2 research outputs found
Consolidate Processing for Improvement of Ethanol Production from Food Waste
To
improve the performance of ethanol production from food waste,
a consolidation process involving both the addition of surfactant
and cell immobilization was investigated. Results showed that the
optimum glucose concentration was 200 g/L for ethanol fermentation
using Saccharomyces cerevisiae as inoculum.
With the addition of 0.5% Tween 80, the ethanol production was improved
from 68.1 to 79.8 g/L, which was attributed to the increased mass
transfer of cells provoked by Tween 80. In a cell-immobilized system,
wheat straw was used as the matrix to carry the cells. A high ethanol
production of 87.8 g/L was obtained with the sequential fermentation
mode due to the high cell density on the cell carrier. The results
of a mass balance calculation revealed that the ethanol production
of food waste achieved 340.4 kg/t (on a dry basis), which provided
an insight that food waste was a suitable substrate for ethanol production.
The main cost was spent on energy consumption in the processes of
food waste sterilization, hydrolysis, fermentation, and ethanol distillation,
and measures for reducing the energy were suggested to improve the
economic performance of ethanol production
Metabolic Remodulation of Chassis and Corn Stover Bioprocessing to Unlock 3‑Hydroxypropionic Acid Biosynthesis from Agrowaste-Derived Substrates
Embracing the principles of sustainable
development,
the valorization of agrowastes into value-added chemicals has nowadays
received significant attention worldwide. Herein, Escherichia
coli was metabolically rewired to convert cellulosic
hydrolysate of corn stover into a key platform chemical, namely, 3-hydroxypropionic
acid (3-HP). First, the heterologous pathways were introduced into E. coli by coexpressing glycerol-3-P dehydrogenase
and glycerol-3-P phosphatase in both single and fusion (gpdp12) forms, making the strain capable of synthesizing glycerol from
glucose. Subsequently, a glycerol dehydratase (DhaB123-gdrAB) and
an aldehyde dehydrogenase (GabD4) were overexpressed to convert glycerol
into 3-HP. A fine-tuning between glycerol synthesis and its conversion
into 3-HP was successfully established by 5′-untranslated region
engineering of gpdp12 and dhaB123-gdrAB. The strain was further metabolically modulated to
successfully prevent glycerol flux outside the cell and into the central
metabolism. The finally remodulated chassis produced 32.91 g/L 3-HP
from the cellulosic hydrolysate of stover during fed-batch fermentation