Potential Role of Sequential Solid-State and Submerged-Liquid Fermentations in a Circular Bioeconomy

An efficient processing of organic solid residues will be pivotal in the development circular bioeconomy. Due to their composition, such comprise a great biochemical conversion potential through fermentations. Generally, carbohydrates and proteins present wastes cannot directly metabolized by microorganisms. Thus, before fermentation, enzymes are used hydrolysis step release digestible sugars nitrogen. Although can efficiently produced from solid-state fermentations (SsF), challenges scale-up SsF technologies, especially bioreactors, have hindered wider application systems. Therefore, most commercial submerged-liquid (SmF) expensive simple sugars. Instead independently evaluating SmF, review covers option combining them sequential process which, firstly then for hydrolysis, yielding suitable medium SmF. The article reviews experimental work that has demonstrated feasibility underlines benefits combination has. Finally, discussion is included which highlights that, unlike typically perceived, should not considered counterpart SmF but, contrast, main advantages each type fermentation accentuated synergistic SsF-SmF.