JBEI highlights December 2019

1. Defining and engineering bioenergy plant feedstock
ideotypes
Background
• Ideotypes are idealized versions of crops used as a goal of breeding programs
• Bioenergy crops require improvement to be economically and environmentally favorable
• Ideotypes should be developed for bioenergy crops to guide bioengineering efforts.
Approach
• We have performed a literature search and synthesize various approaches and goals for engineered feedstock crops
Outcomes and Impacts
• We propose how different different crops can be tailored for the production and accumulation of different types of biomass or
specific bioproducts.
Markel et al. (2020) Curr Opin in Biotechnology., doi: 10.1016/j.copbio.2019.11.014
Tradeoff between value and volume. Cartoon diagram of inverse
correlation between product volume and value per unit.
Carbon allocation in five bioenergy and bioproduct crops. Spider-plots
demonstrating carbon allocation between six major categories: cell
wall C6, cell wall C5, lignin, starch, soluble sugars, and high value small
molecules.

2. Production of tetra-methylpyrazine in
Corynebacterium glutamicum
Background
• Tetra-methylpyrazine (TMP) is a naturally occurring
aromatic molecule and with use as coffee flavoring
• Other potential uses of pyrazines include fire
retardant additives, surface coatings and resins, but
evaluation is limited by difficulties in chemical
synthesis and low yields from natural sources
• Can we identify approaches to produce high
titers of TMP?
Eng et al. (2019) Metabolic Engineering Communications, in press
Approach
• C. glutamicum was engineered to reduce formation of
pyruvate and acetate
• Strains were transformed with different heterologous
gene pathways and assessed for accumulation of TMP
Outcomes and Impacts
• >5g/L TMP was produced using engineered strains of
C. glutamicum
• It was possible to produce both TMP and the biofuel
isopentenol with specific engineered strains
• TMP production was correlated with accumulation of
the immediate pathway precursor, acetoin
• Ionic liquids, a pretreatment reagent, could stimulate
TMP production in engineered strains
• TMP production was demonstrated in a 2L fed-batch
production format