The Possible Role of Manganese(II) Oxidation by Pseudomonas Putida GB-1 in Lignin Degradation

The primary focus of this study was the bacteria Pseudomonas putida GB-1, a manganese-oxidizing, gram-negative rod found in Lake Michigan. What is important is that it contains enzymes that oxidize manganese called multi-copper oxidases, which are in the same family of enzymes as laccases, previously known lignin-degrading enzymes found in fungi. In hopes of uncovering a more effiecient way of breaking down complex plant material for biofuel production, these connections brought up questions to be answered in this project, which are can GB-1 degrade lignin? And does it need Mn oxidation to do so? A series of tests were performed in the Tebo Lab at the Center for Coastal Margin Observation and Prediction within the Oregon Health and Science University that included different variations of solid and liquid bacterial cultures, RT-PCR, and a fluorescent lignin assay to detect lignin degradation in conjunction with manganese oxidation. It was confirmed that GB-1 can break down lignin. Whether it needs manganese oxidation to do so is still unclear. Manganese oxidation is up-regulated in the presence of lignin, but that could also just be a starvation response. It does grow better on lignin, but it is also possible that there might be another pathway that is not manganese-oxidation dependent.