Showing papers by "Zainul Akmar Zakaria published in 2012"

Production and Characterization of Violacein by Locally Isolated Chromobacterium violaceum Grown in Agricultural Wastes

Abstract: 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.

Application of Bacterial Pigments as Colorant

Abstract: In the last decade, investigations about possible use of natural dyes in textile dyeing processes have been carried out by various research groups. Various kind of natural dyes (e.g. Hibiscus mutabilis, Quercus infectoria and Cassia tora L.) were used to dye different types of materials (e.g. cotton, jute, wool, silk and leather) normally in the presence of mordant (e.g. alum, copper sulfate and ferrous sulphate). Studies on the dyeing techniques were attempted using both conventional (alkaline, acidic or neutral baths) and non-conventional methods (ultrasonic, microwave, sonicator and supercritical carbon dioxide fluids). The degree of dyeing was normally compared based on the colorfastness properties which can be defined as the property of a pigment or dye, or materials containing the coloring material, to retain its original hue, without fading, running or changing when wetted, washed, cleaned or stored under normal conditions when exposed to light, heat or other influences. Essentially, this means that different dyes will have different fastness on different materials.

Isolation of Pigment-Producing Bacteria and Characterization of the Extracted Pigments

Abstract: Bacteria produce pigments for various reasons and it plays an important role. Some bacteria such as cyanobacteria have phycobilin pigments to carry out photosynthesis. Other example for pigment-producing bacterial strains includes Serratia marcescens that produces prodigiosin, Streptomyces coelicolor (prodigiosin and actinorhodin), Chromobacterium violaceum (violacein) and Thialkalivibrio versutus (natronochrome and chloronatronochrome). These bacteria can be isolated/cultured/purified from various environmental sources such as water bodies, soil, on plant, in insects and in man or animal. Various growth mediums can be used to isolate different types of bacteria. However, due to the high cost of using synthetic medium, there is a need to develop new low cost process for the production of pigments as well as during the isolation procedure. The use of agro-industrial residues for example, would provide a profitable means of reducing substrate cost. Pigment produced by the bacteria can be isolated using solvent extraction. These pigments can be further purified and characterized for physical and chemical characteristics using various instrumental-based analytical techniques such as TLC, UV–vis Spectroscopy, FTIR, ESI–MS, NMR HPLC and Gel Permeation Chromatography.

Bacterial reduction of CR(vi) at technical scale-the Malaysian experience

Abstract: The bacterial reduction of Cr(VI) from industrial wastewater was evaluated using a 2.0-m(3) bioreactor. Liquid pineapple waste was used as a nutrient for the biofilm community formed inside the bioreactor. The use of rubber wood sawdust as packing material was able to immobilize more than 10(6) CFU mL(-1) of Acinetobacter haemolyticus cells after 3 days of contact time. Complete reduction of 15-240 mg L(-1) of Cr(VI) was achieved even after 3 months of bioreactor operation. Cr(VI) was not detected in the final effluent fraction indicating complete removal of Cr from solution from the flocculation/coagulation step and the unlikely re-oxidation of Cr(III) into Cr(VI). Impatiens balsamina L. and Gomphrena globosa L. showed better growth in the presence of soil-sludge mixture compared to Coleus scutellarioides (L.) Benth. Significant amounts of Cr accumulated at different sections of the plants indicate its potential application in Cr phytoremediation effort. The bacterial-based system was also determined not to be detrimental to human health based on the low levels of Cr detected in the hair and nail samples of the plant operators. Thus, it can be said that bacterial-based Cr(VI) treatment system is a feasible alternative to the conventional system especially for lower Cr(VI) concentrations, where sludge generated can be used as growth supplement for ornamental plant as well as not detrimental to the health of the workers.

Utilisation of Rubber Wood Shavings for the Removal of Cu(II) and Ni(II) from Aqueous Solution

Abstract: The potential of heat and chemically treated rubber wood shavings (RWS) to remove Cu(II) and Ni(II) was evaluated at bench-scale by varying parameters such as initial Cu(II) and Ni(II) concentrations, contact time and adsorbent dosage. Maximum Cu(II) and Ni(II) uptake was achieved using NaOH-treated RWS after 5 h of contact time, pH 5.0 (Cu), 5.5 (Ni) and 6.0 (mixed-metal solution), initial Cu(II) and Ni(II) of 100 mg L−1 and RWS dosage of 0.3% (w/v). Point of zero charge (pHPZC) value of 4.35 suggests the appropriateness of pH range used. Higher Cu(II) and Ni(II) adsorption following NaOH treatment was due to smaller average pore diameter (34.63 A), higher mesopore content and higher surface negativity charge. EDAX analysis confirmed the presence of Cu and Ni on the surface of the RWS. The importance of carboxyl and hydroxyl functional groups during Cu(II) and Ni(II) removal is supported by the FTIR analysis and good correlation (R2 of 0.96–0.99) with the pseudo-second-order adsorption kinetic model. The results indicate the potential of using RWS as an alternative adsorbent to remove Cu(II) and Ni(II) from industrial wastewaters.

Optimization of Pigment Production: Case of Chromobacterium violaceum and Serratia marcescens

Abstract: Due to the high cost of the technology currently used for pigment production on an industrial scale, there is a need to develop a low cost process such as the use of agricultural-waste residues as growth medium, instead of the typical expensive synthetic medium. The use of these nutrient-rich agricultural wastes, which is renewable, abundant and easily available, even offers the potential for the production of value-added products such as specialty chemicals, biofuels and bioplastics. It also provides an ingenious way of protecting the environment by reducing the amount of waste to be treated, hence reducing the threat of environmental contamination. However, the pigment-producing bacteria needs to be adapted to grow in these agricultural-waste residues taking into consideration important growth parameters such as temperature, growth medium and light. Temperature is an important factor as it influences metabolic activities and microbial growth, light may influence the production of photosensitive pigment (directly affecting pigment intensity) while knowledge on the bacterial ability to grow either in solid or liquid growth medium is essential to ensure most of the available agricultural-waste residues can be effectively utilized as growth medium.