Optimization of citric acid production by <Emphasis Type="Italic">Aspergillus niger</Emphasis> NRRL 567 grown in a column bioreactor

Citric acid production using Aspergillus niger NRRL 567 grown on peat moss has been optimized in a column bioreactor using a statistically based method. A 23 full factorial design with eight fermentation conditions was applied to evaluate significance on citric acid production and their interactions between variables, where the three independent variables evaluated were aeration rate, bed depth and temperature. Aeration rate and fermentation temperature were identified to be significant variables. Citric acid production markedly increases with aeration rate and fermentation temperature; however, the bed depth of solid substrate showed an insignificant effect on citric acid production. The optimum fermentation condition for citric acid production in a column bioreactor consisted of aeration rate of 0.84 vvm, bed depth of 22 cm and fermentation temperature of 32 °C. Under a given condition, a maximum citric acid production of 120.6 g/l was predicted and matched well with the experimental value of 123.9 g/kg.     

Lactic acid fermentation of food waste using integrated glucoamylase production

Commercial enzyme is usually needed for the bioconversion of organic waste or biomass. The overall cost could be reduced very significantly if enzyme production could be integrated with its application, avoiding unnecessary steps in enzyme production (such as concentration, recovery and transportation). This investigation attempted to integrate crude glucoamylase production with lactic acid fermentation of food waste. A maximum glucoamylase activity of 1850 U g^?1 was obtained with Aspergillus nigerduring solid‐state fermentation (SSF) of food waste, 14.8 times more than that obtained during submerged fermentation (SmF). The optimum pH for producing glucoamylase was 4.6, and glucoamylase retained 83.5% of peak activity at pH 3.0. Without any recovery treatment, the glucoamylase produced by SSF could be used directly for lactic acid fermentation of food waste. Lactic acid concentration reached 45.5 g L^?1 with the addition of the crude enzyme, 72% higher than the control. No side‐effects were caused by the viable A. niger in the crude enzyme. This work successfully integrated glucoamylase production with lactic acid fermentation. The enzyme produced by SSF of food waste had sufficient activity to be used directly without any treatment. The integrated process proposed in this study was very economical and may be helpful to other bioconversions. Copyright © 2008 Society of Chemical Industry     

Production of L‐lactic acid with very high gravity distillery wastewater from ethanol fermentation by a newly isolated Enterococcus hawaiiensis

BACKGROUND: A great amount of wastewater with high contents of chemical oxygen demand (COD) are produced by ethanol production. It would be useful to utilize distillery wastewater to produce L‐lactic acid, which could be a high additional value byproduct of ethanol production. The fermentation process of L‐lactic acid production by a newly isolated Enterococcus hawaiiensis CICIM‐CU B0114 is reported for the first time. RESULTS: The strain produced 56 g L^?1 of L‐lactic acid after cultivation for 48 h in optimized medium consisting of (g L^?1) 80 glucose, 10 peptone, 10 yeast extract, 1.5 Na₂HPO₄ and 0.2 MgSO₄. E. hawaiiensis CICIM‐CU B0114 was isolated and purified by subculture for growing and producing L‐lactic acid in distillery wastewater of very high gravity (VHG) from ethanol fermentation. L‐lactic acid fermentation was further studied with distillery wastewater substrate in 7 L and 15 L fermentors. The results showed that L‐lactic acid concentrations of 52 g L^?1 and 68 g L^?1 was achieved in 7 L and 15 L fermentors with the initial sugar concentrations of 67 g L^?1 and 87 g L^?1, respectively. CONCLUSION: The production of L‐lactic acid by the newly isolated E. hawaiiensis CICIM‐CU B0114 was carried out and the fermentation medium was optimized by orthogonal experimental design. This new strain holds the promise of L‐lactic acid production utilizing distillery wastewater from VHG ethanol fermentation. Copyright © 2010 Society of Chemical Industry     

gp‐41 protein production by E. coli in unconventional bioreactor coupled with magnetic field generator

BACKGROUND: In this work recombinant gp‐41 protein production by E. coli in an unconventional bioreactor coupled with a magnetic field generator was studied. The submerged fermentation process was carried out by fed‐batch operation, recycling the culture medium externally through a stainless steel spiral U‐shape tube inserted on the inside of a magnetic field generator. The exposure time and magnetic field induction were varied in a range from 1 to 12 h and 10 to 100 mT, respectively, according to a central composite design with centered face. RESULTS: It was found that the inhibitory or stimulatory effect of magnetic field on cell growth and protein production depended on exposure time and magnetic field strength. The production of recombinant gp41 protein was 20% higher than the control. CONCLUSION The procedure here presented could be an easy‐to‐use approach to improve the efficiency of recombinant protein production by E. coli. Copyright © 2007 Society of Chemical Industry     

H‐B‐E (hexanol‐butanol‐ethanol) fermentation for the production of higher alcohols from syngas/waste gas

CO, H₂, and CO₂ are major components of syngas and some industrial CO‐rich waste gases (e.g. waste gases from steel industries), besides some additional minor compounds. It was recently shown that those gases can be bioconverted, by acetogenic/solventogenic bacteria, into ethanol and higher alcohols such as butanol, but also hexanol, through the so‐called HBE fermentation. That process presents some advantages over existing chemical conversion processes. This paper reviews HBE fermentation from C1‐gases after briefly describing the more conventional ABE (acetone‐butanol‐ethanol) fermentation from carbohydrates by Clostridium acetobutylicum, in order to allow for comparison of both processes. Although acetone may appear in carbohydrate fermentation, alcohols are the only major end‐metabolites in the HBE process with Clostridium carboxidivorans. The few acetogenic bacteria known to metabolize C1‐gases and produce butanol or higher alcohols are described. Clostridium carboxidivorans has been used in most cases. Bioconversion of the gaseous substrates takes place in two stages, namely acidogenesis (production of acids) followed by solventogenesis (production of alcohols), characterized by different optimal fermentation conditions. Major parameters affecting each bioconversion stage as well as the overall fermentation process are analyzed. Although it has been claimed that acidification is required in ABE fermentation to initiate the solventogenic stage, strong acidification seems to some extent not to be a prerequisite for solventogenesis in the HBE process. Bioreactors potentially suitable for this type of bioconversion process are described as well. © 2017 Society of Chemical Industry     

Economic feasibility of a pilot-scale fermentative succinic acid production from bakery wastes

In this paper, the techno-economic study for a pilot-scale production of succinic acid from food waste via fermentation was evaluated. The pilot plant was based in Hong Kong and designed for converting 1 tonne/day of bakery waste into succinic acid. The mass and energy balance of the process was simulated by computer package SuperPro Designer^®. The total capital investment for the plant and the total production cost were US$ 1,118,243 and US$ 230,750/year respectively. Overall revenue generated from the process was US$ 374,041/year. The return on investment, payback period and internal rate of return of the project were 12.8%, 7.2 years and 15.3% respectively. The findings indicated that the fermentative succinic acid production from bakery waste was feasible. This is important for attracting investment and industrialization interest on the biorefinery process using domestic wastes as raw materials.     

Molecular weight distribution control in continuous “living” polymerizations through periodic operation of the monomer feed

The main objective of the work is to explore the problem of producing polymers of any desired molecular weight distribution (MWD) in isothermal, solution, “living”, anionic polymerizations carried out in continuous tubular reactors. For this purpose, a novel control scheme was designed and implemented, which involves the periodic operation, of the monomer solution flow rate, with the flow profile automatically derived from the required MWD and other data. For experimental validation, a polymerization rig was especially built that included a process computer and an automatic gel permeation chromatograph. The chromatograph permitted the measurement of the MWD of the reactor effluent in a matter of minutes and the process computer was employed to implement the control policies and to perform the chromatograph data acquisition and reduction. In spite of the practical problems encountered, experiments showed at least a semi-quantitative validity of the method.     

A novel combination of methane fermentation and MBR — Kubota Submerged Anaerobic Membrane Bioreactor process

Methane fermentation is considered one of the best placed biological processes to reduce volume of organic waste while keeping small sludge production and recovering energy. One of the disadvantages of early anaerobic digestion technologies was the long hydraulic retention time thus large capacity tanks were required to hold slow growing methanogenic bacteria. New technological attempts such as upflow anaerobic sludge blanket (UASB), fixed or fluidised bed and membrane bioreactor (MBR) appeared as countermeasures.Kubota’s submerged anaerobic membrane biological reactor (KSAMBR) process has been developed in the last decade and successfully applied in a number of full-scale food and beverage industries. It consists of a solubilization tank and a thermophilic digestion tank, the latter incorporating submerged membranes. The biogas generated can be utilized for water heating via boilers. Both permeate and waste anaerobic sludge are further treated in wastewater treatment facilities.One of the main advantages of KSAMBR is that membranes retain the methanogenic bacteria while dissolved methane fermentation inhibitors such as ammonia are filtered out with the permeate. This makes the KSAMBR process very stable. Furthermore, the digester volumes can be scaled down to 1/3 to 1/5 of the conventional digesters provided that biomass is 3 to 5 times as concentrated.Applications include stillage treatment plants for Shouchu (Japanese spirits made from sweet potato, rice or other grains), potato processing sites, sludge liquor and food factory treatment plants.In summary, it is believed that KSAMBR offers the best possible solution combining the benefits of methane fermentation process with the performance of membrane technology. More details will be presented in the proceedings paper and in the presentation.     

Enhance hydrolytic enzymes production by Aspergillus awamori on supplemented grape pomace

The disposal of grape pomace by wine cellars leads to serious environmental problems. In this work we have evaluated the potential utility of this waste as substrate of fermentation for the production of several hydrolytic enzymes commonly used in the clarification processes in wine cellars and juices industries. Our results have demonstrated that the synthesis of exo-polygalacturonase (exo-PG), xylanase and cellullase by solid state fermentation (SSF) on a mixture of washed grape pomace and orange peels (a natural source of pectin, cellulose and hemicellulose), supplemented with a nutrient solution, increased compared to whole grape pomace. For experiments carried out with suspensions of the same mixed substrates in submerged fermentation (SmF), higher values for pectinase and xylanase were reached but with significant lower exo-PG activity per mL of extract. The activities of these enzymes on mixtures of grape pomace and orange peels, in both SSF and SmF, were similar or even higher to those produced using other agro-industrial wastes, demonstrating therefore its potential utility as an alternative substrate for the production of enzymatic extracts for clarification purposes.     

Application of citric acid as natural adhesive for wood

The development of natural adhesives derived from nonfossil resources is very important for the future. Besides, it is desirable to be safe adhesives without using harmful chemical substances. In this study, application of citric acid as a natural adhesive was investigated. Citric acid powder and bark powder obtained from Acacia mangium were used as raw materials. Citric acid powder was mixed with the bark powder, and the resulting powder mixture was poured into a metal mold. The mold was hot‐pressed at 180°C and 4 MPa for 10 min, and a bark molding was then obtained. The specific modulus of rupture and modulus of elasticity values of the molding containing 20 wt % citric acid were 18.1 MPa and 4.9 GPa, respectively. The molding did not decompose during a repeated boiling treatment. To clarify the effect of tannin on the adhesiveness of molding, bark was separated into tannin and residue. The molding was not obtained while using the tannin due to the marked fluidity, whereas it was obtained while using the residue, the same as while using the bark. It was considered that components other than tannin contributed to the adhesiveness. Based on the results of Fourier transform infrared spectra, the formation of ester linkages between carboxyl groups derived from citric acid and hydroxyl groups in the bark was confirmed. Accordingly, citric acid brought an adhesion by chemical bonding, and it could be used as a safe natural adhesive. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Process intensification in lactic acid production: A review of membrane based processes

Lactic acid the most widely occurring hydroxy-carboxylic acid has traditionally been used as food preservative and acidulent. So long, it has been produced through either chemical synthesis route or fermentation route the latter being the dominating one. Despite its tremendous potential for large scale production and use in a wide variety of applications, cost-effective production of high purity lactic acid has remained a challenge for decades, mainly due to high downstream processing cost. In the recent years, possibility of integration of highly selective membranes with the conventional fermentors has opened a golden opportunity for full commercial exploitation of the tremendous application potential of this wonder chemical. This paper discusses recent developments of such membrane-based processes representing process intensification in production of monomer grade lactic acid while suggesting a very promising production scheme.     

Lactic acid production from dining‐hall food waste by Lactobacillus plantarum using response surface methodology

BACKGROUND: Food waste generally has a high starch content and is rich in nutritional compounds, including lipids and proteins. It therefore represents a potential renewable resource. In this study, dining‐hall food waste was used as a substrate for lactic acid production, and response surface methodology was employed to optimise the fermentation conditions. RESULTS: Lactic acid biosynthesis was significantly affected by the interaction of protease and temperature. Protease, temperature and CaCO₃ had significant linear effects on lactic acid production, while α‐amylase and yeast extract had insignificant effects. The optimal conditions were found to be an α‐amylase activity of 13.86 U g^?1 dried food waste, a protease activity of 2.12 U g^?1 dried food waste, a temperature of 29.31 °C and a CaCO₃ concentration of 62.67 g L^?1, which resulted in a maximum lactic acid concentration of 98.51 g L^?1 (88.75% yield). An increase in inoculum size would be appropriate for accelerating the depletion of initial soluble carbohydrate to enhance the efficiency of α‐amylase in dining‐hall food waste fermentation. CONCLUSION: A suitable regression model for lactic acid production was developed based on the experimental results. Dining‐hall food waste was found to be a good substrate for lactic acid fermentation with high product yield and without nutrient supplementation. Copyright © 2008 Society of Chemical Industry     

剩余污泥与秸秆发酵产酸研究进展

随着我国经济的迅猛发展,人们生活水平的提高,所产生的废物量日益增多。目前利用污泥和秸秆作为碳源发酵产酸是一种变废为宝的处理方式。研究表明,发酵前对污泥与秸秆进行适当的处理,可以使有机质的溶出量增大,从而增加VFA的产量。而从发酵产酸的机理入手,研究其产酸的过程,有利于人为调控发酵参数使得VFA的产出量增加。     

Meßdatenerfassung,Steuerung und Automatisierung bei Apparaten der Mechanischen Flüssigkeitsabtrennung

Data acquisition, control, and automation in equipment for mechanical separation of liquids. Mass- and energy flow in a production process are accompanied by a flow of information. While data processing has reached a high standard, there is a lack of suitable sensors for acquisition of measured data in solid/liquid separation processes. Methods used for acquisition of data relevant to separation engineering are presented for selected separation equipment, possibilities of control with changing product properties are discussed, and unsolved problems of sensor technology are considered.     

Statistical optimization of process parameters for the production of vanillic acid by solid‐state fermentation of groundnut shell waste using response surface methodology

BACKGROUND: Vanillic acid is a flavoring agent and also serves as precursor for vanillin production. Culture medium and fermentation condition for the single step production of vanillic acid from Phanerochaete chrysosporium using lignocellulosic waste as a substrate under solid state fermentation (SSF) were optimized using response surface methodology. RESULTS: The process parameters were chosen by borrowing methodology, and L‐asparagine, pH and moisture content of the solid medium during SSF were identified as the most significant variables. The optimum value of selected variable and their mutual interactions were determined by response surface methodology. The result demonstrated that a yield of 73.58 mg vanillic acid g^?1 substate was predicted under optimum conditions (L‐asparagine 5.98 mmol L^?1 (2.37 mg g^?1 groundnut shell), pH of solid medium 4.51 and moisture content 74.83%). The predicted response was experimentally validated and resulted in a maximum vanillic acid yield of 73.69 mg g^?1 after 8 days of SSF. CONCLUSION: The optimization of fermentation variables resulted in a maximum 10‐fold increase in vanillic acid yield compared with that observed under sub‐optimal conditions (from 7.2 mg g^?1 to 73.69 mg g^?1). Copyright © 2011 Society of Chemical Industry     

正十六烷发酵产生柠檬酸的研究

通过试验筛选出产柠檬酸较高的菌种解脂复膜孢酵母１４６０菌和适宜培养基,确定了适宜的菌种起始浓度和底物浓度,证实谷氨酸对产生柠檬酸的促进作用,对分批培养发酵过程中细胞生长和产物生成速率进行了数学表达。     

Removal of Basic Blue 3 from aqueous solution by <Emphasis Type="Italic">Corynebacterium glutamicum</Emphasis> biomass: Biosorption and precipitation mechanisms

The waste biomass generated from mono sodium glutamate fermentation process, Corynebacterium glutamicum, was evaluated as a biosorbent for the removal of Basic Blue 3 (BB 3), as a model cationic dye, from aqueous solution. A series of batch experiments to study pH edge, precipitation of dye, isotherms and kinetics were undertaken. The solution pH was found to be an important factor in biosorption of BB 3. With increasing the pH, the uptake of BB 3 increased, except at a pH below 2. At pH values below 2, the precipitation of BB 3 occurred rather than biosorption, which resulted in overestimation of the sorption performance. The sorption process could reach quickly to equilibrium after 1 min. The Langmuir and Freundlich models were used to fit the experimental data at different pH conditions. Between them, the Langmuir model described the experimental data very well with high correlation coefficients. Furthermore, C. glutamicum was easily eluted by shifting the solution pH, making repeated sorption/desorption cycle (up to 4 times) possible without significant performance decrease.     

生物酿造乙酸及纯化

阐述了利用生物可再生资源发酵和分离纯化有机原料乙酸的技术,论述了乙酸发酵的固态、固定化细胞和液态深层发酵工艺,可发酵乙酸含量超过220 g/L的液态深层发酵工艺是可再生原料发酵乙酸的最佳选择。分析了乙酸-水体系分离纯化过程的精馏、膜分离和萃取等不同技术,论述了各种分离方法的优点和研究进展,介绍了几种不同分离方法的耦合应用于乙酸-水溶液的分离,提出了利用基因工程等技术改良的产高酸的乙酸菌种以及发酵分离耦合工艺进行乙酸的生物酿造。     

Half‐submerged cultivation method for the microbial desulfurization of waste latex rubber

The common method for microbial desulfurization is the submerged cultivation method. However, its cost is high because of the high consumption of the medium. To cut costs and improve the desulfurization effect, the new half‐submerged cultivation method was used in the microbial desulfurization of waste latex rubber (WLR) by Sphingomonas species With this method, much more WLR was added per unit volume of the culture medium to be desulfurized, and the desulfurization process was done without stirring. The technical conditions, such as the addition of WLR, the addition of polysorbate 80 (Tween 80), and the desulfurization time, for the half‐submerged cultivation method were studied, and its desulfurization effect was compared with that of the traditional submerged cultivation method. The results show that the optimum conditions for the half‐submerged cultivation method were the addition of 40% w/v WLR in the medium without Tween 80 and desulfurization for 10 days. The X‐ray photoelectron spectroscopy and Fourier transform infrared spectroscopy results demonstrate that the decreases in the content of sulfur, S? C bonds, and S? S bonds on the surface of WLR after desulfurization by the half‐submerged cultivation method were greater than those after desulfurization by the submerged cultivation method. The composite of waste latex rubber desulfurized by the submerged cultivation method (SDWLR) and styrene–butadiene rubber (SBR) had better mechanical properties than the composite of waste latex rubber desulfurized by the half‐submerged cultivation method (HDWLR) and SBR. Scanning electron microscopy photographs showed that the combinations of HDWLR and the matrix were better than those of SDWLR and the matrix. Compared with the submerged cultivation method, the half‐submerged cultivation method not only reduced the cost of desulfurization but also improved the desulfurization effect. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41039.     

浅析柠檬酸钠的清洁化生产

针对柠檬酸发酵和柠檬酸钠生产的特点(如主要原材料、发酵废液、废渣等),从节能降耗、原料的最有效利用及废物综合治理等清洁生产角度开展深入地探讨,借鉴近年来不断涌现出来的新理论、新技术,对现有柠檬酸钠生产工艺的两个主要环节进行系统的研究,改革创新,提出符合清洁化生产的新工艺。针对现有工艺解决三个层面的问题:一是提高原料的利用水平;二是降低产品的能源消耗水平;三是充分利用生产过程中废水、废渣,变废为宝。其中既涉及到生产工艺的重新调整,又探讨了一些新技术、新工艺在柠檬酸钠生产中的应用。