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Auto Tag: Genome mining

July 7, 2019

Genome sequencing and analysis of Talaromyces pinophilus provide insights into biotechnological applications.

Species from the genus Talaromyces produce useful biomass-degrading enzymes and secondary metabolites. However, these enzymes and secondary metabolites are still poorly understood and have not been explored in depth because of a lack of comprehensive genetic information. Here, we report a 36.51-megabase genome assembly of Talaromyces pinophilus strain 1-95, with coverage of nine scaffolds of eight chromosomes with telomeric repeats at their ends and circular mitochondrial DNA. In total, 13,472 protein-coding genes were predicted. Of these, 803 were annotated to encode enzymes that act on carbohydrates, including 39 cellulose-degrading and 24 starch-degrading enzymes. In addition, 68 secondary metabolism gene clusters were identified, mainly including T1 polyketide synthase genes and nonribosomal peptide synthase genes. Comparative genomic analyses revealed that T. pinophilus 1-95 harbors more biomass-degrading enzymes and secondary metabolites than other related filamentous fungi. The prediction of the T. pinophilus 1-95 secretome indicated that approximately 50% of the biomass-degrading enzymes are secreted into the extracellular environment. These results expanded our genetic knowledge of the biomass-degrading enzyme system of T. pinophilus and its biosynthesis of secondary metabolites, facilitating the cultivation of T. pinophilus for high production of useful products.

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July 7, 2019

Characterization of Class IIa bacteriocin resistance in Enterococcus faecium.

Vancomycin-resistant enterococci, particularly resistant Enterococcus faecium, pose an escalating threat in nosocomial environments because of their innate resistance to many antibiotics, including vancomycin, a treatment of last resort. Many class IIa bacteriocins strongly target these enterococci and may offer a potential alternative for the management of this pathogen. However, E. faecium’s resistance to these peptides remains relatively uncharacterized. Here, we explored the development of resistance of E. faecium to a cocktail of three class IIa bacteriocins: enterocin A, enterocin P, and hiracin JM79. We started by quantifying the frequency of resistance to these peptides in four clinical isolates of E. faecium We then investigated the levels of resistance of E. faecium 6E6 mutants as well as their fitness in different carbon sources. In order to elucidate the mechanism of resistance of E. faecium to class IIa bacteriocins, we completed whole-genome sequencing of resistant mutants and performed reverse transcription-quantitative PCR (qRT-PCR) of a suspected target mannose phosphotransferase (ManPTS). We then verified this ManPTS’s role in bacteriocin susceptibility by showing that expression of the ManPTS in Lactococcus lactis results in susceptibility to the peptide cocktail. Based on the evidence found from these studies, we conclude that, in accord with other studies in E. faecalis and Listeria monocytogenes, resistance to class IIa bacteriocins in E. faecium 6E6 is likely caused by the disruption of a particular ManPTS, which we believe we have identified. Copyright © 2017 American Society for Microbiology.

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July 7, 2019

Complete genome of Brachybacterium sp. P6-10-X1 isolated from deep-sea sediments of the Southern Ocean

Brachybacterium sp. P6-10-X1 is a rare actinobacterium isolated from deep-sea sediments in the Southern Ocean. To explore the potential of natural product biosynthesis, the genome was completely sequenced. It contained a circular chromosome of 4,385,603 bp with an average GC content of 70.9%. Genome mining revealed four biosynthetic gene clusters potentially producing new natural products.

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July 7, 2019

Complete genome sequence of Amycolatopsis orientalis CPCC200066, the producer of norvancomycin.

Amycolatopsis orientalis CPCC200066 is an actinomycete exploited commercially in China for the production of norvancomycin, an important glycopeptide antibiotic structurally close to the well-known vancomycin. The availability of the complete genome sequence of CPCC200066 would greatly strengthen our understanding of the regulation pattern of norvancomycin biosynthesis and ultimately improve its production, as well as potentiate discoveries of novel bioactive compounds. Here we report the complete genome sequence of A. orientalis CPCC200066, a circular chromosome consisting of 9,490,992bp. Forty putative secondary metabolite biosynthetic gene clusters, including norvancomycin, were predicted, covering 20.3% of the whole genome. To facilitate genetic manipulation of this strain, an efficient transformation system was established by constructing a novel integrative vector pIMBT1, which could be transferred into CPCC200066 by electroporation with high efficiency. FBT1 attB sites were also identified in other known Amycolatopsis genomes, indicating pIMBT1’s prospect to be a novel vector for genus Amycolatopsis. Copyright © 2017 Elsevier B.V. All rights reserved.

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July 7, 2019

Genomic and phenotypic analyses of Pseudomonas psychrotolerans PRS08-11306 reveal a turnerbactin biosynthesis gene cluster that contributes to nitrogen fixation.

Plant-microbe interactions can provide agronomic benefits, such as enhancing nutrient uptake and providing fixed nitrogen. The Pseudomonas psychrotolerans strain PRS08-11306 was isolated from rice seeds and can enhance plant growth. Here, we analyzed the P. psychrotolerans genome, which is ~5Mb, with 4389 coding sequences, 77 tRNAs, and 7 rRNAs. Genome analysis identified a cluster of turnerbactin biosynthetic genes, which are responsible for the production of a catecholate siderophore and contribute to nitrogen fixation for the host. Analysis of the transcription factor mutant ?rpoS, which does not express this gene cluster, confirmed the relationship between the gene cluster and siderophore production. The nitrogen fixation characteristics of the cluster were confirmed in a plant growth-promoting experiment. The annotated full genome sequence of this strain sheds light on the role of P. psychrotolerans PRS08-11306 as a plant beneficial bacterium. Copyright © 2017. Published by Elsevier B.V.

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July 7, 2019

Genome sequences for Streptomyces spp. isolated from disease-suppressive soils and long-term ecological research sites.

We report here the high-quality genome sequences of three Streptomyces spp. isolated as part of a long-term study of microbial soil ecology. Streptomyces sp. strain GS93-23 was isolated from naturally disease-suppressive soil (DSS) in Grand Rapids, MN, and Streptomyces sp. strains S3-4 and 3211-3 were isolated from experimental plots in the Cedar Creek Ecosystem Science Reserve (CCESR). Copyright © 2017 Heinsch et al.

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July 7, 2019

Complete genome sequence of Bacillus subtilis J-5, a potential biocontrol agent.

Bacillus subtilis J-5 was isolated from tomato rhizosphere soil and exhibited strong inhibitory activity against Botrytis cinerea To shed light on the molecular mechanism underlying the biological control on phytopathogens, the whole genome of this strain was sequenced. Genes encoding antimicrobial compounds and the regulatory systems were identified in the genome. Copyright © 2017 Jia et al.

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July 7, 2019

Genome mining and predictive functional profiling of acidophilic rhizobacterium Pseudomonas fluorescens Pt14.

Pseudomonas fluorescens Pt14 is a non-pathogenic and acidophilic bacterium isolated from acidic soil (pH 4.65). Genome sequencing of strain Pt14 was performed using Single Molecule Real Time (SMRT) sequencing to get insights into unique existence of this strain in acidic environment. Complete genome sequence of this strain revealed a chromosome of 5,841,722 bp having 5354 CDSs and 88 RNAs. Phylogenomic reconstruction based on 16S rRNA gene, Average Nucleotide Identity (ANI) values and marker proteins revealed that strain Pt14 shared a common clade with P. fluorescens strain A506 and strain SS101. ANI value of strain Pt14 in relation to strain A506 was found 99.23% demonstrating a very close sub-species association at genome level. Further, orthology determination among these three phylogenetic neighbors revealed 4726 core proteins. Functional analysis elucidated significantly higher abundance of sulphur metabolism (>1×) which could be one of the reasons for the survival of strain Pt14 under acidic conditions (pH 4.65). Acidophilic bacteria have capability to oxidize sulphur into sulphuric acid which in turn can make the soil acidic and genome-wide analysis of P. fluorescens Pt14 demonstrated that this strain contributes towards making the soil acidic.

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July 7, 2019

Identification and characterization of a biosynthetic gene cluster for tryptophan dimers in deep sea-derived Streptomyces sp. SCSIO 03032.

Tryptophan dimers (TDs) are an important class of natural products with diverse bioactivities and share conserved biosynthetic pathways. We report the identification of a partial gene cluster (spm) responsible for the biosynthesis of a class of unusual TDs with non-planar skeletons including spiroindimicins (SPMs), indimicins (IDMs), and lynamicins (LNMs) from the deep-sea derived Streptomyces sp. SCSIO 03032. Bioinformatics analysis, targeted gene disruptions, and heterologous expression studies confirmed the involvement of the spm gene cluster in the biosynthesis of SPM/IDM/LNMs, and revealed the indispensable roles for the halogenase/reductase pair SpmHF, the amino acid oxidase SpmO, and the chromopyrrolic acid (CPA) synthase SpmD, as well as the positive regulator SpmR and the putative transporter SpmA. However, the spm gene cluster was unable to confer a heterologous host the ability to produce SPM/IDM/LNMs. In addition, the P450 enzyme SpmP and the monooxygenase SpmX2 were found to be non-relevant to the biosynthesis of SPM/IDM/LNMs. Sequence alignment and structure modeling suggested the lack of key conserved amino acid residues in the substrate-binding pocket of SpmP. Furthermore, feeding experiments in the non-producing ?spmO mutant revealed several biosynthetic precursors en route to SPMs, indicating that key enzymes responsible for the biosynthesis of SPMs should be encoded by genes outside of the identified spm gene cluster. Finally, the biosynthetic pathways of SPM/IDM/LNMs are proposed to lay a basis for further insights into their intriguing biosynthetic machinery.

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July 7, 2019

An L-threonine transaldolase is required for L-threo-ß-hydroxy-a-amino acid assembly during obafluorin biosynthesis.

ß-Lactone natural products occur infrequently in nature but possess a variety of potent and valuable biological activities. They are commonly derived from ß-hydroxy-a-amino acids, which are themselves valuable chiral building blocks for chemical synthesis and precursors to numerous important medicines. However, despite a number of excellent synthetic methods for their asymmetric synthesis, few effective enzymatic tools exist for their preparation. Here we report cloning of the biosynthetic gene cluster for the ß-lactone antibiotic obafluorin and delineate its biosynthetic pathway. We identify a nonribosomal peptide synthetase with an unusual domain architecture and an L-threonine:4-nitrophenylacetaldehyde transaldolase responsible for (2S,3R)-2-amino-3-hydroxy-4-(4-nitrophenyl)butanoate biosynthesis. Phylogenetic analysis sheds light on the evolutionary origin of this rare enzyme family and identifies further gene clusters encoding L-threonine transaldolases. We also present preliminary data suggesting that L-threonine transaldolases might be useful for the preparation of L-threo-ß-hydroxy-a-amino acids.

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July 7, 2019

Formicamycins, antibacterial polyketides produced by Streptomyces formicae isolated from African Tetraponera plant-ants.

We report a new Streptomyces species named S. formicae that was isolated from the African fungus-growing plant-ant Tetraponera penzigi and show that it produces novel pentacyclic polyketides that are active against MRSA and VRE. The chemical scaffold of these compounds, which we have called the formicamycins, is similar to the fasamycins identified from the heterologous expression of clones isolated from environmental DNA, but has significant differences that allow the scaffold to be decorated with up to four halogen atoms. We report the structures and bioactivities of 16 new molecules and show, using CRISPR/Cas9 genome editing, that biosynthesis of these compounds is encoded by a single type 2 polyketide synthase biosynthetic gene cluster in the S. formicae genome. Our work has identified the first antibiotic from the Tetraponera system and highlights the benefits of exploring unusual ecological niches for new actinomycete strains and novel natural products.

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July 7, 2019

Complete genome sequence of Microbulbifer sp. CCB-MM1, a halophile isolated from Matang Mangrove Forest, Malaysia.

Microbulbifer sp. CCB-MM1 is a halophile isolated from estuarine sediment of Matang Mangrove Forest, Malaysia. Based on 16S rRNA gene sequence analysis, strain CCB-MM1 is a potentially new species of genus Microbulbifer. Here we describe its features and present its complete genome sequence with annotation. The genome sequence is 3.86 Mb in size with GC content of 58.85%, harbouring 3313 protein coding genes and 92 RNA genes. A total of 71 genes associated with carbohydrate active enzymes were found using dbCAN. Ectoine biosynthetic genes, ectABC operon and ask_ect were detected using antiSMASH 3.0. Cell shape determination genes, mreBCD operon, rodA and rodZ were annotated, congruent with the rod-coccus cell cycle of the strain CCB-MM1. In addition, putative mreBCD operon regulatory gene, bolA was detected, which might be associated with the regulation of rod-coccus cell cycle observed from the strain.

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