Biology subjects

Lehtinen, T.

Publications and source records attributed to Lehtinen, T..

4 recordsLinked to original sources

bioRxiv2018

Alkane and wax ester production from lignin derived molecules

Lignin has potential as a sustainable feedstock for microbial production of industrially relevant molecules. However, the required lignin depolymerization yields a heterogenic mixture of aromatic monomers that are challenging substrates for the microorganisms commonly used in industry. Here, we investigated the properties of lignin-derived molecules (LDMs), namely coumarate, ferulate, and caffeate, in the synthesis of biomass and products in a LDM-utilizing bacterial host Acinetobacter baylyi ADP1. The biosynthesis products, wax esters and alkanes, are relevant compounds for the chemical and fuel industries. In A. baylyi ADP1, wax esters are produced by a native pathway, whereas alkanes are produced by a synthetic pathway introduced to the host. Using individual LDMs as substrates, the growth, product formation, and toxicity to cells were monitored with internal biosensors. Of the tested LDMs, coumarate was the most propitious in terms of product synthesis. Wax esters were produced from coumarate with a yield and titer of 40 mg /gcoumarate and 221 mg/L, whereas alkanes were produced with a yield of 62.3 g /gcoumarate and titer of 152 g/L. This study demonstrates the microbial preference for certain LDMs, and highlights the potential of A. baylyi ADP1 as a convenient host for LDM upgrading to value-added products.

bioengineering↗

bioRxiv2018

Synthetic Metabolic Pathway for the Production of 1-Alkenes from Lignin-derived Molecules

Integration of synthetic metabolic pathways to catabolically diverse chassis provides new opportunities for sustainable production. One attractive scenario is the use of abundant waste material to produce readily collectable product, minimizing production costs. Towards that end, we established the production of semivolatile medium-chain -olefins from lignin-derived monomers: we constructed 1-undecene synthesis pathway in Acinetobacter baylyi ADP1 using ferulate as the sole carbon source. In order to overcome the toxicity of ferulate, we first applied adaptive laboratory evolution, resulting in a highly ferulate-tolerant strain. Next, we demonstrated the 1-undecene production from glucose by heterologously expressing a fatty acid decarboxylase UndA and a thioesterase TesA in the wild type strain. Finally, we constructed the alkene synthesis pathway in the ferulate-tolerant strain. We were able to produce 1-undecene from ferulate and collect the product from the culture headspace without downstream processing. This study demonstrates the potential of bacterial lignin upgradation into value-added products.

bioengineering↗

bioRxiv2018

Production of alkanes from CO2 by engineered bacteria

BackgroundMicrobial biosynthesis of alkanes is considered a promising method for the sustainable production of drop-in fuels and chemicals. Carbon dioxide would be an ideal carbon source for these production systems, but efficient production of long carbon chains from CO2 is difficult to achieve in a single organism. A potential solution is to employ acetogenic bacteria for the reduction of CO2 to acetate, and engineer a second organism to convert the acetate into long-chain hydrocarbons.\n\nResultsIn this study, we demonstrate alkane production from CO2 by a system combining the acetogen Acetobacterium woodii and a non-native alkane producer Acinetobacter baylyi ADP1 engineered for alkane production. Nine synthetic two-step alkane biosynthesis pathways consisting of different aldehyde- and alkane-producing enzymes were combinatorically constructed and expressed in A. baylyi. The aldehyde-producing enzymes studied were AAR from Synechococcus elongatus, Acr1 from A. baylyi, and Ramo, a putative dehydrogenase, from Nevskia ramosa. The alkane-producing enzymes were ADOs from S. elongatus and Nostoc punctiforme, and CER1 from Arabidopsis thaliana. The performance of the pathways was evaluated with a twin-layer biosensor, which allowed the monitoring of both the intermediate, fatty aldehyde, as well as the alkane production. The highest alkane production, as indicated by the biosensor, was achieved with a pathway consisting of AAR and ADO from S. elongatus. The performance of this pathway was further improved by balancing the relative expression levels of the enzymes in order to limit the accumulation of the intermediate fatty aldehyde. Finally, the acetogen A. woodii was used to produce acetate from CO2 and H2, and the acetate was used for alkane production by the engineered A. baylyi, thereby leading to the net production of long-chain alkanes from CO2.\n\nConclusionsA modular system for the production of drop-in liquid fuels from CO2 was demonstrated. Among the studied synthetic pathways, the combination of ADO and AAR from S. elongatus was found to be the most efficient in heterologous alkane production in A. baylyi. Furthermore, limiting the accumulation of the fatty aldehyde intermediate was found to be beneficial for the alkane production.

bioengineering↗

bioRxiv2018

Metabolic pairing of aerobic and anaerobic production in a one-pot batch cultivation

BackgroundThe versatility of microbial metabolic pathways enables their utilization in vast number of applications. However, the electron and carbon recovery rates, essentially constrained by limitations of cell energetics, are often too low in terms of process feasibility. Cocultivation of divergent microbial species in a single process broadens the metabolic landscape and thus, the possibilities for more complete carbon and energy utilization.\n\nResultsIn this study, we integrated the metabolisms of two bacteria, an obligate anaerobe Clostridium butyricum and an obligate aerobe Acinetobacter baylyi ADP1. In the process, a glucose-negative mutant of A. baylyi ADP1 first deoxidized the culture allowing C. butyricum to grow and produce hydrogen from glucose. In the next phase, ADP1 produced long chain alkyl esters utilizing the by-products of C. butyricum, namely acetate and butyrate.\n\nConclusionsThe cocultivation of strictly anaerobic and aerobic bacteria allowed the production of both hydrogen gas and long-chain alkyl esters in a simple one-pot batch process. The study demonstrates the potential of metabolic pairing using designed microbial consortia for optimal electron and carbon recovery.

bioengineering↗