Bioproduction of hydrogen by Rhodobacter capsulatus KU002 isolated from leather industry effluents

A preliminary study on photoproduction of hydrogen by Rhodobacter capsulatus KU002 isolated from leather industry effluents under different cultural conditions with various carbon and nitrogen sources was investigated. Hydrogen production was measured using a Gas chromatograph. Lactate promoted more amounts of hydrogen production under anaerobic light conditions and aerobic light conditions. Cumulative hydrogen production by the organism was recorded at various time intervals. Incubation period of 120 h was optimum for production of hydrogen. pH 7.0 ± 0.2 was optimum for production of hydrogen by growing cells, while pH 7.5 ± 0.26 for resting cells. l-cystine was a good nitrogen source for production of hydrogen. Growing cells produced more amount of hydrogen than resting cells. Glutamine was a poor nitrogen source for hydrogen production by Rb. capsulatus. Significance of the above results in the presence of existing literature is discussed.     

Concurrent network diakoptics for electromagnetic field problems

A new modification to circuit-based diakoptics equations which allows the efficient manipulation of equivalent circuit models which represent Maxwell's equations is presented. A formulation of the diakoptics equations is given whereby torn subnetworks used to form the problem domain under consideration can be connected on a nearest neighbor basis. This formulation allows an algorithm which is suitable for implementation on a parallel computer to be written. It has been implemented on a transputer array configured with two different topologies. The computational efficiency of each topology is appraised and considerable computational advantage demonstrated with respect to the classical sequential variant of the technique. The procedure is then applied to sample electromagnetic field problems in order to verify its utility. Finally it is used to compute the performance of a patch microstrip hybrid coupler     

Impact of cultural conditions on photoproduction of hydrogen by Allochromatium sp. GSKRLMBKU-01 isolated from marine water of Visakhapatnam

In the present study, photoproduction of hydrogen by Allochromatium sp. strain GSKRLMBKU-01 isolated from marine water was measured under different cultural conditions. Hydrogen production was measured by using a Gas chromatography using argon gas as a carrier. Among different carbon and nitrogen sources used, succinate induced maximum hydrogen (5.68 ± 0.27 mL) production by immobilized cells, while free cells recorded 4.24 ± 0.30 mL of hydrogen under anaerobic light conditions. Immobilization of cells resulted in increased production of hydrogen. Ammonium chloride promoted more amounts of hydrogen production (2.68 ± 0.29 mL) by free cells, whereas glycine enhanced the hydrogen production upto 4.82 ± 0.36 mL in immobilized cells. In formic acid and urea, less hydrogen production was observed in both free and immobilized cells compared to other sources. Cumulative hydrogen production by the bacterium was recorded with the progress in incubation period. Incubation period of 192 h, pH of 7.0 and temperature at 30 °C were found to be optimum for the maximum hydrogen production. Significance of the above results was discussed in light of existing literature.     

Interaction of silver nanoparticles with an environmentally beneficial bacterium, Pseudomonas chlororaphis

This study explores the potential antimicrobial mechanisms of commercial silver nanoparticles (Ag NPs) in the environmental bacterium, Pseudomonas chlororaphis O6. The 10nm size NPs aggregated in water, as demonstrated by atomic force microscopy. Solubility of the NPs at 10mg/L was 0.28 mg/L (pH 6) and 2.3mg/L (pH 7); release from 10mg/L bulk Ag was below detection. The NPs eliminated cell culturability at 3mg/L, whereas no effect was observed at 10mg/L bulk Ag. Zeta potential measurements revealed that the NPs were negatively charged; unlike Ag ions, their addition to the negatively charged cells did not change cell charge at pH 6, but showed a trend to reduce cell charge at pH 7. Isolated extracellular polymeric substances (EPS) from PcO6 was polydisperse, with negative charge that was neutralized by Ag ions, but not by the NPs. Addition of EPS eliminated Ag NP's toxicity in cells lacking EPS. Intracellular accumulation of OH was not detected in NP-treated cells; however, the use of scavengers suggested the NPs caused extracellular H(2)O(2) production. No evidence was found for loss of membrane integrity upon treatment with the NPs. Our findings indicate that growth of environmental bacteria could be impaired by Ag NPs, depending on the extent of EPS production.     

Mutagens in commercial food processing and its microbial transformation

Food Science and Biotechnology - Mutagens are chemical molecules that have the ability to damage DNA. Mutagens can enter into our body upon consumption of improperly cooked or processed food...     

Effect of carrier ionic strength in microscale cyclical electrical field-flow fractionation

Recent work with cyclical electrical field-flow fractionation systems has shown promise for the technique as a separation and analysis tool, but little is understood about how the carrier composition in the system affects its capabilities. The electrical properties of microscale CyElFFF systems change when the carrier ionic conditions are altered, and it is well known that the effects of increasing ionic strength carriers on retention in normal ElFFF systems are severe. Specifically, retention levels fall significantly. Accordingly, this work seeks to understand the effect that increasing carrier ionic strength in CyElFFF has on nanoparticle retention in the channels. The retention of polystyrene particles in the CyElFFF microsystem is reported at various ionic strengths of ammonium carbonate and at a variety of pH levels. The experiments are compared to the theory of CyElFFF available in the literature. The results indicate that the ionic strength of the carrier has a significant impact on retention and that high ionic strength carrier solutions lead to poor performance of the CyElFFF system. These results have significant impact on the possible uses of the technique and its applications, especially in the biomedical arena.