Agro-industrial by-products valorization for fructooligosaccharide production with Zymomonas mobilis

Fructooligosaccharides (FOS) have gained attention due to their prebiotic properties and potential health benefits. This study explores the production of FOS using Zymomonas mobilis ZM4, a promising candidate for biotechnological processes, utilizing corn steep liquor (CSL) and sugarcane molasses as alternative and sustainable carbon and nitrogen sources. Two distinct media formulations were investigated, namely one composed of CSL supplemented with yeast extract (YE), and another utilizing sugarcane molasses. CSL was evaluated at concentrations of 10 g L^-1 and 12 g L^-1 in combination with YE. The optimal combination, 12 g L^-1 CSL and 8 g L^-1 YE, yielded 60.00 ± 0.44 g L^-1 FOS with a productivity of 1.250 ± 0.009 g L^-1 h^-1, comparable to synthetic media. Molasses, another agro-industrial by-product, was tested at sucrose-equivalent concentrations of 150, 200, and 350 g L^-1. The highest FOS concentration, 58.67 ± 1.64 g L^-1, was achieved with 200 g L^-1 of molasses. Combining CSL and molasses (CSLM media) resulted in 58.15 ± 0.21 g L^-1 of FOS with a yield of 0.307 ± 0.003 g_FOS g_sucrose^-1. The FOS mixture included 1-kestose, 6-kestose, nystose, and neokestose. Although scaling up to a bioreactor led to a lower FOS concentration of 42.31 ± 0.16 g L^-1, the yield remained promising at 0.482 ± 0.008 g_FOS g_sucrose^-1. This study not only highlights the efficient production of FOS using Z. mobilis ZM4 but also demonstrates the potential of using CSL and molasses, byproducts of agro-industrial processes, as cost-effective and sustainable substrates for industrial-scale FOS production. The findings provide valuable insights for the development of bio-based processes for functional oligosaccharide production.