Highlights
39• Liquid pineapple waste, a novel nutritious low cost growth medium.
40• Post-treatment of bacterial effluent for eco-friendly disposal.
41• Violet pigment stable at optimum conditions.
42• Violacein and deoxyviolacein isolated and characterized.
43• Crude violet pigment shows bioactivity. 44 • The first report on the production of violet pigment using liquid pineapple waste 45 medium. 46 47 48 Abstract 49 50 Synthetic pigments have been utilized in numerous industries including textile, cosmetic, 51 food and pharmaceuticals. However, the drawbacks of these pigments, namely toxicity 52 problems have kindle the interest in natural pigments. In view of this, the use of natural 53 pigments such as those from bacterial origin offers interesting alternative for industrial 54 application. However, large scale applications of natural pigments are often hindered by the 55 high production cost. This study evaluates on the feasibility of using liquid pineapple waste 56 for the production of violacein by a locally isolated Chromobacterium violaceum UTM5 both 57 in shake flask and 50 L bioreactor. The use of optimized growth parameters including culture 58 conditions, concentration of liquid pineapple waste and supplementation of L-tryptophan 59 resulted in violacein yield of 16256 ± 440 mg L -1 . Post treatment of the effluent effectively 60 reduced the COD, turbidity and TSS contents to less than 1 mg L -1 , 1.57 ± 0.2 NTU and 2.7 ± 61 0.6 mg L -1 respectively. Violet pigment exhibited good stability during the entire storage 62 period of 30 days at pH 7, temperature 25 -30 °C and under dark condition. The violet 63 pigment has a good antimicrobial activity against selected microorganisms. Of interest, the 64 pigment was active against Staphylococcus aureus ATCC 29213 and methicillin-resistant 65 Staphylococcus aureus (MRSA) ATCC 43300 with MIC value of 7.8 and 15.6 µg mL -1 , 66 respectively. However, the pigment is toxic to the V79-4 Chinese hamster lung cells with low 67 selectivity index. The purified compounds were determined as violacein and deoxyviolacein 68 using FT-IR, LC-MS and NMR respectively. Results confirmed the feasibility of using liquid 69 pineapple waste as a potential low cost growth medium for large-scale cultivation of violet 70 pigment using C. violaceum UTM5. Synthetic colours are mostly used in the food processing and cosmetic industries as natural 81 colorants are expensive, less stable and possess lower intensity. 1,2 Conversely, these 82 synthetic colorants have been or being banned due to their carcinogenicity, hyperallergenicity 83 and toxicological issues. Thus, natural pigments are progressively in an increasing demand as 84 they are biodegradable, non-toxic to humans and have precise differences in colour tones. 3,4 85 A wide range of pigment applications in fields of food, cosmetics, pharmaceuticals and 86 textiles has contributed to its escalating needs by colouring agents in many industries. 1 In 87 comparison to colorants extracted from plant and animals, microorganisms ...
