Microbial hosts for metabolic engineering of lignin bioconversion to renewable chemicals

Abstract This review discusses the use of engineered microbes for bioconversion of lignin from plant biomass to produce renewable chemicals. Existing bacterial hosts for lignin bioconversion are discussed, such as Pseudomonas putida KT2440 and Rhodococcus jostii RHA1, and case studies where they have been engineered to generate aromatic and non-aromatic products are described, and the different types of lignin substrates used for these studies. Other bacteria identified as lignin degraders are described, and the prospects for using other bacteria as hosts for metabolic engineering of lignin degradation are discussed. Recent advances in genetic modification of fungi are also discussed, which could lead to the metabolic engineering of lignin-degrading fungi for bioproduct formation from lignin. Prospects and challenges in this field are discussed, as the field moves from the laboratory to industrial application, including: choice of chassis organism, choice of lignin feedstock, the complexity of polymeric lignin breakdown, and considerations for scale-up and choice of bioproduct.