Estimation of Mercury in Soil, Water and Plants Spectrophotometrically

Trace levels of mercury in soil, environmental water (portable and polluted) and plant specimens (cucumber and pepper) at Koya area – Kurdistan region – Iraq was described by simple procedure, where, no further solvent purification or pre-concentration required steps. The method based on soxhelt extraction with oxalic acid and stannous chloride in acidic media for about 2.5 h, followed by spectrophotometric measurement at λmax of 300 nm. The results show different mercury levels, water samples show (3-215) ppm, while soil samples (5 -150) ppm. Also, some agricultural products show (23 -80) ppm mercury level.

Thermophilic PHB depolymerase of Stenotrophomonas sp., an isolate from the plastic contaminated site is best purified on Octyl-Sepharose CL-4B

There are numerous reports on PHB depolymerases produced by a wide variety of microorganisms isolated from various habitats, however, reports on PHB depolymerase isolated from plastic contaminated sites are scares. Thermophilic PHB polymerase produced by isolates obtained from plastic contaminated sites is expected to have better relevance for its application in plastic/ bioplastic degradation. Although PHB has attracted commercial significance, the inefficient production and recovery methods, inefficient purification of PHB depolymerase and lack of ample knowledge on PHB degradation by PHB depolymerase have hampered its large scale commercialization. Therefore, to ensure the biodegradability of biopolymers, it becomes imperative to study the purification of the biodegrading enzyme system. We report the production, purification, and characterization of extracellular PHB depolymerase from Stenotrophomonas sp. RZS 7 isolated from a plastic contaminated site. The isolate produced extracellular poly-β-hydroxybutyrate (PHB) depolymerase in the mineral salt medium at 30oC during 4 days of incubation under shake flask condition. Purification of the enzyme was carried out by three different methods using PHB as a substrate. Purification of PHB depolymerase by ammonium salt precipitation, column chromatography, and solvent purification method was successfully carried out. Among the purification method tested, the enzyme was best purified by column chromatography on Octyl-Sepharose CL-4B column with maximum (0.7993 U/mg/ml) purification yield. The molecular weight of purified PHB depolymerase (40 kDa) closely resembled with PHB depolymerase of Aureobacterium saperdae.

Solar-driven organic solvent purification enabled by the robust cubic Prussian blue

Cubic Prussian blue nanocrystals are successfully developed for solar-driven purification of a library of organic solvents.