Optimization of α‐amylase production in solid substrate fermentation

Response surface methodology (RSM) was used to optimize the medium components of α‐amylase production using solid substrate fermentation (SSF). Hazelnut cake (HC), peptone, yeast extract (YE), and (NH₄)₂SO₄ were selected as independent variables for optimization. Central composite design (CCD) was used in design experiments and analysis results. This procedure limited the number of actual experiments performed while allowing possible interactions between the independent variables. By using CCD, 30 experiments were performed for determining the interaction of independent variables and optimization of fermentation medium. The P‐value of the coefficient of linear effect of (NH₄)₂SO₄ concentrations, which was obtained as 0.0001 has shown that this parameter has the greatest effect on the production of α‐amylase. Model F‐value (5.62) implies that the model is significant. The highest α‐amylase activity (4895 IU) was measured when the HC, peptone, YE, and (NH₄)₂SO₄ concentrations in the medium were 22.62, 5.20, 1.62, and 6.81 g L^?1, respectively.     

Growth‐promoting properties of yeast extracts produced at different pH values,with different autolysis promoters and bacterial populations

The effect of the autolysis conditions of bakers' yeast on the growth‐promoting properties of the resulting yeast extracts (YE) were examined on cultures of Lactococcus lactis ssp lactis D25 and of Lactococcus lactis ssp cremoris R2. The various YE were produced by conducting autolysis at four pH levels (pH 4.0, 5.5, 7.0 or 8.5) and with or without the autolysis promoters (AP) ethyl acetate or chitosan. To determine if the presence of contaminating bacteria during autolysis affected the YE characteristics, one series of YE was also prepared with the bakers' yeast cell suspension contaminated with 10⁸ CFU/cm^?3 of typical yeast plant bacteria (mostly of the Bacillus genus) at the beginning of autolysis. The growth curves of the lactococci in media supplemented with the various YE were analyzed to determine the maximum optical density (OD_max), the maximum growth rate (µ_max) and the fermentation time (F‐time) at which OD_max was reached. The addition of bacterial contaminants (at 10⁸ CFUcm^?3) did not significantly influence the growth‐promoting properties of YE. The lactococci had higher OD_max and µ_max values when the media contained YE produced at pH 4.0 or 5.5, and these YE contained 40% more total nitrogen than those obtained at pH 7.0 or 8.5. There was no major effect of AP on the biological value of the resulting YE, but a significant interaction between pH and AP was found for L lactis D25. Thus the OD_max of YE produced at pH 7.0 and 8.5 were highest when ethyl acetate was used as autolysis promoter, as compared with control and chitosan at pH 7.0–8.5, while the opposite was obtained with products produced at pH 4.0 and 5.5. This study shows that parameters used to produce YE influence their biological value with respect to the growth‐promoting properties of lactococci. © 2001 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     

Supercritical carbon dioxide extraction of lipids from Pythium irregulare

Lipids that contain polyunsaturated fatty acids (PUFA) have therapeutic value. PUFA, however, degrade in high-temperature, oxygen-rich conditions typical of conventional hot solvent-extraction and distillation methods. Supercritical CO₂ extraction was chosen as an alternative method to recover these valuable compounds from the lower fungus, Pythium irregulare. Freeze-dried biomass was subjected to an aqueous phase and placed into a flow-through extraction apparatus. Extraction of oil from this biomass showed some success for moisture contents as high as 30% (wet basis). The addition of a novel CO₂-philic surfactant to the wet biomass with moisture contents as high as 95% (wet basis) increased the extraction rate of fungal oil by more than an order of magnitude. For tests with extraction times of 5 to 6 h, data for the diffusion-controlled region were modeled with an analytical solution to Fick’s second law. Equilibrium data were also obtained for the fungal oil at two isotherms (40 and 60°C) over a pressure range of 13.7 to 27.5 MPa.     

Free fatty acids inducing mouse lethal toxicity in lipid extracts ofEngraulis japonica,the Japanese anchovy

Mouse lethal toxicity was detected in the ether extract ofEngraulis japonica (anchovy). The mouse toxicity of extracts was more potent from viscera than from other organs. Okadaic acid (C₄₄H₆₈O₁₃) and dinophysistoxin (C₄₅H₇₀O₁₃), lipophilic toxins derived from phytoplankton, which are usually considered to be the diarrhetic shellfish toxins, were not detected in the ether extract of ancovy. There occurred, however, two prominent peaks in high-performance liquid chromatography, which were identified as free eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The mouse toxicity observed correlated with the intensity of these two peaks. Toxicity was reduced considerably by pretreatment with Na₂CO₃. By quantitating EPA toxicity, it was concluded that the toxicity was not due to EPA only but also to DHA. The results indicate that substances in Japanese anchovy associated with mouse lethal toxicity include free polyunsaturated fatty acids, mainly EPA and DHA.     

Solidification of electroplating sludge using alkali-activated pulverized fuel ash as cementitious binder

This work investigated the potential for utilization of alkali-activated PFA as solidification binder to treat electroplating sludge. The sludge was solidified using 30 wt.% of lime and 70 wt.% of PFA. Two alkali activators, Na₂SiO₃ and Na₂CO₃, were added at 0, 4, 6, and 8 wt.%. Results showed that early strength development of lime-PFA cements with Na₂SiO₃ and Na₂CO₃ was considerably higher than those without. Addition of electroplating sludge resulted in reduced strength. The strength reduction was greater when 4% Na₂SiO₃ activator was used than when 8% Na₂CO₃ activator was used. A higher pH of Na₂SiO₃ solution (pH=13.5) compared to that of Na₂CO₃ solution (pH=11.9) resulted in resolubilization of metal hydroxides from the electroplating sludge, which competed with calcium ion for soluble silicate. In addition, Pb, Cd, and Cu were not found in the toxicity characteristic leaching procedure (TCLP) leachates. Cr, Zn, and Fe were detected and in some cases Cr exceeded U.S. EPA allowable limits.     

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     

Influence of Temperature on Growth and Peak Oil Biosynthesis in a Carbon-Limited Medium by <Emphasis Type="Italic">Pythium irregulare</Emphasis>

Kinetic analysis was investigated for a carbon-limited medium (C/N ratio = 5.0) supporting the growth of the 5,8,11,14,17-eicosapentaenoic acid (20:5; ω-3) (EPA)-accumulating fungal organism Pythium irregulare. The productivity and yield parameters at three temperatures, 14, 21, and 28°C, demonstrated growth-coupled synthesis for lipid-free biomass growth and lipid accumulation. For this system, the maximum specific growth rate and theoretical maximum biomass yield based on logistic growth kinetics were used to determine an activation energy of the growth process, E _g, of 36.5 kJ mol⁻¹. At 14, 21, and 28°C, peak lipid yield occurred after culturing for 7, 4, and 3 days, respectively, with peak lipid yields of 8.14, 12.8, and 6.69 g lipid 100 g⁻¹ glucose. At these peak yields, the maximum lipid-free biomass productivity was achieved at the colder 14°C temperature as well as an increased concentration of EPA—10.9 wt%. Despite these enhancements, the maximum relative lipid production (P _R(FA/B)) was achieved at 21°C—19.1%.     

Alkali activation of a novel calcium‐silicate hydraulic binder with CaO/SiO2 = 1.1

A quasi‐amorphous low‐calcium‐silicate hydraulic binder, with an overall CaO/SiO₂ (C/S) molar ratio of 1.1, was produced. This cementitious material was then hydrated with aqueous solutions containing 3 wt% alkalis (either NaOH, Na₂CO₃ or Na₂SiO₃). The evolution of the hydration processes of the samples were monitored by compressive strength testing, XRD, FTIR, ²⁹Si and ²⁷Al MAS NMR, isothermal calorimetry and TGA. It was found that the nearly exclusive hydration product formed was a C‐S‐H phase with a semi‐crystalline structure. More importantly, the paste prepared with the Na₂SiO₃ solution developed compressive strength values similar to those of ordinary portland cements (OPC) with faster early age kinetics. In addition, the isothermal calorimetry results indicated that these new hydraulic binders present much lower heat of hydration values compared with a traditional OPC. The results presented here open the possibility of producing cement with a compressive strength comparable to that of OPC but with lower CO₂ emissions during the production process and with lower hydration heat related problems during the production of concrete structures.     

The preparation of SPEEK/phosphate salts membranes and application for CO2/CH4 separation

SPEEK/phosphate salts membranes were prepared and utilized for CO₂/CH₄ separation. SPEEK with abundant –SO₃H groups and EO groups on polymer chains would be beneficial for CO₂ transport. The doped phosphate salts (NaH₂PO₄, Na₂HPO₄ and Na₃PO₄) with different acid‐base properties increased the water content in the membrane, and water was expected to increase both the solubility and diffusivity of CO₂ in the membrane. All membranes were characterized by FTIR, TGA, and XRD. The CO₂ permeability and CO₂/CH₄ selectivity of SPEEK/Na₃PO₄ membranes were higher than that of SPEEK/NaH₂PO₄ and SPEEK/Na₂HPO₄ membranes. Compared to the pure SPEEK membrane, the CO₂ permeability and CO₂/CH₄ selectivity of SPEEK/Na₃PO₄?10 membrane were increased by 144% and 65%, respectively. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43399.     

Chemical Processes During Energy‐Saving Preparation of Lightweight Ceramics

Lightweight glass‐ceramic material similar to foam glass was obtained at 700°C–800°C directly from alkali‐activated silica clay and zeolitized tuff without preliminary glass preparation. It was characterized by low bulk density of 100–250 kg/m³ and high pore size homogeneity. Chemical processes occurring in alkali‐activated silica clay and zeolitized tuff were studied using X‐ray diffraction, thermal gravimetry, IR‐spectroscopy, and scanning electron microscopy. Pore formation in both compositions is caused by dehydration of hydrated sodium polysilicates (Na₂O·mSiO₂·nH₂O), formed during alkali activation. Additional pore‐forming gas source in alkali‐activated zeolitized tuff is trona, Na₃(CO₃)(HCO₃)·2H₂O, formed during interaction between unbound NaOH and CO₂ and H₂O from air. Influence of mechanical activation of raw materials on chemical processes occurring in alkaline compositions was also studied.     

Supercritical carbon dioxide extraction of cottonseed with co-solvents

Extraction of cottonseed lipids with supercritical carbon dioxide (SC-CO₂) was conducted with and without a cosolvent, ethanol or 2-propanol (IPA). At 7000 psi and 80°C, the reduced pressure, temperature and density of SC-CO₂ was at 6.5, 1.17 and 1.85, respectively; the specific gravity was 0.87. Under these conditions, CO₂ is denser than most liquid extraction agents such as hexane, ethanol and IPA. The extraction of cottonseed with SC-CO₂ gave a yield of more than 30% (moisture-free basis). This is comparable to yields obtained by the more commonly used solvent, hexane. The crude cottonseed oil extracted by SC-CO₂ was visually lighter than refined cottonseed oil. This was substantiated by colorimetric measurements. No gossypol was detected in the crude oil. However, crude oil extracted by SC-CO₂, to which less than 5% of ethanol or IPA as co-solvent was added, containedca. 200 ppm of gossypol, resulting in the typical dark color of cottonseed crude oil with gossypol. CO₂ extracted a small amount of cottonseed phosphatides, about one-third of that extracted by pure ethanol, IPA or hexane. A second extraction with 100% ethanol or IPA after the initial SC-CO₂ extraction produced a water-soluble lipid fraction that contained a significant amount of gossypol, ranging between 1500 and 5000 ppm. Because pure gossypol is practically insoluble in water, this fraction is believed to be made up of gossypol complexed with polysaccharides and phosphatides. Partially presented at the AOCS 1993 Annual Meeting & Expo in Anaheim, California.     

Synthesis of Anisotropic Na0.5Bi0.5TiO3 Crystals Using Different Topochemical Microcrystal Conversion Methods

Na_0.5Bi_0.5TiO₃ (NBT) platelets with high aspect ratio were synthesized from Na_0.5Bi_4.5Ti₄O₁₅ (NBIT) precursors via a topochemical microcrystal conversion in molten salt conditions. The effect of the synthesis parameters, such as the molten salt system, synthesis temperature, and the molar ratio of Na₂CO₃ and NBIT, was investigated. The results showed that NaCl–KCl molten salt environment and excess Na₂CO₃ played a positive role in the synthesis, square‐shaped NBT was obtained at 950°C in NaCl–KCl molten salt and a TiO₂‐free environment, and it was a suitable template candidate to achieve NBT‐based textured ceramics using the reactive template grain growth (RTGG) method.     

Effect of dye auxiliaries on the kinetics of advanced oxidation UV/H2O2 of Acid Orange 7 (AO7)

BACKGROUND: The effect of four dye‐auxiliary chemicals, typically employed in acid dyeing, on the performance of UV/H₂O₂ decolouration of the model non‐biodegradable dye C.I. Acid Orange 7 (AO7) was investigated. The initial concentration of AO7 was 0.150 g L^?1, while the concentration of the auxiliary compounds (NaCl, Na₂SO₄, Na₂CO₃ and CH₃COOH) was varied in the range 1–10 g L^?1. RESULTS: The negative influence of the presence of the dye‐auxiliary compounds studied on the decolouration rate of AO7 decreased in the following order: CH₃COOH > Na₂SO₄ > NaCl > Na₂CO₃. Results were quantified in terms of the observed kinetic rate constant, k_obs (s^?1), of AO7 decolouration as a function of dye auxiliary chemical concentration. The decolouration rate of AO7 decreased as the concentration of dye‐auxiliary compound increased in the range 1–5 g L^?1, while higher concentrations had a minor effect. Upon addition of 5 g L^?1 of CH₃COOH, NaCl and Na₂SO₄, the kinetic rate constant decreased by 39%, 30% and 12%, respectively. CONCLUSIONS: It was concluded that the presence of NaCl, Na₂SO₄ and above all of CH₃COOH should be considered in the design of the treatment of real dye‐bath effluents by UV/H₂O₂. Copyright © 2008 Society of Chemical Industry     

Fermentation optimization for the production of lovastatin by Aspergillus terreus: use of response surface methodology

A Box–Behnken experimental design was used to investigate the effects of five factors—ie oxygen content in the gas phase; concentrations of C, N and P; and fermentation time—on the concentrations of biomass and lovastatin produced in batch cultures of Aspergillus terreus. The values of the various factors in the experiment ranged widely, as follows: 20–80% (v/v) oxygen in the aeration gas; 8–48 g dm^?3 C‐concentration; 0.2–0.6 g dm^?3 N‐concentration; 0.5–2.5 g dm^?3 phosphate‐concentration; and 7–11 days fermentation time. No previous work has used statistical analysis in documenting the interactions between oxygen supply and nutrient concentrations in lovastatin production. The Box–Behnken design identified the oxygen content in the gas phase as the principal factor influencing the production of lovastatin. Both a limitation and excess of oxygen reduced lovastatin titers. A medium containing 48 g dm^?3 C supplied as lactose, 0.46 g dm^?3 N supplied as soybean meal, and 0.79 g dm^?3 phosphate supplied as KH₂PO₄, was shown to support high titers (～230 mg dm^?3) of lovastatin in a 7‐day fermentation in oxygen‐rich conditions (80% v/v oxygen in the aeration gas). Under these conditions, the culture medium had excess carbon but limiting amounts of nitrogen. The optimized fermentation conditions raised the lovastatin titer by four‐fold compared with the worst‐case scenario within the range of factors investigated. Copyright © 2004 Society of Chemical Industry     

Fractionation of menhaden oil ethyl esters using supercritical fluid CO2

Supercritical fluid CO₂ was used to fractionate menhaden oil fatty acid ethyl esters to obtain concentrates of the esters of allcis-5,8,11,14,17-eicosapentaenoic acid (EPA) and allcis-4,7,10,13,16,19-docosahexaenoic acid (DHA). Separation of the ethyl esters was found to occur primarily by carbon number, thus limiting the degree to which the ethyl esters of EPA and DHA could be concentrated. Urea fractionation of whole esters in order to remove saturates, monoenes and dienes prior to fractionation with supercritical fluid CO₂ resulted in concentrates of EPA and DHA in purities exceeding 90%. Several criteria are given for the selection of crude oils in order to maximize both purity and yield of concentrates.     

Supercritical fluid extraction in sunflower seed technology

Sunflower (Helianthus annuus L.) seed represents an important source for edible oil and its protein fraction is also recognised as valuable for human consumption when suitably purified from polyphenols, which negatively affect colour and nutritional value. On this basis, a main research has been developed, with the aim of testing the technical feasibility of a supercritical fluid extraction (SFE) process involving a preliminary supercritical CO₂ (SC‐CO₂) extraction of oil from sunflower de‐hulled seeds, followed by the removal of polyphenols from de‐fatted meal by means of ethanol coupled with SC‐CO₂. The paper reports the experimental protocol followed, together with the kinetics of the extractions, knowledge of which allows the optimisation of working parameters and the determination of process yields.     

Optimization of pullulan production using Ca‐alginate‐immobilized Aureobasidium pullulans by response surface methodology

BACKGROUND: The production of pullulan from synthetic medium by Aureobasidium pullulans P56 immobilized in Ca‐alginate beads was investigated using batch and repeated batch fermentation systems. RESULTS: The highest pullulan concentration (19.52 ± 0.37 g dm^?3) was obtained with 2.0‐2.4 mm beads prepared from 2% sodium alginate solution. Pullulan production was mainly accomplished by immobilized fungal cells since leaked cells in the fermentation medium comprised 17.4% of the total fungal population at the end of fermentation. The pullulan proportion was 84.5% of the total polysaccharide in the fermentation medium. Response surface methodology was used to investigate the effects of three fermentation parameters (initial pH, agitation speed and incubation time) on the concentration of pullulan. Results of the statistical analysis showed that the fit of the model was good in all cases. The maximum pullulan concentration of 21.07 ± 0.48 g dm^?3 was obtained at the optimum concentrations of process variables (pH 7.31, agitation speed 191.5 rpm, incubation time 101.2 h). The gel beads produced pullulan under the optimized conditions for six consecutive batch fermentations without marked activity loss and deformation. CONCLUSION: The results of this study suggest that the immobilization of A. pullulans cells in Ca‐alginate gel beads is suitable for batch and repeated batch production of pullulan. Copyright © 2007 Society of Chemical Industry     

Investigation of factors in the optimisation of penicillin production

Penicillin production trials were carried out in stirred 5-dm³ fermenters to collect data and investigate aspects of the process likely to be important in on-line optimisation. These included the calculation of growth from the production of carbon dioxide, the relation between age and productivity and the effect of dilution and culture replacement. Three types of media were used, a synthetic medium and complex commercial-type nutrient media based on corn-steep liquor or peanut meal together with a nutrient feed and pH control. All gave good results although the synthetic medium tended to show only transient production on some occasions. An equation was devised enabling the correct calculation of the growth curve from carbon dioxide output. It was found that the maintenance energy requirements (as indicated by CO₂ production) were much higher with synthetic medium than with complex media. Decay curves (of Q_pen vs time) were readily calculated using Shu's¹⁷ equation. The highest outputs of penicillin were obtained by dilution or replacement systems, but it was essential to start the process early when the penicillin-producing enzymes were active and stable. It was also necessary to supply glucose at an adequate rate, to hold dissolved oxygen concentration above 25% and avoid too high cell concentrations. It was concluded that theories of penicillin production based on feed-rate or dilution, or on the effect of age, are essentially complementary, both aspects being important in determining the optimal course of the fermentation.     

Enzymatic and chemical synthesis of phosphatidylcholine regioisomers containing eicosapentaenoic acid or docosahexaenoic acid

Regioselective incorporation of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) into phosphatidylcholine (PC) was carried out using enzymatic and chemical synthesis. Incorporation at the sn‐1 position was successfully achieved by lipase‐catalysed esterification of 2‐palmitoyl‐lysophosphatidylcholine (LPC), although in most cases, the enzymes incorporated EPA and DHA at lower rates than other fatty acids. For the incorporation of DHA, Candida antarctica lipase B was the only useful enzyme, while incorporation of EPA was efficiently carried out using either this enzyme or Rhizopus arrhizus lipase. The highest yields in the lipase‐catalysed reactions were obtained at the lowest water activity (close to 0). However, by carrying out the reactions at a higher water activity of 0.22, more EPA and DHA were incorporated. Esterification of 2‐palmitoyl‐LPC with pure EPA at this water activity converted 66 mol‐% of LPC to PC using Rhizopus arrhizus lipase as catalyst. When the fatty acid was DHA and the catalyst Candida antarctica lipase B, 45 mol‐% of PC was obtained. For incorporation of EPA and DHA at the sn‐2 position, phospholipase A₂ was used, but the reaction was very slow. Chemical coupling of 1‐palmitoyl‐LPC and EPA or DHA was more efficient, resulting in complete conversion of LPC.