Biogas Production from Maize: Current State, Challenges and Prospects. 2. Agronomic and Environmental Aspects

Several European countries have expanded the traditional use of anaerobic digestion, i.e. waste treatment, to energy generation through attractive incentives. In some countries, it is further promoted by additional payments to generate biogas from biomass. This review aims to summarise agronomic aspects of methane production from maize, to address resulting abiotic environmental effects and to highlight challenges and prospects. The opportunities of biogas production are manifold, including the mitigation of climate change, decreasing reliance on fossil fuels and diversification of farm income. Although the anaerobic digestion of animal manure is regarded as the most beneficial for reducing greenhouse gas (GHG) emission from manure storage, the energy output can be substantially enhanced by co-digesting manure and maize, which is the most efficient crop for substrate provision in many regions. Although first regarded as beneficial, the rush into biogas production strongly based on maize (Zea mays ssp. mays) is being questioned in view of its environmental soundness. Main areas of concern comprise the spatial concentration of biogas plant together with the high amount of digestate and resulting pollution of surface and ground water, emission of climate-relevant gases and detrimental effects of maize cultivation on soil organic matter degradation. Key challenges that have been identified to enhance the sustainability of maize-based biogas production include (1) the design of regionally adapted maize rotations, (2) an improved management of biogas residues (BR), (3) the establishment of a more comprehensive data base for evaluating soil C fluxes in maize production as well as GHG emissions at the biogas plant and during BR storage and (4) the consideration of direct and indirect land use change impact of maize-based biogas production.     

基因甘蔗：潜能、现状和前景

从基因中在甘蔗上的应用潜能、甘蔗遗传转化的方法及其成效、启动子及选择标记对基因表达和转化体筛选的效应,基因工程甘蔗的成就等几个方面进行综述评述,并提出了进一步的研究方向。     

Biotechnological Potential of Aerobic Methylotrophic Bacteria: A Review of Current State and Future Prospects

Major results of the authors' findings on the implementation of the biotechnological potential of aerobic methylobacteria and methanotrophs for obtaining forage proteins, biopolymers (polybutyrate and polysaccharides), enzymes (oxidoreductases), and bioprotectors (ectoine), as well as for degrading toxic C₁ and C_n compounds, have been reviewed. Unique features of the structural and functional organization of the metabolism of extremophilic (tolerant) methylotrophs are discussed, with a view for their prospective use in various fields of modern biotechnology, including biocatalysis and nanotechnology.     

Current and Potential Biofuel Production from Plant Oils

Environmental concerns and depletion of fossil fuels along with government policies have led to the search for alternative fuels from various renewable and sustainable feedstocks. This review provides a critical overview of the chemical composition of common commercial plant oils, i.e., palm oil, olive oil, rapeseed oil, castor oil, WCO, and CTO and their recent trends toward potential biofuel production. Plant oils with a high energy content are primarily composed of triglycerides (generally >?95%), accompanied by diglycerides, monoglycerides, and free fatty acids. The heat content of plant oils is close to 90% for diesel fuels. The oxygen content is the most important difference in chemical composition between fossil oils and plant oils. Triglycerides can even be used directly in diesel engines. However, their high viscosity, low volatility, and poor cold flow properties can lead to engine problems. These problems require that plant oils need to be upgraded if they are to be used as a fuel in conventional diesel engines. Biodiesel, biooil, and renewable diesel are the three major biofuels obtained from plant oils. The main constraint associated with the production of biodiesel is the cost and sustainability of the feedstock. The renewable diesel obtained from crude tall oil is more sustainable than biofuels obtained from other feedstocks. The fuel properties of renewable diesel are similar to those of fossil fuels with reduced greenhouse gas emissions. In this review, the chemical composition of common commercial plant oils, i.e., palm oil, olive oil, rapeseed oil, castor oil, and tall oil, are presented. Both their major and minor components are discussed. Their compositions and fuel properties are compared to both fossil fuels and biofuels.     

Breeding of Brassica rapa for Biogas Production: Heterosis and Combining Ability of Biomass Yield

The use of plant biomass as substrate for biogas production has recently become of major interest in Europe. Winter Brassica rapa produces high early biomass and could be grown as a pre-crop harvested early in the year followed by a second crop such as maize. The objectives of this study were to estimate heterosis and combining ability of 15 European winter B. rapa cultivars for biomass yield at end of flowering. A half-diallel without reciprocals was conducted among cultivars to produce 105 crosses. These crosses and their parents were evaluated in two years at two locations in Northern Germany. Data collected were days to flowering (DTF), fresh biomass yield (FBY), dry matter content (DMC) and dry biomass yield (DBY). The mean DBY was 5.3 t/ha for the parental cultivars and 5.6 t/ha for their crosses. The crosses surpassed on average their parents by 7.6% for FBY and 5.9% for DBY whereas DMC was 1.4% higher in the parents. Maximum mid parent heterosis was 21.0% for FBY and 30.4% for DBY. Analysis of variance showed that genetic variance was mainly due to specific combining ability (SCA). The correlation between parental performance and general combining ability (GCA) was 0.42** for FBY and 0.53** for DBY. In conclusion, the amount of heterosis in crosses between European winter B. rapa cultivars is not very high on average, but can be up to 30% in the best crosses. Selection of parental combinations with high specific combining ability to produce synthetic cultivars can rapidly improve biomass yield.     

Biogas Production from Steam-Exploded Miscanthus and Utilization of Biogas Energy and CO2 in Greenhouses

The costs of producing protected vegetables comprise up to 78 % of the total operating costs in greenhouses. These expenses mainly result from energy consumption. Increasing energy efficiency and expanding the use of renewable energy sources are essential for global competitiveness. The aim of this study is to optimize methane production from miscanthus and to evaluate the potential use of miscanthus as a source of electrical energy, heat, and CO₂ in vegetable greenhouses. To optimize methane yield, miscanthus was pretreated by steam explosion using different time/temperature combinations. Pretreatment resulted in a more than threefold increase of methane yield from anaerobic digestion (374 l_N?kgVS^?1) compared with untreated miscanthus. Based on technical parameters from two greenhouses (in Northern and Southern Europe), four different energy balances were established. The balances showed that using methane produced by pretreated miscanthus in vegetable greenhouses can enhance the entire process and therefore make it more sustainable.     

Particle Size Reduction during Harvesting of Crop Feedstock for Biogas Production I: Effects on Ensiling Process and Methane Yields

Shortening chopping length at harvest of biogas crops is a basic method of mechanical pretreatment that potentially affects subsequent conservation and biogas production processes. The objective of this study was to assess the influence of a wider range of particle size distributions achieved by laboratory chopping and of practice-oriented short and very short chopping lengths induced by forage harvesters, respectively, on ensiling parameters and methane formation. Shortening the cutting length enhanced lactic acid fermentation during ensiling and increased methane yield, although the effects of ensilage products on methane production partly overlaid the direct positive influence due to reduced particle size. A maximum increase in methane yield of 11?% to 13?% was obtained in the range of median particle lengths of 33 to 6?mm when taking storage losses into account. Thus, very short chopping lengths are beneficial for conservation and methane formation, yet full assessment necessitates further consideration of additional expenditures at harvest.     

Adaptation in Sport: Present State, Problems, Prospects

The current state of the problem of adaptation in sport, its theoretical and practical aspects, and also prospects of its development are considered. Specific features of the mechanisms and regularities of adaptation to exercise were studied in athletes over 15 years. Four stages of adaptive rearrangements are proposed: physiological tension of the organism, adaptation, dysadaptation, and readaptation. Each stage is characterized by specific functional changes and regulatory and energy provision. The concept of a special functional system of adaptation in athletes is based theoretically and confirmed experimentally. Knowledge of the regularities of the development of this system allows us to efficiently and variously influence its links to accelerate adaptation to exercise and to increase training, i.e., to control the adaptation process.     

The Evolution of Human Probiotics: Challenges and Prospects

Probiotics and Antimicrobial Proteins - In recent years, the intestinal microbiota has been found to greatly influence a number of biological processes important for human health and longevity....     

Lignocellulose Biotechnology: Current and Future Prospects

Abstract

Lignocellulose is the most abundant biomass available on Earth. It has attracted considerable attention as an alternate feed stock and energy resource because of the large quantities available and its renewable nature. The potential uses of lignocelluloses are in pulp and paper industries, production of fuel alcohol and chemicals, protein for food, and feed using biotechnological means. The current industrial activity of lignocellulosic biomass fermentation is limited mainly because of the difficulty in economic bioconversion of these materials to value-added products. Considerable improvement in many processes related to lignocellulose biotechnology appeared during the last decade. Current uses of lignocellulosic biomass, process constraints, and areas of future research are discussed here.     

Current Prospects on Production of Microbial Lipid and Other Value-Added Products Using Crude Glycerol Obtained from Biodiesel Industries

Production of microbial lipids using crude glycerol from the biodiesel industry is reviewed in this paper. Approximately 10 wt.% of crude glycerol is obtained for every batch of biodiesel. The crude glycerol accumulated contains various impurities and hence cannot be used for any commercial applications without further purification. Its conversion via biological and chemical routes into valuable products has been studied by different researchers. Varieties of fungal, yeasts, and algal species have been used to produce microbial lipids from crude glycerol. However, research focus on screening a robust industrial oleaginous strain capable of doing this is still on-going. Due to its chemical similarity to vegetable oils, microbial lipids are considered a potential renewable feedstock for biodiesel production and for applications in food and pharmaceutical industries. Its conversion to polyols and subsequently to biobased polymers is also being explored. The rising price of vegetable oils, increasing energy demands, growing environmental concerns, and availability of crude glycerol as a cheap carbon substrate result in considerable potential for the application of these processes in the future.     

转基因农作物育种发展与思考

综述了国内外转基因作物育种及产业化发展现状,指出转基因技术发展已势不可挡,加快推进有利于抢占市场先机和技术制高点,延误时间只会坐失良机而付出更大代价。当前应以主要用作饲料、安全性确有保障的转基因植酸酶玉米和抗虫玉米为重点,尽快突破转基因认识误区和产业发展困境。为此提出了调整和修订不适应发展需要的管理规则和程序、制定转基因玉米产业化推进规划、加强转基因科普宣传和舆论引导等三项建议。     

Silicon and Plants: Current Knowledge and Future Prospects

Journal of Plant Growth Regulation - Silicon (Si) is the most copious element of existence in the lithosphere but still it has not been added into the essential element list. The imperative role of...