Electronic Thesis and Dissertation Repository


Master of Science


Microbiology and Immunology


Dr. Ze-Chun Yuan


Lignin is a polyphenolic heteropolymer constituting between 18 to 35% of lignocellulose and is recognized as preventative of cellulosic biofuel commercialization. Paenibacillus polymyxa CR1 was isolated from naturally degrading corn stover and shown to produce alcohols using lignin as a sole carbon source. Genome sequencing and comparative genomics of P. polymyxa CR1 identified two homologs, a Dyp-type peroxidase and a laccase, which have previously been implicated in lignin metabolism in other bacteria. Knockout mutants of the identified genes displayed no growth deficiency and P. polymyxa CR1 is incapable of metabolizing common aromatic intermediates of lignin, suggesting the bacterium employs a novel catabolic pathway. To identify genes involved in lignin metabolism, a transposon library was generated and screened for abnormal lignin growth phenotypes. The results contained within will help elucidate the genetic basis of known functions helping delineate regulatory pathways and metabolic versatility in P. polymyxa relevant to lignin metabolism.