Characterization of macrophytes for Na+ removal in synthetic Na-salt solution batch under greenhouse conditions.

Sodium salt contamination in the fresh water due to industrial effluents, underground rock salts and inland aquaculture is a major concern needs to be remediated, and subsequently recycled as sustainable bioeconomic strategy. Treatment of saline wastewater requires efficient, cost-effective, rapid, and green technologies, so as to mitigate the negative impacts of salinity on agricultural land. Green technology of phytodesalination is proposed to reduce salinity in the wastewater using salt tolerant plant species. present study was designed with an aim to investigate the sodium (Na+) removal capacity of salt tolerant and high biomass producing macrophytes on synthetic saline wastewater. Sesuvium portulacastrum (sea purslane), Pluchea indica (Indian camphorweed), Typha angustifolia (narrow leaf cattail) and Heliconia psittacorum (heliconia) were collected, cultivated in the greenhouse, subsequently treated with 0 (control) and 217 mM NaCl (salt stress) for 4 weeks. Overall growth performance, physiological change and Na+ removal rate in root and leaf tissues of the candidate plant species were measured. Plants were able to maintain their growth and physiological abilities except for shoot height in T. angustifolia (reduced by 13.7%) and chlorophyll content in S. portulacastrum (reduced by 64%). Major accumulation of Na+ was recorded in the shoots of S. portulacastrum and P. indica (halophytic plant species) and the roots of T. angustifolia and H. psittacorum (glycophytic plant species). Since T. angustifolia and H. psittacorum have high plant biomass, they showed higher Na+ removal efficiency at 4.4% and 5.7%, respectively; whereas due to lower plant biomass, S. portulacastrum and P. indica resulted in the removal of only 0.6 and 0.8% Na+ from the batch, respectively. Based on the information from this investigation, the selected candidate plant species can further be studied in the constructed wetland together with the controlled environments including optimized flowrate, vertical or horizontal flow system, plant densities and Na-removal rate in relation to swamp habitat.Novelty statement: T. angustifolia and H. psittacorum have high plant biomass, they showed higher Na+ removal efficiency at 4.4% and 5.7%, respectively; whereas due to lower plant biomass, S. portulacastrum and P. indica resulted in removal of only 0.6 and 0.8% Na+ from the batch. Based on the information from this investigation, the selected candidate plant species can further be studied in the constructed wetland together with the controlled environments including optimized flowrate, vertical or horizontal flow system, plant densities and Na-removal rate in relation to swamp habitat.

Production of L-phenylalanine from glycerol by a recombinant Escherichia coli.

The production of L-phenylalanine is conventionally carried out by fermentations that use glucose or sucrose as the carbon source. This work reports on the use of glycerol as an inexpensive and abundant sole carbon source for producing L-phenylalanine using the genetically modified bacterium Escherichia coli BL21(DE3). Fermentations were carried out at 37 degrees C, pH 7.4, using a defined medium in a stirred tank bioreactor at various intensities of impeller agitation speeds (300-500 rpm corresponding to 0.97-1.62 m s(-1) impeller tip speed) and aeration rates (2-8 L min(-1), or 1-4 vvm). This highly aerobic fermentation required a good supply of oxygen, but intense agitation (impeller tip speed approximately 1.62 m s(-1)) reduced the biomass and L-phenylalanine productivity, possibly because of shear sensitivity of the recombinant bacterium. Production of L-phenylalanine was apparently strongly associated with growth. Under the best operating conditions (1.30 m s(-1) impeller tip speed, 4 vvm aeration rate), the yield of L-phenylalanine on glycerol was 0.58 g g(-1), or more than twice the best yield attainable on sucrose (0.25 g g(-1)). In the best case, the peak concentration of L-phenylalanine was 5.6 g L(-1), or comparable to values attained in batch fermentations that use glucose or sucrose. The use of glycerol for the commercial production of L-phenylalanine with E. coli BL21(DE3) has the potential to substantially reduce the cost of production compared to sucrose- and glucose-based fermentations.