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July 7, 2019

High-quality draft genome sequence of the actinobacterium Nocardia terpenica IFM 0406, producer of the immunosuppressant brasilicardins, using Illumina and PacBio technologies.

The bacterium Nocardia terpenica IFM 0406 is known as the producer of the immunosuppressant brasilicardin A. Here, we report the completely sequenced genome of strain IFM 0406, which facilitates the heterologous expression of the brasilicardin biosynthetic gene cluster but also unveils the intriguing biosynthetic capacity of the strain to produce secondary metabolites. Copyright © 2016 Buchmann et al.


July 7, 2019

Genome sequence of Pseudomonas citronellolis SJTE-3, an estrogen- and polycyclic aromatic hydrocarbon-degrading bacterium.

Pseudomonas citronellolis SJTE-3, isolated from the active sludge of a wastewater treatment plant in China, can utilize a series of environmental estrogens and estrogen-like toxicants. Here, we report its whole-genome sequence, containing one circular chromosome and one circular plasmid. Genes involved in estrogen biodegradation in this bacterium were predicted. Copyright © 2016 Zheng et al.


July 7, 2019

Identification of the fluvirucin B2 (Sch 38518) biosynthetic gene cluster from Actinomadura fulva subsp. indica ATCC 53714: substrate specificity of the ß-amino acid selective adenylating enzyme FlvN.

Fluvirucins are 14-membered macrolactam polyketides that show antifungal and antivirus activities. Fluvirucins have the ß-alanine starter unit at their polyketide skeletons. To understand the construction mechanism of the ß-alanine moiety in fluvirucin biosyntheses, we have identified the biosynthetic cluster of fluvirucin B2 produced from Actinomadura fulva subsp. indica ATCC 53714. The identified gene cluster contains three polyketide synthases, four characteristic ß-amino acid-carrying enzymes, one decarboxylase, and one amidohydrolase. We next investigated the activity of the adenylation enzyme FlvN, which is a key enzyme for the selective incorporation of a ß-amino acid substrate. FlvN showed strong preference for l-aspartate over other amino acids such as ß-alanine. Based on these results, we propose a biosynthetic pathway for fluvirucin B2.


July 7, 2019

Improve homology search sensitivity of PacBio data by correcting frameshifts.

Single-molecule, real-time sequencing (SMRT) developed by Pacific BioSciences produces longer reads than secondary generation sequencing technologies such as Illumina. The long read length enables PacBio sequencing to close gaps in genome assembly, reveal structural variations, and identify gene isoforms with higher accuracy in transcriptomic sequencing. However, PacBio data has high sequencing error rate and most of the errors are insertion or deletion errors. During alignment-based homology search, insertion or deletion errors in genes will cause frameshifts and may only lead to marginal alignment scores and short alignments. As a result, it is hard to distinguish true alignments from random alignments and the ambiguity will incur errors in structural and functional annotation. Existing frameshift correction tools are designed for data with much lower error rate and are not optimized for PacBio data. As an increasing number of groups are using SMRT, there is an urgent need for dedicated homology search tools for PacBio data.In this work, we introduce Frame-Pro, a profile homology search tool for PacBio reads. Our tool corrects sequencing errors and also outputs the profile alignments of the corrected sequences against characterized protein families. We applied our tool to both simulated and real PacBio data. The results showed that our method enables more sensitive homology search, especially for PacBio data sets of low sequencing coverage. In addition, we can correct more errors when comparing with a popular error correction tool that does not rely on hybrid sequencing.The source code is freely available at https://sourceforge.net/projects/frame-pro/yannisun@msu.edu. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.


July 7, 2019

Genomics-inspired discovery of three antibacterial active metabolites, aurantinins B, C, and D from compost-associated Bacillus subtilis fmb60.

Fmb60 is a wild-type Bacillus subtilis isolated from compost with significant broad-spectrum antimicrobial activities. Two novel PKS clusters were recognized in the genome sequence of fmb60, and then three polyene antibiotics, aurantinins B, C, and D, 1-3, were obtained by bioactivity-guided isolation from the fermentation of fmb60. The structures of aurantinins B-D were elucidated by LC-HRMS and NMR data analysis. Aurantinins C and D were identified as new antimicrobial compounds. The three aurantinins showed significant activity against multidrug-resistant Staphylococcus aureus and Clostridium sporogenes. However, aurantinins B-D did not exhibit any cytotoxicity (IC50 > 100 µg/mL) against LO2 and Caco2 cell lines by MTT assay. Furthermore, using S. aureus as a model bacterium to explore the antibacterial mechanism of aurantinins B-D, it was revealed that the bactericidal activity of aurantinins B-D was related to their ability to disrupt the cell membrane.


July 7, 2019

Complete genome sequence and transcriptome regulation of the pentose utilizing yeast Sugiyamaella lignohabitans.

Efficient conversion of hexoses and pentoses into value-added chemicals represents one core step for establishing economically feasible biorefineries from lignocellulosic material. While extensive research efforts have recently provided advances in the overall process performance, the quest for new microbial cell factories and novel enzymes sources is still open. As demonstrated recently the yeast Sugiyamaella lignohabitans (formerly Candida lignohabitans) represents a promising microbial cell factory for the production of organic acids from lignocellulosic hydrolysates. We report here the de novo genome assembly of S. lignohabitans using the Single Molecule Real-Time platform, with gene prediction refined by using RNA-seq. The sequencing revealed a 15.98 Mb genome, subdivided into four chromosomes. By phylogenetic analysis, Blastobotrys (Arxula) adeninivorans and Yarrowia lipolytica were found to be close relatives of S. lignohabitans Differential gene expression was evaluated in typical growth conditions on glucose and xylose and allowed a first insight into the transcriptional response of S. lignohabitans to different carbon sources and different oxygenation conditions. Novel sequences for enzymes and transporters involved in the central carbon metabolism, and therefore of potential biotechnological interest, were identified. These data open the way for a better understanding of the metabolism of S. lignohabitans and provide resources for further metabolic engineering.© FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.


July 7, 2019

D1FHS, the type strain of the ammonia-oxidizing bacterium Nitrosococcus wardiae spec. nov.: enrichment, isolation, phylogenetic, and growth physiological characterization.

An ammonia-oxidizing bacterium, strain D1FHS, was enriched into pure culture from a sediment sample retrieved in Jiaozhou Bay, a hyper-eutrophic semi-closed water body hosting the metropolitan area of Qingdao, China. Based on initial 16S rRNA gene sequence analysis, strain D1FHS was classified in the genus Nitrosococcus, family Chromatiaceae, order Chromatiales, class Gammaproteobacteria; the 16S rRNA gene sequence with highest level of identity to that of D1FHS was obtained from Nitrosococcus halophilus Nc4(T). The average nucleotide identity between the genomes of strain D1FHS and N. halophilus strain Nc4 is 89.5%. Known species in the genus Nitrosococcus are obligate aerobic chemolithotrophic ammonia-oxidizing bacteria adapted to and restricted to marine environments. The optimum growth (maximum nitrite production) conditions for D1FHS in a minimal salts medium are: 50 mM ammonium and 700 mM NaCl at pH of 7.5 to 8.0 and at 37°C in dark. Because pertinent conditions for other studied Nitrosococcus spp. are 100-200 mM ammonium and <700 mM NaCl at pH of 7.5 to 8.0 and at 28-32°C, D1FHS is physiologically distinct from other Nitrosococcus spp. in terms of substrate, salt, and thermal tolerance.


July 7, 2019

Genomic and transcriptomic analyses reveal the characterization of a crude oil degrading bacterial strain: Pedobacter steynii DX4

Pedobacter steynii DX4, isolated from Qinghai-Tibet plateau, exhibited capability to effectively degrade crude oil at low temperature. In order to illustrate its biodegradation mechanism, whole genome and transcriptome sequencing were performed. It is the first genome of crude oil degrading strain in Pedobacter genus. The P. steynii DX4 genome consists of a single circular chromosome of 6,581,659 bp with an average G+C content of 41.31% and encodes 5464 genes in all. GIs were predicted and comparison analysis was performed between relative species. Genome annotation predicted several hydrocarbon oxygenases, chemotaxis proteins and biosurfactant synthetases. The transcriptional sequences profiled a lot of differently expressed genes when cells respectively grown on crude oil and pyruvate mediums. Crude oil significantly stimulated the expression of the genes related to the hydrocarbon oxidation and resparitory chain. Genomic and transcriptomic analysis of P. steynii DX4 have revealed the machenism of the crude oil degradation in Pedobacter steynii DX4 and provided us with valuable knowledge base to make effective strategy to mitigate the ecological damage caused by crude oil pollution.


July 7, 2019

Characterization of tet(Y)-carrying LowGC plasmids exogenously captured from cow manure at a conventional dairy farm.

Manure from dairy farms has been shown to contain diverse tetracycline resistance genes that are transferable to soil. Here, we focus on conjugative plasmids that may spread tetracycline resistance at a conventional dairy farm. We performed exogenous plasmid isolation from cattle feces using chlortetracycline for transconjugant selection. The transconjugants obtained harbored LowGC-type plasmids and tet(Y). A representative plasmid (pFK2-7) was fully sequenced and this was compared with previously described LowGC plasmids from piggery manure-treated soil and a GenBank record from Acinetobacter nosocomialis that we also identified as a LowGC plasmid. The pFK2-7 plasmid had the conservative backbone typical of LowGC plasmids, though this region was interrupted with an insert containing the tet(Y)-tet(R) tetracycline resistance genes and the strA-strB streptomycin resistance genes. Despite Acinetobacter populations being considered natural hosts of LowGC plasmids, these plasmids were not found in three Acinetobacter isolates from the study farm. The isolates harbored tet(Y)-tet(R) genes in identical genetic surroundings as pFK2-7, however, suggesting genetic exchange between Acinetobacter and LowGC plasmids. Abundance of LowGC plasmids and tet(Y) was correlated in manure and soil samples from the farm, indicating that LowGC plasmids may be involved in the spread of tet(Y) in the environment.© FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.


July 7, 2019

Systems biology-guided biodesign of consolidated lignin conversion

Lignin is the second most abundant biopolymer on the earth, yet its utilization for fungible products is complicated by its recalcitrant nature and remains a major challenge for sustainable lignocellulosic biorefineries. In this study, we used a systems biology approach to reveal the carbon utilization pattern and lignin degradation mechanisms in a unique lignin-utilizing Pseudomonas putida strain (A514). The mechanistic study further guided the design of three functional modules to enable a consolidated lignin bioconversion route. First, P. putida A514 mobilized a dye peroxidase-based enzymatic system for lignin depolymerization. This system could be enhanced by overexpressing a secreted multifunctional dye peroxidase to promote a two-fold enhancement of cell growth on insoluble kraft lignin. Second, A514 employed a variety of peripheral and central catabolism pathways to metabolize aromatic compounds, which can be optimized by overexpressing key enzymes. Third, the ß-oxidation of fatty acid was up-regulated, whereas fatty acid synthesis was down-regulated when A514 was grown on lignin and vanillic acid. Therefore, the functional module for polyhydroxyalkanoate (PHA) production was designed to rechannel ß-oxidation products. As a result, PHA content reached 73% per cell dry weight (CDW). Further integrating the three functional modules enhanced the production of PHA from kraft lignin and biorefinery waste. Thus, this study elucidated lignin conversion mechanisms in bacteria with potential industrial implications and laid out the concept for engineering a consolidated lignin conversion route.


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