(191bi) Metabolism of the Pyrolytic Sugar Levoglucosan and Engineered Pyrolysate Tolerance in Lactococcus lactis

Lactococcus lactis, a gram-positive lactic acid bacterium, is an important organism in the dairy, chemical, and health industries. We have engineered this organism to consume the sugar levoglucosan, produced from pyrolysis of lignocellulosic biomass. Expression of the levoglucosan kinase gene from Lipomyces starkeyi, allows L. lactis to consume pure levoglucosan and levoglucosan-rich bio-oil as a sugar source, producing optically pure L-lactic acid. However, lignocellulosic pyrolysate contains several inhibitory phenolic compounds which limit the growth of bacteria under fermentation conditions. To promote growth of L. lactis in bio-oil, a genome-scale library was constructed from L. lactis subsp. cremoris NZ9000 to identify genes which contribute to growth in bio-oil and confer resistance to inhibitors. Furthermore, we discuss metabolic engineering strategies for in vivo conversion of L-lactate to other high-value chemicals.