Biologically producing adipic acid was estimated to be 20–30%of total production in the long run [16]. Despite the higher mar-ket price and a lot of efforts to synthesize adipic acid biologically,no bio-based adipic acid production methods are economicallyfeasible yet [2,14]. The greatest hurdle of producing adipic acidbiologically is that there were no reliable native-occurring adipatesynthesis pathways found in microorganisms yet. However, withthe fast growth of metabolic engineering and synthetic biology,there are more and more methods available to screen metabolicpathways, integration of orthogonal pathways into host microor-ganisms and balance metabolic flux [17–23]. A lot of efforts havebeen done to search for orthogonal enzymes in nature, which mightcontribute to adipate synthesis. In this article, we primarily reviewthe two biological routes for adipate synthesis: (1) biological accu-mulations of precursors of adipate such as d-glucaric acid andcis,cis-muconic acid, which could be catalyzed to adipate [9,15,24];(2) biological synthesis of adipate directly from carbon sources[25–28]. Moreover, how to use consolidated bioprocessing (CBP) todirectly convert lignocellulosic biomass to adipic acid is also heavilydiscussed here