Detoxification of microcystin-LR in water by Portulaca oleracea cv.

Microcystin-LR (0.02 µg/ml) in the hydroculture medium of Portulaca oleracea cv., became below the detection level (<0.0001 µg/ml) by HPLC analysis after 7 days. The toxicity of microcystin estimated with protein phosphatase inhibition assay, however, remained at 37% of the initial level, indicating that microcystin-LR was transformed by P. oleracea cv. into unknown compound(s) of lower toxicity.

Phytoremediation of 4,4'-thiodiphenol (TDP) and other bisphenol derivatives by Portulaca oleracea cv.

4,4'-Thiodiphenol (TDP) is a bisphenol derivative, and there has been no report on TDP removal by any plants or pure bacterial cultures. The removal of TDP by Portulaca oleracea cv., a floricultural herbal plant, was examined with a hydroculture system, and 97% of TDP was removed after 4 days culture.

Characterization of bisphenol A metabolites produced by Portulaca oleracea cv. by liquid chromatography coupled with tandem mass spectrometry.

The garden plant portulaca (Portulaca oleracea cv.) efficiently removes bisphenol A (BPA), an endocrine-disrupting chemical, from a hydroponic solution, but the molecular mechanisms underlying BPA metabolism by portulaca remain unclear. In this study, BPA metabolites converted by portulaca were analyzed by liquid chromatography coupled with tandem mass spectrometry. We observed the hydroxylation of BPA and the oxidization of it to quinone. Polyphenol oxidases are likely to contribute to BPA degradation by portulaca.

Antibiotics-free stable polyhydroxyalkanoate (PHA) production from carbon dioxide by recombinant cyanobacteria.

A practical antibiotics-free plasmid expression system in cyanobacteria was developed by using the complementation of cyanobacterial recA null mutation with the EscherichiacolirecA gene on the plasmid. This system was applied to the production of polyhydroxyalkanoate (PHA), a biodegradable plastic, and the transgenic cyanobacteria stably maintained the pha genes for PHA production in the antibiotics-free medium, and accumulated up to 52% cell dry weight of PHA.

Molecular cloning and partial characterization of a peroxidase gene expressed in the roots of Portulaca oleracea cv., one potentially useful in the remediation of phenolic pollutants.

Portulaca (Portulaca oleracea cv.) efficiently removes phenolic pollutants from hydroponic solution. In plant roots, peroxidase (PRX) is thought to be involved in the removal of phenolic pollutants by the cross-linking them to cell wall polysaccharides or proteins at the expense of reduction of hydrogen peroxide (H(2)O(2)). In this study, we found that portulaca roots secreted an acidic PRX isozyme that had relatively high H(2)O(2) affinity. We isolated five PRX genes, and the recombinant PRX proteins produced in cultured tobacco cells were partially characterized. Among these genes, PoPRX2 probably encoded the acidic PRX isozyme. PoPRX2 had an extra N-terminal region which has not been reported for other PRX proteins. We found that PoPRX2 oxidized phenolic pollutants, including bisphenol A, octylphenol, nonylphenol, and 17ß-estradiol. In addition, we found that the Cys261 residue of PoPRX2 played an important role in the determination of affinity for H(2)O(2) and stability toward H(2)O(2).

Floricultural Salvia plants have a high ability to eliminate bisphenol A.

The removal of bisphenol A, an endocrine disruptor, by 25 different kinds of Salvia cultivars was examined with hydroculture experiments. All the Salvia cultivars showed a high BPA-eliminating ability, and 100% to 74% of BPA (50 muM) was eliminated after 3 days.

Removal of phenolic endocrine disruptors by Portulaca oleracea.

Portulaca oleracea, a garden plant prevalent from spring to autumn in Japan, showed the ability to efficiently remove from water bisphenol A (BPA), which is well known as an endocrine disrupting compound (EDC) having estrogenic properties. In water culture, 50 muM BPA was almost completely removed within 24 h when the ratio of whole plant weight to the water volume was set up at 1 g to 25 ml. The estrogenic activity of the water decreased in parallel with the elimination of BPA. This plant also rapidly removed other EDCs having a phenol group including octylphenol (OP), nonylphenol (NP), 2,4-dichlorophenol (2,4-DCP) and 17beta-estradiol and, thereby, removed the endocrine disrupting activities. In addition, the ability of P. oleracea to remove BPA was not affected by BPA concentration (up to 250 microM), by cultivation in the dark, by temperatures ranging from 15 degrees C to 30 degrees C, or by pH ranging from 4 to 7. Moreover, the ability of P. oleracea to individually remove BPA, NP, and OP was the same as when they were all present. These results suggest that P. oleracea is a promising material for practical phytoremediation of landfill leachates and industrial wastewater contaminated with the tested EDCs.