Polyhydroxyalkanoate depolymerase (PHAD) can be used for the degradation and recovery of polyhydroxyalkanoate (PHA). In order to develop a PHAD with good stability under high temperature, PHAD from Thermomonospora umbrina (TumPHAD) was heterelogously expressed in Escherichia coli BL21(DE3). At the same time, a mutant A190C/V240C with enhanced stability was obtained via rational design of disulfide bonds. Characterization of enzymatic properties showed that the mutant A190C/V240C had an optimum temperature of 60 ℃, which was 20 ℃ higher than that of the wild type. The half-life at 50 ℃ was 7 hours, at 50 ℃ which was 21 times longer than that of the wild type. The mutant A190C/V240C was used for the degradation of polyhydroxybutyrate (PHB), one of the typical PHA. At 50 ℃, the degradation rate of PHB being treated for 2 hours and 12 hours was 2.1 times and 3.8 times higher than that of the wild type, respectively. The TumPHAD mutant A190C/V240C obtained in this study shows tolerance to high temperature resistance, good thermal stability and strong PHB degradation ability, which may facilitate the degradation and recovery of PHB.
Thermomonospora ; Actinomycetales ; Escherichia coli/genetics* ; Polyhydroxyalkanoates

The discovery of new enzymes for poly(ethylene terephthalate) (PET) degradation has been a hot topic of research globally. Bis-(2-hydroxyethyl) terephthalate (BHET) is an intermediate compound in the degradation of PET and competes with PET for the substrate binding site of the PET-degrading enzyme, thereby inhibiting further degradation of PET. Discovery of new BHET degradation enzymes may contribute to improving the degradation efficiency of PET. In this paper, we discovered a hydrolase gene sle (ID: CP064192.1, 5085270-5086049) from Saccharothrix luteola, which can hydrolyze BHET into mono-(2-hydroxyethyl) terephthalate (MHET) and terephthalic acid (TPA). BHET hydrolase (Sle) was heterologously expressed in Escherichia coli using a recombinant plasmid, and the highest protein expression was achieved at a final concentration of 0.4 mmol/L of isopropyl-β-d-thiogalactoside (IPTG), an induction duration of 12 h and an induction temperature of 20 ℃. The recombinant Sle was purified by nickel affinity chromatography, anion exchange chromatography, and gel filtration chromatography, and its enzymatic properties were also characterized. The optimum temperature and pH of Sle were 35 ℃ and 8.0, and more than 80% of the enzyme activity could be maintained in the range of 25-35 ℃ and pH 7.0-9.0 and Co²⁺ could improve the enzyme activity. Sle belongs to the dienelactone hydrolase (DLH) superfamily and possesses the typical catalytic triad of the family, and the predicted catalytic sites are S129, D175, and H207. Finally, the enzyme was identified as a BHET degrading enzyme by high performance liquid chromatography (HPLC). This study provides a new enzyme resource for the efficient enzymatic degradation of PET plastics.
Actinomycetales/genetics* ; Hydrolases/metabolism* ; Phthalic Acids/chemistry* ; Polyethylene Terephthalates/metabolism*

Tsukamurella pulmonis is an aerobic actinomycete. We report a catheter-related bacteremia of T. pulmonis. A 39 yr-old male with ALL was hospitalized to receive bone marrow transplantation (BMT). Although the patient developed a high fever at the 7th hospital day (HD), it subsided with vancomycin treatment, and he received BMT at 9th HD. Fever resurged at 16th HD despite sustained treatment with vancomycin, meropenem, and amphotericin B, but subsided with removal of Hickman catheter (HC) at 19th HD. Three sets of blood cultures comprising one from the HC and two from venipunctures were taken at 7th, 16th, and 19th HD, and the distal tip of the HC was also cultured. The aerobic vials of all 3 HC-withdrawn blood cultures and one peripheral blood culture taken at 19HD and the HC tip culture grew long, straight, thin gram-positive rods that were positive on modified Kinyoun stain. This organism showed tiny, rough, grey colonies after 3-day incubation and grew to large flat colonies when incubation was extended. It was catalase-positive, urease-positive, and alkaline-slant/alkaline-deep on triple sugar iron agar, and hydrolyzed hypoxanthine. The sequence of 1,296 base pairs of 16S rRNA of this organism showed a 100.0% homology with the published sequence of T. pulmonis DSM 44142T. To our knowledge, this is the first report of T. pulmonis bacteremia in Korea.
Actinomycetales/classification/genetics/isolation & purification ; Actinomycetales Infections/diagnosis/*microbiology/therapy ; Adult ; Bacteremia/*diagnosis/microbiology/therapy ; Bone Marrow Transplantation ; Catheter-Related Infections/*microbiology ; Humans ; Leukemia, Myeloid, Acute/therapy ; Male ; Phylogeny ; RNA, Ribosomal, 16S/genetics

In order to characterize a thermostable urate oxidase (Uox) from Microbacterium sp. strain ZZJ4-1, we cloned its gene (uox). The open reading frame of uox contained 894 base pairs and encoded a protein with 297 amino acids. Alignment of gene sequences indicated there was no obvious identity with the most reported uox and that 72% identity was found with uox from Arthrobacter globiformis. We inserted the gene into the plasmid pET-15b to construct an expression vector pET-15b-uox and got it induced expression in Escherichia coli BL21 (DE3). After the purification of the recombinant Uox by the HisBind column, we studied some properties of it. It was composed of subunits with a molecular mass of about 35 kDa. The optimal temperature and pH was 30 degrees C and pH 7.5. It was stable below 65 degrees C and from pH 8.5 to 11.0. The Km value was 0.22 mmol/L with the uric acid as the substrate. Ag+, Zn2+, CU2+ and SDS could totally inhibit its activity while Tween 20, Tween 80 and Triton X-100 had a slight promotion effect. The thermal stability of this enzyme was the most excellent among the reported recombinant Uox. Based on this property, it would be very useful in the application.
Actinomycetales ; enzymology ; genetics ; Amino Acid Sequence ; Cloning, Molecular ; Enzyme Stability ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; genetics ; Molecular Sequence Data ; Recombinant Proteins ; biosynthesis ; genetics ; Urate Oxidase ; genetics ; metabolism

A gene replacement/disruption system of Amycolatopsis mediterranei U32 was developed based on the established electroporation conditions as well as appropriate selective markers. Through two-step selection, ahbas gene in U32 was replaced by a promoterless alpha-amylase gene constructed on the plasmid pDK110 of E. coli. The first single-crossover and the second double-crossover frequencies were approximately 0.5%-0.7% and 2%, respectively. Denaturation of the plasmid pDK110 increased the integration frequency about 7-10 folds, while electric shock treatment of the single-crossover recombinants increased the frequency of second crossover recombination about 5 folds. Employing denatured DNA fragments containing an apramycin-resistance gene flanked with regions of the respective genes, One-step disruption of rifO and amrA genes of U32 was also achieved with an efficiency of 30-50 transformants per microgram of DNA.
Actinomycetales ; drug effects ; genetics ; growth & development ; DNA, Bacterial ; genetics ; Drug Resistance, Microbial ; genetics ; Genes, Bacterial ; genetics ; Mutagenesis ; Nebramycin ; analogs & derivatives ; pharmacology ; Plasmids ; genetics ; Recombination, Genetic

Fermentation and induction conditions for recombinant Escherichia coli expressing Thermobifida fusca cutinase were optimized in flasks and 3L fermenter. Surface modification of poly (ethylene terephthalate) fibers with cutinase was also discussed. The results showed that, cutinase yield reached 128 U/mL by adding 2 g/L inducer lactose and 0.5% glycine. In the fed-batch culture in a 3 L fermenter, the maximum biomass cutinase activity was up to 506 U/mL, which is the highest bacterial cutinase activity reported by far. Recombinant cutinase was used to modify polyester fibers and terephthalic acid substance was detected by using UV analysis. The dyeing and wetting properties of cutinase treated fibers were higher than untreated fibers. Combined utilization of cutinase and Triton X-100 can significantly improve the hydrophilicity of polyester. This is the first report of surface modification on polyester fibers by bacterial cutinase.
Actinomycetales ; enzymology ; genetics ; Carboxylic Ester Hydrolases ; biosynthesis ; chemistry ; genetics ; Escherichia coli ; genetics ; metabolism ; Fermentation ; Polyethylene Glycols ; chemistry ; Polyethylene Terephthalates ; Recombinant Proteins ; biosynthesis ; genetics ; Surface Properties

Streptoverticillum caespitosus ATCC27422 is a producing strain of mitomycin A for cancer therapy. Taking the advantage of the conserved sequences of genes flanking the oriC of high G + C Gram-positive bacteria, a 1.3 kb DNA fragment containing oriC and its flanking region was cloned by PCR. Nuleotide sequence comparisons revealed that the cloned fragment is more than 80% identical to the same region of S. coelicolor. There are 22 DnaA-boxes in the oriC region, and the conserved sequence of DnaA-box is TTGTCCACA. The plasmid containing the oriC of S. caespitosus was constructed (pMJ9), and it was able to transform the protoplast of Streptomyces lividans ZX7 at the frequency of 3.2 x 10(2) transformants/micrograms plasmid DNA. The colony and mycelia's morphology of the transformants are normal. The constructed plasmid can exist stable in the host as a low copy extra-chromosome replicon. The high rate of the homology and the cross genus replication initiation activity suggests close relationship between Streptomyces and Streptoverticillum in the evolution. While the maximum likelihood phylogenetic tree based upon the oriC of S. caespitosus and several Streptomyces spp. revealed that S. caespitosus differed extensively from the Streptomyces spp. This result supports the separation of Streptoverticillum from Streptomyces.
Actinomycetales ; genetics ; Base Sequence ; Blotting, Southern ; Cloning, Molecular ; Conserved Sequence ; Molecular Sequence Data ; Plasmids ; Replication Origin ; genetics ; Streptomyces ; genetics ; Transformation, Bacterial

Wuxistatin, a novel and potent statin, is converted from lovastatin by Amycolatopsis sp. CGMCC1149. In the bioconversion, lovastatin is firstly hydroxylated by a hydroxylase. To obtain the critical hydroxylase, a novel hydroxylase gene was isolated from Amycolatopsis sp. CGMCC1149 by Degenerate PCR and Self-Formed Adaptor PCR and expressed in Escherichia coli. BLAST sequence analysis revealed that the gene belonged to cytochrome P450 gene superfamily and could encode a 403-amino-acid protein with a molecular weight of 44.8 kDa. The secondary structure prediction result showed that this protein contained many typical functional regions of P450, such as oxygen binding site, ion-pair region and heme binding region. Meanwhile, a catalytic function verification system was constructed by NADH, ferredoxin and ferredoxin reductase which could catalyze lovastatin hydroxylation into the target product. These would be helpful for further studies in large-scale production of wuxistatin.
Actinomycetales ; enzymology ; genetics ; Amino Acid Sequence ; Butyrates ; metabolism ; Cloning, Molecular ; Cytochrome P-450 Enzyme System ; genetics ; metabolism ; Hydroxylation ; Industrial Microbiology ; Lovastatin ; metabolism ; Molecular Sequence Data

A beta-D-xylosidase from Leifsonia shinshuensis DICP 16 was purified to apparent homogeneity using a combination of ammonium sulfate precipitation, DE 52 anion-exchange, Q-Sepharose Fast Flow anion-exchange, Toyopearl Butyl 650C hydrophobic-interaction and Sephacryl S-300 HR gel-permeation chromatography. The purified xylosidase consisted of two same subunits and had the relative molecular weight of 180 kD as determined by SDS-PAGE and gel-permeation chromatography. The maximal beta-D-xylosidase activity occurred at 55 degrees C and pH 7.0. It was stable at 45 degrees C and retained its original activity for 60 min. The stability declined rapidly when the temperature rose above 55 degrees C. The xylosidase was stable in the pH range from 6.0 to 11.0 for 20 h. At pH 7.0 and 45 degrees C the Km for p-nitrophenyl-beta-D-xylopyranoside (pNPX) was 1.04 mmol/L and the Vmx was 0.095 mmol nitrophenol/min/mg xylosidase. The enzyme was inhibited strongly by Fe2+ and Cu2+. It exhibited low levels of activity against other artificial substrates, compared to its activity against pNPX. When different natural xylosides were used as the substrates, the xylosidase showed distinct hydrolysis ability. It could hydrolyze 20-C, beta-(1-->6)-xyloside of ginsenoside Rb3 (G-Rb3) into ginsenoside Rd, but did not hydrolyze the other beta-D-glucosidic bonds of G-Rb3. Additionally, the xylosidase could not hydrolyze C-7 xylosyl-bearing taxanes.
Actinomycetales ; classification ; enzymology ; Amino Acid Sequence ; Culture Media ; Hydrogen-Ion Concentration ; Molecular Sequence Data ; Sequence Analysis, Protein ; Temperature ; Xylosidases ; chemistry ; genetics ; isolation & purification

The aromatic-ring-hydroxylating dioxygenase is a key enzyme that initiates the biodegradation of polycyclic aromatic hydrocarbons in bacteria. In the present study, a novel dioxygenase sequence was cloned from Terrabacter sp. FLO using a genome walking method. The dioxygenase was cloned into pET17 and actively expressed in E.coli BL21 (DE3) in co-expression with electron transfer chain proteins. The recombinant dioxygenase was found to transform phenanthrene, fluorene, pyrene and fluoranthene into the cis-dihydrodiol metabolites.
Actinomycetales ; enzymology ; genetics ; Bacterial Proteins ; genetics ; metabolism ; Biodegradation, Environmental ; Cloning, Molecular ; Dioxygenases ; genetics ; metabolism ; Electrophoresis, Polyacrylamide Gel ; Escherichia coli ; genetics ; metabolism ; Fluorenes ; metabolism ; Hydroxylation ; Molecular Sequence Data ; Phenanthrenes ; metabolism ; Polycyclic Aromatic Hydrocarbons ; metabolism ; Pyrenes ; metabolism ; Recombinant Proteins ; metabolism