Enzymatic properties and degradation characterization of a bis(2-hydroxyethyl) terephthalate hydrolase from Saccharothrix sp / 生物工程学报

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.

Draft genome analysis of Dietzia sp. 111N12-1, isolated from the South China Sea with bioremediation activity

Abstract Dietzia sp. 111N12-1, isolated from the seawater of South China Sea, shows strong petroleum hydrocarbons degradation activity. Here, we report the draft sequence of approximately 3.7-Mbp genome of this strain. To the best of our knowledge, this is the first genome sequence of Dietzia strain isolated from the sea. The genome sequence may provide fundamental molecular information on elucidating the metabolic pathway of hydrocarbons degradation in this strain.

Transcriptional profiling of genes involved in n-hexadecane compounds assimilation in the hydrocarbon degrading Dietzia cinnamea P4 strain

The petroleum-derived degrading Dietzia cinnamea strain P4 recently had its genome sequenced and annotated. This allowed employing the data on genes that are involved in the degradation of n-alkanes. To examine the physiological behavior of strain P4 in the presence of n-alkanes, the strain was grown under varying conditions of pH and temperature. D. cinnamea P4 was able to grow at pH 7.0-9.0 and at temperatures ranging from 35 ºC to 45 ºC. Experiments of gene expression by real-time quantitative RT-PCR throughout the complete growth cycle clearly indicated the induction of the regulatory gene alkU (TetR family) during early growth. During the logarithmic phase, a large increase in transcriptional levels of a lipid transporter gene was noted. Also, the expression of a gene that encodes the protein fused rubredoxin-alkane monooxygenase was enhanced. Both genes are probably under the influence of the AlkU regulator.

Micetoma por Actinomadura madurae en el pie: reporte de un caso en Chile / Actinomadura madurae mycetoma of the foot: report of one case

Mycetoma is a chronic infection that affects skin, subcutaneous tissue and bone. Its etiology can be mycotic or bacterial. It affects mainly the lower extremities ofmiddie age men livingin tropical climates. We repon a 44 year-old male ¡ivingin a template zone, consulting for swelling and pain in the left foot, lasting for 10 years. Physical examination showed a swollen left foot with hyperpigmented skin and a few crustedpapules. Radiology showed an extensive bone involvement of the midfoot with several oval and radiolucid images. Magnetic resonance showed son and bone tissue involvement, with múltiple oval and low intensity images in TI and T2. The biopsy was compatible with an unspecific chronic osteomyelitis. A bacterial identification by polymerase chain reaction and sequencing in the biopsy determined the presence of an Actinomadura madurae. Treatment with cotrimoxazol was started).

Mouse footpad pathogenicity of leprosy derived nocardioform bacteria cultivated in vitro.

In vitro cultures of the nocardioform bacteria from leprosy-infected tissues consisted of granules and bacilli. Inoculation of these granules into mouse footpads (MFP) produced a mild, localised, inflammation for 4-6 weeks. The granules evoked typical granulomatous response in the subcutaneous tissue and showed gradual disintegration. Infiltration of muscles, connective tissue and epithelial cells by bacillary/mycelial masses was seen very frequently, and that of nerve bundles occasionally. Plenty of mycelial tufts emanated from many 'macrophage globi'. By 6-8 months, the granules disintegrated nearly completely releasing a large number of acid-fast bacilli (AFB), single layered rings of AFB, small globi and some residual mycelia. These AFB, harvested from the MFP, were similar to or indistinguishable from the bacillary preparations from the in vitro cultures and from the leprosy bacillus obtained directly from humans or as passaged into the MFP, on the basis of many criteria studied, including the 36k gene positivity.