The potential use of papaya and banana peels as substrate to enhance the pigment production of Gram-positive bacterial strain isolated from Holothuria (Lessonothuria) pardalis

Aims: The microbial pigment can be the best promising alternative to replace synthetic colorant. However, due to the high cost of synthetic medium for microbial pigment production, there is a need to develop a new low-cost medium of bacterial pigment production. This study aims to investigate the potential of banana and papaya peels as alternative low-cost substrates for a carotenoid-producing bacterium, B12 strain (bacteria strain isolated from Holothuria (Lessonothuria) pardalis). Methodology and results: B12 strain identified as an aerobic bacterium with non-motile, diplobacilli shaped and Gram -positive bacteria. The fermentation was optimized with different parameters included the effect of temperature, time, concentrations, pHs, carbon and nitrogen sources to find the optimum relative pigment concentration produced by B12. The results showed that the B12 strain produced the highest relative pigment concentration measured at 450 nm when the strain was cultivated at 37 degrees C and pH 7 in the culture medium incorporated with the combination of dried papaya peels and banana peels (100% v/v with ratio 1:1) at 72 h of incubation. Lactose, peptone and yeast were observed as the best carbon and nitrogen sources to increase the pigment concentration of B12 strain. Stability of the pigment was studied at different physiochemical stress, and it showed the pigment obtained from dried papaya and banana substrates can tolerate and stable under stress condition. Conclusion, significance and impact of study: This can be concluded that the combination of dried papaya and banana peels worked well as substrate and can be utilized as a fermentation medium to replace the synthetic medium which is more expensive and uneconomical for industry application. Besides, it also helps in managing waste and solving the pollution problem due to the increasing of biochemical oxygen demand (BOD) and chemical oxygen demand (COD).