The present work highlighted the production of violacein by the locally isolated Chromobacterium violaceum (GenBank accession no. HM132057) in various agricultural waste materials (sugarcane bagasse, solid pineapple waste, molasses, brown sugar), as an alternative to the conventional rich medium. The highest yield for pigment production (0.82 g L⁻¹) was obtained using free cells when grown in 3 g of sugarcane bagasse supplemented with 10% (v/v) of L-tryptophan. A much lower yield (0.15 g L⁻¹) was obtained when the cells were grown either in rich medium (nutrient broth) or immobilized onto sugarcane bagasse. Violacein showed similar chemical properties as other natural pigments based on the UV-Vis, Fourier transform infrared spectroscopy, thin-layer chromatography, nuclear magnetic resonance, and mass spectrometry analysis. The pigment is highly soluble in acetone and methanol, insoluble in water or non-polar organic solvents, and showed good stability between pH 5-9, 25-100 °C, in the presence of light metal ions and oxidant such as H₂O₂. However, violacein would be slowly degraded upon exposure to light. This is the first report on the use of cheap and easily available agricultural wastes as growth medium for violacein-producing C. violaceum.
A bacterial strain, designated UTM-3 T , isolated from the rhizosphere soil of Artocarpus integer (cempedak) in Malaysia was studied to determine its taxonomic position. Cells were Gramstain-negative, non-spore-forming rods, devoid of flagella and gliding motility, that formed yellowpigmented colonies on nutrient agar and contained MK-6 as the predominant menaquinone.Comparative analysis of the 16S rRNA gene sequence of strain UTM-3 T with those of the most closely related species showed that the strain constituted a distinct phyletic line within the genus Chryseobacterium with the highest sequence similarities to Chryseobacterium lactis NCTC 11390 T , Chryseobacterium viscerum 687B-08 T
The capability of a technique to reconstruct a tomographic image of flaws existence on gas pipeline via reverse ultrasonic tomography is presented. The ultrasonic tomography system is developed to monitor flaws circumferentially on pipeline with contactless measurement of distance from sensors to the pipe. In oil and gas industry, the applications of ultrasonic tomography technique for flaw detection in pipeline are limited as this technology is still in its infancy. The design of the ultrasonic tomography system consists of ultrasonic sensing system, data acquisition and image reconstruction system. A reflection mode of ultrasonic sensor is used where the output ultrasonic signal reflected from the pipe to the sensor is acquired. The collected data will be used in image reconstruction system to visualize the image. In image reconstruction process, a linear back projection algorithm is used in order to reconstruct the image of the pipe profile with flaws existence. The back projection algorithm is derived by the mathematical relationship of forward and inverse problem. This reconstruction algorithm is implemented in Matlab software to analyze the performance of the technique for different projection and arrays. Through the simulated result, the reconstructed image based on four projections is found to be less smeared compared to the image based on two projections. The effect of aliasing on the image is also reduced as the number of projection is increased. Several images of pipe with flaws existence are reconstructed based on four projections, with 7 x 7 arrays of pixels and twenty-eight of ultrasonic sensors.
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