scholarly journals Two-dimensional isobutyl acetate production pathways to improve carbon yield

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Yohei Tashiro ◽  
Shuchi H. Desai ◽  
Shota Atsumi
Keyword(s):  
Two Dimensional ◽  
Carbon Yield ◽  
Acetate Production ◽  
Isobutyl Acetate

scholarly journals Single mutation at a highly conserved region of chloramphenicol acetyltransferase enables thermophilic isobutyl acetate production directly from cellulose by Clostridium thermocellum

2019 ◽  
Author(s):  
Hyeongmin Seo ◽  
Jong-Won Lee ◽  
Sergio Garcia ◽  
Cong T. Trinh
Keyword(s):  
Lignocellulosic Biomass ◽  
Clostridium Thermocellum ◽  
Consolidated Bioprocessing ◽  
Potential Drop ◽  
Chloramphenicol Acetyltransferase ◽  
Single Mutation ◽  
Acetate Production ◽  
Isobutyl Acetate ◽  
Ester Biosynthesis ◽  
Conserved Region

ABSTRACTBackgroundEsters are versatile chemicals and potential drop-in biofuels. To develop a sustainable production platform, microbial ester biosynthesis using alcohol acetyltransferases (AATs) has been studied for decades. Volatility of esters endows thermophilic production with advantageous downstream product separation. However, due to the limited thermal stability of AATs known, the ester biosynthesis has largely relied on use of mesophilic microbes. Therefore, developing thermostable AATs is important for thermophilic ester production directly from lignocellulosic biomass by the thermophilic consolidated bioprocessing (CBP) microbes, e.g., Clostridium thermocellum.ResultsIn this study, we engineered a thermostable chloramphenicol acetyltransferase from Staphylococcus aureus (CATSa) for enhanced isobutyl acetate production at elevated temperature. We first analyzed the broad alcohol substrate range of CATSa. Then, we targeted a highly conserved region in the binding pocket of CATSa for mutagenesis. The mutagenesis revealed that F97W significantly increased conversion of isobutanol to isobutyl acetate. Using CATSa F97W, we demonstrated the engineered C. thermocellum could produce isobutyl acetate directly from cellulose.ConclusionsThis study highlights that CAT is a potential thermostable AAT that can be harnessed to develop the thermophilic CBP microbial platform for biosynthesis of designer bioesters directly from lignocellulosic biomass.

scholarly journals Single mutation at a highly conserved region of chloramphenicol acetyltransferase enables isobutyl acetate production directly from cellulose by Clostridium thermocellum at elevated temperatures

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Hyeongmin Seo ◽  
Jong-Won Lee ◽  
Sergio Garcia ◽  
Cong T. Trinh
Keyword(s):  
Lignocellulosic Biomass ◽  
Clostridium Thermocellum ◽  
Elevated Temperatures ◽  
Consolidated Bioprocessing ◽  
Chloramphenicol Acetyltransferase ◽  
Single Mutation ◽  
Acetate Production ◽  
Isobutyl Acetate ◽  
Ester Biosynthesis ◽  
Conserved Region

Abstract Background Esters are versatile chemicals and potential drop-in biofuels. To develop a sustainable production platform, microbial ester biosynthesis using alcohol acetyltransferases (AATs) has been studied for decades. Volatility of esters endows high-temperature fermentation with advantageous downstream product separation. However, due to the limited thermostability of AATs known, the ester biosynthesis has largely relied on use of mesophilic microbes. Therefore, developing thermostable AATs is important for ester production directly from lignocellulosic biomass by the thermophilic consolidated bioprocessing (CBP) microbes, e.g., Clostridium thermocellum. Results In this study, we engineered a thermostable chloramphenicol acetyltransferase from Staphylococcus aureus (CATSa) for enhanced isobutyl acetate production at elevated temperatures. We first analyzed the broad alcohol substrate range of CATSa. Then, we targeted a highly conserved region in the binding pocket of CATSa for mutagenesis. The mutagenesis revealed that F97W significantly increased conversion of isobutanol to isobutyl acetate. Using CATSa F97W, we demonstrated direct conversion of cellulose into isobutyl acetate by an engineered C. thermocellum at elevated temperatures. Conclusions This study highlights that CAT is a potential thermostable AAT that can be harnessed to develop the thermophilic CBP microbial platform for biosynthesis of designer bioesters directly from lignocellulosic biomass.

scholarly journals Endogenous esterases of Clostridium thermocellum are identified and disrupted for enhanced isobutyl acetate production from cellulose

2019 ◽  
Author(s):  
Hyeongmin Seo ◽  
Preston N. Nicely ◽  
Cong T. Trinh
Keyword(s):  
Lignocellulosic Biomass ◽  
Clostridium Thermocellum ◽  
Ester Hydrolysis ◽  
Acetate Production ◽  
Functional Roles ◽  
Medium Chain ◽  
Isobutyl Acetate ◽  
Acetate Degradation ◽  
Dependent Pathway ◽  
Carbohydrate Esterases

ABSTRACTMedium chain esters are potential drop-in biofuels and versatile chemicals. Currently, these esters are largely produced by the conventional chemical process that uses harsh operating conditions and requires high energy input. Alternatively, the microbial conversion route has recently emerged as a promising platform for sustainable and renewable ester production. The ester biosynthesis pathways can utilize either esterases/lipases or alcohol acyltransferase (AAT), but the AAT-dependent pathway is more thermodynamically favorable in aqueous fermentation environment. Even though cellulolytic thermophiles such as Clostridium thermocellum harboring the engineered AAT-dependent pathway can directly convert lignocellulosic biomass into esters, the production is currently not efficient and requires optimization. One potential bottleneck is the ester degradation caused by the endogenous carbohydrate esterases (CEs) whose functional roles are poorly understood. In this study, we developed a simple, high-throughput colorimetric assay to screen the endogenous esterases of C. thermocellum responsible for ester hydrolysis. We identified, characterized, and disrupted two critical endogenous esterases that significantly contributes to isobutyl acetate degradation in C. thermocellum. We demonstrated that not only did the engineered esterase-deficient strain alleviate ester hydrolysis but also helped improve isobutyl acetate production while not affecting its robust metabolism for effective cellulose assimilation.IMPORTANCECarbohydrate esterases (CEs) are important enzymes in the deconstruction of lignocellulosic biomass by the cellulolytic thermophile C. thermocellum, yet some are potential ester degraders in a microbial ester production system. Currently, the functional roles of CEs for hydrolyzing medium chain esters and negatively affecting the ester microbial biosynthesis are not well understood. This study discovered novel CEs responsible for isobutyl acetate degradation in C. thermocellum and hence identified one of the critical bottlenecks for direct conversion of lignocellulosic biomass into esters.

Spectrophotometric measurements of objective-prism spectra

1966 ◽  
Vol 24 ◽  
pp. 118-119
Author(s):  
Th. Schmidt-Kaler
Keyword(s):  
Progress Report ◽  
Two Dimensional ◽  
Objective Prism ◽  
Made In

I should like to give you a very condensed progress report on some spectrophotometric measurements of objective-prism spectra made in collaboration with H. Leicher at Bonn. The procedure used is almost completely automatic. The measurements are made with the help of a semi-automatic fully digitized registering microphotometer constructed by Hög-Hamburg. The reductions are carried out with the aid of a number of interconnected programmes written for the computer IBM 7090, beginning with the output of the photometer in the form of punched cards and ending with the printing-out of the final two-dimensional classifications.

Introductory paper

1966 ◽  
Vol 24 ◽  
pp. 3-5
Author(s):  
W. W. Morgan
Keyword(s):  
Line Intensity ◽  
Classification Scheme ◽  
Two Dimensional ◽  
Spectral Classification ◽  
Dimensional Array ◽  
Rr Lyrae ◽  
Metallic Line ◽  
Introductory Paper ◽  
Parameter Varying ◽  
Definition Of

1. The definition of “normal” stars in spectral classification changes with time; at the time of the publication of theYerkes Spectral Atlasthe term “normal” was applied to stars whose spectra could be fitted smoothly into a two-dimensional array. Thus, at that time, weak-lined spectra (RR Lyrae and HD 140283) would have been considered peculiar. At the present time we would tend to classify such spectra as “normal”—in a more complicated classification scheme which would have a parameter varying with metallic-line intensity within a specific spectral subdivision.

A one-dimensional self-gravitating stellar gas

1966 ◽  
Vol 25 ◽  
pp. 46-48 ◽  
Author(s):  
M. Lecar
Keyword(s):  
Gravitational Field ◽  
Phase Space ◽  
Motion Picture ◽  
Space Distribution ◽  
Two Dimensional ◽  
One Dimensional ◽  
Phase Space Distribution ◽  
Dimensional Phase Space ◽  
The Mean

“Dynamical mixing”, i.e. relaxation of a stellar phase space distribution through interaction with the mean gravitational field, is numerically investigated for a one-dimensional self-gravitating stellar gas. Qualitative results are presented in the form of a motion picture of the flow of phase points (representing homogeneous slabs of stars) in two-dimensional phase space.

Analysis of the 9th November 1990 flare

2000 ◽  
Vol 179 ◽  
pp. 229-232
Author(s):  
Anita Joshi ◽  
Wahab Uddin
Keyword(s):  
Image Processing ◽  
Two Dimensional ◽  
Temporal Behaviour ◽  
Contour Maps ◽  
Dimensional Measurements ◽  
Processing Software ◽  
Image Processing Software

AbstractIn this paper we present complete two-dimensional measurements of the observed brightness of the 9th November 1990Hαflare, using a PDS microdensitometer scanner and image processing software MIDAS. The resulting isophotal contour maps, were used to describe morphological-cum-temporal behaviour of the flare and also the kernels of the flare. Correlation of theHαflare with SXR and MW radiations were also studied.

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