Sustainable bioprocessing of acid-treated rice straw residue for canthaxanthin production

The viability of utilizing biomass as a substitute for energy has been the subject of research recently due to the increasing focus on the circular economy. The complex and resistant structures of lignocellulosic waste materials, in particular, need efficient pretreatment and enzymatic saccharification in order to liberate the necessary saccharides, which can then be further fermented by pigment-producing microbe Dietzia sp. The isolated-strain-grown glucose was obtained from acid-treated rice straw residue. Acid treatment removed the hemicelluloses, and the lignin and cellulose remained intact within the rice straw. Hemicelluloses are used for the production of different products (Singh et al., 2021, Qaseem et al., 2021). Alkali treatment separates cellulose (Pal et al., 2022) from lignin, and further cellulose is saccaharified by cellulase enzymes to obtain free glucose for fermentation. The pigment was extracted in absolute ethanol. The colour values L*, a*, b*, and c* and the hue of the fermented pigment were also determined. Column chromatography was performed to purify the extracted pigment. The extracted pigment was identified by thin-layer chromatography. The pigment was characterized by a UV--Vis spectrophotometer and UPLC. The pH, temperature stability, and antimicrobial activity of canthaxanthin were determined. The isolated pigment has industrial potential, which can be used in food, pharma, and beverages as a colorant and also in nutraceuticals.

References

Singh, S., Kaur, D., Yadav, S.K. and Krishania, M., 2021. Process scale-up of an efficient acid-catalyzed steam pretreatment of rice straw for xylitol production by C. Tropicalis MTCC 6192. Bioresource Technology, 320, p.124422.

Qaseem, M.F., Shaheen, H. and Wu, A.M., 2021. Cell wall hemicellulose for sustainable industrial utilization. Renewable and Sustainable Energy Reviews, 144, p.110996.

Pal, P., Li, H. and Saravanamurugan, S., 2022. Removal of lignin and silica from rice straw for enhanced accessibility of holocellulose for the production of high-value chemicals. Bioresource Technology, 361, p.127661.