Biotechnological Perspectives of Pyrolysis Oil for a Bio-Based Economy

Lignocellulosic biomass is an important feedstock for a potential future bio-based economy. Owing to its compact structure, suitable decomposition technologies will be necessary to make it accessible for biotechnological conversion. While chemical and enzymatic hydrolysis are currently established methods, a promising alternative is provided by fast pyrolysis. The main resulting product thereof, referred to as pyrolysis oil, is an energy-rich and easily transportable liquid. Many of the identified constituents of pyrolysis oil, however, have previously been reported to display adverse effects on microbial growth. In this Opinion we discuss relevant biological, biotechnological, and technological challenges that need to be addressed to establish pyrolysis oil as a reliable microbial feedstock for a bio-based economy of the future. Lignocellulosic biomass, the most abundant renewable resource, is a substantial feedstock for a future bio-based economy. Owing to its compact structure, suitable decomposition technologies for biotechnological use are required. Fast pyrolysis converts lignocellulose into a liquid known as pyrolysis oil. The potential of this alternative and cheap carbon source is currently being assessed for biotechnological applications. The properties of pyrolysis oil make its application very challenging. Several approaches have been reported for circumventing the restrictions imposed by pyrolysis oil. Tolerance engineering is an especially promising emerging trend. First proofs of principle using pyrolysis oil as a substrate for industrially relevant bioproduction have been reported in which strains and process technologies are specifically tailored to converting this complex substrate.