Background: Protein-based bioconversion has been demonstrated as a sustainable approach to produce higher alcohols and ammonia fertilizers. However, owing to the switchover from transcription mediated by the bacterial RNA polymerase σ to that mediated by alternative σ factors, the biofuel production driven by σ-dependent promoters declines rapidly once cells enter the stationary phase or encounter stresses. To enhance biofuel production, in this study the growth phase-independent and nitrogen-responsive transcriptional machinery mediated by the σ is exploited to drive robust protein-to-fuel conversion.
Results: We demonstrated that disrupting the ammonia assimilation pathways driven by glutamate dehydrogenase and glutamine synthetase could sustain the activity of σ-mediated transcription under ammonia-accumulating conditions. In addition, two σ-dependent promoters, and , were identified as suitable candidates for driving pathway expression. Using these promoters, biofuel production from proteins was shown to persist to the stationary phase, with the net production in the stationary phase being 1.7-fold higher than that derived from the optimal reported σ-dependent promoter lacO. Biofuel production reaching levels 1.3- to 3.4-fold higher than those of the σ-dependent promoters was also achieved by and under stressed conditions. Moreover, the σ-dependent promoters realized more rapid and stable production than that of σ-dependent promoters during fed-batch fermentation, producing up to 4.78 g L of total biofuels.
Conclusions: These results suggested that the nitrogen-responsive transcriptional machinery offers the potential to decouple production from growth, highlighting this system as a novel candidate to realize growth phase-independent and stress-resistant biofuel production.
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http://dx.doi.org/10.1186/s13068-020-1667-5 | DOI Listing |
Environ Technol
February 2025
Technology Institute, University of Passo Fundo, Passo Fundo, RS, Brazil.
Food waste offers a potential source for bioethanol production, but productivity depends on the chemical composition of the raw materials and the processes involved. However, assessment of the environmental sustainability of these processes is often absent and can be carried out using the Life Cycle Assessment (LCA) methodology. This study aimed to perform an LCA on bioethanol production from mixtures of different wastes, including tubers, fruits, and processed foods, focusing on the gate-to-gate phase.
View Article and Find Full Text PDFBiotechnol Biofuels Bioprod
January 2025
College of Life Sciences, Henan Agricultural University, 218 Ping-an Ave., Zhengzhou, 450046, China.
Background: Aspergillus niger is an important lignocellulose-degrading enzyme-producing strain. Multiple regulatory factors regulate the synthesis of lignocellulose-degrading enzymes in A. niger.
View Article and Find Full Text PDFMetab Eng
January 2025
Biological Systems & Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA; Joint BioEnergy Institute, 5885 Hollis Street, Emeryville, CA, USA. Electronic address:
Prenol and isoprenol are promising advanced biofuels and serve as biosynthetic precursors for pharmaceuticals, fragrances, and other industrially relevant compounds. Despite engineering improvements that circumvent intermediate cytotoxicity and lower energy barriers, achieving high titer 'mevalonate (MVA)-derived' prenol has remained elusive. Difficulty in selective prenol production stems from the necessary isomerization of isopentenyl diphosphate (IPP) to dimethylallyl diphosphate (DMAPP) as well as the intrinsic toxicity of these diphosphate precursors.
View Article and Find Full Text PDFJ Am Soc Mass Spectrom
January 2025
Department of Chemistry, Center for Innovative Technology, Vanderbilt University, Nashville, Tennessee 37235, United States.
Desorption electrospray ionization mass spectrometry imaging (DESI-MSI) provides direct analytical readouts of small molecules that can be used to characterize the metabolic phenotypes of genetically engineered bacteria. In an effort to accelerate the time frame associated with the screening of mutant libraries, we have developed a high-throughput DESI-MSI analytical workflow implementing a single raster line-scan strategy that facilitates the collection of location-resolved molecular information from engineered strains on a subminute time scale. Evaluation of this "Fast-Pass" DESI-MSI phenotyping workflow on analytical standards demonstrated the capability of acquiring full metabolic profiling information with a throughput of ∼40 s per sample.
View Article and Find Full Text PDFCompr Rev Food Sci Food Saf
January 2025
Department of Dairy Technology, College of Dairy Science and Technology, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana, India.
The Jerusalem artichoke (JA), a plantrelated to sunflowers and native to North America, has long been valued for its versatility, especially during periods of food scarcity. This resilient crop serves multiple purposes, functioning as a vegetable, medicinal herb, grazing crop, and even a biofuel source. In recent years, interest in JA has grown, largely due to its high nutritional profile and associated health benefits.
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