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Auto Tag: Biodegradation

July 7, 2019  |  

Complete genome sequence of industrial biocontrol strain Paenibacillus polymyxa HY96-2 and further analysis of Its biocontrol mechanism.

Paenibacillus polymyxa (formerly known as Bacillus polymyxa) has been extensively studied for agricultural applications as a plant-growth-promoting rhizobacterium and is also an important biocontrol agent. Our team has developed the P. polymyxa strain HY96-2 from the tomato rhizosphere as the first microbial biopesticide based on P. polymyxa for controlling plant diseases around the world, leading to the commercialization of this microbial biopesticide in China. However, further research is essential for understanding its precise biocontrol mechanisms. In this paper, we report the complete genome sequence of HY96-2 and the results of a comparative genomic analysis between different P. polymyxa strains. The complete genome size of HY96-2 was found to be 5.75 Mb and 5207 coding sequences were predicted. HY96-2 was compared with seven other P. polymyxa strains for which complete genome sequences have been published, using phylogenetic tree, pan-genome, and nucleic acid co-linearity analysis. In addition, the genes and gene clusters involved in biofilm formation, antibiotic synthesis, and systemic resistance inducer production were compared between strain HY96-2 and two other strains, namely, SC2 and E681. The results revealed that all three of the P. polymyxa strains have the ability to control plant diseases via the mechanisms of colonization (biofilm formation), antagonism (antibiotic production), and induced resistance (systemic resistance inducer production). However, the variation of the corresponding genes or gene clusters between the three strains may lead to different antimicrobial spectra and biocontrol efficacies. Two possible pathways of biofilm formation in P. polymyxa were reported for the first time after searching the KEGG database. This study provides a scientific basis for the further optimization of the field applications and quality standards of industrial microbial biopesticides based on HY96-2. It may also serve as a reference for studying the differences in antimicrobial spectra and biocontrol capability between different biocontrol agents.

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July 7, 2019  |  

Characterization and genome analysis of a phthalate esters-degrading strain Sphingobium yanoikuyae SHJ.

A bacterium capable of utilizing dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), and diisobuthyl phthalate (DIBP) as the sole carbon and energy source was isolated from shallow aquifer sediments. The strain was identified as Sphingobium yanoikuyae SHJ based on morphological characteristics, 16S rDNA gene phylogeny, and whole genome average nucleotide identity (ANI). The degradation half-life of DBP with substrate concentration of 8.5 and 50.0 mg/L by strain SHJ was 99.7 and 101.4 hours, respectively. The optimum degradation rate of DBP by SHJ was observed at 30°C and weak alkaline (pH 7.5). Genome sequence of the strain SHJ showed a circular chromosome and additional two circular plasmids with whole genome size of 5,669,383 bp and GC content of 64.23%. Functional annotation of SHJ revealed a total of 5,402 genes, with 5,183 protein-encoding genes, 143 pseudogenes, and 76 noncoding RNA genes. Based on genome annotation, 44 genes were identified to be involved in PAEs hydrolysis potentially. Besides, a region with size of about 6.9 kb comprised of seven ORFs, which is located on the smaller plasmid pSES189, was presumed to be responsible for the biodegradation of phthalate. These results provide insights into the genetic basis of DBP biodegradation in this strain.

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July 7, 2019  |  

Complete genome sequence of Bacillus sp. HBCD-sjtu, an efficient HBCD-degrading bacterium.

Environmental pollution caused by the release of industrial chemicals is currently one of the most important environmental harms. Manufacturing chemicals can be biodegraded, and valuable intermediates can be used as pharmacophores in drug targeting and have several other useful purposes. Hexabromocyclododecane (HBCD), a non-aromatic brominated flame retardant, is a toxic compound that consists of a cycloaliphatic ring of 12 carbon atoms to which six bromine atoms are attached. It is formed by bromination of cis-trans-trans-1,5,9-cyclododecatriene, but its use is now restricted in several countries, because it is an environmental pollutant. Little is known about whether bacteria can degrade HBCD. A bacterial strain that degrades HBCD was recently isolated using enrichment culture techniques. Based on morphological, biochemical and phylogenetic analysis this isolate was categorized as Bacillus cereus and named strain HBCD-sjtu. Maximum growth and HBCD-degrading activity were observed when this strain was grown at 30 °C, pH 7.0 and 200 RPM in mineral salt medium containing 0.5 mm HBCD. The genome of strain HBCD-sjtu, which consists of only one circular chromosome, was sequenced. This whole genome sequence will be crucial for illuminating the molecular mechanisms of HBCD degradation.

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July 7, 2019  |  

Bioaugmentated activated sludge degradation of progesterone: Kinetics and mechanism

Progesterone (PGT) is not completely removed in conventional treatment plants, and the processing results may have adverse effects on aquatic organisms. In this study, an effective PGT-degradation bacterium, Rhodococcus sp. HYW, was newly isolated from the pharmaceutical plant and was used to augment degradation of PGT. When grown in a mineral medium (MM) containing a trace amount of PGT (500?µg/L) as the sole carbon and energy source, the results show that 99% of PGT was degraded within 1?h and followed the first-order reaction kinetics. Bioaugmentation of PGT-contaminated activated sludge greatly enhanced the PGT degradation rate (~91%) and its derivatives degradation rate were also greatly improved (>83%). The process of PGT degradation in non-bioaugmented PGT-contaminated activated sludge (NBS) and bioaugmentation activated sludge with the bacterial consortium(BS) also conforms to the first-order kinetic model. Furthermore, 12 and 11 biodegradation products for PGT in the NBS and BS were identified using HPLC-LTQ-Orbitrap XL™, respectively. Based on these biodegradation products, two degradation pathways for PGT in NBS and BS were proposed, respectively. Comparing the degradation kinetics and metabolites, it was found that BS degrades PGT more rapidly and can further convert PGT to a small molecular acid. Finally, to reveal the probable cause for the differences in the PGT degradation efficiency and products in the NBS and BS.

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July 7, 2019  |  

Complete genome sequence of soil actinobacteria Streptomyces cavourensis TJ430.

A new actinobacteria Streptomyces cavourensis TJ430 was isolated from the mountain soil collected from the southwest of China. In previous study, TJ430 showed striking bactericidal activities and strong ability of antibiotic production. Here, we report complete genome of this bacterium, consisting of 7.6?Mb linear chromosome and 0.2?Mb plasmids. It was predicted 6450 genes in chromosome and 225 genes in plasmids, as well as 12 gene islands in chromosome. Abundant genes have predicted functions in antibiotic metabolism and stress resistance. A whole-genome comparison of S. cavourensis TJ430, S. coelicolor A3(2), and S. lividans 66 indicates that TJ430 has a relatively high degree of strain specificity. The 16S rRNA phylogenetic tree shows the high identities (99.79%) of TJ430 with S. cavourensis DSM40300. TJ430 is a new and rare Streptomyces species, and analysis of its genome helps us to better understand primary metabolism mechanism of this isolate, as well as the evolutionary biology.© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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July 7, 2019  |  

Complete genome sequence of Marinobacterium aestuarii ST58-10T, a benzene-degrading bacterium isolated from estuarine sediment.

Marinobacterium aestuarii ST58-10Twas identified as a benzene-degrading aerobic bacterium isolated from estuarine sediment in the Republic of Korea. The ge- nome of strain ST58-10Twas found to be composed of a single circular chromosome (5,191,608bp) with a G+C content of 58.78% and harboring 4,473 protein-coding genes. The assembled sequence data will help elucidate potential metabolic pathways and mechanisms responsible for the hydrocarbon-degrading ability of M. aestuarii ST58-10T.

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July 7, 2019  |  

The molecular basis for the intramolecular migration (NIH shift) of the carboxyl group during para-hydroxybenzoate catabolism.

The NIH shift is a chemical rearrangement in which a substituent on an aromatic ring undergoes an intramolecular migration, primarily during an enzymatic hydroxylation reaction. The molecular mechanism for the NIH shift of a carboxyl group has remained a mystery for 40 years. Here, we elucidate the molecular mechanism of the reaction in the conversion of para-hydroxybenzoate (PHB) to gentisate (GA, 2, 5-dihydroxybenzoate). Three genes (phgABC) from the PHB utilizer Brevibacillus laterosporus PHB-7a encode enzymes (p-hydroxybenzoyl-CoA ligase, p-hydroxybenzoyl-CoA hydroxylase and gentisyl-CoA thioesterase, respectively) catalyzing the conversion of PHB to GA via a route involving CoA thioester formation, hydroxylation concomitant with a 1, 2-shift of the acetyl CoA moiety and thioester hydrolysis. The shift of the carboxyl group was established rigorously by stable isotopic experiments with heterologously expressed phgABC, converting 2, 3, 5, 6-tetradeutero-PHB and [carboxyl-13 C]-PHB to 3, 4, 6-trideutero-GA and [carboxyl-13 C]-GA respectively. This is distinct from the NIH shifts of hydrogen and aceto substituents, where a single oxygenase catalyzes the reaction without the involvement of a thioester. The discovery of this three-step strategy for carboxyl group migration reveals a novel role of the CoA thioester in biochemistry and also illustrates the diversity and complexity of microbial catabolism in the carbon cycle.© 2018 John Wiley & Sons Ltd.

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July 7, 2019  |  

The complete genomic sequence of a novel cold-adapted bacterium, Planococcus maritimus Y42, isolated from crude oil-contaminated soil.

Planococcus maritimus Y42, isolated from the petroleum-contaminated soil of the Qaidam Basin, can use crude oil as its sole source of carbon and energy at 20 °C. The genome of P. maritimus strain Y42 has been sequenced to provide information on its properties. Genomic analysis shows that the genome of strain Y42 contains one circular DNA chromosome with a size of 3,718,896 bp and a GC content of 48.8%, and three plasmids (329,482; 89,073; and 12,282 bp). Although the strain Y42 did not show a remarkably higher ability in degrading crude oil than other oil-degrading bacteria, the existence of strain Y42 played a significant role to reducing the overall environmental impact as an indigenous oil-degrading bacterium. In addition, genome annotation revealed that strain Y42 has many genes responsible for hydrocarbon degradation. Structural features of the genomes might provide a competitive edge for P. maritimus strain Y42 to survive in oil-polluted environments and be worthy of further study in oil degradation for the recovery of crude oil-polluted environments.

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July 7, 2019  |  

Identification and genome analysis of Deinococcus actinosclerus SJTR1, a novel 17ß-estradiol degradation bacterium.

Biodegradation with microorganisms is considered as an efficient strategy to remove the environmental pollutants. In this work, Deinococcus actinosclerus SJTR1 isolated from the wastewater was confirmed with great degradation capability to 17ß-estradiol, one typical estrogen chemical. It could degrade nearly 90% of 17ß-estradiol (10 mg/L) in 5 days and transform it into estrone; its degradation kinetics fitted for the first-order kinetic equation. The whole genome sequence of D. actinosclerus SJTR1 was obtained and annotated, containing one chromosome (3,315,586 bp) and four plasmids (ranging from 17,267 bp to 460,244 bp). A total of 3913 CDSs and 73 RNA genes (including 12 rRNA genes, 50 tRNA genes, and 11 ncRNA genes) were identified in its whole genome sequence. On this basis, a series of potential genes involved in steroid metabolism and stress responses of D. actinosclerus SJTR1 were predicted. It is the first report of Deinococcus strain with the degradation capability to estrogens. This work could enrich the genome sources of the estrogen-degrading strains and promote the degradation mechanism study of 17ß-estradiol in bacteria.

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July 7, 2019  |  

Genome analysis of Vallitalea guaymasensis strain L81 isolated from a deep-sea hydrothermal vent system.

Abyssivirga alkaniphila strain L81T, recently isolated from a black smoker biofilm at the Loki’s Castle hydrothermal vent field, was previously described as a mesophilic, obligately anaerobic heterotroph able to ferment carbohydrates, peptides, and aliphatic hydrocarbons. The strain was classified as a new genus within the family Lachnospiraceae. Herein, its genome is analyzed and A. alkaniphila is reassigned to the genus Vallitalea as a new strain of V. guaymasensis, designated V. guaymasensis strain L81. The 6.4 Mbp genome contained 5651 protein encoding genes, whereof 4043 were given a functional prediction. Pathways for fermentation of mono-saccharides, di-saccharides, peptides, and amino acids were identified whereas a complete pathway for the fermentation of n-alkanes was not found. Growth on carbohydrates and proteinous compounds supported methane production in co-cultures with Methanoplanus limicola. Multiple confurcating hydrogen-producing hydrogenases, a putative bifurcating electron-transferring flavoprotein—butyryl-CoA dehydrogenase complex, and a Rnf-complex form a basis for the observed hydrogen-production and a putative reverse electron-transport in V. guaymasensis strain L81. Combined with the observation that n-alkanes did not support growth in co-cultures with M. limicola, it seemed more plausible that the previously observed degradation patterns of crude-oil in strain L81 are explained by unspecific activation and may represent a detoxification mechanism, representing an interesting ecological function. Genes encoding a capacity for polyketide synthesis, prophages, and resistance to antibiotics shows interactions with the co-occurring microorganisms. This study enlightens the function of the fermentative microorganisms from hydrothermal vents systems and adds valuable information on the bioprospecting potential emerging in deep-sea hydrothermal systems.

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July 7, 2019  |  

Genomics and biochemistry investigation on the metabolic pathway of milled wood and alkali lignin-derived aromatic metabolites of Comamonas serinivorans SP-35.

The efficient depolymerization and utilization of lignin are one of the most important goals for the renewable use of lignocelluloses. The degradation and complete mineralization of lignin by bacteria represent a key step for carbon recycling in land ecosystems as well. However, many aspects of this process remain unclear, for example, the complex network of metabolic pathways involved in the degradation of lignin and the catabolic pathway of intermediate aromatic metabolites. To address these subjects, we characterized the deconstruction and mineralization of lignin with milled wood lignin (MWL, the most representative molecule of lignin in its native state) and alkali lignin (AL), and elucidated metabolic pathways of their intermediate metabolites by a bacterium named Comamonas serinivorans SP-35.The degradation rate of MWL reached 30.9%, and its particle size range was decreased from 6 to 30 µm to 2-4 µm-when cultured with C. serinivorans SP35 over 7 days. FTIR analysis showed that the C-C and C-O-C bonds between the phenyl propane structures of lignin were oxidized and cleaved and the side chain structure was modified. More than twenty intermediate aromatic metabolites were identified in the MWL and AL cultures based on GC-MS analysis. Through genome sequencing and annotation, and from GC-MS analysis, 93 genes encoding 33 enzymes and 5 regulatory factors that may be involved in lignin degradation were identified and more than nine metabolic pathways of lignin and its intermediates were predicted. Of particular note is that the metabolic pathway to form the powerful antioxidant 3,4-dihydroxyphenylglycol is described for the first time in bacteria.Elucidation of the ß-aryl ether cleavage pathway in the strain SP-35 indicates that the ß-aryl ether catabolic system is not only present in the family of Sphingomonadaceae, but also other species of bacteria kingdom. These newly elucidated catabolic pathways of lignin in strain SP-35 and the enzymes responsible for them provide exciting biotechnological opportunities for lignin valorization in future.

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