Effect of plasma activated water on Escherichia coli disinfection and quality of kale and spinach.

Plasma activated water (PAW) is one of the promising technologies for fresh food disinfection. In this study, PAW was generated by activating water under nonthermal plasma for 10, 20, 30, 45 and 60 min. The effectiveness of Escherichia coli inactivation by PAW treatment on kale and spinach samples was assessed. The differences between kale and spinach samples in terms of the product quality and nutritional characteristics upon PAW treatment was also investigated. Further, changes in leaf structure and surface morphology upon PAW treatment was also evaluated through FTIR cuticle analysis and SEM imaging of leaf surfaces. Results showed that, around 6 log CFU/g reduction in E. coli population was observed in PAW-45 min treatment. However, PAW treatment significantly reduced the total chlorophyll content in both kale and spinach. The total phenolic content, flavonoid content and ascorbic content were altered according to the PAW activation time. Further, kale and spinach behaved differently in terms of antioxidant activity and membrane electrolytic leakage values upon PAW treatment. Clear changes in the cuticular layer and the surface morphological characteristics of the leaf samples were observed after PAW which could be the reason for the significant differences between kale and spinach characteristics in response to PAW treatments.

Carbon neutral electricity production by Synechocystis sp. PCC6803 in a microbial fuel cell.

The aim of this work was to illustrate the use of photosynthetic microbes in a microbial fuel cell to produce electricity without the requirement of an external carbon source. This research here describes the use of a cyanobacterium Synechocystis PCC6803, to produce electricity without any net CO(2) production in a two-chambered MFC. Conditions for optimum electricity production were determined through standardizing operating parameters. A maximum power density of 6.7mWm(-3)(anode chamber volume) was achieved under high intensity lighting (10,000lux). Light intensity and wavelength directly affected electricity production, indicating the pivotal role played by photosynthesis. The maximum removal of CO(2) was 625mmolm(-3) over 20h under high intensity light. The results presented here will contribute to the understanding of how cyanobacteria can be exploited for the direct conversion of CO(2) to electric current.

Use of Mycobacterium austroafricanum IFP 2012 in a MTBE-degrading bioreactor.

Mycobacterium austroafricanum IFP 2012 is able to slowly grow on methyl tert-butyl ether (MTBE), a fuel oxygenate widely used as a gasoline additive. The potential of M. austroafricanum IFP 2012 for aerobic MTBE degradation was investigated in the presence of a secondary carbon source, isopropanol. The strain was then tested for MTBE biodegradation at the laboratory-scale in a fixed-bed reactor using perlite as the matrix, and isopropanol was injected once a week to maintain M. austroafricanum IFP 2012 biomass inside the perlite bed. The biofilter was operated for 85 days at an influent flow rate of 20 ml/h by varying the MTBE concentration from 10 to 20 mg/l. The hydraulic retention time was fixed at 5 days. The removal of MTBE depended on the inlet MTBE concentration and a MTBE removal efficiency higher than 99% was obtained for MTBE concentrations up to 15 mg/l. A set of 16S rRNA gene primers specific for M. austroafricanum species was used to analyze the DNA extracted from the biofilter effluent in order to detect the presence of M. austroafricanum IFP 2012 and to estimate the effect of periodic injections of isopropanol on the release of the strain from the perlite bed. The results demonstrated that the injection of isopropanol served to maintain an active MTBE degrading biomass in the biofilter and that this system could be used to effectively treat MTBE contaminated groundwater.