Research Highlights

Lignin contains aromatic subunits joined by various chemical linkages, making it challenging to produce single products from this plant polymer. Microbes can funnel lignin-derived aromatics into target chemicals, but this requires strategies to cleave major inter-unit linkages. This study showed the bacterium Novosphingobium aromaticivorans can catabolize β-5 (phenylcoumaran) linked aromatics, which account for up to 12% of interunit bonds in lignin. 

The engineered poplars demonstrated a higher saccharification efficiency than the wild-type poplars. Under the same pretreatment conditions, the researchers observed a greater monosaccharide release from the modified lignin. In addition, the trees produced high-value phenolics that are easily accessible to support other specialty chemical industries.

High aromatic loading rates, hollow-fiber membranes, and NH4OH for pH control contributed to the highest PDC productivities reported to date. Results revealed a trade-off between maximizing high productivity or product titer in the MBR system. 

The study demonstrates the potential of microbial communities to produce chemicals from agroindustrial residues, converting organic waste into useful products and contributing to sustainable circular economy. The machine learning tools can be adapted to evaluate other microbial communities in similar reactor settings. 

Zymomonas mobilis has properties that make it a good candidate for industrial biofuel production: high catabolic rate, low biomass generation, resistance to inhibitors in lignocellulosic hydrolysates; an a growing set of genetic engineering tools. Recent efforts have targeted Z. mobilis for isobutanol production, but isobutanol toxicity limits growth and productivity. The physiological effects of isobutanol on Z. mobilis are poorly understood.  

This study demonstrates the viability of low-productivity former cropland for long-term bioenergy production and suggests there is no single crop best suited for all such soils. Yield trends suggest polyculture may outperform monocultures over the long term.

Many bacteria use self-assembling, protein-based organelles to form a semipermeable barrier that keeps out toxic or volatile intermediates while allowing substrates and products to pass through. Such microcompartments could be used to encapsulate non-native enzymes and incorporate challenging metabolic pathways into industrially relevant bacteria such as Zymomonas mobilis.    

Water stress during switchgrass growth caused by the soil type may affect the yeast fermentability, which may not be evident through initial evaluation of upstream biomass metrics such as biomass yield, composition, and digestibility.

Researchers used existing land cover data sets to train a computer algorithm to classify land use patterns in satellite imagery. These classifiers were then used to map cropland annually from 1986 to 2018 at a 30-meter resolution. Researchers then identified the location and time of abandonment using a moving temporal window for each pixel and estimated the accuracy against visually interpreted sample locations and publicly available datasets.  

Belowground carbon content was higher in the switchgrass grown in prairie soil. Switchgrass grown in prairie soils situated on slopes also had higher biomass carbon in both the above- and belowground plant growth as compared to switchgrass grown in the prairie soil of depressions. Prairie systems consistently outcompete monoculture systems in plant diversity, carbon content, and microbial carbon content.