Vol. 1(2) SEP 2011 - SAVAP International

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Academic Research International ISSN: 2223-9553 Volume 1, Issue 2, September 2011 CONCLUSIONS This study shows that there is a great potential for the destruction of H 2 S gas by using doped TiO 2 nanoparticles. 95-99% destruction of H 2 S gas was observed in this study, but further studies need to be carried out by varying the temperature and dopant concentrations to find out the maximum degradation efficiency using optimum dopant concentration of sulphur doped TiO 2 nanoparticles at a particular temperature. In addition, other dopants having large diameters for better adsorption of sulphur should also be explored. This study can provide a viable option for in-situ destruction of H 2 S gas in the processes which are carried out at high temperatures and also, it does not require any UV or special arrangements for its reactions to proceed as explored by some of the authors for photocatalytic gas phase destruction of H 2 S gas. ACKNOWLEDGEMENT The author gratefully acknowledges the cooperation and access to fixed bed catalyst system provided by the nanoscience and catalysis division labs of National Centre for Physics, Islamabad, Pakistan. REFERENCES 1. H 2 S Q&A, department of environmental quality, Michigan USA. http://www.michigan.gov/deq/0,1607,7-135-3311_4111_4231-9162-- ,00.html#3._How_does_H2S_occur_in_oil_and_gas_wel (accessed 6 July 2011) 2. Jardim, W. F., Huang, C.P. (1996). Gas phase destruction of VOCs by Heterogeneous Photocatalysis, Proceedings of the 6 th International Symposium of Chemical Oxidation, Technology for the Nineties, Vanderbilt University, Nashville, USA. 3. Maria, C. C., Rosana, M. A., Jardim, W. F. (1998). Gas-phase destruction of H 2 S using TiO 2 /UV- VIS. Journal of Photochemistry and Photobiology A: Chemistry, 112, 73-80. 4. Mills B. (1995). Review of methods of odour control. J. Filtration and Separation, 32(02), 147- 152. 5. Tajammul, H., Khaiber, K., and Hussain, R. (2009). Size control synthesis of sulfur doped titanium dioxide (anatase) nanoparticles, its optical property and its photo catalytic reactivity for CO 2 + H 2 O conversion and phenol degradation. Journal of Natural Gas Chemistry, 18, 383–391. 6. Tomar M., Abdullah T.H.A. (1994). Evaluation of chemicals to control the generation of malodorous hydrogen sulfide in waste water. J. Water Res., 28(12), 2545-2552 Copyright © 2011 SAVAP International www.savap.org.pk www.journals.savap.org.pk 73
Academic Research International ISSN: 2223-9553 Volume 1, Issue 2, September 2011 ISOLATION AND CHARACTERIZATION OF INDIGENOUS LUMINESCENT MARINE BACTERIA FROM KARACHI COAST Aisha Nawaz Center for Molecular Genetics, University of Karachi PAKISTAN ashnawaz2002@yahoo.com Nuzhat Ahmed Center for Molecular Genetics, University of Karachi PAKISTAN ABSTRACT A luminescent bacterial strain was isolated from sea water samples from the shore of the Arabian Sea, Pakistan. The isolate was identified as Vibrio harveyi species upon biochemical and 16SrRNA gene analysis and coded N6. The isolated strain was subjected to physical and genetic characterization. Upon study of the genetic markers present in the isolate, it was observed that the bacterium tolerated up to 7% of Sodium chloride in simple nutrient broth medium. Unlike commonly reported luminescent bacteria, the indigenous isolate N6 showed optimum growth at 37ºC. Resistance towards low concentrations of Cadmium chloride and Copper sulfate was also recorded in N6. Of the various antibiotics screened for resistance, N6 was highly resistant to Ampicillin. No plasmid DNA was observed in the strain. The best carbon source supplemented in minimal medium was determined to be 0.2% of gluconate which gave the best growth but luminescence was not achieved on minimal medium in presence of carbon sources like glycerol, gluconate, glucose, fructose, sucrose, starch nannitol, lactose, galactose and maltose. Presence of the lux operon was determined by performing PCR for the luxAB genes, the PCR product obtained was sequenced to reveal major similarities with previously reported luxAB genes. Keywords: 16S rRNA PCR identification, Characterization, Growth optimization, Isolation, Vibrio harveyi, luxAB genes PCR. INRODUCTION Luminous bacteria are the most widely distributed light-emitting organisms, most of which are found in sea water and the remainder living in the terrestrial or fresh water environment. These luminescent bacteria are usually found in symbiotic association with a host organism but are also capable of living free. The most common habitats are as free-living species in the ocean, as saprophytes growing on dead fish or meat, as gut symbionts in the digestive tracts of marine fish, as parasites in crustacean and insects and as light organ symbionts in teleost fishes and squid (Hastings, 1986). These bacteria are all Gram negative rods and can function as facultative anaerobes (Baumann et al, 1983 & Nealson and Hastings, 1979)). Almost all luminous bacteria have been classified into three genera Vibrio, Photobacterium and Xenorhabdus, with most of the species being marine in nature (Baumann et al, 1983 & Campbell, 1989). The light emitting bacteria that have been investigated in most detail are Vibrio harveyi, V. fischeri, Photobacterium phosphoreum, P. leognathi and Xenorhabdus luminescens. The Vibrio harveyi strains have not yet been found as symbionts, although they are readily isolated from varying marine habitats (Meighen, 1991), these species may also be found on the surface of marine animals or in their gut (Baumann et al, 1973 & Ruby and Morin, 1979). The luminescence of these bacteria is attributed to the presence of an intricately working group of genes of the lux operon basically containing the genes luxICDABEG (Meighen, 1991). This luminescent system is self contained as the substrate and the enzyme for the luminescent reaction is made by the lux system itself. The enzyme working in this reaction is known as luciferase which is a heterodimer comprising of an α and a β subunit, the substrate is a long chain fatty aldehyde specific for each specie of the luminescent bacterium. In case of Vibrio harveyi, this aldehyde is either a Copyright © 2011 SAVAP International www.savap.org.pk www.journals.savap.org.pk 74
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Vol. 1(2) SEP 2011 - SAVAP International

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