclassified as a new species of Microcella, and Microcella pacifica comb. nov. (type strain, KN1116T=CGMCC 1.17143T=KCTC 49299T) is proposed. In addition, an emended description of Microcella is proposed based on this study.

Microbial community regulation and performance enhancement in gas biofilters by interrupting bacterial communication

BACKGROUND

Controlling excess biomass accumulation and clogging is important for maintaining the performance of gas biofilters and reducing energy consumption. Interruption of bacterial communication (quorum quenching) can modulate gene expression and alter biofilm properties. However, whether the problem of excess biomass accumulation in gas biofilters can be addressed by interrupting bacterial communication remains unknown.

RESULTS

In this study, parallel laboratory-scale gas biofilters were operated with Rhodococcus sp. BH4 (QQBF) and without Rhodococcus sp. BH4 (BF) to explore the effects of quorum quenching (QQ) bacteria on biomass accumulation and clogging. QQBF showed lower biomass accumulation (109 kg/m³) and superior operational stability (85-96%) than BF (170 kg/m³; 63-92%) at the end of the operation. Compared to BF, the QQBF biofilm had lower adhesion strength and decreased extracellular polymeric substance production, leading to easier detachment of biomass from filler surface into the leachate. Meanwhile, the relative abundance of quorum sensing (QS)-related species was found to decrease from 67 (BF) to 56% (QQBF). The QS function genes were also found a lower relative abundance in QQBF, compared with BF. Moreover, although both biofilters presented aromatic compounds removal performance, the keystone species in QQBF played an important role in maintaining biofilm stability, while the keystone species in BF exhibited great potential for biofilm formation. Finally, the possible influencing mechanism of Rhodococcus sp. BH4 on biofilm adhesion was demonstrated. Overall, the results of this study achieved excess biomass control while maintaining stable biofiltration performance (without interrupting operation) and greatly promoted the use of QQ technology in bioreactors. Video Abstract.

Microcella aerolata sp. nov., isolated from electronic waste-associated bioaerosols

A Gram-positive, non-motile, non-spore-forming and short rod-shaped actinomycete strain, designated GA224^T, was isolated from electronic waste-associated bioaerosols. The optimal growth conditions for this isolate, a facultatively anaerobic bacterium, were 37 °C and pH 8.0. The cell-wall peptidoglycan type was B2γ, with 2,4-diaminobutyric acid (DAB) as the diamino acids, while the major menaquinone was MK-12. The polar lipid profile was composed of diphosphatidylglycerol, phosphatidylglycerol, unidentified phospholipids, unidentified glycolipids and an unidentified lipid. The major cellular fatty acids were anteiso-C_15:0 and iso-C_16:0. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain GA224^T fell within the genus Microcella. The draft genome of strain GA224^T comprised 2,495,189 bp with a G + C content of 72.2 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain GA224^T and the type strain of the type species of Microcella species were lower than 95% and 70%, respectively. Based on the phenotypic, chemotaxonomic and genomic data, strain GA224^T represents a novel species, for which the name Microcella aerolata sp. nov. is proposed, with GA224^T as the type strain (= GDMCC 1.2165 ^T = JCM 34462 ^T).

Microcella flavibacter sp. nov., isolated from marine sediment, and reclassification of Chryseoglobus frigidaquae, Chryseoglobus indicus, and Yonghaparkia alkaliphila as Microcella frigidaquae comb. nov., Microcella indica nom. nov., and Microcella alkalica nom. nov

A novel Gram-staining positive, aerobic, rod-shaped, non-motile and yellow-pigmented actinobacterium, designated strain WY83^T, was isolated from a marine sediment of Indian Ocean. Strain WY83^T grew optimally at 30-35 °C, pH 7-8 and with 0-3% (w/v) NaCl. The predominant menaquinones were MK-10, MK-11 and MK-12, and the major fatty acids were C_19:1 ω9c/C19:1 ω11c, anteiso-C_15:0, C_17:0 3OH, and iso-C_16:0. The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol and one unidentified glycolipid. The cell-wall peptidoglycan contained lysine as a diamino acid. The DNA G + C content was 72.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences and ninety-two bacterial core genes indicated that strain WY83^T formed an evolutionary lineage with Chryseoglobus frigidaquae JCM 14730^T, Chryseoglobus indicus CTD02-10-2^T, Yonghaparkia alkaliphila JCM 15138^T, Microcella alkaliphila DSM 18851^T and Microcella putealis DSM 19627^T within the radiation enclosing members of the family Microbacteriaceae. All pairwise percentage of conserved proteins between strain WY83^T and the closely related phylogenetic neighbors were greater than 65%. The average nucleotide identity and in silico DNA-DNA hybridization values were both below the thresholds used for the delineation of a new species. On the basis of the evidence presented, strains WY83^T, Y. alkaliphila JCM 15138^T, C. frigidaquae JCM 14730^T, M. alkaliphila DSM 18851^T and M. putealis DSM 19627^T should belong to different species of the same genus. Strain WY83^T represents a novel species of the genus Microcella, for which the name Microcella flavibacter sp. nov. is proposed. The type strain is WY83^T (= KCTC 39637^T = MCCC 1A07099^T). Furthermore, Chryseoglobus frigidaquae, Chryseoglobus indicus, and Yonghaparkia alkaliphila were reclassified as Microcella frigidaquae comb. nov., Microcella indica nom. nov., and Microcella alkalica nom. nov., respectively.

A rapid and efficient method for the extraction and identification of menaquinones from Actinomycetes in wet biomass

Background

Menaquinones are constituents of prokaryote cell membranes where they play important functions during electron transport. Menaquinone profiles are strongly recommended for species classification when proposing a new Actinomycetes taxon. Presently, the most widely used methods to determine menaquinones are based on freeze-dried cells. Taxonomic research in our lab has revealed that menaquinone concentrations are low for some species of the genus Microbacterium, leading to difficulties in identifying menaquinones.

Results

Menaquinones extracted using the novel lysozyme-chloroform-methanol (LCM) method were comparable in quality to those obtained using the Collins method, the most widely used method. All tested strains extracted via the LCM method showed higher concentrations of menaquinones than those extracted via the Collins method. For some Microbacterium strains, the LCM method exhibited higher sensitivity than the Collins method, and more trace menaquinones were detected with the LCM method than the Collins method. In addition, LCM method is faster than the Collins method because it uses wet cells.

Conclusion

The LCM method is a simple, rapid and efficient technique for the extraction and identification of menaquinones from Actinomycetes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02240-z.

Marinisubtilis pacificus gen. nov., sp. nov., a Member of the Family Microbacteriaceae Isolated From a Deep-Sea Seamount

A Gram-stain-positive, yellow, aerobic, slender rod-shaped bacterial strain, designated KN1116^T, was isolated from a deep-sea seamount. Phylogenetic analysis based on 16S rRNA gene sequence showed that strain KN1116^T was related to the genus Chryseoglobus and had highest 16S rRNA gene sequence identity with Chryseoglobus frigidaquae CW1^T (98.5%). The predominant cellular fatty acids were anteiso-C_15:0 and iso-C_16:0. The quinone system for strain KN1116^T comprised menaquinone MK-12, MK-11, MK-10 and MK-13. The polar lipid profile contained diphosphatidylglycerol, phosphatidylglycerol, six unknown glycolipids, two unidentified phospholipids and one unknown polar lipid. The cell-wall peptidoglycan of strain KN1116^T was of the type B1β, containing 2,4-diaminobutyric acid as the diamino acid. Genome sequencing revealed the strain KN1116^T has a genome size of 2.7 Mbp and a G+C content of 69.4 mol%. Based on phenotypic, chemotaxonomic, phylogenetic and genomic data, strain KN1116^T represents a novel species of a novel genus of the family Microbacteriaceae, for which the name Marinisubtilis pacificus gen. nov., sp. nov. is proposed. The type strain of Marinisubtilis pacificus is KN1116^T (=CGMCC 1.17143^T =KCTC 49299^T).

Do combined nanoscale polystyrene and tetracycline impact on the incidence of resistance genes and microbial community disturbance in Enchytraeus crypticus?

It has been proved that nanoplastics can effectively adsorb pollutants and thus influence their behavior and availability. The combined toxic effects of nanoplastic and its adsorbed pollutant on the soil fauna are still not well known. We used high-throughput quantitative PCR to explore the effects of oral nanoscale polystyrene and tetracycline exposure on antibiotic resistance genes in the soil invertebrate Enchytraeus crypticus, and used bacterial 16S rRNA gene amplification sequencing to examine the response of the microbiome of E. crypticus. After 14 days of tetracycline and nanoscale polystyrene exposure, we terminated exposure and monitored the restoration of ARGs and microbiome in the E. crypticus. Results showed that the number of ARGs, especially macrolide-lincosamide-streptogramin B (MLSB), tetracycline ARGs, as well as multidrug ARGs, increased with exposure to nanoscale polystyrene and tetracycline. The abundance of Aminoglycoside and Beta_Lactamase ARGs in E. crypticus also significantly increased. The exposure significantly perturbed the abundance of families Microbacteriaceae, Streptococcaceae, Enterobacteriaceae, Rhodocyclaceae and Sphinomonadaceae. After terminating exposure for 14 days, the diversity and abundance of ARGs were not completely restored, while the microbiome was not permanently changed but reversibly impacted.

Presence of Legionella spp. in cooling towers: the role of microbial diversity, Pseudomonas, and continuous chlorine application

Legionnaires' disease (LD) is a severe pneumonia caused by several species of the genus Legionella, most frequently by Legionella pneumophila. Cooling towers are the most common source for large community-associated outbreaks. Colonization, survival, and proliferation of L. pneumophila in cooling towers are necessary for outbreaks to occur. These steps are affected by the chemical and physical parameters of the cooling tower environment. We hypothesize that the bacterial community residing in the cooling tower could also affect the presence of L. pneumophila. A 16S rRNA gene targeted amplicon sequencing approach was used to study the bacterial community of cooling towers and its relationship with the Legionella spp. and L. pneumophila communities. The results indicated that the water source shaped the bacterial community of cooling towers. Several taxa were enriched and positively correlated with Legionella spp. and L. pneumophila. In contrast, Pseudomonas showed a strong negative correlation with Legionella spp. and several other genera. Most importantly, continuous chlorine application reduced microbial diversity and promoted the presence of Pseudomonas creating a non-permissive environment for Legionella spp. This suggests that disinfection strategies as well as the resident microbial population influences the ability of Legionella spp. to colonize cooling towers.

Puzihella rosea gen. nov., sp. nov., a novel member of the family Microbacteriaceae isolated from freshwater

Two Gram-stain-positive, aerobic, pink, curved, rod-shaped, non-motile bacterial strains, designated MI-28T and SKY-11, were isolated from freshwater samples taken from a river and fish pond, respectively. Based on characterization using a polyphasic approach, the two strains showed highly similar phenotypic, physiological and genetic profiles. They demonstrated 99.9 % 16S rRNA gene sequence similarity and a 93-95 % DNA-DNA relatedness value, suggesting that they represent a single genomic species. Phylogenetic analyses, based on 16S rRNA gene sequences, showed that strains MI-28T and SKY-11 form a distinct lineage with respect to closely related genera within the family Microbacteriaceae of the class Actinobacteria, which is most closely related to Rhodoluna and Pontimonas, and levels of 16S rRNA gene sequence similarity with the type species of related genera were less than 95 %. Cell-wall analysis showed that the peptidoglycan contained 2,4-diaminobutyric acid, alanine, glycine and glutamic acid. The predominant fatty acids were iso-C14 : 0, anteiso-C15 : 0 and iso-C16 : 0. The polar lipid profile consisted of a mixture of phosphatidylglycerol, diphosphatidylglycerol, an uncharacterized glycolipid and an uncharacterized aminophospholipid. The major polyamine was putrescine. The major isoprenoid quinone was MK-10. The G+C content of DNA was between 62.6 and 62.9 mol%. On the basis of the genotypic and phenotypic data, strains MI-28T and SKY-11 represent a novel genus and species of the family Microbacteriaceae, for which the name Puzihella rosea gen. nov., sp. nov. is proposed. The type strain of the type species is MI-28T (=BCRC 80688T=LMG 27848T=KCTC 29239T).

Korean indigenous bacterial species with valid names belonging to the phylum Actinobacteria

To understand the isolation and classification state of actinobacterial species with valid names for Korean indigenous isolates, isolation source, regional origin, and taxonomic affiliation of the isolates were studied. At the time of this writing, the phylum Actinobacteria consisted of only one class, Actinobacteria, including five subclasses, 10 orders, 56 families, and 330 genera. Moreover, new taxa of this phylum continue to be discovered. Korean actinobacterial species with a valid name has been reported from 1995 as Tsukamurella inchonensis isolated from a clinical specimen. In 1997, Streptomyces seoulensis was validated with the isolate from the natural Korean environment. Until Feb. 2016, 256 actinobacterial species with valid names originated from Korean territory were listed on LPSN. The species were affiliated with three subclasses (Acidimicrobidae, Actinobacteridae, and Rubrobacteridae), four orders (Acidimicrobiales, Actinomycetales, Bifidobacteriales, and Solirubrobacterales), 12 suborders, 36 families, and 93 genera. Most of the species belonged to the subclass Actinobacteridae, and almost of the members of this subclass were affiliated with the order Actinomycetales. A number of novel isolates belonged to the families Nocardioidaceae, Microbacteriaceae, Intrasporangiaceae, and Streptomycetaceae as well as the genera Nocardioides, Streptomyces, and Microbacterium. Twenty-six novel genera and one novel family, Motilibacteraceae, were created first with Korean indigenous isolates. Most of the Korean indigenous actionobacterial species were isolated from natural environments such as soil, seawater, tidal flat sediment, and fresh-water. A considerable number of species were isolated from artificial resources such as fermented foods, wastewater, compost, biofilm, and water-cooling systems or clinical specimens. Korean indigenous actinobacterial species were isolated from whole territory of Korea, and especially a large number of species were from Jeju, Gyeonggi, Jeonnam, Daejeon, and Chungnam. A large number of novel actinobacterial species continue to be discovered since the Korean government is encouraging the search for new bacterial species and researchers are endeavoring to find out novel strains from extreme or untapped environments.

Lysinimonas soli gen. nov., sp. nov., isolated from soil, and reclassification of Leifsonia kribbensis Dastager et al. 2009 as Lysinimonas kribbensis sp. nov., comb. nov

A Gram-stain-positive, non-motile rod, designated strain SGM3-12T, was isolated from paddy soil in Suwon, Republic of Korea. 16S rRNA gene sequence analysis revealed that the strain represented a novel member of the family Microbacteriaceae . The nearest phylogenetic neighbour was Leifsonia kribbensis MSL-13T (97.4 % 16S rRNA gene sequence similarity). Strain SGM3-12T and Leifsonia kribbensis MSL-13T formed a distinct cluster within the family Microbacteriaceae . Strain SGM3-12T contained MK-12(H2) and MK-11(H2) as the predominant menaquinones with moderate amounts of MK-12 and MK-11; anteiso-C15 : 0 and iso-C16 : 0 as the major cellular fatty acids (>10 % of total); and diphosphatidylglycerol, phosphatidylglycerol and unidentified glycolipids as the polar lipids. The peptidoglycan type of the isolate was B1δ with l-Lys as the diagnostic cell-wall diamino acid. On the basis of these results, strain SGM3-12T represents a novel species within a new genus, for which the name Lysinimonas soli gen. nov., sp. nov. is proposed (the type strain of the type species is SGM3-12T = KACC 13362T = NBRC 107106T). It is also proposed that Leifsonia kribbensis be transferred to this genus as Lysinimonas kribbensis comb. nov. (the type strain is MSL-13T = DSM 19272T = JCM 16015T = KACC 21108T = KCTC 19267T).

Pontimonas salivibrio gen. nov., sp. nov., a new member of the family Microbacteriaceae isolated from a seawater reservoir of a solar saltern

A Gram-staining-positive, non-motile, strictly aerobic, non-spore-forming, vibrio-shaped bacterial strain, CL-TW6(T), was isolated from a reservoir seawater sample from a solar saltern in Korea. Analysis of the 16S rRNA gene sequence of strain CL-TW6(T) revealed a clear affiliation with the family Microbacteriaceae. Strain CL-TW6(T) showed the closest phylogenetic relationships with the genera Yonghaparkia and Microcella, with 16S rRNA gene sequence similarity of 94.8-95.3%. The strain grew in the presence of 1-9% sea salts, at 15-35 °C and at pH 7.0-9.0. The major cellular fatty acids of strain CL-TW6(T) were anteiso-C15:0 (32.6%), iso-C16:0 (20.4%), iso-C15:0 (13.2%) and iso-C14:0 (11.8%) and the major menaquinones were MK-9 and MK-10. Cell-wall analysis showed that the peptidoglycan of strain CL-TW6(T) contained 2,4-diaminobutyric acid, alanine, glycine and glutamic acid. The major polar lipids were diphosphatidylglycerol and phosphatidylglycerol. The genomic DNA G+C content of strain CL-TW6(T) was 60.0 mol%. The combined phenotypic, chemotaxonomic and phylogenetic data showed clearly that strain CL-TW6(T) could be distinguished from members of the family Microbacteriaceae with validly published names. Thus, strain CL-TW6(T) should be classified as representing a novel genus and species in the family Microbacteriaceae, for which the name Pontimonas salivibrio gen. nov., sp. nov. is proposed. The type strain of Pontimonas salivibrio is CL-TW6(T) (=KCCM 90105(T) =JCM 18206(T)).

Compostimonas suwonensis gen. nov., sp. nov., isolated from spent mushroom compost

A Gram-positive, aerobic, non-motile, short rod, designated SMC46T, was isolated from a spent mushroom compost sample collected in the Suwon region, South Korea. 16S rRNA gene sequence analysis revealed that strain SMC46T was a member of the family Microbacteriaceae ; however, the isolate formed a branch separate from other genera within the family. Sequence similarity between strain SMC46T and other members of the family Microbacteriaceae was ≤97 %, the highest sequence similarity being with Frigoribacterium faeni 801T and Frondihabitans australicus E1HC-02T (both 97.0 %). Some chemotaxonomic properties of strain SMC46T were consistent with those of the family Microbacteriaceae : MK-11 and MK-12 as the predominant menaquinones, anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0 as the major cellular fatty acids and diphosphatidylglycerol, phosphatidylglycerol and an unidentified glycolipid as the polar lipids. However, strain SMC46T contained a B-type peptidoglycan not previously found in the family Microbacteriaceae . The DNA G+C content was 68 mol%. On the basis of phenotypic, chemotaxonomic and phylogenetic distinctiveness, strain SMC46T was considered to represent a novel genus and species in the family Microbacteriaceae , for which the name Compostimonas suwonensis gen. nov., sp. nov. is proposed. The type strain of the type species is SMC46T ( = KACC 13354T  = NBRC 106304T).

Microbial deterioration of artistic tiles from the façade of the Grande Albergo Ausonia & Hungaria (Venice, Italy)

The Grande Albergo Ausonia & Hungaria (Venice Lido, Italy) has an Art Nouveau polychrome ceramic coating on its façade, which was restored in 2007. Soon after the conservation treatment, many tiles of the façade decoration showed coloured alterations putatively attributed to the presence of microbial communities. To confirm the presence of the biological deposit and the stratigraphy of the Hungaria tiles, stereomicroscope, optical and environmental scanning electron microscope observations were made. The characterisation of the microbial community was performed using a PCR-DGGE approach. This study reported the first use of a culture-independent approach to identify the total community present in biodeteriorated artistic tiles. The case study examined here reveals that the coloured alterations on the tiles were mainly due to the presence of cryptoendolithic cyanobacteria. In addition, we proved that the microflora present on the tiles was generally greatly influenced by the environment of the Hungaria hotel. We found several microorganisms related to the alkaline environment, which is in the range of the tile pH, and related to the aquatic environment, the presence of the acrylic resin Paraloid B72® used during the 2007 treatment and the pollutants of the Venice lagoon.

Marisediminicola antarctica gen. nov., sp. nov., an actinobacterium isolated from the Antarctic

Strain ZS314T was isolated from a sandy intertidal sediment sample collected from the coastal area off the Chinese Antarctic Zhongshan Station, east Antarctica (6 ° 22′ 13″ S 7 ° 21′ 41″ E). The cells were Gram-positive, motile, short rods. The temperature range for growth was 0–26 °C and the pH for growth ranged from 5 to 10, with optimum growth occurring within the temperature range 18–23 °C and pH range 6.0–8.0. Growth occurred in the presence of 0–6 % (w/v) NaCl, with optimum growth occurring in the presence of 2–4 % (w/v) NaCl. Strain ZS314T had MK-10 as the major menaquinone and anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0 as major fatty acids. The cell-wall peptidoglycan type was B2β with ornithine as the diagnostic diamino acid. The major polar lipids were diphosphatidylglycerol and phosphatidylglycerol. The genomic DNA G+C content was approximately 67 mol%. Phylogenetic analysis based on 16S rRNA gene sequence similarity showed that strain ZS314T represents a new lineage in the family Microbacteriaceae. On the basis of the phylogenetic analyses and phenotypic characteristics, a new genus, namely Marisediminicola gen. nov., is proposed, harbouring the novel species Marisediminicola antarctica sp. nov. with the type strain ZS314T (=DSM 22350T =CCTCC AB 209077T).

Reclassification of Leifsonia ginsengi (Qiu et al. 2007) as Herbiconiux ginsengi gen. nov., comb. nov. and description of Herbiconiux solani sp. nov., an actinobacterium associated with the phyllosphere of Solanum tuberosum L

In the context of studying the effects of transgenic fructan-producing potatoes on the community structure of phyllosphere bacteria, a group of strains closely related to the species Leifsonia ginsengi was isolated. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the new isolates and L. ginsengi DSM 19088(T) formed a lineage at the genus level and this finding was supported by chemotaxonomic characterization. The peptidoglycan type of the representative isolate, K134/01(T), and L. ginsengi DSM 19088(T) was B2γ, with d- and l-diaminobutyric acid as the diagnostic diamino acid and glycine, alanine and threo-3-hydroxyglutamic acid. The almost-complete substitution of glutamic acid by threo-3-hydroxyglutamic acid supported the differentiation of the new strains from recognized species of the genus Leifsonia. Furthermore, the detection of substantial amounts of the fatty acid cyclohexyl-C(17 : 0) in the new isolates and L. ginsengi DSM 19088(T) was a prominent chemotaxonomic feature for a clear demarcation of these strains from all genera of the family Microbacteriaceae that display the B2γ cell-wall type. Comparative phylogenetic and phenotypic analyses of the isolates and L. ginsengi DSM 19088(T) revealed the separate species status of the isolates. On the basis of these results, it is proposed that L. ginsengi should be classified as the type species of a novel genus, Herbiconiux gen. nov., with the name Herbiconiux ginsengi gen. nov., comb. nov. (type strain wged11(T) = CGMCC 4.3491(T) = JCM 13908(T) = DSM 19088(T) = NBRC 104580(T)). The phyllosphere isolates are assigned to a novel species, Herbiconiux solani sp. nov. (type strain K134/01(T) = DSM 19813(T) = LMG 24387(T) = NBRC 106740(T)).

Chryseoglobus frigidaquae gen. nov., sp. nov., a novel member of the family Microbacteriaceae

A motile, rod-shaped, yellow-pigmented bacterium, designated strain CW1(T), was isolated from a water-cooling system in the Republic of Korea. Cells were Gram-stain-positive, aerobic, catalase-positive and oxidase-negative. Strain CW1(T) formed slender rods with unusual bulbous protuberances. The major fatty acids were iso-C(16 : 1) (33.7 %), anteiso-C(15 : 0) (27.2 %), iso-C(14 : 0) (13.3 %) and C(16 : 0) (10.8 %). The cell-wall peptidoglycan was of type B2beta, containing lysine as the diamino acid. The respiratory quinones were menaquinones with 12, 13 and 14 isoprene units. A phylogenetic tree based on 16S rRNA gene sequences showed that strain CW1(T) formed an evolutionary lineage within the radiation enclosing members of the family Microbacteriaceae and was related to, but distant from, members of the genera Microcella and Yonghaparkia. On the basis of the evidence presented, strain CW1(T) is considered to represent a novel species of a new genus in the family Microbacteriaceae, for which the name Chryseoglobus frigidaquae gen. nov., sp. nov. is proposed. The type strain of Chryseoglobus frigidaquae is CW1(T) (=KCTC 13142(T) =JCM 14730(T)).

An update of the structure and 16S rRNA gene sequence-based definition of higher ranks of the class Actinobacteria, with the proposal of two new suborders and four new families and emended descriptions of the existing higher taxa

The higher ranks of the class Actinobacteria were proposed and described in 1997. At each rank, the taxa were delineated from each other solely on the basis of 16S rRNA gene sequence phylogenetic clustering and taxon-specific 16S rRNA signature nucleotides. In the past 10 years, many novel members have been assigned to this class while, at the same time, some members have been reclassified. The new 16S rRNA gene sequence information and the changes in phylogenetic positions of some taxa influence decisions about which 16S rRNA nucleotides to define as taxon-specific. As a consequence, the phylogenetic relationships of Actinobacteria at higher levels may need to be reconstructed. Here, we present new 16S rRNA signature nucleotide patterns of taxa above the family level and indicate the affiliation of genera to families. These sets replace the signatures published in 1997. In addition, Actinopolysporineae subord. nov. and Actinopolysporaceae fam. nov. are proposed to accommodate the genus Actinopolyspora, Kineosporiineae subord. nov. and Kineosporiaceae fam. nov. are proposed to accommodate the genera Kineococcus, Kineosporia and Quadrisphaera, Beutenbergiaceae fam. nov. is proposed to accommodate the genera Beutenbergia, Georgenia and Salana and Cryptosporangiaceae fam. nov. is proposed to accommodate the genus Cryptosporangium. The families Nocardiaceae and Gordoniaceae are proposed to be combined in an emended family Nocardiaceae. Emended descriptions are also proposed for most of the other higher taxa.

Isolation of bacteria whose growth is dependent on high levels of CO2 and implications of their potential diversity

Although some bacteria require an atmosphere with high CO(2) levels for their growth, CO(2) is not generally supplied to conventional screening cultures. Here, we isolated 84 bacterial strains exhibiting high-CO(2) dependence. Their phylogenetic affiliations imply that high-CO(2) culture has potential as an effective method to isolate unknown microorganisms.

Labedella gwakjiensis gen. nov., sp. nov., a novel actinomycete of the family Microbacteriaceae

A Gram-positive, non-motile, non-mycelium-forming, rod-shaped actinomycete, designated KSW2-17T, was isolated from dried seaweed collected from beach sand along the coast of Jeju, Republic of Korea. The organism had ornithine as the diagnostic cell-wall diamino acid, MK-10 and MK-11 as the major menaquinones, and phosphatidylglycerol and diphosphatidylglycerol as polar lipids. The fatty acid profile included predominantly iso- and anteiso-branched acids and a minor amount of tuberculostearic acid (10-methyl C18 : 0). The DNA G+C content was 68.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that the seaweed isolate formed a distinct clade within the radiation of the family Microbacteriaceae and had highest sequence similarity (96.1–96.3 %) to members of the genera Cryobacterium, Frigoribacterium and Rathayibacter. On the basis of phenotypic and genotypic evidence, strain KSW2-17T is considered to represent a novel species of a new genus, for which the name Labedella gwakjiensis gen. nov., sp. nov. is proposed. The type strain is KSW2-17T (=JCM 14008T=KCTC 19176T).

Gene Sequence Phylogenies of the Family Microbacteriaceae

The type strains of 32 species of 13 genera of the family Microbacteriaceae were analysed with respect to gene-coding phylogeny for DNA gyrase subunit B (gyrB), RNA-polymerase subunit B (rpoB), recombinase A (recA), and polyphosphate kinase (ppk). The resulting gene trees were compared with the 16S rRNA gene phylogeny of the same strains. The topology of neighbour-joining and maximum parsimony phylogenetic trees, based on nucleic-acid sequences and protein sequences of housekeeping genes, differed from one another, and no gene tree was identical to that of the 16S rRNA gene tree. Most genera analysed containing >1 strain formed phylogenetically coherent taxa. The three pathovars of Curtobacterium flaccumfaciens clustered together to the exclusion of the type strains of other Curtobacterium species in all DNA - and protein-based analyses. In no tree did the distribution of a major taxonomic marker, i.e., diaminobutyric acid versus lysine and/or ornithine in the peptidoglycan, or acyl type of peptidoglycan, correlate with the phylogenetic position of the organisms. The changing phylogenetic position of Agrococcus jenensis was unexpected: This strain defined individual lineages in the trees based on 16S rRNA and gyrB and showed identity with Microbacterium saperdae in the other three gene trees.