期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2022
卷号：119
期号：30
DOI：10.1073/pnas.2122309119
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
The establishment of a carbon-negative bioeconomy that eliminates the need for crude oil will require a range of bioproducts. Accumulating value-added bioproducts directly in bioenergy crops can be an important strategy for enabling economically competitive biorefineries that produce a range of renewable fuels and replacements for petrochemicals. However, microbial chassis may have advantages over plants for some products. To date, there has been no systematic analysis aimed at comparing microbial production routes with
in planta accumulation to establish breakeven targets for yields and accumulation rates. In this study, we provide generalizable insights into these breakeven points by exploring four bioproducts (4-hydroxybenzoic acid [4-HBA], 2-pyrone-4,6-dicarboxylic acid [PDC], muconic acid, and catechol) currently produced both in plants and by microbial hosts.
Plants and microbes share common metabolic pathways for producing a range of bioproducts that are potentially foundational to the future bioeconomy. However,
in planta accumulation and microbial production of bioproducts have never been systematically compared on an economic basis to identify optimal routes of production. A detailed technoeconomic analysis of four exemplar compounds (4-hydroxybenzoic acid [4-HBA], catechol, muconic acid, and 2-pyrone-4,6-dicarboxylic acid [PDC]) is conducted with the highest reported yields and accumulation rates to identify economically advantaged platforms and breakeven targets for plants and microbes. The results indicate that
in planta mass accumulation ranging from 0.1 to 0.3 dry weight % (dwt%) can achieve costs comparable to microbial routes operating at 40 to 55% of maximum theoretical yields. These yields and accumulation rates are sufficient to be cost competitive if the products are sold at market prices consistent with specialty chemicals ($20 to $50/kg). Prices consistent with commodity chemicals will require an order-of-magnitude-greater accumulation rate for plants and/or yields nearing theoretical maxima for microbial production platforms. This comparative analysis revealed that the demonstrated accumulation rates of 4-HBA (3.2 dwt%) and PDC (3.0 dwt%) in engineered plants vastly outperform microbial routes, even if microbial platforms were to reach theoretical maximum yields. Their recovery and sale as part of a lignocellulosic biorefinery could enable biofuel prices to be competitive with petroleum. Muconic acid and catechol, in contrast, are currently more attractive when produced microbially using a sugar feedstock. Ultimately, both platforms can play an important role in replacing fossil-derived products.
