volcanii and E. coli. pAJ successfully expressed proteins in Hfx. volcanii or E. coli, rendering it feasible to express target proteins in corresponding domains. In addition, pAJ contains a multiple cloning site with 11 restriction sites and a 6×His tag sequence, and the vector size was decreased to 8903 bp. To the best of our knowledge, pAJ is the first reported shuttle expression vector that can express proteins in both Bacteria and Archaea. Importantly, pAJ can even express the haloarchaeal heat shock click here protein DnaK in both domains. In conclusion, this novel vector only provides researchers with a new means to manipulate genes
or express proteins in Haloarchaea but also serves as a convenient tool for the comparative study of the function of some highly conserved genes in Haloarchaea and in Bacteria. “
“The present study describes the assimilation of phenanthrene by an aerobic bacterium, Ochrobactrum sp. strain PWTJD, isolated from municipal waste-contaminated soil sample
utilizing phenanthrene as a sole source of carbon and energy. The isolate was identified as Ochrobactrum sp. based on the morphological, nutritional and biochemical characteristics as well as 16S rRNA gene sequence analysis. A combination of chromatographic analyses, oxygen uptake assay and enzymatic studies confirmed the degradation of phenanthrene by the strain PWTJD via 2-hydroxy-1-naphthoic acid, salicylic acid and catechol. The strain PWTJD could also utilize 2-hydroxy-1-naphthoic acid and MEK inhibitor salicylic acid, while the former was metabolized by a ferric-dependent meta-cleavage dioxygenase. In the lower pathway, salicylic acid was metabolized to catechol and was further degraded by catechol 2,3-dioxygenase to 2-hydroxymuconoaldehyde acid, ultimately leading to tricarboxylic acid cycle intermediates. This is the first report of
the complete degradation of a polycyclic aromatic hydrocarbon molecule by Gram-negative Ochrobactrum sp. describing the involvement of the meta-cleavage pathway of 2-hydroxy-1-naphthoic acid in phenanthrene assimilation. Polycyclic aromatic hydrocarbons (PAHs) comprise a large science and diverse group of priority environmental pollutants, which are ubiquitous contaminants derived from both natural and anthropogenic activities. Their abundance in the environment is of great concern, because many of them have been shown to be toxic, mutagenic and/or carcinogenic in nature (Mastrangelo et al., 1996; Marston et al., 2001; Xue & Warshawsky, 2005). The stability, persistency and carcinogenic index of PAHs increase with an increase in the number of aromatic rings, structural angularity and hydrophobicity (Marston et al., 2001). Phenanthrene has often been used as a model compound to study the microbial metabolism of bay- and K-region-containing PAHs because its structural skeletons are found in many carcinogenic PAHs.