The optimization of l-lactic acid production from sweet sorghum juice by mixed fermentation of Bacillus coagulans and Lactobacillus rhamnosus under unsterile conditions

The cost reduction of raw material and sterilization could increase the economic feasibility of l-lactic acid fermentation, and the development of an cost-effective and efficient process is highly desired. To improve the efficiency of open fermentation by Lactobacillus rhamnosus based on sweet sorghum juice (SSJ) and to overcome sucrose utilization deficiency of Bacillus coagulans, a mixed fermentation was developed. Besides, the optimization of pH, sugar concentration and fermentation medium were also studied. Under the condition of mixed fermentation and controlled pH, a higher yield of 96.3% was achieved, compared to that (68.8%) in sole Lactobacillus rhamnosus fermentation. With an optimized sugar concentration and a stepwise-controlled pH, the l-lactic acid titer, yield and productivity reached 121gL(-1), 94.6% and 2.18gL(-1)h(-1), respectively. Furthermore, corn steep powder (CSP) as a cheap source of nitrogen and salts was proved to be an efficient supplement to SSJ in this process.

Co-generation of microbial lipid and bio-butanol from corn cob bagasse in an environmentally friendly biorefinery process

Biorefinery process of corn cob bagasse was investigated by integrating microbial lipid and ABE fermentation. The effects of NaOH concentration on the fermentations performance were evaluated. The black liquor after pretreatment was used as substrate for microbial lipid fermentation, while the enzymatic hydrolysates of the bagasse were used for ABE fermentation. The results demonstrated that under the optimized condition, the cellulose and hemicellulose in raw material could be effectively utilized. Approximate 87.7% of the polysaccharides were converted into valuable biobased products (∼175.7g/kg of ABE along with ∼36.6g/kg of lipid). At the same time, almost half of the initial COD (∼48.9%) in the black liquor could be degraded. The environmentally friendly biorefinery process showed promising in maximizing the utilization of biomass for future biofuels production.

Improvement of l-lactic acid productivity from sweet sorghum juice by repeated batch fermentation coupled with membrane separation

In order to efficiently produce l-lactic acid from non-food feedstocks, sweet sorghum juice (SSJ), which is rich of fermentable sugars, was directly used for l-lactic acid fermentation by Lactobacillus rhamnosus LA-04-1. A membrane integrated repeated batch fermentation (MIRB) was developed for productivity improvement. High-cell-density fermentation was achieved with a final cell density (OD620) of 42.3, and the CCR effect was overcomed. When SSJ (6.77gL(-1) glucose, 4.51gL(-1) fructose and 50.46gL(-1) sucrose) was used as carbon source in MIRB process, l-lactic acid productivity was increased significantly from 1.45gL(-1)h(-1) (batch 1) to 17.55gL(-1)h(-1) (batch 6). This process introduces an effective way to produce l-lactic acid from SSJ.

Effect of dilute alkaline pretreatment on the conversion of different parts of corn stalk to fermentable sugars and its application in acetone-butanol-ethanol fermentation

To investigate the effect of dilute alkaline pretreatment on different parts of biomass, corn stalk was separated into flower, leaf, cob, husk and stem, which were treated by NaOH in range of temperature and chemical loading. The NaOH-pretreated solid was then enzymatic hydrolysis and used as the substrate for batch acetone-butanol-ethanol (ABE) fermentation. The results demonstrated the five parts of corn stalk could be used as potential feedstock separately, with vivid performances in solvents production. Under the optimized conditions towards high product titer, 7.5g/L, 7.6g/L, 9.4g/L, 7g/L and 7.6g/L of butanol was obtained in the fermentation broth of flower, leaf, cob, husk and stem hydrolysate, respectively. Under the optimized conditions towards high product yield, 143.7g/kg, 126.3g/kg, 169.1g/kg, 107.7g/kg and 116.4g/kg of ABE solvent were generated, respectively.

The Fit between External Involvement and Business Environment

Previous studies are inconsistent in their findings about the relationship between external involvement and performance. The authors attribute this inconsistency to the misfit between external involvement and business environment. Drawing the concept of fit between information processing capabilities and needs from information processing theory, they develop the fitting patterns between external involvement and business environment and examine their impacts on performance. Information processing capabilities are measured by the degree of two types of external involvement in the NPD process and information processing needs are assessed based on three dimensions of business environment. Cluster analysis was used to develop the taxonomies of fit between external involvement and business environment. Analysis of variance (ANOVA) was used to examine the impacts of fitting patterns between external involvement and business environment on performance. The results reveal six fitting patterns between external involvement and business environment. ANOVA results show that the fitting patterns between external involvement and business environment are related to both operational performance and business performance, supporting our fit theory.

Acetone-butanol-ethanol from sweet sorghum juice by an immobilized fermentation-gas stripping integration process

In this study, sweet sorghum juice (SSJ) was used as the substrate in a simplified ABE fermentation-gas stripping integration process without nutrients supplementation. The sweet sorghum bagasse (SSB) after squeezing the fermentable juice was used as the immobilized carrier. The results indicated that the productivity of ABE fermentation process was improved by gas stripping integration. A total 24g/L of ABE solvents was obtained from 59.6g/L of initial sugar after 80h of fermentation with gas stripping. Then, long-term of fed-batch fermentation with continuous gas stripping was further performed. 112.9g/L of butanol, 44.1g/L of acetone, 9.5g/L of ethanol (total 166.5g/L of ABE) was produced in overall 312h of fermentation. At the same time, concentrated ABE product was obtained in the condensate of gas stripping.

Biorefinery of corn cob for microbial lipid and bio-ethanol production: An environmental friendly process

Microbial lipid and bio-ethanol were co-generated by an integrated process using corn cob bagasse as raw material. After pretreatment, the acid hydrolysate was used as substrate for microbial lipid fermentation, while the solid residue was further enzymatic hydrolysis for bio-ethanol production. The effect of acid loading and pretreatment time on microbial lipid and ethanol production were evaluated. Under the optimized condition for ethanol production, ∼131.3g of ethanol and ∼11.5g of microbial lipid were co-generated from 1kg raw material. On this condition, ∼71.6% of the overall fermentable sugars in corn cob bagasse could be converted into valuable products. At the same time, at least 33% of the initial COD in the acid hydrolysate was depredated.

Effect of acid pretreatment on different parts of corn stalk for second generation ethanol production

In this study, the effects of different parts of corn stalk, including stem, leaf, flower, cob and husk on second generation ethanol production were evaluated. FTIR, XRD and SEM were performed to investigate the effect of dilute acid pretreatment. The bagasse obtained after pretreatment were further hydrolyzed by cellulase and used as the substrate for ethanol fermentation. As results, hemicelluloses fractions in different parts of corn stalk were dramatically removed and the solid fractions showed vivid compositions and crystallinities. Compared with other parts of corn stalk, the cob had higher sugar content and better enzymatic digestibility. The highest glucose yield of 94.2% and ethanol production of 24.0 g L(-1) were achieved when the cob was used as feedstock, while the glucose yield and the ethanol production were only 86.0% and 17.1 g L(-1) in the case of flower.

Effective multiple stages continuous acetone-butanol-ethanol fermentation by immobilized bioreactors: Making full use of fresh corn stalk

In order to make full use of the fresh corn stalk, the sugar containing juice was used as the sole substrate for acetone-butanol-ethanol production without any nutrients supplement, and the bagasse after squeezing the juice was used as the immobilized carrier. A total 21.34g/L of ABE was produced in batch cells immobilization system with ABE yield of 0.35g/g. A continuous fermentation containing three stages with immobilized cells was conducted and the effect of dilution rate on fermentation was investigated. As a result, the productivity and ABE solvents concentration reached 0.80g/Lh and 19.93g/L, respectively, when the dilution rate in each stage was 0.12/h (corresponding to a dilution rate of 0.04/h in the whole system). And the long-term operation indicated the continuous multiple stages ABE fermentation process had good stability and showed the great potential in future industrial applications.

Ethanol fermentation integrated with PDMS composite membrane: An effective process

The polydimethylsiloxane (PDMS) membrane, prepared in water phase, was investigated in separation ethanol from model ethanol/water mixture and fermentation-pervaporation integrated process. Results showed that the PDMS membrane could effectively separate ethanol from model solution. When integrated with batch ethanol fermentation, the ethanol productivity was enhanced compared with conventional process. Fed-batch and continuous ethanol fermentation with pervaporation were also performed and studied. 396.2-663.7g/m(2)h and 332.4-548.1g/m(2)h of total flux with separation factor of 8.6-11.7 and 8-11.6, were generated in the fed-batch and continuous fermentation with pervaporation scenario, respectively. At the same time, high titre ethanol production of ∼417.2g/L and ∼446.3g/L were also achieved on the permeate side of membrane in the two scenarios, respectively. The integrated process was environmental friendly and energy saving, and has a promising perspective in long-terms operation.

Efficient l-lactic acid production from sweet sorghum bagasse by open simultaneous saccharification and fermentation

An open SSF process using B. coagulans LA1507 introduces an effective way to produce l-lactic acid from abundant SSB.

Open fermentative production of L-lactic acid using white rice bran by simultaneous saccharification and fermentation

To reduce raw material cost for lactic acid production, white rice bran as an important byproduct in rice milling, was used in l-lactic acid production by open simultaneous saccharification and fermentation (SSF). Although one thermotolerant strain was used at a temperature as high as 50°C, the open fermentation was still inefficient due to the indigenous thermophilic bacteria from corn steep liquor powder. A stepwise controlled pH was proposed in open SSF process, and no complicated pretreatment or sterilization was needed before fermentation. In batch fermentation, 117 gL(-1) lactic acid was obtained, and the productivity and yield reached 2.79 gL(-1) h(-1) and 98.75%, respectively. These results showed an efficient way to develop high value-added products from white rice bran.

Efficient magnesium lactate production with in situ product removal by crystallization

In this paper, attempts were made to develop an in situ product removal process for magnesium lactate production based on crystallization. The crystallization was conducted at 42°C without seed crystal addition. The product concentration, productivity and yield of fermentation coupled with in situ product removal (ISPR) reached 143 g L(-1), 2.41 g L(-1)h(-1) and 94.3%. In four cycles of crystallization, the average reuse rate of fermentation medium and removal rate of product reached 64.0% and 77.7%. At the same time, ISPR fermentation saved 40% water, 41% inorganic salts and 43% yeast extract (YE) as compared to fed-batch fermentation. The process introduces an effective way to reduce the amount of waste water and the raw material cost in magnesium lactate fermentation.

Multiple Large Shareholder Structure and Governance: The Role of Shareholder Numbers, Contest for Control, and Formal Institutions in Chinese Family Firms

The principal–principal (PP) perspective of corporate governance shows that multiple large shareholder (MLS) structure has competing monitoring and entrenchment governance effects. We argue that the dominant effect depends on contest for control among large shareholders and the number of large shareholders involved. Using data from Chinese family listed companies from 2004 to 2007, this study shows inverse U-shaped relationships between contest for control and corporate market value, as measured by Tobin's Q, and between the number of large shareholders and corporate market value. Findings indicate that at low to medium levels of contest for control or number of large shareholders, formal institutions can strengthen MLS structure's monitoring effect and can help this effect last longer. As a whole, the findings extend the institution-based view in the context of family corporate governance by showing that formal institutions can shape the ability of MLS structure to exert governance.

Continuous l-lactic acid production from defatted rice bran hydrolysate using corn stover bagasse immobilized carrier

In this paper, l-lactic acid (LLA) was produced using defatted rice bran hydrolysate.

[Effect of fast capacitance compensation method on improving the action potential firing accuracy of nerve cell]

Patch-clamp is used to study all sorts of ionic channels and their regulations with measuring pA current of cell ionic channel, but the fast capacitance (C-fast) compensation and slow capacitance (C-slow) compensation transient currents are caused by measuring objects and measuring instruments themselves which will change the properties of action potentials. The present paper firstly discusses the C-Fast transient currents affecting membrane capacitance and membrane potential, and then draws a conclusion that the changes of membrane potential affect the properties of action potential through analyzing the changes of membrane potential in H-H model. Based on this conclusion, we discuss the influence mechanisms mainly through the analysis of traditional C-fast compensation errors, and focus discussion on the shape of electrode capacitance affecting C-fast. This method can not only improve the compensation speed greatly, but also improve the compensation precision from the electrode shape as much as possible.

[Effect of pulse magnetic field on distribution of neuronal action potential]

The biological effect on the organism generated by magnetic field is widely studied. The present study was aimed to observe the change of sodium channel under magnetic field in neurons. Cortical neurons of Kunming mice were isolated, subjected to 15 Hz, 1 mT pulse magnetic stimulation, and then the currents of neurons were recorded by whole-cell patch clamp. The results showed that, under magnetic stimulation, the activation process of Na(+) channel was delayed, and the inactivation process was accelerated. Given the classic three-layer model, the polarization diagram of cell membrane potential distribution under pulse magnetic field was simulated, and it was found that the membrane potential induced was associated with the frequency and intensity of magnetic field. Also the effect of magnetic field-induced current on action potential was simulated by Hodgkin-Huxley (H-H) model. The result showed that the generation of action potential was delayed, and frequency and the amplitudes were decreased when working current was between -1.32 μA and 0 μA. When the working current was higher than 0 μA, the generation frequency of action potential was increased, and the change of amplitudes was not obvious, and when the working current was lower than -1.32 μA, the time of rising edge and amplitudes of action potential were decreased drastically, and the action potential was unable to generate. These results suggest that the magnetic field simulation can affect the distribution frequency and amplitude of action potential of neuron via sodium channel mediation.

A study of structure and properties of molecularly thin methanol film using the modified surface forces apparatus

A novel approach for studying the adsorption and evaporation processes of molecularly thin methanol film by the modified surface forces apparatus (M-SFA) is reported. This method can be used precisely to measure the thickness, morphology, and mechanical properties of the film confined between two mica surfaces in a real-time manner at gas atmosphere. By observing the adsorption and evaporation processes of the methanol molecule, it is found that the first adsorbed layer of the methanol film on the mica surface behaves as a solid-like structure. The thickness of this layer is measured to be about 3.2 Å, approximately equal to the diameter of a methanol molecule. Besides, this first adsorbed layer can carry normalized loads of more than 5.6 atm due to the carrying capacity conserved by the bond of mica-OH. The outer layers of the methanol film are further adsorbed with the increase of the exposure time, which are liquid-like and can be easily eliminated out from the substrate. The present study suggests that the interacting mode between hydroxy and mica is of great potential in material science and biomedical systems.