Enhancement of liquid/gas production during co-pyrolysis of vacuum residue and plastics due to synergistic interactions.

Vacuum residue (VR) was copyrolysed with polyethylene (PE) or polystyrene (PS) in a batch reactor to investigate the corresponding synergistic pyrolytic interactions. The synergistic interactions between VR and plastic pyrolysates enhanced liquid and gas production while reducing coke formation, as compared with VR-only and plastic-only pyrolysis. The pyrolysis of 9:1 w/w VR: PE (PE with M = 3 MDa) and 9:1 w/w VR/PS (PS with M ≈ 350 kDa) mixtures produced oil in yields of 28.

Determination and potential importance of diterpene (kaur-16-ene) emitted from dominant coniferous trees in Japan.

Reactive volatile organic compounds (VOCs) are known to affect atmospheric chemistry. Biogenic VOCs (BVOCs) have a significant impact on regional air quality due to their large emission rates and high reactivities. Diterpenes (most particularly, kaur-16-ene) were detected in all of the 205 enclosure air samples collected over multiple seasons at two different sites from Cryptomeria japonica and Chamaecyparis obtusa trees, the dominant coniferous trees in Japan,.

Desulfurization characteristics of thermophilic Paenibacillus sp. strain A11-2 against asymmetrically alkylated dibenzothiophenes.

The thermophilic bacterium Paenibacillus sp. A11-2, which can utilize dibenzothiophene (DBT) as the sole sulfur source at high temperature (45-55 degrees C), was investigated for its ability to cleave carbon-sulfur bonds in the dibenzothiophene (DBT) ring with asymmetrical alkyl substitution, such as methyl, dimethyl, trimethyl, ethyl and propyl DBTs. The biodesulfurization products of each of these alkylated DBTs (Cx-DBTs) were identified and quantitatively determined.

Selective cleavage of the two CS bonds in asymmetrically alkylated dibenzothiophenes by Rhodococcus erythropolis KA2-5-1.

The Rhodococcus erythropolis strain KA2-5-1 was characterized by its ability to cleave carbon-sulfur bonds in the dibenzothiophene (DBT) ring by asymmetrically alkyl substitution, such as C2-DBTs (e.g., dimethyl and ethyl DBTs) and C3-DBTs (e.

Purification and characterization of dibenzothiophene sulfone monooxygenase and FMN-dependent NADH oxidoreductase from the thermophilic bacterium Paenibacillus sp. strain A11-2.

A dibenzothiophene (DBT) sulfone monooxygenase (TdsA), which catalyses the oxidative CS bond cleavage of DBT sulfone to produce 2-(2-hydroxyphenyl)benzenesulfinate (HPBS) was purified from the thermophilic DBT desulfurizing bacterium Paenibacillus sp. strain A11-2 by multistep chromatography. The molecular mass of the purified enzyme was determined to be 120 kDa by gel filtration and the subunit molecular mass was calculated to be 48 kDa by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) indicating a dimeric structure.

Cloning and expression of the gene encoding the thermophilic NAD(P)H-FMN oxidoreductase coupling with the desulfurization enzymes from Paenibacillus sp. A11-2.

The gene encoding the NAD(P)H-flavin oxidoreductase (flavin reductase) which couples with the thermophilic dibenzothiophene (DBT)-desulfurizing monooxygenases of Paenibacillus sp. A11-2 was cloned in Escherichia coli and designated tdsD. Nucleotide sequence analysis suggested that the gene product consisted of 200 amino acids and showed about 30%, 27% and 26% amino acid sequence similarity to the major flavin reductase of Vibrio fischeri, the NADH dehydrogenase of Thermus thermophilus and several oxygen-insensitive NAD(P)H nitroreductases in the Enterobacteriaceae family, respectively.

Identification of the gene encoding a NAD(P)H-flavin oxidoreductase coupling with dibenzothiophene (DBT)-desulfurizing enzymes from the DBT-nondesulfurizing bacterium Paenibacillus polymyxa A-1.

The gene encoding NAD(P)H-flavin oxidoreductase (flavin reductase), which couples efficiently with dibenzothiophene (DBT)-desulfurizing monooxygenases of Rhodococci, was cloned from a DBT-non-desulfurizing bacterium Paenibacillus polymyxa A-1 in Escherichia coli, and designated as flv. Cell-free extracts from the recombinant exhibited a flavin reductase activity about forty times higher than that of the E. coli carrying the vector DNA only.

A novel enzyme, 2'-hydroxybiphenyl-2-sulfinate desulfinase (DszB), from a dibenzothiophene-desulfurizing bacterium Rhodococcus erythropolis KA2-5-1: gene overexpression and enzyme characterization.

Dibenzothiophene (DBT), a model of organic sulfur compound in petroleum, is microbially desulfurized to 2-hydroxybiphenyl (2-HBP), and the gene operon dszABC was required for DBT desulfurization. The final step in the microbial DBT desulfurization is the conversion of 2'-hydroxybiphenyl-2-sulfinate (HBPSi) to 2-HBP catalyzed by DszB. In this study, DszB of a DBT-desulfurizing bacterium Rhodococcus erythropolis KA2-5-1 was overproduced in Escherichia coli by coexpression with chaperonin genes, groEL/groES, at 25 degrees C.

Desulfurization of benzothiophene by the Gram-negative bacterium, Sinorhizobium sp. KT55.

Sinorhizobium sp. KT55 was the first Gram-negative isolate to be capable of utilizing benzothiophene as the sole source of sulfur. By GC-MS analysis of metabolites of benzothiophene by this strain, benzothiophene sulfone, benzo[e][1,2]oxathiin S-oxide and o-hydroxystyrene were detected, suggesting that the benzothiophene desulfurization pathway of this strain is benzothiophene-->benzothiophene sulfoxide-->benzothiophene sulfone-->benzo[e][1,2]oxathiin S-oxide-->o-hydroxystyrene.

Kinetic analysis of microbial desulfurization of model and light gas oils containing multiple alkyl dibenzothiophenes.

The reaction mechanism of biodesulfurization was investigated using whole cells of Rhodococcus erythropolis KA2-5-1, which have the ability to convert dibenzothiophene (DBT) into 2-hydroxybiphenyl. The desulfurization patterns of alkyl DBTs were represented by the Michaeis-Menten equation. The values of rate constants, the limiting maximal velocity (Vmax) and Michaelis constant (Km), for desulfurization of alkyl DBTs were calculated.

Improvement of desulfurization activity in Rhodococcus erythropolis KA2-5-1 by genetic engineering.

Rhodococcus erythropolis KA2-5-1 can desulfurize dibenzothiophene (DBT) into 2-hydroxybiphenyl. A cryptic plasmid, pRC4, which was derived from R. rhodochrous IFO3338, was combined with an Escherichia coli vector to construct an E.

Application of solid-phase extraction to the analysis of the isomers generated in biodesulfurization against methylated dibenzothiophenes.

A solid-phase extraction (SPE) technique was applied to analyze and characterize the biodesulfurization reactions against asymmetrically methylated dibenzothiophenes (mDBTs) such as 1-, 2-, 3- and 4-methyldibenzothiophenes present in fossil fuels. Recently, we found that these mDBTs are efficiently degraded by the bacterial strain, Rhodococcus erythropolis KA2-5-1. Separation and concentration of the microbial desulfurization products from each of the mDBTs could be carried out with high efficiency and reproducibility by the SPE procedure.

Demonstration of the carbon-sulfur bond targeted desulfurization of benzothiophene by thermophilic Paenibacillus sp. strain A11-2 capable of desulfurizing dibenzothiophene.

Paenibacillus sp. strain A11-2, which had been primarily isolated as a bacterial strain capable of desulfurizing dibenzothiophene to produce 2-hydroxybiphenyl at high temperatures, was found to desulfurize benzothiophene more efficiently than dibenzothiophene. The desulfurized product was identified as o-hydroxystyrene by GC-MS and 1H-NMR analysis.

Desulfurization of alkylated forms of both dibenzothiophene and benzothiophene by a single bacterial strain.

Thirty-five bacterial strains capable of converting dibenzothiophene into 2-hydroxybiphenyl were isolated. Among them Rhodococcus erythropolis KA2-5-1 was chosen for further characterization because of its ability to retain high desulfurization activity stably. PCR cloning and DNA sequencing of a KA2-5-1 genomic DNA fragment showed that it was practically identical with dszABC genes from Rhodococcus sp.

Alkylated benzothiophene desulfurization by Rhodococcus sp. strain T09.

A benzothiophene desulfurizing bacterium was isolated and identified as Rhodococcus sp. strain T09. Growth assays revealed that this strain assimilated, as the sole sulfur source, various organosulfur compounds that cannot be assimilated by the well-studied dibenzothiophene-desulfurizing Rhodococcus sp.

Operon structure and functional analysis of the genes encoding thermophilic desulfurizing enzymes of Paenibacillus sp. A11-2.

Paenibacillus A11-2 can efficiently cleave two carbon&bond;sulfur bonds in dibenzothiophene (DBT) and alkyl DBTs, which are refractory by conventional petroleum hydrodesulfurization, to remove sulfur atom at high temperatures. An 8.7-kb DNA fragment containing the genes for the DBT desulfurizing enzymes of A11-2 was cloned in Escherichia coli and characterized.