Ethanol fermentation and potential.

Ethyl alcohol is one of the United States and world's major chemicals. Beverage alcohol in the United States must be prepared from cereal grains or other natural products. The U.S. industrial alcohol market has remained relatively stable for several years at approximately 300 million gallons annually. Most of this has been produced synthetically from petroleum raw material (gas and oil). These raw materials are experiencing major price increases and are in short supply. The production of ethyl alcohol from cereal grains and cellulosic raw materials by fermentation is technically feasible and has been proven. Alcohol produced from all such materials is equal to synthetic alcohol in quality and performance. Competitive economics have controlled the basic raw materials used. The major potential new ethyl alcohol market is as a component of automobile fuels. A 10% alcohol-gasoline blend in the United States would annually require over 10 billion gallons of anhydrous alcohol. Use of alcohol for this purpose is technically feasible. However, alcohol has not been economically competitive to date.     

Molecular aspects of sucrose transport and its metabolism to starch during seed development in wheat: A comprehensive review

Wheat is one of the most important crops globally, and its grain is mainly used for human food, accounting for 20% of the total dietary calories. It is also used as animal feed and as a raw material for a variety of non-food and non-feed industrial products such as a feedstock for the production of bioethanol. Starch is the major constituent of a wheat grain, as a result, it is considered as a critical determinant of wheat yield and quality. The amount and composition of starch deposited in wheat grains is controlled primarily by sucrose transport from source tissues to the grain and its conversion to starch. Therefore, elucidation of the molecular mechanisms regulating these physiological processes provides important opportunities to improve wheat starch yield and quality through biotechnological approaches. This review comprehensively discusses the current understanding of the molecular aspects of sucrose transport and sucrose-to-starch metabolism in wheat grains. It also highlights the advances and prospects of starch biotechnology in wheat.     

Breeding and growth of Rhizopus in raw cassava by solid state fermentation

Nineteen Rhizopus strains were selected and tested for their growth capacity on raw cassava starch and their ability to produce amylase when grown on solid-state fermentations. Only three strains grew significantly on this natural substrate. Glucoamylase production was higher on raw cassava than on cooked cassava. After 48 h of fermentation, the protein content of cassava was increased from 1.75% to 11.3%. The byproducts of fermentation were fumaric acid, lactid acid and ethanol.     

Production of ethanol by raw starch hydrolysis and fermentation of damaged grains of wheat and sorghum

The simultaneous saccharification and fermentation was used to produce ethanol from raw starch of damaged quality wheat and sorghum grains by utilising crude amylase preparation from B. subtilis VB2 and an amylolytic yeast strain S. cerevisiae VSJ4. Various concentrations of damaged wheat and sorghum starch from 10% to 30%W/V were used and 25% was found to be optimum for damaged wheat and sorghum starch yielding 4.40%V/V and 3.50%V/V ethanol respectively. Whereas 25% raw starch of fine quality wheat and sorghum grains gave an yield of 5.60%V/V and 5.00%V/V respectively. The process was carried out at 35v°C, 5.8 pH and 200 rpm for 4 days.     

Engineering yeasts for raw starch conversion

Next to cellulose, starch is the most abundant hexose polymer in plants, an import food and feed source and a preferred substrate for the production of many industrial products. Efficient starch hydrolysis requires the activities of both α-1,4 and α-1,6-debranching hydrolases, such as endo-amylases, exo-amylases, debranching enzymes, and transferases. Although amylases are widely distributed in nature, only about 10?% of amylolytic enzymes are able to hydrolyse raw or unmodified starch, with a combination of α-amylases and glucoamylases as minimum requirement for the complete hydrolysis of raw starch. The cost-effective conversion of raw starch for the production of biofuels and other important by-products requires the expression of starch-hydrolysing enzymes in a fermenting yeast strain to achieve liquefaction, hydrolysis, and fermentation (Consolidated Bioprocessing, CBP) by a single organism. The status of engineering amylolytic activities into Saccharomyces cerevisiae as fermentative host is highlighted and progress as well as challenges towards a true CBP organism for raw starch is discussed. Conversion of raw starch by yeast secreting or displaying α-amylases and glucoamylases on their surface has been demonstrated, although not at high starch loading or conversion rates that will be economically viable on industrial scale. Once efficient conversion of raw starch can be demonstrated at commercial level, engineering of yeast to utilize alternative substrates and produce alternative chemicals as part of a sustainable biorefinery can be pursued to ensure the rightful place of starch converting yeasts in the envisaged bio-economy of the future.     

Protozoans—the first food of larval herring (Clupea harengus L.)?

In short-run experiments herring larvae at the end of the yolk sac stage (S_L 6.5 to 8.5 m) were fed with maize and potato starch to investigate the effect of particle size on food selection. About 20% of the larvae ingested these particles during the experiments. In the case of maize starch (3 to 26 μm grain size) the size classes from 14 to 25 μm and in the case of potato starch (5 to 80 μm) the size classes larger than 29 μm were preferred. The highest numbers of ingested grains per larva were 150 maize starch grains and 57 potato starch grains. The selective uptake of these size classes leads to the conclusion that planktonic organisms in this size range—in other words mostly protozoans—may play an important role as a first food source of herring larvae.     

Distillers grains as an energy source and effect of drying on protein availability

The use of distillers byproducts as energy sources would expand the market for these byproducts. Drying of these byproducts may produce changes that affect the nutritional value. A series of experiments was conducted to evaluate distillers byproducts as an energy source for finishing cattle and to compare wet vs. dried byproducts. The energy value of wet distillers byproducts was 132 to 174% the value of dry rolled corn for finishing cattle when the byproducts were fed as 40% of the diet dry matter. Distillers dried grains plus solubles were 130% the energy value of corn. Acid detergent insoluble nitrogen level of the dried grains did not affect feeding value. Distillers dried grains plus solubles were equal in protein value to wet byproducts when fed to growing calves. Acid detergent insoluble nitrogen level did not affect protein utilization of dried distillers byproducts.     

植物体内淀粉磷酸化的生物学研究进展

植物中淀粉是主要储存碳水化合物形式,是食品和工业应用中最重要的植物原材料之一。而植物淀粉中惟一的取代是磷酸化作用,更体现了淀粉的独特性能。淀粉的品质和理化性质影响其应用。因此对淀粉的研究是有重要意义的。主要介绍了淀粉磷酸化作用机制,概述GWD功能与磷酸化作用和淀粉代谢的关系的生物学研究进展,并在此基础上讨论利用基因工程改良淀粉品质的可能途径以及今后的研究任务。     

Exopolysaccharide production from Sclerotium glucanicum NRRL 3006 and Botryosphaeria rhodina DABAC-P82 on raw and hydrolysed starchy materials

AIMS: Evaluation of fermentative usage of raw starchy materials for exopolysaccharide (EPS) production by Sclerotium glucanicum NRRL 3006 and Botryosphaeria rhodina DABAC-P82. METHODS AND RESULTS: Non-hydrolysed corn starch, soft wheat flour, potato flour, cassava flour, sweet and industrial potato flours, and corn starch hydrolysed to different dextrose equivalent (DE) were tested in shaken culture for EPS production. Both fungal strains produced EPS on all tested materials but the production was maximum on hydrolysed corn starch (30.5 and 19.8 g l(-1) by B. rhodina and S. glucanicum on corn starch at 100 and 62 DE, respectively). CONCLUSIONS: Raw starchy materials as such and, in particular, partially or totally hydrolysed corn starch could be used profitably for EPS production by S. glucanicum and B. rhodina. SIGNIFICANCE AND IMPACT OF THE STUDY: The excellent EPS production, productivity and yield of B. rhodina DABAC-P82 when grown on 60 g l(-1) of totally hydrolysed corn starch.     

Codon-optimized glucoamylase sGAI of Aspergillus awamori improves starch utilization in an industrial yeast

The development of a yeast that converts raw starch to ethanol in one step (called consolidated bioprocessing) could yield large cost reductions in the bioethanol industry. The aim of this study was to develop an efficient amylolytic Saccharomyces cerevisiae strain suitable for industrial bioethanol production. A native and codon-optimized variant of the Aspergillus awamori glucoamylase gene were expressed in the S. cerevisiae Y294 laboratory strain. Codon optimization resulted to be effective and the synthetic sequence sGAI was then δ-integrated into a S. cerevisiae strain with promising industrial fermentative traits. The mitotically stable recombinant strains showed high enzymatic capabilities both on soluble and raw starch (2425 and 1140 nkat/g dry cell weight, respectively). On raw corn starch, the engineered yeasts exhibited improved fermentative performance with an ethanol yield of 0.42 (g/g), corresponding to 75?% of the theoretical maximum yield.     

一株生淀粉酶产生菌的分离鉴定及酶学性质研究

采用苔酚蓝-生淀粉法从贵州遵义百年磨坊的磨盘下的土样中筛选得到一株具有生淀粉降解能力的丝状真菌,经形态学鉴定和ITS核苷酸序列比对确定该菌为Rhizopus microsporusvar.chinensis。本文首次报道了由Rhizopus microsporus var.chinensis产生的生淀粉酶。通过酶学性质研究发现,该菌株所产生淀粉酶拥有较好的温度耐受性和较宽的pH适用范围,具有一定的工业应用价值。     

A COMPARISON OF ALPHA-AMYLASES FROM THE LATEX OF THREE SELECTED SPECIES OF EUPHORBIA (EUPHORBIACEAE)

A technique for the partial purification of α-amylases from latex of Euphorbia heterophylla, E. marginata, and E. tirucalli is described. The enzymes were found to be similar to other higher plant amylases using the criteria of molecular weight, pH characteristics, kinetics, number of isozymes, and blue value-reducing value patterns. Carbohydrases other than α-amylases were not detectable in latex. The amylases were employed to examine their capacity to digest latex starch grains which are common components of the laticiferous cell in this genus. Laticifer starch grains are not susceptible to in vitro amylolysis. Removal of the starch grain membrane with Triton X-100, damaging the grain, or treating the grains with α-amylases from diverse biological sources had little effect upon hydrolysis. Grains incubated with pullulanase followed by α-amylase caused a slight but significant increase in hydrolysis of raw laticifer starch grains. These studies indicate that the nonarticulated laticifer in Euphorbia is a cul de sac for certain primary and secondary metabolic products and that the indigestible and morphologically complex starch grains in the latex have evolved to function in a secondary role within the laticifer.     

Fish skin as a biomaterial for halal collagen and gelatin

Around 40% of the total catch weight of fish is regarded as byproducts, consisting of skin, fins, bones, scales, viscera, etc. The utilization of these byproducts is important to increase their commercial values as well as to prevent environmental pollution. Meanwhile, nowadays, it is getting a global trend to provide foods and other industrial materials which have been accredited as halal products for Moslem communities. As a way of processing fish byproducts to meet the halal criteria, preparation of collagen and gelatin would be useful to fulfill the market demand. As a result of screening studies on fishery byproducts, fish skin has been found to be the good source for halal collagen and gelatin, which show satisfactory quality compared with those from bovine sources which could cause bovine spongiform encephalopathy (BSE).     

Engineering Saccharomyces cerevisiae for direct conversion of raw,uncooked or granular starch to ethanol

The production of raw starch-degrading amylases by recombinant Saccharomyces cerevisiae provides opportunities for the direct hydrolysis and fermentation of raw starch to ethanol without cooking or exogenous enzyme addition. Such a consolidated bioprocess (CBP) for raw starch fermentation will substantially reduce costs associated with energy usage and commercial granular starch hydrolyzing (GSH) enzymes. The core purpose of this review is to provide comprehensive insight into the physiological impact of recombinant amylase production on the ethanol-producing yeast. Key production parameters, based on outcomes from modifications to the yeast genome and levels of amylase production, were compared to key benchmark data. In turn, these outcomes are of significance from a process point of view to highlight shortcomings in the current state of the art of raw starch fermentation yeast compared to a set of industrial standards. Therefore, this study provides an integrated critical assessment of physiology, genetics and process aspects of recombinant raw starch fermenting yeast in relation to presently used technology. Various approaches to strain development were compared on a common basis of quantitative performance measures, including the extent of hydrolysis, fermentation-hydrolysis yield and productivity. Key findings showed that levels of α-amylase required for raw starch hydrolysis far exceeded enzyme levels for soluble starch hydrolysis, pointing to a pre-requisite for excess α-amylase compared to glucoamylase for efficient raw starch hydrolysis. However, the physiological limitations of amylase production by yeast, requiring high biomass concentrations and long cultivation periods for sufficient enzyme accumulation under anaerobic conditions, remained a substantial challenge. Accordingly, the fermentation performance of the recombinant S. cerevisiae strains reviewed in this study could not match the performance of conventional starch fermentation processes, based either on starch cooking and/or exogenous amylase enzyme addition. As an alternative strategy, the addition of exogenous GSH enzymes during early stages of raw starch fermentation may prove to be a viable approach for industrial application of recombinant S. cerevisiae, with the process still benefitting from amylase production by CBP yeast during later stages of cultivation.     

基因工程改良淀粉品质

淀粉对人类生活十分重要,它不仅是人们的能量和营养来源,而且还是重要的工业原材料。对于淀粉合成过程及淀粉的加工、使用一直是淀粉研究的重点内容。淀粉的合成在最后阶段涉及到３个关键性的酶是：ＡＤＰＧ焦磷酸化酶、淀粉合成酸以及淀粉分支酶。它们分别催化ＡＤＰ－葡萄糖的形成、葡聚糖链的延伸以及分支链的形成。另外淀粉去分支酶对淀粉最终结构的形成也起到重要作用。本文将介绍上述４个酶近年来的生物化学和分子生物学研究     

THE ULTRASTRUCTURAL MORPHOLOGY AND ONTOGENY OF OAT COLEOPTILE PLASTIDS

Structurally similar proplastids occur in the shoot, scutellum, and root of the oat embryo at the start of germination. These proplastids follow several pathways of differentiation, depending on their location within an organ and on previous exposure to light. During the first 24 hr of germination morphologically similar amyloplasts are formed from the preexisting proplastids in most of the cells of the seedling. After about 24 hr in the light, unique chloroplasts begin to develop in a subepidermal ring of small cortical parenchyma cells in the coleoptile and give the organ a pale green color. At 48 and 72 hr the coleoptile chloroplasts and etioplasts are conspicuously different from the corresponding leaf plastids in morphology and ontogeny but contain typical photosynthetic grana and prolamellar bodies. Study of the ontogeny of plastids in the epidermal and nongreening parenchymal regions of dark grown coleoptiles shows that these plastids undergo significant losses in starch content, and some increase of membranes within the plastid, related to the age of the cell. Light has little effect on the structure of these plastids. It is suggested that the ontogeny of all the plastid types of the oat seedling begins with a common precursor—a relatively simple proplastid that is present at the time of germination. Starch grains showing two distinct types of erosion, apparently enzymatic, were observed in oat coleoptile plastids. In one type (grooved appearance) the starch grains are consistently associated with plastid membranes, while in the other type (irregular, spiny appearance) the starch grains are associated with the plastid stroma only. We suggest that there are two enzyme systems for metabolizing starch in oat plastids—one membrane-bound and the other free in the stroma.     

Metabolic engineering of the yeast Hansenula polymorpha for the construction of efficient ethanol producers

Until recently, the methylotrophic yeast has not been considered as a potential producer of biofuels, particularly, ethanol from lignocellulosic hydrolysates. The first work published 10 years ago revealed the ability of the thermotolerant methylotrophic yeast Hansenula polymorpha to ferment xylose—one of the main sugars of lignocellulosic hydrolysates—which has made the yeast a promising organism for high-temperature alcoholic fermentation. Such a feature of H. polymorpha could be used in the implementation of a potentially effective process of simultaneous saccharification and fermentation (SSF) of raw materials. SSF makes it possible to combine enzymatic hydrolysis of raw materials with the conversion of the sugars produced into ethanol: enzymes hydrolyze polysaccharides to monomers, which are immediately consumed by microorganisms (producers of ethanol). However, the efficiency of alcoholic fermentation of major sugars produced via hydrolysis of lignocellulosic raw materials and, especially, xylose by wild strains of H. polymorpha requires significant improvements. In this review, the main results of metabolic engineering of H. polymorpha for the construction of improved producers of ethanol from xylose, starch, xylan, and glycerol, as well as that of strains with increased tolerance to high temperatures and ethanol, are represented.     

Adsorption-elution purification of chimeric <Emphasis Type="Italic">Bacillus stearothermophilus</Emphasis> leucine aminopeptidase II with raw-starch-binding activity

Summary A chimericBacillus stearothermophilus leucine aminopeptidase II (LAPsbd) has been constructed by introducing the raw-starch-binding domain of Bacillus sp. strain TS-23 α-amylase into the enzyme. LAPsbd was adsorbed onto raw starch and the adsorbed enzyme could be eluted from the adsorbent by soluble starch in 20 mM Tris–HCl buffer (pH 8.0). The adsorption of LAPsbd onto raw starch was affected by raw starch concentration, pH, and temperature, while the temperature and incubation time had no obvious effects on the elution of adsorbed enzyme. The molecular weight of purified enzyme was estimated to be 61 kDa. About 84% of LAPsbd in the cell free extract was recovered through one adsorption–elution cycle with a purification of 20-fold. The high quantity and purity of the recovered enzyme coupled with the easy performance make the adsorption–elution procedure suitable for industrial applications.     

Material flow analysis and material use efficiency of Brazil's mortar and concrete supply chain

Cementitious materials, mostly concrete and mortar, account for about one‐third of all materials extraction worldwide. Material flow data in this industry are still unsatisfactory, especially related to unused extraction materials, quarry wastes, and water consumption, aspects which usually are not included in environmental analysis studies. The aim of this study is to conduct a material flow analysis (MFA) of the Brazilian concrete and mortar supply chain to quantify material use efficiency (ME) and dematerialization potential. The MFA includes extraction, production, and construction stages for the following indicators: i) unused extraction; ii) quarry waste; iii) water consumption; iv) material wastage; v) raw material consumption; vi) energy carriers; and vii) atmospheric emissions. The results demonstrated that the primary raw material footprint is about 456 million metric tons (Mt) corresponding to a metabolic rate of 2.2 metric tons/capita (t/capita). After including unused extraction, quarry wastes, water consumption, and secondary materials this value increases to 4.1 t/capita corresponding to a total material consumption of 840 Mt. Concrete and mortar can be produced using two routes—mixing on site or industrial mixing. We conclude that the industrial scenario allows for dematerialization by about 8% for concrete and 24% for mortar, by mass; and the average material use efficiency is low, at about 53% for concrete and 34% for mortar.     

Energetics of stockfeed production

In a study of energy use in the stockfeed industry of Victoria, Australia, the use of support energy was measured in the production of raw materials, stockfeed manufacture, and transport of materials and stockfeeds to and from the mills. In the production of rations for broiler and layer poultry, pigs and dairy cows, the largest quantities of support energy were used in the production of raw materials (59–78% of the total). Stockfeed manufacture comprised 12–24% of total energy use, and transport, both to and from mills, accounted for 10–17% of the total. Support energy inputs ranged from 3000 MJ/t for a dairy ration to 6000 MJ/t for a broiler chicken ration. The latter contained about 12% of animal byproducts, for which the energy cost of production was over 10 000 MJ/t, whereas raw materials of plant origin involved energy costs of production of less than 4000 MJ/t. Nearly two-thirds of the energy cost of stockfeed manufacture was incurred in the pelleting operation, and the heavy dependence on road, rather than rail, transport resulted in high transport energy costs. The metabolisable energy available to the animal from the compounded rations was two to three times greater than the support energy required to produce them.