Decanter cake waste as a renewable substrate for biobutanol production by Clostridium beijerinckii

The aim of this study was to determine if decanter cake waste from a palm oil mill could be used as a renewable substrate for biobutanol production. Decanter cake waste was first hydrolyzed to fermentable sugars by nitric acid and detoxified by activated-charcoal. The detoxified hydrolysate supplemented with whey protein and ammonium sulfate as cheap nitrogen sources, was used for butanol production by growing cells of Clostridium beijerinckii. The detoxified hydrolysate was also used as a co-substrate for direct conversion of butyric acid to butanol in a nitrogen-free medium. By these two steps, C. beijerinckii produced 3.42 g/L of butanol with a yield of 0.28 C-mol butanol/C-mol carbon in the first step and produced 6.94 g/L of butanol with a yield of 0.47 C-mol butanol/C-mol carbon in the second step. This study has showed that decanter cake waste could serve as a low-cost substrate for biobutanol production.     

生物丁醇代谢工程的研究进展

丁醇作为一种重要的大宗化学品具有广泛的用途,同时又是一种潜在的生物燃料。随着能源与环境危机的日益加重,利用可再生原料通过微生物法生产丁醇受到全世界的普遍关注。代谢工程为定向改造微生物生产丁醇提供了有力的工具。通过改造经典的丙酮丁醇发酵和定向改造模式微生物生产丁醇是生物丁醇研究的两个重要方向。笔者从代谢工程改造的角度评述近5年来生物丁醇研究的进展,同时讨论了生物丁醇研究中需要着力解决的问题。     

Single-cell microfluidics: opportunity for bioprocess development

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Microfluidics for cell factory and bioprocess development

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Bioenergy production and sustainable development: science base for policymaking remains limited

The possibility of using bioenergy as a climate change mitigation measure has sparked a discussion of whether and how bioenergy production contributes to sustainable development. We undertook a systematic review of the scientific literature to illuminate this relationship and found a limited scientific basis for policymaking. Our results indicate that knowledge on the sustainable development impacts of bioenergy production is concentrated in a few well‐studied countries, focuses on environmental and economic impacts, and mostly relates to dedicated agricultural biomass plantations. The scope and methodological approaches in studies differ widely and only a small share of the studies sufficiently reports on context and/or baseline conditions, which makes it difficult to get a general understanding of the attribution of impacts. Nevertheless, we identified regional patterns of positive or negative impacts for all categories – environmental, economic, institutional, social and technological. In general, economic and technological impacts were more frequently reported as positive, while social and environmental impacts were more frequently reported as negative (with the exception of impacts on direct substitution of GHG emission from fossil fuel). More focused and transparent research is needed to validate these patterns and develop a strong science underpinning for establishing policies and governance agreements that prevent/mitigate negative and promote positive impacts from bioenergy production.     

Biohydrogen production and bioprocess enhancement: A review

This paper provides an overview of the recent advances and trends in research in the biological production of hydrogen (biohydrogen). Hydrogen from both fossil and renewable biomass resources is a sustainable source of energy that is not limited and of different applications. The most commonly used techniques of biohydrogen production, including direct biophotolysis, indirect biophotolysis, photo-fermentation and dark-fermentation, conventional or “modern” techniques are examined in this review. The main limitations inherent to biochemical reactions for hydrogen production and design are the constraints in reactor configuration which influence biohydrogen production, and these have been identified. Thereafter, physical pretreatments, modifications in the design of reactors, and biochemical and genetic manipulation techniques that are being developed to enhance the overall rates and yields of biohydrogen generation are revisited.     

Biohydrogen production and bioprocess enhancement: a review

This paper provides an overview of the recent advances and trends in research in the biological production of hydrogen (biohydrogen). Hydrogen from both fossil and renewable biomass resources is a sustainable source of energy that is not limited and of different applications. The most commonly used techniques of biohydrogen production, including direct biophotolysis, indirect biophotolysis, photo-fermentation and dark-fermentation, conventional or "modern" techniques are examined in this review. The main limitations inherent to biochemical reactions for hydrogen production and design are the constraints in reactor configuration which influence biohydrogen production, and these have been identified. Thereafter, physical pretreatments, modifications in the design of reactors, and biochemical and genetic manipulation techniques that are being developed to enhance the overall rates and yields of biohydrogen generation are revisited.     

Applications of metabolic modeling to drive bioprocess development for the production of value-added chemicals

Increasing numbers of value added chemicals are being produced using microbial fermentation strategies. Computational modeling and simulation of microbial metabolism is rapidly becoming an enabling technology that is driving a new paradigm to accelerate the bioprocess development cycle. In particular, constraint-based modeling and the development of genome-scale models of industrial microbes are finding increasing utility across many phases of the bioprocess development workflow. Herein, we review and discuss the requirements and trends in the industrial application of this technology as we build toward integrated computational/experimental platforms for bioprocess engineering. Specifically we cover the following topics: (1) genome-scale models as genetically and biochemically consistent representations of metabolic networks; (2) the ability of these models to predict, assess, and interpret metabolic physiology and flux states of metabolism; (3) the model-guided integrative analysis of high throughput ‘omics’ data; (4) the reconciliation and analysis of on- and off-line fermentation data as well as flux tracing data; (5) model-aided strain design strategies and the integration of calculated biotransformation routes; and (6) control and optimization of the fermentation processes. Collectively, constraint-based modeling strategies are impacting the iterative characterization of metabolic flux states throughout the bioprocess development cycle, while also driving metabolic engineering strategies and fermentation optimization.     

Application of systems biology for bioprocess development

Random mutagenesis or genetic modification of an organism without consideration of its consequences to the entire system might cause unwanted changes in cellular metabolism. Systems metabolic engineering thus aims to develop strains by performing metabolic engineering within a systems biology framework, in which entire cellular networks are optimized and fermentation and downstream processes are considered at early stages. Thus, regulatory, metabolic and other cellular networks are engineered in an integrated manner. Here, we review the applications of systems biology for the development of strains and bioprocesses by means of several successful examples and, furthermore, discuss future prospects.     

Bacterial milking: A novel bioprocess for production of compatible solutes

A novel biotechnological process called "bacterial milking" has been established for the production of compatible solutes using the Gram-negative bacterium Halomonas elongata. Following a high-cell-density fermentation which provided biomass up to 48 g cell dry weight per liter, we applied alternating osmotic shocks in combination with crossflow filtration techniques to harvest the compatible solutes ectoine and hydroxyectoine. H. elongata, like other halophilic or halotolerant microorganisms, produces compatible solutes in response to the salinity of the medium. When transferred to a low salinity medium (osmotic downshock), H. elongata cells rapidly released their solutes to achieve osmotic equilibrium. Subsequent reincubation in a medium of higher salt concentration resulted in resynthesis of these compatible solutes and-after a defined regeneration time-the procedure could be repeated. By repeatedly performing this "bacterial milking" process (at least nine times) we were able to produce large amounts of ectoines with a biomass productivity of 155 mg of ectoine per cycle per gram cell dry weight. Further purification of the products was achieved by a simple two-step procedure based on cation exchange chromatography and crystallization. The principles described in this article may also be useful for the production of other low-molecular-weight compounds.     

Enzymes in biotechnology: Critical platform technologies for bioprocess development

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Essential prerequisites for successful bioprocess development of biological CH4 production from CO2 and H2

The production and storage of energy from renewable resources steadily increases in importance. One opportunity is to utilize carbon dioxide (CO₂)-type hydrogenotrophic methanogens, which are an intriguing group of microorganisms from the domain Archaea, for conversion of hydrogen and CO₂ to methane (CH₄). This review summarizes the current state of the art of bioprocess development for biological CH₄ production (BMP) from pure cultures with pure gasses. The prerequisites for successful quantification of BMP by using closed batch, as well as fed-batch and chemostat culture cultivation, are presented. This review shows that BMP is currently a much underexplored field of bioprocess development, which mainly focuses on the application of continuously stirred tank reactors. However, some promising alternatives, such as membrane reactors have already been adapted for BMP. Moreover, industrial-based scale-up of BMP to pilot scale and larger has not been conducted. Most crucial parameters have been found to be those, which influence gas-limitation fundamentals, or parameters that contribute to the complex effects that arise during medium development for scale-up of BMP bioprocesses, highly stressing the importance of holistic BMP quantification by the application of well-defined physiological parameters. The much underexplored number of different genera, which is mainly limited to Methanothermobacter spp., offers the possibility of additional scientific and bioprocess development endeavors for the investigation of BMP. This indicates the large potential for future bioprocess development considering the possible application of bioprocessing technological aspects for renewable energy storage and power generation.     

Combining genetic engineering and bioprocess concepts for improved phenylpropanoid production

The group of natural aromatic compounds known as phenylpropanoids has diverse applications, but current methods of production which are largely based on synthesis from petrochemicals or extraction from agricultural biomass are unsustainable. Bioprocessing is a promising alternative, but improvements in production titers and rates are required to make this method profitable. Here the recent advances in genetic engineering and bioprocess concepts for the production of phenylpropanoids are presented for the purpose of identifying successful strategies, including adaptive laboratory evolution, enzyme engineering, in-situ product removal, and biocatalysis. The pros and cons of bacterial and yeast hosts for phenylpropanoid production are discussed, also in the context of different phenylpropanoid targets and bioprocess concepts. Finally, some broad recommendations are made regarding targets for continued improvement and areas requiring specific attention from researchers to further improve production titers and rates.     

Potential utilization of guar gum industrial waste in vermicompost production

Recycling of guar gum industrial waste through vermitechnology was studied under laboratory conditions by using composting earthworm Perionyx excavatus (Perrier). Three different combination of guar gum industrial waste namely guar gum industrial waste:cow dung:saw dust in 40:30:30 ratio (T1), guar gum industrial waste:cow dung:saw dust in 60:20:20 ratio (T2), and guar gum industrial waste:cow dung:saw dust in 75:15:10 ratio (T3) were used for vermicomposting experiments. Chemical changes during vermicomposting were measured and comparatively T2 showed great increase (from its initial level) for total N (25.4%), phosphorus (72.8%) and potassium (20.9%) than the other treatments. T2 also showed higher vermicomposting coefficient (VC), higher mean biomass for P. excavatus (146.68 mg) and higher cocoon production (about 21.9% and 645.5% more than the T1 and T3, respectively). Maximum earthworm mortality during vermicomposting was recorded with T3 treatment while zero mortality was recorded for T2 treatment after 150 days. Overall, T2 treatment appeared to be an ideal combination for enhancing maximum biopotential of earthworms to management guar gum industrial waste as well as for earthworm biomass and cocoon production.     

畜牧业可持续发展的综合评价

畜牧业可持续发展的评价不仅有助于了解目前畜牧业发展的现状和程度,而且对于预测畜牧业发展的趋势,制定畜牧产业政策及相应的法律法规都具有重要的意义．首先,简述了畜牧业可持续发展的含义．然后,在分析现有的可持续发展评价理论和研究方法的基础上,针对畜牧业发展的特点,提出了以环境经济学为手段,以生态承载能力理论为基础,借助生态资源、环境功能价值的货币化表达。评价畜牧业可持续发展的一整套评价理论和方法．最后,对畜牧业可持续发展的具体评价方法以及评价指标的选取作了简要的阐述．     

The development and applications of thermal biosensors for bioprocess monitoring

Enzyme thermistors are biosensors that use thermal resistors to measure the heat change caused by an enzymatic reaction. They combine the selectivity of enzymes with the sensitivity of biosensors and allow continuous analysis in a flow-injection mode. They can be used to monitor fermentation systems, biocatalysis, enzyme-catalysed synthesis and clinical and food technology. This article gives an overview of the general principles of enzyme thermistors, the sampling process and the ongoing developments in the field of bioprocess monitoring.     

Improvement of bioprocess monitoring: development of novel concepts

The advancement of bioprocess monitoring will play a crucial role to meet the future requirements of bioprocess technology. Major issues are the acceleration of process development to reduce the time to the market and to ensure optimal exploitation of the cell factory and further to cope with the requirements of the Process Analytical Technology initiative. Due to the enormous complexity of cellular systems and lack of appropriate sensor systems microbial production processes are still poorly understood. This holds generally true for the most microbial production processes, in particular for the recombinant protein production due to strong interaction between recombinant gene expression and host cell metabolism. Therefore, it is necessary to scrutinise the role of the different cellular compartments in the biosynthesis process in order to develop comprehensive process monitoring concepts by involving the most significant process variables and their interconnections. Although research for the development of novel sensor systems is progressing their applicability in bioprocessing is very limited with respect to on-line and in-situ measurement due to specific requirements of aseptic conditions, high number of analytes, drift, and often rather low physiological relevance. A comprehensive survey of the state of the art of bioprocess monitoring reveals that only a limited number of metabolic variables show a close correlation to the currently explored chemical/physical principles. In order to circumvent this unsatisfying situation mathematical methods are applied to uncover "hidden" information contained in the on-line data and thereby creating correlations to the multitude of highly specific biochemical off-line data. Modelling enables the continuous prediction of otherwise discrete off-line data whereby critical process states can be more easily detected. The challenging issue of this concept is to establish significant on-line and off-line data sets. In this context, online sensor systems are reviewed with respect to commercial availability in combination with the suitability of offline analytical measurement methods. In a case study, the aptitude of the concept to exploit easily available online data for prediction of complex process variables in a recombinant E. coli fed-batch cultivation aiming at the improvement of monitoring capabilities is demonstrated. In addition, the perspectives for model-based process supervision and process control are outlined.     

Applications of modelling for bioprocess design and control in industrial production

The on-line measurement of the relevant parameters and the control conception for three production processes for fine chemicals by fermentation and biotransformation at the 15 m³ scale were developed. The models describe the bioprocesses which successfully result in fully automated manufacturing steps. Modelling also proved to be a valuable tool for a better insight into biochemical fundamentals of the processes. Moreover, proper use of data logging, modelling and process control was important for quality, since two processes were controlled on-line and quality relevant deviations were registered early. Finally, combining modelling with simulation, we could drastically reduce both development time and cost.List of Symbols F l/h flux - V l volume - U ₀ g/l nicotinonitrile concentration influx - U g/l actual nicotinonitrile concentration - q _ug/gh specific educt (=nicotinonitrile) transformation rate - x g/l biocatalyst concentration - p ₀ g/l nicotinamide concentration influx - p g/l actual nicotinamide concentration - q _pg/gh specific product (=nicotinamide) formation rate - k parameter loss of activity - q _{u, max}g/gh max. specific educt transformation rate - K _ug/l saturation constant for nicotinonitrile - K _ig/l inhibition constant for nicotinonitrile - K _iig/l inhibition constant for nicotinamide - MW _Ag/mol molecular weight for nicotinonitrile - MW _Bg/mol molecular weight for nicotinamide - NS Nicotinic acid - 6-HNS 6-Hydroxynicotinic acid - r _{NS, 6HNS} g/lh 6-HNS production rate - r _{6HNS, X} g/lh biomass production rate - r _{NS, 6HNS, max} g/lh max. 6-HNS production rate - S _NS g/l actual NS concentration - K _{S, NS} g/l saturation constant for NS - K _{i, 6HNS} g/l inhibition constant for 6-HNS - K _o2 g/l saturation constant for oxygen - r _{6HNS, X, max} g/lh max. biomass production rate - S _6HNS g/l actual 6-HNS concentration - K _{ii, NS} g/l inhibition constant for NS - RQ mol/mol respiration quotient - S _xylg/l actual xylene concentration - K _{i, xyl}g/ inhibition constant for xylene - K _{i, DMPY}g/ inhibition constant for 2,5-dimethylpyrazine - r _Xg/lh biomass production rate - r _{X, max}g/lh max. biomass production rate - K _{s, xyl}g/l saturation constant for xylene - S _DMPYg/l actual concentration of DMPY - K _{i, MPCA}g/ inhibition constant for MPCA - K _O2g/ saturation constant for oxygen - S _MPCAg/l actual MPCA concentration - S _O2g/l actual oxygen concentration - r _MPCAg/lh MPCA production rate - r _{MPCA, max}g/lh max. MPCA production rate - k _lgl inhibition constant for the intermediates - k _{s, DMPY}gl saturation constant for DMPY