Dataset Information

Evaluation of engineered low-lignin poplar for conversion into advanced bioproducts.

ABSTRACT:

Background

Lignocellulosic resources are promising feedstocks for the manufacture of bio-based products and bioenergy. However, the inherent recalcitrance of biomass to conversion into simple sugars currently hinders the deployment of advanced bioproducts at large scale. Lignin is a primary contributor to biomass recalcitrance as it protects cell wall polysaccharides from degradation and can inhibit hydrolytic enzymes via non-productive adsorption. Several engineering strategies have been designed to reduce lignin or modify its monomeric composition. For example, expression of bacterial 3-dehydroshikimate dehydratase (QsuB) in poplar trees resulted in a reduction in lignin due to redirection of metabolic flux toward 3,4-dihydroxybenzoate at the expense of lignin. This reduction was accompanied with remarkable changes in the pools of aromatic compounds that accumulate in the biomass.

Results

The impact of these modifications on downstream biomass deconstruction and conversion into advanced bioproducts was evaluated in the current study. Using ionic liquid pretreatment followed by enzymatic saccharification, biomass from engineered trees released more glucose and xylose compared to wild-type control trees under optimum conditions. Fermentation of the resulting hydrolysates using Rhodosporidium toruloides strains engineered to produce α-bisabolene, epi-isozizaene, and fatty alcohols showed no negative impact on cell growth and yielded higher titers of bioproducts (as much as + 58%) in the case of QsuB transgenics trees.

Conclusion

Our data show that low-recalcitrant poplar biomass obtained with the QsuB technology has the potential to improve the production of advanced bioproducts.

SUBMITTER: Lin CY

PROVIDER: S-EPMC9790118 | biostudies-literature | 2022 Dec

REPOSITORIES: biostudies-literature

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Publications

Evaluation of engineered low-lignin poplar for conversion into advanced bioproducts.

Lin Chien-Yuan CY Geiselman Gina M GM Liu Di D Magurudeniya Harsha D HD Rodriguez Alberto A Chen Yi-Chun YC Pidatala Venkataramana V Unda Faride F Amer Bashar B Baidoo Edward E K EEK Mansfield Shawn D SD Simmons Blake A BA Singh Seema S Scheller Henrik V HV Gladden John M JM Eudes Aymerick A

Biotechnology for biofuels and bioproducts 20221225 1

<h4>Background</h4>Lignocellulosic resources are promising feedstocks for the manufacture of bio-based products and bioenergy. However, the inherent recalcitrance of biomass to conversion into simple sugars currently hinders the deployment of advanced bioproducts at large scale. Lignin is a primary contributor to biomass recalcitrance as it protects cell wall polysaccharides from degradation and can inhibit hydrolytic enzymes via non-productive adsorption. Several engineering strategies have bee ...[more]

PMID: 36567331

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Project description:Hybrid poplar (Populus alba?×?grandidentata; p39) wild type (WT) and QsuB transgenic low-lignin lines were previously described (Unda et al., 2022). WT and lines QsuB1, QsuB5, and QsuB15 were grown in a greenhouse as described in Lin et al., 2022. Samples for metabolomic analyses were collected after a growth period of six months. Stems were cut 5 cm above the root collar and segments of 5 cm were collected above the 1st (bottom), 20th (middle), and 40th (top) internodes. The bark was peeled and developing xylem tissue was collected by scraping the surface of the debarked segments using a razor blade. This approach generated developing xylem samples from the mature (bottom segment), intermediate (middle segment), and immature (top segment) parts of the stem. All the samples were immediately placed in liquid nitrogen, and stored at ?80 °C until time of use. Frozen samples were pulverized with a ball mill (Retsch) using stainless steel jars and grinding balls. Four biological replicates from each transgenic poplar line and WT control were used for metabolomic analyses. The data showed that some changes in metabolite abundance occur only in a specific tissue such as the xylem, phloem, or periderm. In the poplar line that exhibits the strongest reduction of lignin, we found that ~19% of the detected metabolite ions had different abundances in the xylem from mature stems. Changes affect predominantly the shikimate and phenylpropanoid pathways, secondary cell wall metabolism, and result in significant accumulation of hydroxybenzoates that derive from protocatechuate and salicylate. Unda et al., 2022: https://doi.org/10.1111/nph.18136 Lin et al., 2022: https://doi.org/10.1186/s13068-022-02245-4. The work (proposal:https://doi.org/10.46936/10.25585/60000514) conducted by the U.S. Department of Energy Joint Genome Institute (https://ror.org/04xm1d337), a DOE Office of Science User Facility, is supported by the Office of Science of the U.S. Department of Energy operated under Contract No. DE-AC02-05CH11231.

Project description:BackgroundWe previously developed several strategies to engineer plants to produce cost-efficient biofuels from plant biomass. Engineered Arabidopsis plants with low xylan and lignin content showed normal growth and improved saccharification efficiency under standard growth conditions. However, it remains to be determined whether these engineered plants perform well under drought stress, which is the primary source of abiotic stress in the field.ResultsUpon exposing engineered Arabidopsis plants to severe drought, we observed better survival rates in those with a low degree of xylan acetylation, low lignin, and low xylan content compared to those in wild-type plants. Increased pectic galactan content had no effect on drought tolerance. The drought-tolerant plants exhibited low water loss from leaves, and drought-responsive genes (RD29A, RD29B, DREB2A) were generally up-regulated under drought stress, which did not occur in the well-watered state. When compared with the wild type, plants with low lignin due to expression of QsuB, a 3-dehydroshikimate dehydratase, showed a stronger response to abscisic acid (ABA) in assays for seed germination and stomatal closure. The low-lignin plants also accumulated more ABA in response to drought than the wild-type plants. On the contrary, the drought tolerance in the engineered plants with low xylan content and low xylan acetylation was not associated with differences in ABA content or response compared to the wild type. Surprisingly, we found a significant increase in galactose levels and sugar released from the low xylan-engineered plants under drought stress.ConclusionsThis study shows that plants engineered to accumulate less lignin or xylan are more tolerant to drought and activate drought responses faster than control plants. This is an important finding because it demonstrates that modification of secondary cell walls does not necessarily render the plants less robust in the environment, and it shows that substantial changes in biomass composition can be achieved without compromising plant resilience.

Dataset Information

Evaluation of engineered low-lignin poplar for conversion into advanced bioproducts.

Background

Results

Conclusion

Publications

Evaluation of engineered low-lignin poplar for conversion into advanced bioproducts.

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