1.0. Introduction 4044 2.0. Biomass Chemistry and Growth Rates 4047 2.1. Lignocellulose and Starch-Based Plants 4047 2.2. Triglyceride-Producing Plants 4049 2.3. Algae 4050 2.4. Terpenes and Rubber-Producing Plants 4052 3.0. Biomass Gasification 4052 3.1. Gasification Chemistry 4052 3.2. Gasification Reactors 4054 3.3. Supercritical Gasification 4054 3.4. Solar Gasification 4055 3.5. Gas Conditioning 4055 4.0. Syn-Gas Utilization 4056 4.1. Hydrogen Production by Water−Gas Shift Reaction 4056

/pdf/synthesis-of-transportation-fuels-from-biomass-chemistry-3sckhzoqoz.pdf

Synthesis of transportation fuels from biomass: chemistry, catalysts, and engineering.

https://faculty.washington.edu/renatab/courses/PSE490/downloads/pretreatment.pdf

Features of promising technologies for pretreatment of lignocellulosic biomass.

Fundamental features of microbial cellulose utilization are examined at successively higher levels of aggregation encompassing the structure and composition of cellulosic biomass, taxonomic diversity, cellulase enzyme systems, molecular biology of cellulase enzymes, physiology of cellulolytic microorganisms, ecological aspects of cellulase-degrading communities, and rate-limiting factors in nature. The methodological basis for studying microbial cellulose utilization is considered relative to quantification of cells and enzymes in the presence of solid substrates as well as apparatus and analysis for cellulose-grown continuous cultures. Quantitative description of cellulose hydrolysis is addressed with respect to adsorption of cellulase enzymes, rates of enzymatic hydrolysis, bioenergetics of microbial cellulose utilization, kinetics of microbial cellulose utilization, and contrasting features compared to soluble substrate kinetics. A biological perspective on processing cellulosic biomass is presented, including features of pretreated substrates and alternative process configurations. Organism development is considered for "consolidated bioprocessing" (CBP), in which the production of cellulolytic enzymes, hydrolysis of biomass, and fermentation of resulting sugars to desired products occur in one step. Two organism development strategies for CBP are examined: (i) improve product yield and tolerance in microorganisms able to utilize cellulose, or (ii) express a heterologous system for cellulose hydrolysis and utilization in microorganisms that exhibit high product yield and tolerance. A concluding discussion identifies unresolved issues pertaining to microbial cellulose utilization, suggests approaches by which such issues might be resolved, and contrasts a microbially oriented cellulose hydrolysis paradigm to the more conventional enzymatically oriented paradigm in both fundamental and applied contexts.

/pdf/microbial-cellulose-utilization-fundamentals-and-4yec12qx1c.pdf

Microbial cellulose utilization: fundamentals and biotechnology.

Pretreatments to enhance the digestibility of lignocellulosic biomass

Pretreatment technologies for an efficient bioethanol production process based on enzymatic hydrolysis: A review

When a chromogenic Limulus Amoebocyte Lysate (LAL) assay and a tube gelation LAL assay were compared for the detection of Gram-negative bacteria using a strain of Pseudomonas putida, the detection level (approximately 10(3) cfu/ml) and cost of the assays were approximately the same for both assays but the reading was more precise for the chromogenic substrate assay. A modified chromogenic assay was devised for detection of Ps. putida in milk.

Comparison of a gelation and a chromogenic Limulus (LAL) assay for the detection of gram-negative bacteria, and the application of the latter assay to milk.

Yeast strains from more than 31 different genera were screened for the enantioselective reduction of bicyclo[2.2.2]octane-2,6-dione (1). Reducing activity was found in 80% of the screened yeasts. Bicyclo[2.2.2]octane-2,6-dione was enantioselectively reduced (>98% ee) to (1R,4S,6S)-6-hydroxybicyclo[2.2.2]octane-2-one (−)-2 by 69% of the strains. Enantioselective reduction of the diketone to (1S,4R,6S)-6-hydroxybicyclo[2.2.2]octane-2-one ((+)-3, >98% ee) as a major product is reported for the first time. Candida tropicalis UOFS Y-0534 and Candida wickerhamii UOFS Y-0652 displayed this unusual diastereoselectivity.

Screening of yeast species for the stereo-selective reduction of bicyclo[2.2.2]octane-2,6-dione

Cellulolytic enzyme production in aqueous two-phase systems withTrichoderma reesei Rutgers C30 has been investigated. The influ ence of different phase systems, as well as addition of media compo nents and substrate on enzyme production have been studied. Extractive enzyme production in fed-batch cultivations was per formed in a phase system composed of PEG 8000 5%-Dextran T500 7% with 1% Solka-Floc BW 200 as substrate. The cellulolytic enzyme system was intermittently withdrawn with the top phase. Addition of media components every 24 h and cellulose every 72 h gave an aver age enzyme activity in the withdrawn top phase of 2.2 FPU/mL dur ing 170 h cultivation. The corresponding productivity was 18 FPU/lh. The productivity was increased to 24 FPU/l.h when media compo nents and cellulose were added every 72 h. The average enzyme con centration was then 1.6 FPU/mL. The results are discussed in relation to methods for cellulolytic enzyme production involving immobiliza tion and cell recycling.

Influence of cultivation conditions on the production of cellulolytic enzymes withTrichoderma reesei Rutgers C30 in aqueous two-phase systems

The present invention relates to a method for improved ethanol production from xylose utilising strain of Saccharomyces cerevisiae comprising genes for overexpression of xylose reductase, xylitol dehydrogenase and xylulokinase, wherein in addition to said genes, one or more specific genes of a defined group is overexpressed, and/or one or more genes of a defined group is deleted.

Saccharomyces cerevisiae mutant

In a recent study combining transcriptome analyses of a number of recombinant laboratory and industrial S. cerevisiae strains with improved xylose utilization and their respective control strains, the ORF YLR042c was identified as a downregulated gene and it was shown that the gene deletion improved aerobic growth on xylose in the tested strain background. In the present study, the influence of deleting YLR042c on xylose fermentation was investigated in two different xylose-fermenting strains: TMB3001, which expresses genes from the initial xylose catabolizing pathway, including heterologous xylose reductase (XR) and xylitol dehydrogenase (XDH) and endogenous xylulokinase (XK); and TMB3057, which, in addition to the initial xylose catabolizing pathway, overexpresses the endogenous genes encoding the non-oxidative pentose phosphate pathway enzymes. The deletion of YLR042c led to improved aerobic growth on xylose in both strain backgrounds. However, the effect was more significant in the strain with the poorer growth rate on xylose (TMB3001). Under anaerobic conditions, the deletion of YLR042c increased the specific xylose consumption rate and the ethanol and xylitol yields. In strain TMB3057, xylose consumption was also improved at low concentrations and during co-fermentation of xylose and glucose. The effect of the gene deletion and overexpression was also tested for different carbon sources. Altogether, these results suggest that YLR042c influences xylose and the assimilation of carbon sources other than glucose, and that the effect could be at the level of sugar transport or sugar signalling.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/yea.1777

Bärbel Hahn-Hägerdal

Papers

Comparison of a gelation and a chromogenic Limulus (LAL) assay for the detection of gram-negative bacteria, and the application of the latter assay to milk.

Screening of yeast species for the stereo-selective reduction of bicyclo[2.2.2]octane-2,6-dione

Influence of cultivation conditions on the production of cellulolytic enzymes withTrichoderma reesei Rutgers C30 in aqueous two-phase systems

Saccharomyces cerevisiae mutant

The deletion of YLR042c improves ethanolic xylose fermentation by recombinant Saccharomyces cerevisiae