Production of flexirubin pigment from Chryseobacterium artocarpi CECT 8497 using banana peel waste as supplement

Abstract

As the present trend throughout the world is shifting towards the use of eco-friendly and biodegradable commodities, the demand for natural colorants is increasing. The production of bacterial pigments from agricultural wastes and application of the pigments as natural colorants have been investigated by many researchers. Banana peel waste is highly nutritious owing to its high levels of starch, crude protein, fibre and vitamins in nature that facilitates microbial growth. Flexirubin is a yellowish orange-colour pigment produced from Chryseobacterium artocarpi CECT 8497 that exhibits pharmacological properties including antibacterial activity and a potential anticancer when formulated with silver nanoparticles. Previous reports have shown that the pigment production by C. artocarpi CECT 8497 is largely influenced by chemical components, such as lactose, L-tryptophan, and potassium dihydrogen phosphate (KH2PO4). However, pigment production by physical means, such as controlling the bioreactor condition in order to obtain maximum pigment yield, has not been much reported. Hence, in this study, one-variable-at-a-time (OVAT) approach was employed to seek for the physical key determinants, which are agitation rate, aeration rate, and temperature that would impose a significant effect on the production of flexirubin pigment. The pigment production in a 2-L bioreactor was then optimized using the self-learning particle swarm optimization (PSO) algorithm. The OVAT results show that at a temperature of 30°C, aeration rate of 2 L/min, and agitation rate of 250 rpm, afforded highest flexirubin pigment yield of 0.144 g/L. However, under optimized conditions, namely temperature of 29.80°C, aeration rate of 2.23 L/min and agitation of 245 rpm, slightly higher pigment yield (0.176 g/L) was obtained compared to the predicted yield (0.151 g/L). The pigment produced has the potential to be used as ink for plastic food packaging and as an antibacterial detergent. The findings of this study would be useful for increasing the efficiency in producing natural pigment using a low-cost medium in a pilot scale or even in an industrial scale. The application of pigment as ink for plastic food packaging and as antibacterial detergent will be the development of safe products for better future.