Molecular characterization and heterologous expression of quinate dehydrogenase gene from Gluconobacter oxydans IFO3244.

The quinate dehydrogenase (QDH) from Gluconobacter oxydans IFO3244 exhibits high affinity for quinate, suggesting its application in shikimate production. Nucleotide sequence analysis of the qdh gene revealed a full-length of 2475-bp encoding an 824-amino acid protein. The qdh gene has the unusual TTG translation initiation codon. Conserved regions and a signature sequence for the quinoprotein family were observed. Phylogenetic analysis demonstrated relatedness of QDH from G. oxydans to other quinate/shikimate dehydrogenases with the highest similarity (56%) with that of Acinetobacter calcoaceticus ADP1 and lower similarity (36%) with a membrane-bound glucose dehydrogenase of Escherichia coli. The function of the gene coding for QDH was confirmed by heterologous gene expression in pyrroloquinoline quinone-synthesizing Pseudomonas putida HK5.

A biosurfactant from Burkholderia cenocepacia BSP3 and its enhancement of pesticide solubilization.

AIMS: To isolate a biosurfactant (BS)-producing bacterium, to characterize the BS properties and to evaluate its ability to enhance pesticide solubilization for further application in environmental remediation. METHODS AND RESULTS: Five BS-producing bacteria were isolated from fuel oil-contaminated soil. Among them, Burkholderia cenocepacia BSP3 exhibited the highest emulsification index and was chosen for further study. Glucose-containing medium supplemented with nitrate or sunflower seed oil provided suitable conditions for growth and BS production. The BS was identified as a glucolipid, having a critical micelle concentration (CMC) of 316 mg l(-1). It could lower the surface tension of deionized water to 25 +/- 0.2 mN m(-1) and exhibited good emulsion stability. Finally, the application of the BS to facilitate pesticide solubilization demonstrated that this BS at the concentration below and above its CMC could enhance the apparent water solubility of three pesticides, i.e. methyl parathion, ethyl parathion and trifluralin. CONCLUSIONS: Burkholderia cenocepacia BSP3 is a BS-producing bacterium isolated from oil-contaminated soil. The BS was identified as a glucolipid having a molecular mass of 550.4 g mol(-1). An apparent yield of the BS was 6.5 +/- 0.7 g l(-1). This glucolipid-type BS noticeably enhanced pesticide solubilization suggesting its role in environmental remediation. SIGNIFICANCE AND IMPACT OF THE STUDY: A glucolipid type BS normally found in marine micro-organisms was isolated from a soil-bacterium. Due to its surface active properties and good performance in enhancement of pesticide solubilization, it could be used as a solubilizing agent for environmental remediation and synergistic treatment with bioremediation of pesticide-contaminated soil.

Abundance and diversity of functional genes involved in the degradation of aromatic hydrocarbons in Antarctic soils and sediments around Syowa Station.

Hydrocarbon catabolic genes were investigated in soils and sediments in nine different locations around Syowa Station, Antarctica, using conventional PCR, real-time PCR, cloning, and sequencing analysis. Polycyclic aromatic hydrocarbon ring-hydroxylating dioxygenase (PAH-RHD)-coding genes from both Gram-positive and Gram-negative bacteria were observed. Clone libraries of Gram-positive RHD genes were related to (i) nidA3 of Mycobacterium sp. py146, (ii) pdoA of Terrabacter sp. HH4, (iii) nidA of Diaphorobacter sp. KOTLB, and (iv) pdoA2 of Mycobacterium sp. CH-2, with 95-99% similarity. Clone libraries of Gram-negative RHD genes were related to the following: (i) naphthalene dioxygenase of Burkholderia glathei, (ii) phnAc of Burkholderia sartisoli, and (iii) RHD alpha subunit of uncultured bacterium, with 41-46% similarity. Interestingly, the diversity of the Gram-positive RHD genes found around this area was higher than those of the Gram-negative RHD genes. Real-time PCR showed different abundance of dioxygenase genes between locations. Moreover, the PCR-denaturing gradient gel electrophoresis (DGGE) profile demonstrated diverse bacterial populations, according to their location. Forty dominant fragments in the DGGE profiles were excised and sequenced. All of the sequences belonged to ten bacterial phyla: Proteobacteria, Actinobacteria, Verrucomicrobia, Bacteroidetes, Firmicutes, Chloroflexi, Gemmatimonadetes, Cyanobacteria, Chlorobium, and Acidobacteria. In addition, the bacterial genus Sphingomonas, which has been suggested to be one of the major PAH degraders in the environment, was observed in some locations. The results demonstrated that indigenous bacteria have the potential ability to degrade PAHs and provided information to support the conclusion that bioremediation processes can occur in the Antarctic soils and sediments studied here.

Phytoremediation of bisphenol A and total dissolved solids by the mangrove plant, Bruguiera gymnorhiza.

Bruguiera gymnorhiza, an evergreen mangrove tree, is tolerant of bisphenol A (BPA) and has potential BPA removal capability. BPA is highly toxic to plants at high concentrations, wherein they exhibit damaged symptoms such as chlorosis, necrosis, and wilting. The LD50 of BPA toxicity for this plant was statistically estimated to be 39.97 mg L(-1). B. gymnorhiza can reduce COD from 15408 +/- 246 to 49 +/- 30 mg L(-1) by (approximately 99% reduction of the initial value) and can reduce content to levels below the industrial effluent standard of Thailand (<120 mg L(-1)) within 48 days. This plant can completely remove BPA from the solution within 51 days of treatment. Polysaccharides and organic acids were found in the solution and were caused by plant response to the toxicity of BPA. In addition, B. gymnorrhiza can also reduce total dissolved solids (TDS) and salinity in real wastewater. Therefore, B. gymnorrhiza has potential for removal of BPA and TDS in contaminated in wastewater.

Bisphenol A removal by the Dracaena plant and the role of plant-associating bacteria.

Dracaena sanderiana and Dracaena fragrans plants, as representatives of native, tropical, evergreen plants with fibrous root systems, were evaluated for bisphenol A (BPA) tolerance and uptake capability. D. sanderiana demonstrated significantly higher BPA removal capability than D. fragrans. Therefore, it was chosen for further study. D. sanderiana tolerated BPA toxicity levels up to 80 microM, while higher BPA concentrations damaged the plant. In the sterile hydroponic system with an initial BPA concentration of 20 microM, the plant could uptake approximately 50% of the BPA. The plant's ability to translocate BPA was confirmed by the detection of BPA that accumulated at the roots and stems, but not at the leaves of the plant. Upon BPA exposure, the D. sanderiana secreted extracellular plant mucilage as a protective barrier to the toxic compound. In the non-sterile treatment, the BPA dissipation was contributed not only by the D. sanderiana plant, but also by the co-existing microbes. The BPA reached 85% of the initial concentration at 20 microM. Among the six plant-associating bacterial isolates, Bacillus cereus strain BPW4 and Enterobacter sp. strain BPW5 colonized the D. sanderiana root surface and facilitated BPA dissipation in the hydroponic treatment system. In addition, the success of the BPA treatment in the hazardous waste landfill leachate demonstrated the potential application of D. sanderiana plant in the phytoremediation of BPA contaminated wastewater or industrial leachate.

An organic solvent-, detergent-, and thermo-stable alkaline protease from the mesophilic, organic solvent-tolerant Bacillus licheniformis 3C5.

Bacillus licheniformis 3C5, isolated as mesophilic bacterium, exhibited tolerance towards a wide range of non-polar and polar organic solvents at 45 degrees C. It produced an extracellular organic solvent-stable protease with an apparent molecular mass of approximately 32 kDa. The inhibitory effect of PMSF and EDTA suggested it is likely to be an alkaline serine protease. The protease was active over abroad range of temperatures (45-70 degrees C) and pH (8-10) range with an optimum activity at pH 10 and 65 degrees C. It was comparatively stable in the presence ofa relatively high concentration (35% (v/v)) of organic solvents and various types of detergents even at a relatively high temperature (45 degrees C). The protease production by B. licheniformis 3C5 was growth-dependent. The optimization of carbon and nitrogen sources for cell growth and protease production revealed that yeast extract was an important medium component to support both cell growth and the protease production. The overall properties of the protease produced by B. licheniformis 3C5 suggested that this thermo-stable, solvent-stable, detergent-stable alkaline protease is a promising potential biocatalyst for industrial and environmental applications.