Phylogenomic analyses of the genus Actinoplanes: description of four novel genera

The genus Actinoplanes comprises 57 species (in February 2024) that are important components of ecosystems and are widely used in biotechnology, especially pharmaceuticals. Phylogenetic analysis of the family Micromonosporaceae (based on the 16S rRNA gene sequence) allowed us to group members of different genera into separate clades; however, the genus Actinoplanes was divided into three separate clades. Such phylogenetic heterogeneity could be due to the limitations of 16S rRNA gene analysis. In response to this heterogeneity, genomic phylogeny was performed. Phylogenomic reconstruction based on 324 single-copy orthologous genes allowed us to divide the genus Actinoplanes first into four clades and then, based on average nucleotide identity analysis, into five clades. Finally, chemotaxonomic analysis of each clade confirmed each clade's distinctiveness and the necessity to reclassify the genus Actinoplanes. The obtained data allowed us to divide the genus Actinoplanes into five genera: Actinoplanes, Paractinoplanes, Winogradskya, Symbioplanes and Amorphoplanes.

Actinoplanes oblitus sp. nov., producing the glycopeptide antibiotic A477

In 1973, Eli Lilly and Company described the filamentous actinomycete producing the glycopeptide antibiotic A477 as an Actinoplanes species on the basis of its morphological and physiological features and deposited it as NRRL 3884T. In this paper, we report that the phylogenetic analysis based on the 16S rRNA gene sequence and the whole genome phylogenomic study indicate that NRRL 3884T forms a distinct monophyletic line within the genus Actinoplanes, being most closely related to Actinoplanes octamycinicus NBRC 14524T [99.6 % 16S rRNA gene similarity, 89.4 % average nucleotide identity (ANI), 46.0 % digital DNA-DNA hybridization (dDDH)] and Actinoplanes ianthinogenes NBRC 13996T (98.8 % 16S rRNA gene similarity, 89.0 % ANI, 47.0 % dDDH). NRRL 3884T forms an extensively branched, non-fragmented vegetative mycelium; either sterile aerial hyphae or regular subglobose sporangia are formed depending on cultivation conditions. The cell wall contains meso-2,6-diaminopimelic acid and 2,6-diamino-3-hydroxypimelic acid and the diagnostic sugars are glucose, mannose and ribose with a minor amount of rhamnose. The predominant menaquinone (MK) is MK-9(H4), with minor amounts of MK-9(H2), MK-9(H6) and MK-9(H8). Mycolic acids are absent. The diagnostic phospholipids are diphosphatidylglycerol and phosphatidylethanolamine. The major cellular fatty acids are anteiso-C17 : 0, iso-C16 : 0 and iso-C15 : 0, with moderate amounts of anteiso-C15 : 0 and iso-C17 : 0. The genomic G+C content is 71.5 mol%. Significant differences in the genomic, morphological, chemotaxonomic and biochemical data between NRRL 3884T and the two most closely related Actinoplanes type strains clearly demonstrate that NRRL 3884T represents a novel species of the genus Actinoplanes, for which the name Actinoplanes oblitus sp. nov. is proposed. The type strain is NRRL 3884T (=DSM 116196T).

Screening of marine sediment-derived microorganisms and their bioactive metabolites: a review

Marine sediments are one of the largest habitats on Earth, and their unique ecology, such as high salinity, high pressure, and hypoxia, may activate certain silent genes in marine microbes, resulting in microbes, enzymes, active products, and specific metabolic pathways that can adapt to these specific ecological environments. Marine sediment-derived microorganisms and their bioactive metabolites are of great significance and have potential commercial development prospects for food, pharmaceutical, chemical industries, agriculture, environmental protection and human nutrition and health. In recent years, although there have been numerous scientific reports surrounding marine sediment-derived microorganisms and their bioactive metabolites, a comprehensive review of their research progress is lacking. This paper presents the development and renewal of traditional culture-dependent and omics analysis techniques and their application to the screening of marine sediment-derived microorganisms producing bioactive substances. It also highlights recent research advances in the last five years surrounding the types, functional properties and potential applications of bioactive metabolites produced by marine sediment-derived microorganisms. These bioactive metabolites mainly include antibiotics, enzymes, enzyme inhibitors, sugars, proteins, peptides, and some other small molecule metabolites. In addition, the review ends with concluding remarks on the challenges and future directions for marine sediment-derived microorganisms and their bioactive metabolites. The review report not only helps to deepen the understanding of marine sediment-derived microorganisms and their bioactive metabolites, but also provides some useful information for the exploitation and utilization of marine microbial resources and the mining of new compounds with potential functional properties.

Three novel Actinoplanes species isolated by using polyaspartic acid as a water-retaining agent for the enrichment in situ

Three novel actinomycete strains, designated TRM66264-DLM^T, TRM88002^T and TRM88003^T, were isolated by using polyaspartic acid as a water-retaining agent for the enrichment in situ. The 16S rRNA gene sequence and phylogenetic analyses of three strains indicated that they belonged to the genus Actinoplanes. The phylogenetically closest strains of TRM66264-DLM^T, TRM88002^T and TRM88003^T were Actinoplanes bogorensis LIPI11-2-Ac043^T (98.4 %), Actinoplanes abujensis A4029^T (98.0 %) and Actinoplanes ferrugineus IFO15555^T (98.1 %), respectively. The major polar lipids of strains TRM66264-DLM^T and TRM88002^T were phosphatidylethanolamine and disphosphatidylglycerol, while strain TRM88003^T only had phosphatidylethanolamine. The predominant menaquinones of strain TRM66264-DLM^T were identified as MK-9(H₄) and MK-9 (H₆). Strains TRM88002^T and TRM88003^T had MK-9(H₄). The cell-wall peptidoglycan of three strains contained meso-diaminopimelic acid. The whole-cell sugars of strain TRM66264-DLM^T were identified as arabinose, glucose, galactose and xylose. Strains TRM88002^T and TRM88003^T mainly had arabinose and glucose. The DNA G+C content of strains TRM66264-DLM^T, TRM88002^T and TRM88003^T were 70.48, 70.46 and 70.64 mol%, respectively. Genotypic and phenotypic analysis confirmed that all three strains sre new members of the genus Acinoplanes. Therefore, it is proposed that strains TRM66264-DLM^T, TRM88002^T and TRM88003^T represent three novel species of the genus Actinoplanes, for which the names Actinoplanes polyasparticus sp. nov. (type strain TRM66264-DLM^T=CCTCC AA 2021015^T=LMG 32389^T), Actinoplanes hotanensis sp. nov. (type strain TRM88002^T=CCTCC AA 2021036^T=LMG 32621^T) and Actinoplanes aksuensis sp. nov. (type strain TRM88003^T=CCTCC AA 2021037 ^T=LMG 32622^T) are proposed.

Actinoplanes lichenicola sp. nov. and Actinoplanes ovalisporus sp. nov., isolated from lichen in Thailand

Two actinobacteria, designated as strain LDG1-01^T and LDG1-06^T, were isolated from lichen samples collected in Thailand. Results of morphological characterization, chemotaxonomic studies and 16S rRNA gene analysis indicated that both strains were members of the genus Actinoplanes. MK-9(H₄) was found as the major menaquinone. The major fatty acids were anteiso-C_15 : 0, iso-C_15 : 0, iso-C_16 : 0 and anteiso-C_17 : 0. Phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol were observed as the polar lipids, but differences in minor unidentified polar lipids were found between the strains. Results of comparative genome analysis based on average nucleotide identity and digital DNA-DNA hybridization calculations revealed that both strains showed values below 95 and 70 %, respectively, from each other and closely related Actinoplanes type strains. Based on data from this polyphasic study, strains LDG1-01^T and LDG1-06^T represent novel species of the genus Actinoplanes. The names proposed are Actinoplanes lichenicola sp. nov. (type strain, LDG1-01^T (=JCM 33066^T=TISTR 2982^T) and Actinoplanes ovalisporus sp. nov. (type strain, LDG1-06^T=JCM 33067^T=TISTR 2983^T).

Actinoplanes solisilvae sp. nov., Isolated from Birch Forest Soil

A novel actinomycete, designated strain LAM7112^T, was isolated from soil sample collected from a birch forest in Xinjiang Uygur Autonomous Region, China. The new isolate was found to be able to grow at 20-45 °C (optimum: 35 °C), pH 5.0-10.0 (optimum: 7.0) and in the presence of 0-10.0% (optimum: 3.0%) (w/v) NaCl. The isolate formed very scantily irregular sporangia containing motile spores on the substrate mycelium. Phylogenetic analysis of 16S rRNA gene sequences indicated that the new isolate was closely related to members of the family Micromonosporaceae, with highest similarites to Actinoplanes ferrugineus X-14695^T (97.4%), Micromonospora zamorensis DSM 45600^T (97.3%) and Micromonospora aurantiaca ATCC 27029^T (97.3%). In the phylogenetic trees, strain LAM7112^T formed a stable phylogenetic subclade within the genus Actinoplanes. The genomic DNA G + C content was 70.0 mol%. The major fatty acids (> 10%) were determined to be iso-C_16:0, anteiso-C_15:0 and anteiso-C_17:0. The predominant menaquinones were identified as MK-9 (H₂), MK-9 (H₄) and MK-9 (H₆). The major polar lipids were found to be diphosphatidylglycerol, phosphatidylinositol and phosphatidylethanolamine. The diagnostic amino acid of the cell wall peptidoglycan was determined to be meso-diaminopimelic acid. The diagnostic sugars in cell hydrolysates were determined to be glucose and ribose. On the basis of its phenotypic, phylogenetic and chemotaxonomic characteristics, strain LAM7112^T (= CGMCC 4.7580^T = JCM 32512^T) is proposed to represent the type strain of a novel species of the genus Actinoplanes, for which the name Actinoplanes solisilvae is proposed.

Actinoplanes deserti sp. nov., isolated from a desert soil sample

A novel actinomycete, designated strain YIM CF22^T, was isolated from a desert soil sample collected from Turpan in Xinjiang Uyghur Autonomous Region, north-western China. The taxonomic position of the strain YIM CF22^T is described based on a polyphasic approach. Strain YIM CF22^T was found to form irregular sporangia on agar media. It contains meso-diaminopimelic acid in the cell wall peptidoglycan. The major menaquinone was identified as MK-9(H₄); the polar lipids were identified as diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, two unidentified phospholipids and two unidentified glycolipids. The whole cell sugars were found to be ribose, mannose, galactose, glucose and xylose. The major cellular fatty acids were found to be (> 5%) iso-C_16:0 (43.5%), anteiso-C_17:0 (10.2%), iso-C_15:0 (7.1%), C_17:1 ω8c (6.3%) and iso H-C_16:1 (5.9%). The G+C content was determined to be 70.8%. 16S rRNA gene sequence analysis of strain YIM CF22^T showed high similarity (97.0%) to Actinoplanes rishiriensis NBRC 108556^T. The strain also showed high 16S rRNA gene sequence similarities to Verrucosispora sediminis CGMCC 4.3550^T (96.9%) and Micromonospora tulbaghiae DSM 45142^T (96.8%). Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain YIM CF22^T clusters with A. rishiriensis NBRC 108556^T, Actinoplanes globisporus JCM 3186^T and Actinoplanes rhizophilus NEAU-A-2^T. Based on the differential phenotypic characteristics and the results of DNA-DNA relatedness and phylogenetic analysis, it is proposed that strain YIM CF22^T represents a novel species of the genus Actinoplanes, for which the name Actinoplanes deserti sp. nov. is proposed. The type strain is YIM CF22^T (= KCTC 39543^T = CCTCC AB2018113^T).

Diversity, Novelty, and Antimicrobial Activity of Endophytic Actinobacteria From Mangrove Plants in Beilun Estuary National Nature Reserve of Guangxi, China

Endophytic actinobacteria are one of the important pharmaceutical resources and well known for producing different types of bioactive substances. Nevertheless, detection of the novelty, diversity, and bioactivity on endophytic actinobacteria isolated from mangrove plants are scarce. In this study, five different mangrove plants, Avicennia marina, Aegiceras corniculatum, Kandelia obovota, Bruguiera gymnorrhiza, and Thespesia populnea, were collected from Beilun Estuary National Nature Reserve in Guangxi Zhuang Autonomous Region, China. A total of 101 endophytic actinobacteria strains were recovered by culture-based approaches. They distributed in 7 orders, 15 families, and 28 genera including Streptomyces, Curtobacterium, Mycobacterium, Micrococcus, Brevibacterium, Kocuria, Nocardioides, Kineococcus, Kytococcus, Marmoricola, Microbacterium, Micromonospora, Actinoplanes, Agrococcus, Amnibacterium, Brachybacterium, Citricoccus, Dermacoccus, Glutamicibacter, Gordonia, Isoptericola, Janibacter, Leucobacter, Nocardia, Nocardiopsis, Pseudokineococcus, Sanguibacter, and Verrucosispora. Among them, seven strains were potentially new species of genera Nocardioides, Streptomyces, Amnibacterium, Marmoricola, and Mycobacterium. Above all, strain 8BXZ-J1 has already been characterized as a new species of the genus Marmoricola. A total of 63 out of 101 strains were chosen to screen antibacterial activities by paper-disk diffusion method and inhibitors of ribosome and DNA biosynthesis by means of a double fluorescent protein reporter. A total of 31 strains exhibited positive results in at least one antibacterial assay. Notably, strain 8BXZ-J1 and three other potential novel species, 7BMP-1, 5BQP-J3, and 1BXZ-J1, all showed antibacterial bioactivity. In addition, 21 strains showed inhibitory activities against at least one "ESKAPE" resistant pathogens. We also found that Streptomyces strains 2BBP-J2 and 1BBP-1 produce bioactive compound with inhibitory activity on protein biosynthesis as result of translation stalling. Meanwhile, Streptomyces strain 3BQP-1 produces bioactive compound inducing SOS-response due to DNA damage. In conclusion, this study proved mangrove plants harbored a high diversity of cultivable endophytic actinobacteria, which can be a promising source for discovery of novel species and bioactive compounds.