Engineering improved ethylene production: Leveraging systems biology and adaptive laboratory evolution

Ethylene is a small hydrocarbon gas widely used in the chemical industry. Annual worldwide production currently exceeds 150 million tons, producing considerable amounts of CO₂ contributing to climate change. The need for a sustainable alternative is therefore imperative. Ethylene is natively produced by several different microorganisms, including Pseudomonas syringae pv. phaseolicola via a process catalyzed by the ethylene-forming enzyme (EFE), subsequent heterologous expression of EFE has led to ethylene production in non-native bacterial hosts including Escherichia coli and cyanobacteria. However, solubility of EFE and substrate availability remain rate-limiting steps in biological ethylene production. We employed a combination of genome-scale metabolic modelling, continuous fermentation, and protein evolution to enable the accelerated development of a high efficiency ethylene producing E. coli strain, yielding a 49-fold increase in production, the most significant improvement reported to date. Furthermore, we have clearly demonstrated that this increased yield resulted from metabolic adaptations that were uniquely linked to EFE (wild type versus mutant). Our findings provide a novel solution to deregulate metabolic bottlenecks in key pathways, which can be readily applied to address other engineering challenges.

Reconciling the Sustainable Manufacturing of Commodity Chemicals with Feasible Technoeconomic Outcomes : Assessing the investment case for heat integrated aerobic gas fermentation

The manufacturing industry must diverge from a ‘take, make and waste’ linear production paradigm towards more circular economies. Truly sustainable, circular economies are intrinsically tied to renewable resource flows, where vast quantities need to be available at a central point of consumption. Abundant, renewable carbon feedstocks are often structurally complex and recalcitrant, requiring costly pretreatment to harness their potential fully. As such, the heat integration of supercritical water gasification (SCWG) and aerobic gas fermentation unlocks the promise of renewable feedstocks such as lignin. This study models the technoeconomics and life cycle assessment (LCA) for the sustainable production of the commodity chemicals, isopropanol and acetone, from gasified Kraft black liquor. The investment case is underpinned by rigorous process modelling informed by published continuous gas fermentation experimental data. Time series analyses support the price forecasts for the solvent products. Furthermore, a Monte Carlo simulation frames an uncertain boundary for the technoeconomic model. The technoeconomic assessment (TEA) demonstrates that production of commodity chemicals priced at ~US$1000 per tonne is within reach of aerobic gas fermentation. In addition, owing to the sequestration of biogenic carbon into the solvent products, negative greenhouse gas (GHG) emissions are achieved within a cradle-to-gate LCA framework. As such, the heat integrated aerobic gas fermentation platform has promise as a best-in-class technology for the production of a broad spectrum of renewable commodity chemicals.

P5491Gender differences in long-term outcomes and predictors of all-cause mortality after percutaneous coronary intervention

Background

Gender disparities have been consistently reported in the nature, presentation, and treatment of coronary artery disease, leading to significant outcome differences. Previous reports have suggested that after adjusting for differing baseline and procedural characteristics female gender was an independent predictor of all-cause mortality after Percutaneous Coronary Intervention (PCI). We examined this issue using data from the Genesis Cardiovascular Outcomes Registry (GCOR).

Methods

We prospectively collected data on 10,989 PCI procedures from January 2009 to January 2018 from 12 Australian Hospitals, and compared the baseline patient and procedural characteristics and 1-year mortality by gender.

Results

Female patients were more likely than males to present with NSTEMI (23.0% vs. 21.1%, p=0.042), however less likely to have prior MI (19.5% vs. 24.2%, p<0.001) or PCI (28.8% vs 33.6%, p<0.001). Procedural success rates were similar between females and males (97.2%). On multivariate logistic regression, female gender had a higher rate of all cause mortality (OR 0.58, 95% CI 0.31 to 1.07; P=0.08) but similar rates of MACE (OR 0.84, 95% CI 0.55 to 1.07, P=0.42). Variables contributing to an increased risk of mortality in female patients, included a history of previous heart failure (OR 2.45, 95% CI 1.15 to 5.22; p=0.02), myocardial infarction (OR 2.06, 95% CI 1.09 to 3.90; p=0.026), and peripheral vascular disease (OR 2.69, 95% CI 1.32 to 5.47; p=0.006). Performing PCI to the LMCA significantly increased the risk of mortality in female patients (OR 3.84, 95% CI 1.14 to 12.9; p=0.029), and the use of BMS vs DES contributed to a worse outcome in women compared to men (OR 0.46, 95% CI 0.25 to 0.84; p=0.012). The presence of hypercholesterolaemia in women significantly increased the risk of mortality (OR 0.44, 95% CI 0.22 to 0.86; p=0.016).

Multivariate logistic regression assessing 1-year outcome by gender for all-cause mortality, MACE, and unplanned admissions Outcome Male (vs female) Odds ratio 95% CI P-value Death (143) 0.58 0.31 to 1.07 0.08 MACE (334) 0.84 0.55 to 1.28 0.42 Unplanned readmission (888) 0.79 0.63 to 0.98 0.04

Conclusion

Women have significant differences in baseline characteristics and increased all-cause mortality at 1 year compared to men, although overall MACE rates are similar. This study increases awareness of women at high risk, highlighting the need to improve the care of women undergoing PCI.