Nur Zulaikha Yusof

Application of Bacterial Pigments as Colorant

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

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.

Solid State Fermentation Utilizing Agro-Industrial Waste for Microbial Pigment Production

Microbial pigments due to their better biodegradability and higher compatibility with the environment offer promising avenues for various industrial applications like food, cloth, painting, cosmetics, pharmaceuticals, plastics, etc. Nevertheless, the current bacterial pigment productions are not effective to meet their industrial needs. Current research on microbial pigments signify that genetic engineering for strain improvement, optimization of bioprocess modeling and utilizing cheap agro-industrial residues as substrates are key developmental strategies to maximize pigment production. Solid-state fermentation (SSF) has been reassessed as an alternative to submerged fermentation and could be a possible strategy for the cost-effective production of microbial pigments. The investment for SSF is usually lower than that of submerged fermentation, since it uses waste agricultural residues. This chapter summarizes the effective way to produce microbial pigments in agro-industrial waste (SSF) for its wide-ranging industrial applications and commercial viability.

Application of violet pigment from Chromobacterium violaceum UTM5 in textile dyeing

Abstract Natural dyes and pigments are emerged as an important alternative to potentially harmful synthetic dyes. There is a growing demand for eco-friendly/non-toxic colourants specifically for textile dyeing because of its sustainability, green chemistry and improved eco-balances. The present study aimed to evaluate the dyeing potential of violet pigment from Chromobacterium violaceum UTM5. Dye-ability of violet pigment on different fabrics, i.e. pure cotton, pure silk, pure rayon, jacquard rayon, silk satin, cotton and polyester were tested using mordants and colour fastness tests were performed. Results from this study showed that violet pigment is capable of dyeing both natural and synthetic fibres. The use of slake lime mordant resulted in darker colour for cotton and silk satin. The colour fastness test showed fair to excellent (3/4) rating for fabrics dyed with violet pigment. This study demonstrates that violet pigment may have commercial demand in the textile industry.

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

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.