High-Concentration Alkane Output via In Situ Thermal-Assisted Photocatalytic Decarboxylation of Biomass-Derived Fatty Acid

Production of alkane fuels from fatty acids by photocatalytic decarboxylation is presently challenging due to low product output efficiency. Here, we report a high-efficiency photocatalytic decarboxylation route, achieving the transformation of high-concentration bioderived long-chain fatty acids to C1-shortened n-alkanes only by using the in situ heat from the photothermal conversion of Fe3O4. Through the use of high-boiling-point n-alkane solvents for getting the maximum reaction temperature, the single output concentration of Cn–1 n-alkane was upgraded from a traditional far less than mmol/L level to the unprecedented mol/L level. We suggest that the heat enhances the strain of aimed C–COO– bond by forcing the standing C-chain down at room temperature onto the Fe3O4 surface, leading photoinduced hole–electron pair easily to be close to and react with the energy-storing C–COO– bond. Meanwhile, the photogenerated electron consumption can shift from conventional PCET of the photo-Koble reaction into a stepwise pathway to form a more favorable carbanion (R–) intermediate that reacting with H+ into RH is highly accelerated with lifting the temperature. Our findings open a new way to upgrade the output efficiency of photocatalytic decarboxylation reaction by reusing the vast majority of incident light energy in a heat form

High-Concentration Alkane Output via In Situ Thermal-Assisted Photocatalytic Decarboxylation of Biomass-Derived Fatty Acid

Production of alkane fuels from fatty acids by photocatalytic decarboxylation is presently challenging due to low product output efficiency. Here, we report a high-efficiency photocatalytic decarboxylation route, achieving the transformation of high-concentration bioderived long-chain fatty acids to C1-shortened n-alkanes only by using the in situ heat from the photothermal conversion of Fe3O4. Through the use of high-boiling-point n-alkane solvents for getting the maximum reaction temperature, the single output concentration of Cn–1 n-alkane was upgraded from a traditional far less than mmol/L level to the unprecedented mol/L level. We suggest that the heat enhances the strain of aimed C–COO– bond by forcing the standing C-chain down at room temperature onto the Fe3O4 surface, leading photoinduced hole–electron pair easily to be close to and react with the energy-storing C–COO– bond. Meanwhile, the photogenerated electron consumption can shift from conventional PCET of the photo-Koble reaction into a stepwise pathway to form a more favorable carbanion (R–) intermediate that reacting with H+ into RH is highly accelerated with lifting the temperature. Our findings open a new way to upgrade the output efficiency of photocatalytic decarboxylation reaction by reusing the vast majority of incident light energy in a heat form

High-Concentration Alkane Output via In Situ Thermal-Assisted Photocatalytic Decarboxylation of Biomass-Derived Fatty Acid

Production of alkane fuels from fatty acids by photocatalytic decarboxylation is presently challenging due to low product output efficiency. Here, we report a high-efficiency photocatalytic decarboxylation route, achieving the transformation of high-concentration bioderived long-chain fatty acids to C1-shortened n-alkanes only by using the in situ heat from the photothermal conversion of Fe3O4. Through the use of high-boiling-point n-alkane solvents for getting the maximum reaction temperature, the single output concentration of Cn–1 n-alkane was upgraded from a traditional far less than mmol/L level to the unprecedented mol/L level. We suggest that the heat enhances the strain of aimed C–COO– bond by forcing the standing C-chain down at room temperature onto the Fe3O4 surface, leading photoinduced hole–electron pair easily to be close to and react with the energy-storing C–COO– bond. Meanwhile, the photogenerated electron consumption can shift from conventional PCET of the photo-Koble reaction into a stepwise pathway to form a more favorable carbanion (R–) intermediate that reacting with H+ into RH is highly accelerated with lifting the temperature. Our findings open a new way to upgrade the output efficiency of photocatalytic decarboxylation reaction by reusing the vast majority of incident light energy in a heat form

Mining of the Pyrrolamide Antibiotics Analogs in <i>Streptomyces netropsis</i> Reveals the Amidohydrolase-Dependent “Iterative Strategy” Underlying the Pyrrole Polymerization

<div><p>In biosynthesis of natural products, potential intermediates or analogs of a particular compound in the crude extracts are commonly overlooked in routine assays due to their low concentration, limited structural information, or because of their insignificant bio-activities. This may lead into an incomplete and even an incorrect biosynthetic pathway for the target molecule. Here we applied multiple compound mining approaches, including genome scanning and precursor ion scan-directed mass spectrometry, to identify potential pyrrolamide compounds in the fermentation culture of <i>Streptomyces netropsis</i>. Several novel congocidine and distamycin analogs were thus detected and characterized. A more reasonable route for the biosynthesis of pyrrolamides was proposed based on the structures of these newly discovered compounds, as well as the functional characterization of several key biosynthetic genes of pyrrolamides. Collectively, our results implied an unusual “iterative strategy” underlying the pyrrole polymerization in the biosynthesis of pyrrolamide antibiotics.</p></div

In-frame deletion of <i>pya25</i> and <i>pya26</i> in <i>S. netropsis</i>.

<p>HPLC analysis of pyrrolamides production in <i>S. netropsis</i> wild-type strain, the mutant strains WDY002 (Δ<i>pya25</i>) and WDY003 (Δ<i>pya26</i>), and the complementation strains WDY004 (negative control) and WDY005. Congocidine, Compound <b>3</b>, and Distamycin are indicated. The characteristic absorbance wave-length for pyrrolamides is 297 nm.</p

Identification of Congocidine (1), Distamycin (2), and a novel pyrrolamide compound (3) in <i>S. netropsis</i>.

<p>(A) High resolution mass spectrum of Congocidine and Distamycin. (B) Precursor ion scan-directed mass spectrum to identify compound <b>3</b>. Base peak chromatograms of precursor ion scan are shown. Ions of <i>m</i>/<i>z</i> 273 and 247 are daughter ions of compound <b>3</b>, and were used as the queries.</p

Organization of the pyrrolamides biosynthesis-related genes identified from <i>S. ambofaciens</i> (a congocidine producer) and <i>S. netropsis</i>.

<p>The deduced functions of each gene are summarized in Table S1 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099077#pone.0099077.s001" target="_blank">File S1</a>. Homologies in sequence are indicated by plain and dashed lines (the latter pattern is for the separate gene cluster).</p

Illustration of the “iterative strategy” underlying pyrrolamide biosynthesis.

<p>The putative amidohydrolase Pya25 catalyzed the deacetylation of PCP-tethered pyrrolamide biosynthesis intermediates and determined the number of the pyrrole groups assembled into various pyrrolamides. A, adenylation domain; C, condensation domain; PCP, peptidyl carrier protein.</p

Identification of the novel pyrrolamide compounds 4 (A), 5 (B), 6 (C), and 7 (D).

<p>High resolution mass spectrum and MS/MS patterns of each compound are shown.</p