Chilean euphorbiaceae species as sources of fuels and raw chemicals

The potential of some species of Chilean Euphorbiaceae as sources of hydrocarbon-like materials was evaluated. Samples of plants excluding roots, were analyzed for CH₂Cl₂ extractives, resins and hydrocarbons. The presence of waxes and natural rubber (cis-1,4-polyisoprene) was confirmed using spectroscopic and chromatographic methods. C/H values for representative fractions were calculated and extracted samples from selected species analyzed for apparent protein contents. Results suggested that at least two species, Euphorbia lactiflua and Euphorbia copiapina might have an industrial potential.     

Photosynthetic terpene hydrocarbon production for fuels and chemicals

Photosynthetic hydrocarbon production bypasses the traditional biomass hydrolysis process and represents the most direct conversion of sunlight energy into the next‐generation biofuels. As a major class of biologically derived hydrocarbons with diverse structures, terpenes are also valuable in producing a variety of fungible bioproducts in addition to the advanced ‘drop‐in’ biofuels. However, it is highly challenging to achieve the efficient redirection of photosynthetic carbon and reductant into terpene biosynthesis. In this review, we discuss four major scientific and technical barriers for photosynthetic terpene production and recent advances to address these constraints. Collectively, photosynthetic terpene production needs to be optimized in a systematic fashion, in which the photosynthesis improvement, the optimization of terpene biosynthesis pathway, the improvement of key enzymes and the enhancement of sink effect through terpene storage or secretion are all important. New advances in synthetic biology also offer a suite of potential tools to design and engineer photosynthetic terpene platforms. The systemic integration of these solutions may lead to ‘disruptive’ technologies to enable biofuels and bioproducts with high efficiency, yield and infrastructure compatibility.     

Non-conventional hosts for the production of fuels and chemicals

Biotechnology offers a green alternative for the production of fuels and chemicals using microbes. Although traditional model hosts such as Escherichia coli and Saccharomyces cerevisiae have been widely studied and used, they may not be the best hosts for industrial application. In this review, we explore recent advances in the use of nonconventional hosts for the production of a variety of fuel, cosmetics, perfumes, food, and pharmaceuticals. Specifically, we highlight twenty-seven popular molecules with a special focus on recent progress and metabolic engineering strategies to enable improved production of fuels and chemicals. These examples demonstrate the promise of nonconventional host engineering.     

L-丙氨酸厌氧发酵关键技术及产业化

传统氨基酸制造主要是通过化学合成或好氧发酵实现。相对于化学合成,微生物发酵可以实现以可再生资源为原料直接生产氨基酸,减少了对石油基原料的依赖,解决了化学合成高污染、高能耗等问题。好氧发酵具有生长快、产量高等特点,但好氧发酵中大量碳源用于细胞生长容易造成糖酸转化率低、能耗高等问题。厌氧发酵是近年来新出现的氨基酸生产模式,具有操作简单、无需通氧、糖酸转化率高容易接近理论最大值等优势。L-丙氨酸是国际上首个实现厌氧发酵产业化生产的氨基酸。本文以L-丙氨酸为例,综述了氨基酸厌氧发酵过程中的关键问题及其在产业化实施中的应用。未来,随着厌氧发酵关键技术在更多化合物生物制造技术中的突破,这种低成本、高效、低碳环保型发酵方式将会带来更大的经济价值和社会效益。     

Biomass-derived volatile fatty acid platform for fuels and chemicals

The typical biorefinery platforms are sugar, thermochemical (syngas), carbon-rich chains, and biogas platforms, each offering unique advantages and disadvantages. The sugar platform uses hexose and pentose sugars extracted or converted from plant body mass. The thermochemical (syngas) platform entails a chemical or biological conversion process using pyrolysis or gasification of plants to produce biofuels. The carbon-rich chains platform is used to produce biodiesel from long-chain fatty acids or glycerides. In the present work, we suggest a new platform using volatile fatty acids (VFAs) for the production of biofuels and biochemicals production. The VFAs are short-chain fatty acids composed mainly of acetate and butyrate in the anaerobic digestion (AD) process, which does not need sterilization, additional hydrolysis enzymes (cellulose or xylanase), or a high cost pretreatment step. VFAs are easily produced from almost all kinds of biomass with low lignin content (terrestrial, aquatic, and marine biomass) by the AD process. Considering that raw material alone constitutes 40∼80% of biofuel production costs, biofuels made from VFAs derived from waste organic biomass potentially offer significant economical advantage.     

Metabolic engineering of yeast for production of fuels and chemicals

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Methane fermentation of selected lignocellulosic materials

Seven lignocellulosic materials: corn stover, napier grass, wood grass, newspaper, white fir and wheat straw from two different crops; two pure cellulosics: Solka Floc BW200 and Whatman No. 5 filter paper; and glucose, propionic and acetic acids were subjected to long-term batch methane fermentation. Ninety per cent of the original COD was recovered as methane gas from the two pure cellulosics and glucose. For the lignocellulosics, depending on the material, variations from over 80% conversion efficiency to methane for corn stover to less than 10% for white fir were observed. Generally, herbaceous materials were degraded faster and more extensively than woody biomass. A first-order rate model described well the methane fermentation process for the lignocellulosics tested, but was a poor model for the soluble substrates. It was not possible to predict either the biodegradability or the rate of methane fermentation with a reasonable degree of accuracy based solely on the lignin content of the lignocellulosic materials.     

Bioprocessing of bio-based chemicals produced from lignocellulosic feedstocks

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Development of biocatalysts for production of commodity chemicals from lignocellulosic biomass

Lignocellulosic biomass is recognized as potential sustainable source for production of power, biofuels and variety of commodity chemicals which would potentially add economic value to biomass. Recalcitrance nature of biomass is largely responsible for the high cost of its conversion. Therefore, it is necessary to introduce some cost effective pretreatment processes to make the biomass polysaccharides easily amenable to enzymatic attack to release mixed fermentable sugars. Advancement in systemic biology can provide new tools for the development of such biocatalysts for sustainable production of commodity chemicals from biomass. Integration of functional genomics and system biology approaches may generate efficient microbial systems with new metabolic routes for production of commodity chemicals. This paper provides an overview of the challenges that are faced by the processes converting lignocellulosic biomass to commodity chemicals. The critical factors involved in engineering new microbial biocatalysts are also discussed with more emphasis on commodity chemicals.     

Xylose as a carrier for boron containing compounds

A xylosylated carborane was synthesized by standard carbohydrate methodology and tested on normal HFL-1 cells as well as transformed T24 cells. The xylosylated carborane initiated glycosaminoglycan (GAG) synthesis in both cell lines and treatment with the carborane gave a pronounced translocation of proteoglycans to the nuclei of T24 cells. However, most of the boron-containing compounds were secreted to the medium. We conclude that xylosides carrying carboranes are not suitable for boron neutron capture therapy (BNCT) for T24 cells. However, the uptake of boron-containing xyloside, the GAG priming capacity, and the nuclear translocation of glypican-1 make this xyloside a candidate for further investigation for selectivity toward other tumor cell lines.     

Microbial production of fatty acid-derived fuels and chemicals

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Trends and challenges in the microbial production of lignocellulosic bioalcohol fuels

Bioalcohols produced by microorganisms from renewable materials are promising substitutes for traditional fuels derived from fossil sources. For several years already ethanol is produced in large amounts from feedstocks such as cereals or sugar cane and used as a blend for gasoline or even as a pure biofuel. However, alcohols with longer carbon chains like butanol have even more suitable properties and would better fit with the current fuel distribution infrastructure. Moreover, ethical concerns contradict the use of food and feed products as a biofuel source. Lignocellulosic biomass, especially when considered as a waste material offers an attractive alternative. However, the recalcitrance of these materials and the inability of microorganisms to efficiently ferment lignocellulosic hydrolysates still prevent the production of bioalcohols from these plentiful sources. Obviously, no known organism exist which combines all the properties necessary to be a sustainable bioalcohol producer. Therefore, breeding technologies, genetic engineering and the search for undiscovered species are promising means to provide a microorganism exhibiting high alcohol productivities and yields, converting all lignocellulosic sugars or are even able to use carbon dioxide or monoxide, and thereby being highly resistant to inhibitors and fermentation products, and easy to cultivate in huge bioreactors. In this review, we compare the properties of various microorganisms, bacteria and yeasts, as well as current research efforts to develop a reliable lignocellulosic bioalcohol producing organism.     

Solid substrate fermentation for cellulase production using palm kernel cake as a renewable lignocellulosic source in packed-bed bioreactor

Palm kernel cake (PKC), is an agro-industrial residue created in the palm oil industry, and large quantities of PKC are produced in Malaysia. Sustainable development of the palm oil industry in Malaysia demands an economical technology for the environmentally friendly utilization of PKC in industrial utility systems. This research was carried out to evaluate the use of PKC in the production of cellulase by the cultivation of Aspergillus niger FTCC 5003 in a laboratory packed-bed bioreactor for seven days. A central composite design was used to perform eighteen trials of solid substrate fermentation under selected conditions of incubation temperature, initial moisture content of substrate, and airflow rate. Experimental results showed that a cellulase yield of 244.53 U/g of dry PKC was obtained when 100 g of PKC was hydrolyzed at an incubation temperature of 32.5°C, an initial moisture level of 60%, and an aeration rate of 1.5 L/min/g PKC. An empirical second-order polynomial model was adjusted to the experimental data to evaluate the effects of the studied operating variables on cellulase production. The statistical model revealed that the quadratic term for initial moisture content had a significant effect on the production of cellulase (P < 0.01). The regression model also indicated that the quadratic terms for incubation temperature and interaction effects between initial moisture content and aeration rate significantly influenced cellulase production (P < 0.05). The empirical model determined that the optimum conditions for cellulase production were an incubation temperature of 31.0°C, an initial moisture content of 59.0% and an airflow rate of 1.55 L/min/g PKC.     

Bio-based production of chemicals, materials and fuels -Corynebacterium glutamicum as versatile cell factory

Since their discovery almost 60 years ago, Corynebacterium glutamicum and related subspecies are writing a remarkable success story in industrial biotechnology. Today, these gram-positive soil bacteria, traditionally well-known as excellent producers of L-amino acids are becoming flexible, efficient production platforms for various chemicals, materials and fuels. This development is intensively driven by systems metabolic engineering concepts integrating systems biology and synthetic biology into strain engineering.     

Photosynthetic production of fuels and chemicals in immobilized systems

Whole cells of algae, cyanobacteria and photosynthetic bacteria entrapped in alginate gels or polyurethane foams can retain their photo-synthetic activities for months and in some cases for years. Such immobilized cells can be used in bioreactors for the production of H₂, NH₃, NADPH₂, carbohydrates, hydrocarbons, etc., with sunlight as the energy source.     

Production of fuels and chemicals from waste by microbiomes

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Biorefining of biomass to liquid fuels and organic chemicals

The production of liquid and gaseous fuels and industrial chemicals from selected biomass by a process known as biorefining is reviewed. Four broad categories of biomass appear to be suitable feedstocks: woody biomass and forest residues, agricultural residues, directly fermentable crop-grown biomass, and municipal solid waste and sewage sludge. Through the development of suppressed methane fermentation techniques, it is possible to produce valuable organic chemicals such as acetic acid and ethyl acetate, and liquid fuel (rather than fuel gas) by exercising various processing alternatives. Thus the entire field of methane fermentation has been broadened. In the petroleum refining industry, it is usually desirable to produce from crude oil an optimal mixture of industrial organic chemicals and fuels, a concept known as coproduction. The biorefining process reviewed appears to be adaptable to this same concept of coproduction using biomass as a feedstock.