Lentzea sokolovensis sp. nov., Lentzea kristufekii sp. nov. and Lentzea miocenica sp. nov., rare actinobacteria from Miocene lacustrine sediment of the Sokolov Coal Basin, Czech Republic.

The taxonomic position of three actinobacterial strains, BCCO 10_0061T, BCCO 10_0798T, and BCCO 10_0856T, recovered from bare soil in the Sokolov Coal Basin, Czech Republic, was established using a polyphasic approach. The multilocus sequence analysis based on 100 single-copy genes positioned BCCO 10_0061T in the same cluster as Lentzea waywayandensis, strain BCCO 10_0798T in the same cluster as Lentzea flaviverrucosa, Lentzea californiensis, Lentzea violacea, and Lentzea albidocapillata, and strain BCCO 10_0856T clustered together with Lentzea kentuckyensis and Lentzea alba. Morphological and chemotaxonomic characteristics of these strains support their assignment to the genus Lentzea. In all three strains, MK-9(H4) accounted for more than 80 % of the isoprenoid quinone. The diagnostic diamino acid in the cell-wall peptidoglycan was meso-diaminopimelic acid. The whole-cell sugars were rhamnose, ribose, mannose, glucose, and galactose. The major fatty acids (>10 %) were iso-C15 : 0, anteiso-C15 : 0, iso-C16 : 0, and C16 : 0. The polar lipids were diphosphatidylglycerol, methyl-phosphatidylethanolamine, phosphatidylethanolamine, hydroxy-phosphatidylethanolamine, phosphatidylglycerol, and phosphatidylinositol. The genomic DNA G+C content of strains (mol%) was 68.8 for BCCO 10_0061T, 69.2 for BCCO 10_0798T, and 68.5 for BCCO 10_0856T. The combination of digital DNA-DNA hybridization results, average nucleotide identity values and phenotypic characteristics of BCCO 10_0061T, BCCO 10_0798T, and BCCO 10_0856T distinguishes them from their closely related strains. Bioinformatic analysis of the genome sequences of the strains revealed several biosynthetic gene clusters (BGCs) with identities >50 % to already known clusters, including BGCs for geosmin, coelichelin, ε-poly-l-lysine, and erythromycin-like BGCs. Most of the identified BGCs showed low similarity to known BGCs (<50 %) suggesting their genetic potential for the biosynthesis of novel secondary metabolites. Based on the above results, each strain represents a novel species of the genus Lentzea, for which we propose the name Lentzea sokolovensis sp. nov. for BCCO 10_0061T (=DSM 116175T), Lentzea kristufekii sp. nov. for BCCO 10_0798T (=DSM 116176T), and Lentzea miocenica sp. nov. for BCCO 10_0856T (=DSM 116177T).

Proposal of Shuttleworthella gen. nov. and Nostocoides gen. nov. as replacement names for the illegitimate prokaryotic generic names Shuttleworthia and Tetrasphaera, respectively.

The prokaryotic generic name Shuttleworthia Downes et al. 2002 is illegitimate because it is a later homonym of the plant genus Shuttleworthia Meisner 1840 and the mollusk genus Shuttleworthia Baker 1941 (Principle 2 and Rule 51b(5) of the International Code of Nomenclature of Prokaryotes). We therefore propose the replacement generic name Shuttleworthella, with type species Shuttleworthella satelles comb. nov. The prokaryotic generic name Tetrasphaera Maszenan et al. 2000 is illegitimate because it is a later homonym of Tetrasphaera Popofsky 1913 (Protozoa, Radiolaria) and of Tetrasphaera Górka 1965 (a fossil dinoflagellate) (Rule 51b(4) of the International Code of Nomenclature of Prokaryotes). We therefore propose the replacement generic name Nostocoides, with type species Nostocoides japonicum comb. nov.

Isoptericola luteus sp. nov., a novel yellow bacterium isolated from soil.

An aerobic, non-motile, Gram-stain-positive bacterium, designated strain NEAU-Y5T, was isolated from a soil sample collected from Northeast Agricultural University, Heilongjiang province. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NEAU-Y5T belonged to the genus and showed high 16S rRNA sequence similarity to Isoptericola variabilis (98.9 %), Isoptericola nanjingensis (98.9 %), Isoptericola cucumis (98.5 %), Isoptericola hypogeus (98.5 %), Isoptericola dokdonensis (98.5 %), Isoptericola jiangsuensis (98.3 %), and Isoptericola halalbus (98.1 %), followed by other members of the genus Isoptericola (<98 %), and phylogenetically clustered with I. dokdonensis and I. jiangsuensis. Strain NEAU-Y5T was found to grow at 4-40 °C (optimum, 28 °C), pH 6.0-12.0 (optimum, pH 7.0), and tolerated 0-6 % NaCl (w/v). The cell-wall peptidoglycan type was l-Lys-d-Asp. The whole-cell hydrolysates contained glucose, galactose, and ribose. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, hydroxyphosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside, and glucosamine unknown phospholipid. Major fatty acids were anteiso-C15 : 0 and anteiso-C17 : 0. The predominant menaquinone was MK-9(H4). The DNA G+C content was 73.4 mol%. The digital DNA-DNA hybridization and average nucleotide identity values between strain NEAU-Y5T and the type strains of the genus Isoptericola ranged from 18.6 to 23.5 % and from 77.3 to 81.6 %, respectively. Based on morphological, physiological, chemotaxonomic, and phylogenetic data, as well as digital DNA-DNA hybridization and average nucleotide identity values, the novel strain NEAU-Y5T could be differentiated from its closest relatives. Therefore, the strain represents a novel species of the genus Isoptericola, for which the name Isoptericola luteus sp. nov. is proposed. The type strain is NEAU-Y5T (=CCTCC AA 2019087T=DSM 110637T).

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

The taxonomic position of strain BMG 8361T, isolated from sandstone collected in the Sahara Desert of Southern Tunisia, was refined through a polyphasic taxonomic investigation. Colonies of BMG 8361T were pale-orange coloured, irregular with a dry surface and produced a diffusible pink or brown pigment depending on media. The Gram-positive cells were catalase-positive and oxidase-negative. The strain exhibited growth at 10-40 °C and pH values ranging from 5.5 to 9.0, with optima at 28-35 °C and pH 6.5-8.0. Additionally, BMG 8361T demonstrated the ability to grow in the presence of up to 1 % NaCl (w/v) concentration. The peptidoglycan of the cell wall contained meso-diaminopimelic acid, glucose, galactose, xylose, ribose, and rhamnose. The predominant menaquinones consisted of MK-9(H4) and MK-9. The main polar lipids were phosphatidylcholine, phosphatidylinositol, glycophosphatidylinositol, diphosphatidylglycerol, phosphatidylethanolamine, and two unidentified lipids. Major cellular fatty acids were iso-C16 : 0, iso-C16 : 1 h, and C17 : 1 ω8c. Phylogenetic analyses based on both the 16S rRNA gene and whole-genome sequences assigned strain BMG 8361T within the genus Blastococcus. The highest pairwise sequence similarity observed in the 16S rRNA gene was 99.5 % with Blastococcus haudaquaticus AT 7-14T. However, when considering digital DNA-DNA hybridization and average nucleotide identity, the highest values, 48.4 and 86.58 %, respectively, were obtained with Blastococcus colisei BMG 822T. These values significantly undershoot the recommended thresholds for establishing new species, corroborating the robust support for the distinctive taxonomic status of strain BMG 8361T within the genus Blastococcus. In conjunction with the phenotyping results, this compelling evidence leads to the proposal of a novel species we named Blastococcus brunescens sp. nov. with BMG 8361T (=DSM 46845T=CECT 8880T) as the type strain.

The comparative plastisphere microbial community profile at Kung Wiman beach unveils potential plastic-specific degrading microorganisms.

Background: Plastic waste is a global environmental issue that impacts the well-being of humans, animals, plants, and microorganisms. Microplastic contamination has been previously reported at Kung Wiman Beach, located in Chanthaburi province along with the Eastern Gulf of Thailand. Our research aimed to study the microbial population of the sand and plastisphere and isolate microorganisms with potential plastic degradation activity. Methods: Plastic and sand samples were collected from Kung Wiman Beach for microbial isolation on agar plates. The plastic samples were identified by Fourier-transform infrared spectroscopy. Plastic degradation properties were evaluated by observing the halo zone on mineral salts medium (MSM) supplemented with emulsified plastics, including polystyrene (PS), polylactic acid (PLA), polyvinyl chloride (PVC), and bis (2-hydroxyethyl) terephthalate (BHET). Bacteria and fungi were identified by analyzing nucleotide sequence analysis of the 16S rRNA and internal transcribed spacer (ITS) regions, respectively. 16S and ITS microbiomes analysis was conducted on the total DNA extracted from each sample to assess the microbial communities. Results: Of 16 plastic samples, five were identified as polypropylene (PP), four as polystyrene (PS), four as polyethylene terephthalate (PET), two as high-density polyethylene (HDPE), and one sample remained unidentified. Only 27 bacterial and 38 fungal isolates were found to have the ability to degrade PLA or BHET on MSM agar. However, none showed degradation capabilities for PS or PVC on MSM agar. Notably, Planococcus sp. PP5 showed the highest hydrolysis capacity of 1.64 ± 0.12. The 16S rRNA analysis revealed 13 bacterial genera, with seven showing plastic degradation abilities: Salipiger, Planococcus, Psychrobacter, Shewanella, Jonesia, Bacillus, and Kocuria. This study reports, for the first time of the BHET-degrading properties of the genera Planococcus and Jonesia. Additionally, The ITS analysis identified nine fungal genera, five of which demonstrated plastic degradation abilities: Aspergillus, Penicillium, Peacilomyces, Absidia, and Cochliobolus. Microbial community composition analysis and linear discriminant analysis effect size revealed certain dominant microbial groups in the plastic and sand samples that were absent under culture-dependent conditions. Furthermore, 16S and ITS amplicon microbiome analysis revealed microbial groups were significantly different in the plastic and sand samples collected. Conclusions: We reported on the microbial communities found on the plastisphere at Kung Wiman Beach and isolated and identified microbes with the capacity to degrade PLA and BHET.

Improving the production of carbamoyltobramycin by an industrial Streptoalloteichus tenebrarius through metabolic engineering.

Tobramycin is an essential and extensively used broad-spectrum aminoglycoside antibiotic obtained through alkaline hydrolysis of carbamoyltobramycin, one of the fermentation products of Streptoalloteichus tenebrarius. To simplify the composition of fermentation products from industrial strain, the main byproduct apramycin was blocked by gene disruption and constructed a mutant mainly producing carbamoyltobramycin. The generation of antibiotics is significantly affected by the secondary metabolism of actinomycetes which could be controlled by modifying the pathway-specific regulatory proteins within the cluster. Within the tobramycin biosynthesis cluster, a transcriptional regulatory factor TobR belonging to the Lrp/AsnC family was identified. Based on the sequence and structural characteristics, tobR might encode a pathway-specific transcriptional regulatory factor during biosynthesis. Knockout and overexpression strains of tobR were constructed to investigate its role in carbamoyltobramycin production. Results showed that knockout of TobR increased carbamoyltobramycin biosynthesis by 22.35%, whereas its overexpression decreased carbamoyltobramycin production by 10.23%. In vitro electrophoretic mobility shift assay (EMSA) experiments confirmed that TobR interacts with DNA at the adjacent tobO promoter position. Strains overexpressing tobO with ermEp* promoter exhibited 36.36% increase, and tobO with kasOp* promoter exhibited 22.84% increase in carbamoyltobramycin titer. When the overexpressing of tobO and the knockout of tobR were combined, the production of carbamoyltobramycin was further enhanced. In the shake-flask fermentation, the titer reached 3.76 g/L, which was 42.42% higher than that of starting strain. Understanding the role of Lrp/AsnC family transcription regulators would be useful for other antibiotic biosynthesis in other actinomycetes. KEY POINTS: • The transcriptional regulator TobR belonging to the Lrp/AsnC family was identified.  • An oxygenase TobO was identified within the tobramycin biosynthesis cluster. • TobO and TobR have significant effects on the synthesis of carbamoyltobramycin.

Resuscitation of baijiu pit mud bacteria based on Rpf protein of Umezawaea beigongshangensis.

The pit mud in the Baijiu fermentation cellar is an abundant microbial resource that is closely related to the quality of baijiu. However, many naturally existing species might be in a viable but nonculturable (VBNC) state, posing challenges to the isolation and application of functional species. Herein, a previously isolated strain from baijiu mash, Umezawaea beigongshangensis, was found to contain the rpf gene that encodes resuscitation promotion factor (Rpf). Therefore, the gene was cloned and heterologously expressed, and the recombinant protein (Ub-Rpf 2) was purified. Ub-Rpf 2 was found to significantly promote the growth of resuscitated VBNC state Corynebacterium beijingensis and Sphingomonas beigongshangensis. To determine the resuscitation effect of Ub-Rpf 2 on real ecological samples, the protein was supplemented in pit mud for enrichment culture. Results revealed that specific families and genera were enriched in abundance upon Ub-Rpf 2 incubation, including a new family of Symbiobacteraceae and culturable Symbiobacterium genus. Furthermore, 14 species belonging to 12 genera were obtained in Ub-Rpf 2 treated samples, including a suspected novel species. This study lays a foundation for applying Rpf from U. beigongshangensis to exploit microbial resources in baijiu pit mud.

Discovery of sesquiterpenoids from an actinomycete Crossiella cryophila through genome mining and heterologous expression.

Genome mining of the Actinomycete Crossiella cryophila facilitated the discovery of a minimal terpenoid biosynthetic gene cluster of cry consisting of a class I terpene cyclase CryA and a CYP450 monooxygenase CryB. Heterologous expression of cry allowed the isolation and characterization of two new sesquiterpenoids, ent-viridiflorol (1) and cryophilain (2). Notably, cryophilain (2) possesses a 5/7/3-fused tricyclic skeleton bearing a distinctive bridgehead hydroxy group. The combined in vivo and in vitro experiments revealed that CryA, the first ent-viridiflorol terpene cyclase, catalyzes farnesyl diphosphate to form the 5/7/3 sesquiterpene core scaffold and P450 CryB serves as a tailoring enzyme responsible for installing a hydroxy group at the bridgehead carbon.

Potential of different species of actinobacteria in the management of Meloidogyne javanica.

Root-knot nematodes (RKN) are one of the most harmful soil-borne plant pathogens in the world. Actinobacteria are known phytopathogen control agents. The aim of this study was to select soil actinobacteria with control potential against the RKN (Meloidogyne javanica) in tomato plants and to determine mechanisms of action. Ten isolates were tested and a significant reduction was observed in the number of M. javanica eggs, and galls 46 days after infestation with the nematode. The results could be explained by the combination of different mechanisms including parasitism and induction of plant defense response. The M. javanica eggs were parasited by all isolates tested. Some isolates reduced the penetration of juveniles into the roots. Other isolates using the split-root method were able to induce systemic defenses in tomato plants. The 4L isolate was selected for analysis of the expression of the plant defense genes TomLoxA, ACCO, PR1, and RBOH1. In plants treated with 4L isolate and M. javanica, there was a significant increase in the number of TomLoxA and ACCO gene transcripts. In plants treated only with M. javanica, only the expression of the RBOH1 and PR1 genes was induced in the first hours after infection. The isolates were identified using 16S rRNA gene sequencing as Streptomyces sp. (1A, 3F, 4L, 6O, 8S, 9T, and 10U), Kribbella sp. (5N), Kitasatospora sp. (2AE), and Lentzea sp. (7P). The efficacy of isolates from the Kitasatospora, Kribbella, and Lentzea genera was reported for the first time, and the efficacy of Streptomyces genus isolates for controlling M. javanica was confirmed. All the isolates tested in this study were efficient against RKN. This study provides the opportunity to investigate bacterial genera that have not yet been explored in the control of M. javanica in tomatoes and other crops.

Streptomycetes as Microbial Cell Factories for the Biotechnological Production of Melanin.

Melanins are complex, polymeric pigments with interesting properties like UV-light absorbance ability, metal ion chelation capacity, antimicrobial action, redox behaviors, and scavenging properties. Based on these characteristics, melanins might be applied in different industrial fields like food packaging, environmental bioremediation, and bioelectronic fields. The actual melanin manufacturing process is not environmentally friendly as it is based on extraction and purification from cuttlefish. Synthetic melanin is available on the market, but it is more expensive than animal-sourced pigment and it requires long chemical procedures. The biotechnological production of microbial melanin, instead, might be a valid alternative. Streptomycetes synthesize melanins as pigments and as extracellular products. In this review, the melanin biotechnological production processes by different Streptomyces strains have been revised according to papers in the literature. The different fermentation strategies to increase melanin production such as the optimization of growth conditions and medium composition or the use of raw sources as growth substrates are here described. Diverse downstream purification processes are also reported as well as all the different analytical methods used to characterize the melanin produced by Streptomyces strains before its application in different fields.

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.

Bosea beijingensis sp. nov., Telluria beijingensis sp. nov. and Agrococcus beijingensis sp. nov., isolated from baijiu mash.

The baijiu fermentation environment hosts a variety of micro-organisms, some of which still remain uncultured and uncharacterized. In this study, the isolation, cultivation and characterization of three novel aerobic bacterial strains are described. The cells of strain REN20T were Gram-negative, strictly aerobic, motile and grew at 26-37 °C, at pH 6.0-9.0 and in the presence of 0-5.0   % (w/v) NaCl. The cells of strain REN29T were Gram-negative, strictly aerobic, motile and grew at 15-30 °C, at pH 6.0-9.0 and in the presence of 0-10.0   % (w/v) NaCl. The cells of strain REN33T were Gram-positive, strictly aerobic, motile and grew at 15-37 °C, at pH 5.0-10.0 and in the presence of 0-7.0   % (w/v) NaCl. The digital DNA-DNA hybridization and average nucleotide identity by orthology values between type strains in related genera and REN20T (20.3-36.8 % and 79.8-89.9  %), REN29T (20.3-36.8  % and 74.5-88.5  %) and REN33T (22.6-48.6  % and 75.8-84.2  %) were below the standard cut-off criteria for the delineation of bacterial species, respectively. Based on polyphasic taxonomy analysis, we propose three new species, Bosea beijingensis sp. nov. (=REN20T=GDMCC 1.2894T=JCM 35118T), Telluria beijingensis sp. nov. (=REN29T=GDMCC 1.2896T=JCM 35119T) and Agrococcus beijingensis sp. nov. (=REN33T=GDMCC 1.2898T=JCM 35164T), which were recovered during cultivation and isolation from baijiu mash.

Rathayibacter tanaceti sp. nov., a Novel Actinobacterium from Tanacetum vulgare Infested by Foliar Nematode Aphelenchoides sp.

Two novel yellow-pigmented, rod-shaped and non-motile coryneform actinobacteria, strains VKM Ac-2596T and VKM Ac-2761, were isolated from a plant Tanacetum vulgare (Asteraceae) infested by foliar nematode Aphelenchoides sp. The strains exhibited the highest 16S rRNA gene sequence similarities to Rathayibacter agropyri CA4T (99.71%), Rathayibacter rathayi DSM 7485T (99.65%) and Rathayibacter iranicus VKM Ac-1602T (99.65%). The pairwise average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between VKM Ac-2596T and VKM Ac-2671 towards the type strains of Rathayibacter species did not exceed 85.24% and 29.40%, respectively, that are well below the thresholds for species delineation. The target strains had key chemotaxonomic properties typical of the genus Rathayibacter, namely, the DAB-based peptidoglycan, rhamnose and mannose as the predominant sugars and a rhamnomannan in the cell, the major menaquinone MK-10 and fatty acids of iso-anteiso type, with a large proportion of anteiso-15:0. The strains showed clear differences from the recognized Rathayibacter species in several phenotypic characteristics, including the difference in the composition of cell wall glycopolymers. Based on the results obtained in this study and the data published previously, we provide a description of a new species, Rathayibacter tanaceti sp. nov., with DL-642T (= VKM Ac-2596T = LMG 33114T) as the type strain.

Sciscionella sediminilitoris sp. nov., a Marine Actinomycete Isolated from Cape Rochado, Malaysia, and the Emendations to the Description of the Genus Sciscionella.

In this study, we employed a polyphasic approach to determine the taxonomic position of a newly isolated actinomycete, designated SE31T, obtained from a sediment sample collected at Cape Rochado, Malaysia. Phylogenetic analysis of the 16S rRNA gene sequence revealed that strain SE31T belonged to the family Pseudonocardiaceae and exhibited the highest sequence similarity (98.9%) to Sciscionella marina. Further genomic analysis demonstrated a 93.4% average nucleotide identity and 54.4% digital DNA-DNA hybridization relatedness between strain SE31T and S. marina. The chemotaxonomic characteristics of strain SE31T were typical of the genus Sciscionella, including cell-wall chemotype IV (with meso-diaminopimelic acid as the diagnostic diamino acid, and arabinose and galactose as whole-cell sugars). The identified polar lipids of strain SE31T were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylmethylethanolamine, and hydroxyphosphatidymethylethanolamine. The primary menaquinone observed was MK-9(H4), and the major cellular fatty acid was iso-C16:0. The genomic DNA size of strain SE31T was determined to be 7.4 Mbp with a G+C content of 68.7%. Based on these comprehensive findings, strain SE31T represents a novel species within the genus Sciscionella, in which the name Sciscionella sediminilitoris sp. nov. is proposed. The type strain of Sciscionella sediminilitoris is SE31T (= DSM 46824T = TBRC 5134T).

Biodegradation of polystyrene and polyethylene by Microbacterium esteraromaticum SW3 isolated from soil.

Plastic pollution is a common concern of global environmental pollution. Polystyrene (PS) and polyethylene (PE) account for almost one-third of global plastic production. However, so far, there have been few reports on microbial strains capable of simultaneously degrading PS and PE. In this study, Microbacterium esteraromaticum SW3, a non-pathogenic microorganism that can use PS or PE as the only carbon source in the mineral salt medium (MM), was isolated from plastics-contaminated soil and identified. The optimal growth conditions for SW3 in MM were 2% (w/v) PS or 2% (w/v) PE, 35°C and pH 6.3. A large number of bacteria and obvious damaged areas were observed on the surface of PS and PE products after inoculated with SW3 for 21 d. The degradation rates of PS and PE by SW3 (21d) were 13.17% and 5.39%, respectively. Manganese peroxidase and lipase were involved in PS and PE degradation by SW3. Through Fourier infrared spectroscopy detection, different functional groups such as carbonyl, hydroxyl and amidogen groups were produced during the degradation of PS and PE by SW3. Moreover, PS and PE were degraded into alkanes, ketones, carboxylic acids, esters and so on detected by GC-MS. Collectively, we have isolated and identified SW3, which can use PS or PE as the only carbon source in MM as well as degrade PS and PE products. This study not only provides a competitive candidate strain with broad biodegradability for the biodegradation of PS and/or PE pollution, but also provides new insights for the study of plastic biodegradation pathways.

Curtobacterium salicis sp. nov., isolated from willow tree stems in Washington state.

Curtobacterium sp. strain WW7 is a Gram-positive, non-motile, orange rod-shaped bacterium isolated from branches of wild willow (Salix sitchensis) trees. The WW7T strain has optimum growth in the temperature range between 25 and 30 °C, a pH range of 6-7.7, and tolerates up to 5.5% (w/v) of NaCl. The genome sequencing of strain WW7T revealed a genome size of approximately 3.8 Mbp and a G + C content of 71.3 mol%. The phylogenomic analyses support the WW7T affiliation to a novel Curtobacterium lineage, with Curtobacterium herbarum being the closest type-strain. Chemotaxonomic analysis indicates that the carbon sources assimilation profile of strain WW7T was similar to the type strains, i.e. Curtobacterium luteum, Curtobacterium albidum, and Curtobacterium flaccumfaciens, while no assimilation of the organic acids succinate, alpha-ketobutyrate, mono methyl-succinate, and lactate was observed. Finally, fatty acid methyl ester analysis identifies anteiso-C15:0 and anteiso-C17:0 as major cellular fatty acids which is a common feature for members of the Curtobacterium genus. Based on the results of phylogenomic and chemotaxonomic analyses, strain WW7T represents a novel Curtobacterium lineage, for which the name Curtobacterium salicis sp. nov. is proposed. The type strain is WW7T (DSM 34805T-NRRL B-68078T).

Actinomycetospora lemnae sp. nov., A Novel Actinobacterium Isolated from Lemna aequinoctialis Able to Enhance Duckweed Growth.

Duckweed-associated actinobacteria are co-existing microbes that affect duckweed growth and adaptation. In this study, we aimed to report a novel actinobacterium species and explore its ability to enhance duckweed growth. Strain DW7H6T was isolated from duckweed, Lemna aequinoctialis. Phylogenetic analysis based on its 16S rRNA gene sequence revealed that the strain was most closely related to Actinomycetospora straminea IY07-55T (99.0%), Actinomycetospora chibensis TT04-21T (98.9%), Actinomycetospora lutea TT00-04T (98.8%) and Actinomycetospora callitridis CAP 335T (98.4%). Chemotaxonomic and morphological characteristics of strain DW7H6T were consistent with members of the genus Actinomycetospora, while average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) between the draft genomes of this strain and its closely related type strains were below the proposed threshold values used for species discrimination. Based on chemotaxonomic, phylogenetic, phenotypic, and genomic evidence obtained, we describe a novel Actinomycetospora species, for which the name Actinomycetospora lemnae sp. nov. is proposed. The type strain is DW7H6T (TBRC 15165T, NBRC 115294T). Additionally, the duckweed-associated actinobacterium strain DW7H6T was able to enhance duckweed growth when compared to the control, in which the number of fronds and biomass dry weight were increased by up to 1.4 and 1.3 fold, respectively. Moreover, several plant-associated gene features in the genome of strain DW7H6T potentially involved in plant-microbe interactions were identified.

Glycomyces niveus sp. nov., a novel actinomycete isolated from sandy soil.

A novel mycelium-forming actinomycete, designated strain NEAU-S30T, was isolated from the sandy soil of a sea beach in Shouguang city, Shandong province, PR China. The strain developed long chains of non-motile cylindrical spores with smooth surfaces on aerial mycelia. The results of a polyphasic taxonomic study indicated that NEAU-S30T represented a member of the genus Glycomyces. The results of 16S rRNA gene sequence analysis indicated that NEAU-S30T was closely related to 'Glycomycesluteolus' (98.97 % sequence similarity), Glycomycesalgeriensis (98.90 %), 'Glycomyces tritici' (98.83 %) and Glycomyces lechevalierae (98.76 %). The average nucleotide identity (ANI) values between NEAU-S30T and 'G. luteolus' NEAU-A15, G. algeriensis DSM 44727T, 'G. tritici' NEAU-C2 and G. lechevalierae DSM 44724T were 87.77, 87.53, 87.41 and 87.80 %, respectively. The digital DNA G+C content of the genomic DNA was 70.5 %. The whole-cell sugars contained ribose and xylose. The predominant menaquinones were MK-10(H2), MK-10(H4) and MK-10(H6). The predominant fatty acids were anteiso-C15 : 0, iso-C16 : 0, anteiso-C17 : 0 and iso-C15 : 0. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphoglycolipid, phosphatidylinositol, phosphatidylinositol mannoside and an unidentified glycolipid. On the basis of the results of comparative analysis of genotypic, phenotypic and chemotaxonomic data, the novel actinomycete strain NEAU-S30T (=JCM 33975T=CGMCC 4.7890T) represents the type strain of a novel species within the genus Glycomyces, for which the name Glycomyces niveus sp. nov. is proposed.

Combinatorial Biosynthesis of 3-O-Carbamoylmaytansinol by Rational Engineering of the Tailoring Steps of Ansamitocins.

Currently, most maytansine-containing antibody-drug conjugates (ADCs) in clinical trials are prepared with DM1 or DM4, which in turn is synthesized mainly from ansamitocin P-3 (AP-3), a bacterial maytansinoid, isolated from Actinosynnema pretiosum. However, due to the high self-toxicity of AP-3 to A. pretiosum, the yield of AP-3 has been difficult to improve. Herein, a new maytansinoid with much lower self-toxicity to A. pretiosum, 3-O-carbamoylmaytansinol (CAM, 3), was designed and generated by introducing the 3-O-carbamoyltransferase gene asc21b together with the N-methyltransferase genes from exogenous maytansinoid gene clusters into the 3-O-acyltransferase gene (asm19) deleted mutant HGF052. Meanwhile, two new shunt products, 20-O-demethyl-19-dechloro-N-demethyl-4,5-desepoxy-CAM (4) and 20-O-demethyl-N-demethyl-4,5-desepoxy-CAM (5) were identified from the recombinant strain. Furthermore, by screening of liquid fermentation media, overexpression of bottleneck tailoring enzymes and the pathway-specific activator, the titer of CAM reached 498 mg/L in the engineered strain. Since the 3-O-carbamoyl group of CAM can be removed by chemical cleavage as AP-3 to produce maytansinol, our work suggests that CAM may be a promising alternative to AP-3 in the future development of ADCs.

Myceligenerans pegani sp. nov., an endophytic actinomycete isolated from Peganum harmala L. in Xinjiang, PR China.

An endophytic actinomycete designated TRM65318T, was isolated from the root of Peganum harmala L. Its taxonomic status was determined using a polyphasic approach. Comparative 16S rRNA gene sequence analysis indicated that strain TRM65318T is phylogenetically most closely related to Myceligenerans salitolerans XHU 5031T (98.15 %) and Myceligenerans xiligouense DSM 15700T (97.78 %). The peptidoglycan belonged to type A4α. The polar lipids were phosphatidylinositol, phosphatidylglycerol, diphosphatidylglycerol, two unknown lipids and three glycolipids. The predominant menaquinones were MK-9(H4) and MK-9(H6) and the whole-cell sugars contained glucose, mannose and galactose. Major fatty acids were anteiso-C15 : 0, iso-C15 : 0 and C16 : 0. Strain TRM65318T had a genome size of 5881012 bp with a genome G+C content of 71.79 mol%. The average nucleotide identity and DNA-DNA hybridization values between strain TRM65318T and the most closely related species were much lower than the thresholds commonly used to define species. At the same time, differences in phenotypic and genotypic data showed that strain TRM65318T could be clearly distinguished from M. salitolerans XHU 5031T. Therefore, it is concluded that strain TRM65318T represents a novel species of the genus of Myceligenerans. The proposed name for this organism is Myceligenerans pegani sp. nov., with type strain TRM65318T (=CCTCC AA 2019057T=LMG 31679T).