Use of solvents and environmental friendly materials for applications in Green Chemistry

The present Thesis studies three alternative solvent groups as sustainable replacement of traditional organic solvents. Some aspects of fluorinated solvents, supercritical fluids and ionic liquids, have been analysed with a critical approach and their effective “greenness” has been evaluated from the points of view of the synthesis, the properties and the applications. In particular, the attention has been put on the environmental and human health issues, evaluating the eco-toxicity, the toxicity and the persistence, to underline that applicability and sustainability are subjects with equal importance. The “green” features of fluorous solvents and supercritical fluids are almost well-established; in particular supercritical carbon dioxide (scCO2) is probably the “greenest” solvent among the alternative solvent systems developed in the last years, enabling to combine numerous advantages both from the point of view of industrial/technological applications and eco-compatibility. In the Thesis the analysis of these two classes of alternative solvents has been mainly focused on their applicability, rather than the evaluation of their environmental impact. Specifically they have been evaluated as alternative media for non-aqueous biocatalysis. For this purpose, the hydrophobic ion pairing (HIP), which allows solubilising enzymes in apolar solvents by an ion pairing between the protein and a surfactant, has been investigated as effective enzymatic derivatisation technique to improve the catalytic activity under homogeneous conditions in non conventional media. The results showed that the complex enzyme-surfactant was much more active both in fluorous solvents and in supercritical carbon dioxide than the native form of the enzyme. Ionic liquids, especially imidazolium salts, have been proposed some years ago as “fully green” alternative solvents; however this epithet does not take into account several “brown” aspects such as their synthesis from petro-chemical starting materials, their considerable eco-toxicity, toxicity and resistance to biodegradation, and the difficulty of clearly outline applications in which ionic liquids are really more advantageous than traditional solvents. For all of these reasons in this Thesis a critical analysis of ionic liquids has been focused on three main topics: i) alternative synthesis by introducing structural moieties which could reduce the toxicity of the most known liquid salts, and by using starting materials from renewable resources; ii) on the evaluation of their environmental impact through eco-toxicological tests (Daphnia magna and Vibrio fischeri acute toxicity tests, and algal growth inhibition), toxicity tests (MTT test, AChE inhibition and LDH release tests) and fate and rate of aerobic biodegradation in soil and water; iii) and on the demonstration of their effectiveness as reaction media in organo-catalysis and as extractive solvents in the recovery of vegetable oil from terrestrial and aquatic biomass. The results about eco-toxicity tests with Daphnia magna, Vibrio fischeri and algae, and toxicity assay using cultured cell lines, clearly indicate that the difference in toxicity between alkyl and oxygenated cations relies in differences of polarity, according to the general trend of decreasing toxicity by decreasing the lipophilicity. Independently by the biological approach in fact, all the results are in agreement, showing a lower toxicity for compounds with oxygenated lateral chains than for those having purely alkyl lateral chains. These findings indicate that an appropriate choice of cation and anion structures is important not only to design the IL with improved and suitable chemico-physical properties but also to obtain safer and eco-friendly ILs. Moreover there is a clear indication that the composition of the abiotic environment has to be taken into account when the toxicity of ILs in various biological test systems is analysed, because, for example, the data reported in the Thesis indicate a significant influence of salinity variations on algal toxicity. Aerobic biodegradation of four imidazolium ionic liquids, two alkylated and two oxygenated, in soil was evaluated for the first time. Alkyl ionic liquids were shown to be biodegradable over the 6 months test period, and in contrast no significant mineralisation was observed with oxygenated derivatives. A different result was observed in the aerobic biodegradation of alkylated and oxygenated pyridinium ionic liquids in water because all the ionic liquids were almost completely degraded after 10 days, independently by the number of oxygen in the lateral chain of the cation. The synthesis of new ionic liquids by using renewable feedstock as starting materials, has been developed through the synthesis of furan-based ion pairs from furfural. The new ammonium salts were synthesised in very good yields, good purity of the products and wide versatility, combining low melting points with high decomposition temperatures and reduced viscosities. Regarding the possible applications as surfactants and biocides, furan-based salts could be a valuable alternative to benzyltributylammonium salts and benzalkonium chloride that are produced from non-renewable resources. A new procedure for the allylation of ketones and aldehydes with tetraallyltin in ionic liquids was developed. The reaction afforded high yields both in sulfonate-containing ILs and in ILs without sulfonate upon addition of a small amount of sulfonic acid. The checked reaction resulted in peculiar chemoselectivity favouring aliphatic substrates towards aromatic ketones and good stereoselectivity in the allylation of levoglucosenone. Finally ILs-based systems could be easily and successfully recycled, making the described procedure environmentally benign. The potential role of switchable polarity solvents as a green technology for the extraction of vegetable oil from terrestrial and aquatic biomass has been investigated. The extraction efficiency of terrestrial biomass rich in triacylglycerols, as soy bean flakes and sunflower seeds, was comparable to those of traditional organic solvents, being the yield of vegetable oils recovery very similar. Switchable polarity solvents as been also exploited for the first time in the extraction of hydrocarbons from the microalga Botryococcus braunii, demonstrating the efficiency of the process for the extraction of both dried microalgal biomass and directly of the aqueous growth medium. The switchable polarity solvents exhibited better extraction efficiency than conventional solvents, both with dried and liquid samples. This is an important issue considering that the harvest and the dewatering of algal biomass have a large impact on overall costs and energy balance.

In vivo and in vitro effects of genistein as obesogenic/anti-obesogenic compound in the lipid metabolism of rainbow trout (Oncorhynchus mykiss)

Nowadays, soy is one of the most used ingredients in the formulation of fish feed, due to the ample market supply, lower market price, high protein concentration and favorable amino acid composition. Nevertheless, soybean meal products are rich and primary diet source of phytoestrogens, as genistein, which may have a potential negative impact on growth, hormonal regulation and lipid metabolism in fish. The principal aim of this study was to better understand in vivo and in vitro genistein’s effects on lipid metabolism of rainbow trout. In adipose tissue it was showed an unclear role of genistein on lipid metabolism in rainbow trout, and in liver an anti-obesogenic effect, with an up-regulation of autophagy-related genes LC3b (in adipose tissue) and ATG4b (in liver and adipose tissue), a down-regulation of apoptosis-related genes CASP3 (in adipose tissue) and CASP8 (in liver). An increase of VTG mRNA levels in liver was also observed. Genistein partially exerted these effects via estrogen- receptor dependent mechanism. In white muscle, genistein seemed to promote lipid turnover, up-regulating lipogenic (FAS and LXR) and lipolytic (HSL, PPARα and PPARβ) genes. It seemed that genistein could exert its lipolytic role via autophagic way (up-regulation of ATG4b and ATG12l), not through an apoptotic pathway (down-regulation of CASP3). The effects of genistein on lipid-metabolism and apoptosis-related genes in trout muscle were not dose-dependent, only on autophagy-related genes ATG4B and ATG12l. Moreover, a partial estrogenic activity of this phytoestrogen was also seen. Through in vitro analysis (MTT and ORO assay), instead, it was observed an anti-obesogenic effect of genistein on rainbow trout adipocytes, and this effect was not mediated by ERs. Both in vivo and in vitro, genistein exerted its effects in a dose-dependent manner.

La Sojización: The Soyization" of the Argentine Countryside in the Province of Santa Fe"

In the present era of transnational capitalism, some scholars contend that capital accumulation is achieved primarily through dispossession. This paper seeks to analyze the effects of this dispossession upon small agricultural producers in the developing world. By employing the example of soy producers in Argentina, it should become abundantly clear that the issues confronting these farmers are not simply domestic questions but rather indicative of larger structural issues embedded in the global capitalist system.

Characterization of a Giardia lamblia WB C6 clone resistant to the isoflavone formononetin

Giardia lamblia is a common intestinal-dwelling protozoan and causes diarrhoea in humans and animals worldwide. For several years, a small number of drugs such as the 5-nitroimidazole metronidazole (MET) or the thiazolide nitazoxanide (NTZ) have been used for chemotherapy against giardiasis. However, various pre-clinical and clinical investigations revealed that antigiardial chemotherapy may be complicated by emergence of giardial resistance to these drugs. The present study addressed the question if isoflavones with antigiardial activity, such as daidzein (DAI) or formononetin (FOR), may serve as alternative compounds for treatment of giardiasis. For this purpose, the potential of G. lamblia clone WB C6 to form resistance to FOR and related isoflavones was tested in vitro. In the line of these experiments, a clone (C3) resistant to isoflavones, but sensitive to MET and NTZ, was generated. Affinity chromatography on DAI-agarose using cell-free extracts of G. lamblia trophozoites resulted in the isolation of a polypeptide of approximately 40 kDa, which was identified by mass spectrometry as a nucleoside hydrolase (NH) homologue (EAA37551.1). In a nucleoside hydrolase assay, recombinant NH hydrolysed all nucleosides with a preference for purine nucleosides and was inhibited by isoflavones. Using quantitative RT-PCR, the expression of genes that are potentially involved in resistance formation was analysed, namely NH and genes encoding variant surface proteins (VSPs, TSA417). The transcript level of the potential target NH was found to be significantly reduced in C3. Moreover, drastic changes were observed in VSP gene expression. This may indicate that resistance formation in Giardia against isoflavones is linked to, and possibly mediated by, altered gene expression. Taken together, our results suggest FOR or related isoflavones as an alternative antigiardial agent to overcome potential problems of resistance to drugs like MET or NTZ. However, the capacity of Giardia to develop resistance to isoflavones can potentially interfere with this alternative treatment of the disease.

Rapid diagnosis of experimental meningitis by bacterial heat production in cerebrospinal fluid

BACKGROUND: Calorimetry is a nonspecific technique which allows direct measurement of heat generated by biological processes in the living cell. We evaluated the potential of calorimetry for rapid detection of bacterial growth in cerebrospinal fluid (CSF) in a rat model of bacterial meningitis. METHODS: Infant rats were infected on postnatal day 11 by direct intracisternal injection with either Streptococcus pneumoniae, Neisseria meningitidis or Listeria monocytogenes. Control animals were injected with sterile saline or heat-inactivated S. pneumoniae. CSF was obtained at 18 hours after infection for quantitative cultures and heat flow measurement. For calorimetry, 10 microl and 1 microl CSF were inoculated in calorimetry ampoules containing 3 ml trypticase soy broth (TSB). RESULTS: The mean bacterial titer (+/- SD) in CSF was 1.5 +/- 0.6 x 108 for S. pneumoniae, 1.3 +/- 0.3 x 106 for N. meningitidis and 3.5 +/- 2.2 x 104 for L. monocytogenes. Calorimetric detection time was defined as the time until heat flow signal exceeded 10 microW. Heat signal was detected in 10-microl CSF samples from all infected animals with a mean (+/- SD) detection time of 1.5 +/- 0.2 hours for S. pneumoniae, 3.9 +/- 0.7 hours for N. meningitidis and 9.1 +/- 0.5 hours for L. monocytogenes. CSF samples from non-infected animals generated no increasing heat flow (<10 microW). The total heat was the highest in S. pneumoniae ranging from 6.7 to 7.5 Joules, followed by L. monocytogenes (5.6 to 6.1 Joules) and N. meningitidis (3.5 to 4.4 Joules). The lowest detectable bacterial titer by calorimetry was 2 cfu for S. pneumoniae, 4 cfu for N. meningitidis and 7 cfu for L. monocytogenes. CONCLUSION: By means of calorimetry, detection times of <4 hours for S. pneumoniae and N. meningitidis and <10 hours for Listeria monocytogenes using as little as 10 microl CSF were achieved. Calorimetry is a new diagnostic method allowing rapid and accurate diagnosis of bacterial meningitis from a small volume of CSF.

Influence of body temperature on bacterial growth rates in experimental pneumococcal meningitis in rabbits

We examined the role of fever as a host defense in experimental pneumococcal meningitis in rabbits. Twelve hours after intracisternal inoculation of an encapsulated type 3 Streptococcus pneumoniae strain, body temperature was manipulated by using two different anesthetic drugs: pentobarbital, which did not affect temperature, and urethane, which mitigated the febrile response to infection. Growth rates of pneumococci in cerebrospinal fluid were dramatically influenced by modification of the febrile response. Rabbits whose fever was not suppressed had mean bacterial doubling times of 2.76 +/- 1.43 h. Animals with a blunted febrile response had a significantly faster mean bacterial growth rate (doubling time = 1.10 +/- 0.27 h; P less than 0.02). When the antipyretic effect of urethane was counteracted by raising the ambient temperature, animals also showed a marked reduction in pneumococcal growth rates. In vitro, the pneumococci grew well at 37 degrees C in Trypticase soy broth (doubling time = 0.61 +/- 0.05 h) and in pooled rabbit cerebrospinal fluid (doubling time = 0.85 +/- 0.07 h). However, at 41 degrees C neither medium supported growth. Thus, body temperature appears to be a critical determinant of pneumococcal growth rates in experimental meningitis, and fever could be a host defense in this disease.

Study of the effect of biodiesel fuel on passive oxidation in a catalyzed particulate filter

A 2007 Cummins ISL 8.9L direct-injection common rail diesel engine rated at 272 kW (365 hp) and 317 kW (425 hp) was used to load the filter to 2.2 g/L and passively oxidize particulate matter (PM) within an aftertreatment system consisting of a diesel oxidation catalyst (DOC) and catalyzed particulate filter (CPF). The tests conducted with the engine rated at 365 hp used a 2007 DOC and CPF. The tests conducted with the engine rated at 425 hp used a 2010 DOC and 2007 CPF. Understanding the passive NO2 oxidation kinetics of PM within the CPF allows for reducing the frequency of active regenerations (hydrocarbon injection) and the associated fuel penalties. Modeling the passive oxidation of accumulated PM in the CPF will lead to creating accurate state estimation strategies. The MTU 1-D CPF model will be used to simulate data collected from this study to examine differences in the PM oxidation kinetics when soy methyl ester (SME) biodiesel is used as the source of fuel for the engine, and when the engine is operated at a higher power rating. A test procedure developed by Hutton et al. [1, 2] was modified to improve the ability to model the experimental data and provide additional insight into passively oxidized PM in a partially regenerated CPF. A test procedure was developed to allow PM oxidation rates by NO2 to be determined from engine test cell data. An experimental matrix consisting of CPF inlet temperatures from 250 to 450 °C with varying NOX/PM from 25 to 583and NO2/PM ratios from 5 to 240 was used. SME biodiesel was volumetrically blended with ULSD in 10% (B10) and 20% (B20) portions. This blended fuel was then used to evaluate the effect of biodiesel on passive oxidation rates. Four tests were performed with B10 and four tests with B20. Gathering data to determine the effect of fuel type (ULSD and biodiesel blends) on PM oxidation is the primary goal. The engine used for this testing was then configured to a higher power rating and one of the tests planned was performed. Additional testing is scheduled to take place with ULSD fuel to determine the affect the engine rating has on the PM oxidation. The experimental reaction rates during passive oxidation varied based upon the average CPF temperature, NO2 concentrations, and the NOX/PM ratios for each engine rating and with all fuels. The data analysis requires a high fidelity model that includes NO2 and thermal oxidation mechanisms and back diffusion to determine the details of the PM oxidation process.

AGROFORESTRY ADDRESSING SOCIAL AND ENVIRONMENTAL ISSUES IN PARAGUAY

Paraguay is characterized in part by an economy reliant on a massive soy industry and as facing social and economic challenges resulting from highly inequitable distribution of wealth and land ownership, particularly for smallholder farmers in the rural areas of the country. Yerba mate (Ilex paraguariensis), a native tree of which the leaves are used in tea, has become an increasingly common crop grown among common among smallholder farmers (owners of 10 hectares or less) as a viable alternative to soy production on a small scale. In the rural agricultural community of Libertad del Sur, located in the heart of the severely deforested Bosque Atlántico del Alto-Paraná, a series of development initiatives including tree nurseries and agroforestry projects with yerba mate were implemented with involvement of several governmental and nongovernmental organizations. Research was conducted to identify effectiveness of an agroforestry strategy to promote reforestation activities and sustainable agriculture to achieve economic and subsistence goals of the rural population. Despite a severe drought impacting initial research goals, important lessons are considered regarding promotion of development work within the community as well as community perceptions towards development agencies. Pursuit of compromise between community member and agency goals using sustainable agricultural practices is identified as an effective means to promote mutually beneficial development strategies.

Finely Textured Lean Beef as an Ingredient for Processed Meats

Lean, finely textured beef (LFTB) is a lean product derived from beef-fat trimmings. Characterization of LFTB showed that, while it is high in total protein, the LFTB contains more serum and connective tissue proteins and less myofibrillar proteins than muscle meat. Because of the protein differences, LFTB has less functionality in processed meats, resulting in lower yields and softer texture. Appropriate use of sodium chloride, sodium tripolyphosphate, k-carrageenan, or isolated soy protein achieved desired stability and yields in frankfurters with FTLB. The softer texture may be used to advantage in high-protein, low-fat meat products where excessive toughness or firmness is often a problem.

Effects of different types of solid feeds on health status and performance of Swiss veal calves. I. Basic feeding with milk by-products

The objective of this study was to identify a suitable alternative to the current practice of complementing the feeding of milk by-products with straw. The influence of 5 different types of solid feeds on health and performance of Swiss veal calves was investigated in 2 production cycles of 200 veal calves each with a mean initial age of 40 days (d). The calves were housed in groups of 40 in stalls with outside pen. Liquid feeding consisted of a milk by-product combined with an additional skim milk powder ad libitum. Groups were assigned to 1 of the 5 following experimental solid feeds provided ad libitum: mix (composition: soy flakes, corn, barley, wheat, oat, barley middling, plant oil, molasses), whole plant corn pellets, corn silage, hay, and wheat straw as control. Daily dry matter intake per calf averaged 2.25 kg of the liquid food, 0.16 kg of straw, 0.33 kg of mix, 0.47 kg of corn silage, 0.38 kg of corn pellets, and 0.39 kg of hay. No significant differences (P > 0.05) among groups were found in calf losses that amounted to 4.8 % (68 % because of gastrointestinal disorders). Four percent of the calves were slaughtered prematurely. Daily doses of antibiotics were higher in the mix (36.9 d, P < 0.01) and in the corn silage groups (35 d, P < 0.01) compared to control. Compared to the 4 other groups, calves of the straw group showed the highest prevalence of abnormal ruminal content (73 %, P < 0.05), of abnormal ruminal papillae (42 %, P < 0.05), of abomasal fundic lesions (13.5 %, P < 0.1), and the lowest number of chewing movements per bolus (45, P < 0.05). The hemoglobin concentration averaged 85 g/l at the beginning and 99 g/l at the end of the fattening period with no significant differences among groups (P > 0.1). The duration of the fattening period averaged 114 d, slaughter age 157 d, and carcass weight 122 kg. The average daily weight gain (ADG) was highest in the control group straw (1.35 kg), and lowest in the hay group (1.22 kg, P < 0.01). The number of carcasses classified as C, H, and T (very high to medium quality) was lower in the hay group compared to straw (P < 0.01). No significant differences between groups were found in meat color (P > 0.1): 73 % of the carcasses were assessed as pale (267/364), 18 % as pink (66/364), and 9 % (31/364) as red. The results reveal that whole-plant corn pellets are most consistent with an optimal result combining the calves' health and fattening performance. Therefore, it can be recommended as an additional solid feed for veal calves under Swiss conditions.

Biochanin A and prunetin improve epithelial barrier function in intestinal CaCo-2 cells via downregulation of ERK, NF-κB, and tyrosine phosphorylation

The single-layered gut epithelium represents the primary line of defense against environmental stressors; thereby monolayer integrity and tightness are essentially required to maintain gut health and function. To date only a few plant-derived phytochemicals have been described as affecting intestinal barrier function. We investigated the impact of 28 secondary plant compounds on the barrier function of intestinal epithelial CaCo-2/TC-7 cells via transepithelial electrical resistance (TEER) measurements. Apart from genistein, the compounds that had the biggest effect in the TEER measurements were biochanin A and prunetin. These isoflavones improved barrier tightness by 36 and 60%, respectively, compared to the untreated control. Furthermore, both isoflavones significantly attenuated TNFα-dependent barrier disruption, thereby maintaining a high barrier resistance comparable to nonstressed cells. In docking analyses exploring the putative interaction with the tyrosine kinase EGFR, these novel modulators of barrier tightness showed very similar values compared to the known tyrosine kinase inhibitor genistein. Both biochanin A and prunetin were also identified as potent reducers of NF-κB and ERK activation, zonula occludens 1 tyrosine phosphorylation, and metalloproteinase-mediated shedding activity, which may account for the barrier-improving ability of these isoflavones.

Effect of lipid bilayer properties on the photocycle of green proteorhodopsin

The significance of specific lipids for proton pumping by the bacterial rhodopsin proteorhodopsin (pR) was studied. To this end, it was examined whether pR preferentially binds certain lipids and whether molecular properties of the lipid environment affect the photocycle. pR's photocycle was followed by microsecond flash-photolysis in the visible spectral range. It was fastest in phosphatidylcholine liposomes (soy bean lipid), intermediate in 3-[(3-cholamidopropyl) dimethylammonio] propanesulfonate (CHAPS): 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bicelles and in Triton X-100, and slowest when pR was solubilized in CHAPS. In bicelles with different lipid compositions, the nature of the head groups, the unsaturation level and the fatty acid chain length had small effects on the photocycle. The specific affinity of pR for lipids of the expression host Escherichia coli was investigated by an optimized method of lipid isolation from purified membrane protein using two different concentrations of the detergent N-dodecyl-β-d-maltoside (DDM). We found that 11 lipids were copurified per pR molecule at 0.1% DDM, whereas essentially all lipids were stripped off from pR by 1% DDM. The relative amounts of copurified phosphatidylethanolamine, phosphatidylglycerol, and cardiolipin did not correlate with the molar percentages normally present in E. coli cells. The results indicate a predominance of phosphatidylethanolamine species in the lipid annulus around recombinant pR that are less polar than the dominant species in the cell membrane of the expression host E. coli.

Pyogranulomatous pneumonia in goats caused by an undescribed Porphyromonas species, "Porphyromonas katsikii".

A yet-undescribed bacterial species, tentatively named "Porphyromonas katsikii," was isolated from individuals of a small goat herd with pyogranulomatous pneumonia during an outbreak of acute respiratory disease. The isolated bacteria grew in the form of black-pigmented colonies after 14 days of incubation under anaerobic conditions at 37°C on a tryptic soy blood agar medium. The bacteria were identified as a yet-undescribed Porphyromonas species by determination of the nucleotide sequence of the rrs 16S rRNA gene, and this species was tentatively named Porphyromonas katsikii. PCR amplification with specific primers for this yet-undescribed species revealed the presence of P. katsikii in the lung tissue of all affected animals, while no PCR signals were evidenced from the lungs of healthy goats or from goats with pasteurellosis caused by Mannheimia haemolytica. These data indicate P. katsikii as the causative agent of acute respiratory distress. P. katsikii is phylogenetically related to Porphyromonas somerae and Porphyromonas levii, which cause pathologies in humans and animals, respectively. P. katsikii was not detected by PCR from samples of the gingival pockets or of the faces of healthy goats.

Proceedings of the 14th Annual Biochemical Engineering Symposium

The Annual Biochemical Engineering Symposium series is devoted to presentations by students on their research topics. The fourteenth event, held in 1984, was organized at the University of Missouri–Columbia. It was attended by the biochemical engineering faculty and the students from Colorado State University, Iowa State University, Kansas State University, University of Missouri–Columbia, University of Missouri–Rolla and Washington University, St. Louis. Contents"Estimation of Product Formation Kinetics and Microbial Yield Parameters for Anaerobic Organic Acid and Solvent Production," M.D. Oner, Kansas State University "Characterization of Soy Protein Texturization in a Complex Bioreactor," J.L. Ibave, Colorado State University "Acid and Solvent Fermentations Using Mixed Cultures," D. Stevens, University of Missouri–Columbia "Preliminary Process Design for Ethanol from Sweet Sorghum Ensilage Feedstock," Keith D. Lange, Colorado State University "Lamella Settlers in Ethanol Fermentation," Yong Jayanata, University of Missouri–Columbia "Bubble Size Distribution in the Down Flow Section of an Air-Lift Column," Snehal A. Patel and C.H. Lee, Kansas State University "The Sensitivity of Plant Cells to Shear Stress," Morris Z. Resenberg and Eric H. Dunlap, Washington University, St. Louis "Estimation of Growth Yield Parameters Associated with Microbial Growth," Hyeon Y. Lee, Kansas State University "Capillary Gas Chromatography of Trimethylsilylated Trisaccharides," Etienne J.M. Selosse, Iowa State University "Subsite Mapping of an Endo-Xylanase Labeled Xylooligo-saccharides," Bernard Y. Tao, Iowa State University "Cellulase Enzyme Recycle," Kate M.V. Baptie, Colorado State University "Non-Homogeneous Poisson Renewal Reward Process for Modelling Enzymatic Hydrolysis of Cellulose," M.M. Gharpuray and L.T. Fan, Kansas State University

Proceedings of the Twenty-First Annual Biochemical Engineering Symposium

The 21st Annual Biochemical Engineering Symposium was held at Colorado State University on April 20, 1991. The primary goals of this symposium series are to provide an opportunity for students to present and publish their research work and to promote informal discussions on biochemical engineering research. Contents High Density Fed-Batch Cultivation and Energy Metabolism of Bacillus thuringtensis; W.-M. Liu, V. Bihari, M. Starzak, and R.K. Bajpai Influences of Medium Composition and Cultivation Conditions on Recombinant Protein Production by Bacillus subtilis; K. Park, P.M. Linzmaier, and K.F. Reardon Characterization of a Foreign Gene Expression in a Recombinant T7 Expression System Infected with λ Phages; F. Miao and D.S. Kompala Simulation of an Enzymatic Membrane System with Forced Periodic Supply of Substrate; N. Nakaiwa, M. Yashima, L.T. Fan, and T. Ohmori Batch Extraction of Dilut Acids in a Hollow Fiber Module; D.G. O'Brien and C.E. Glatz Evaluation of a New Electrophoretic Device for Protein Purification; M.-J. Juang and R.G. Harrison Crossflow Microfiltration and Membrane Fouling for Yeast Cell Suspension; S. Redkar and R. Davis Interaction of MBP-β-Galactosidase Fusion Protein with Starch; L. Taladriz and Z. Nikolov Predicting the Solubility of Recombinant Proteins in Escherichia coli; D.L. Wilkinson and R.G. Harrison Evolution of a Phase-Separated, Gravity-Independent Bioractor; P.E. Villeneuve and E.H. Dunlop A Strategy for the Decontamination of Soils Containing Elevated Levels of PCP; S. Ghoshal, S. K. Banelji, and RK. Bajpai Practical Considerations for Implementation of a Field Scale In-Situ Bioremediation Project; J.P. McDonald, CA Baldwin, and L.E. Erickson Parametric Sensitivity Studies of Rhizopus oligosporus Solid Substrate Fermentation; J. Sargantanis, M.N. Karim, and V.G. Murphy, and RP. Tengerdy Production of Acetyl-Xylan Esterase from Aspergillus niger; M.R Samara and J.C. Linden Biological and Latex Particle Partitioning in Aqueous Two-Phase Systems; D.T.L. Hawker, RH. Davis, P.W. Todd, and R Lawson Novel Bioreactor /Separator for Microbial Desulfurization of Coal; H. Gecol, RH. Davis, and J .R Mattoon Effect of Plants and Trees on the Fate, Transport and Biodegradation of Contaminants in the Soil and Ground Water; W. Huang, E. Lee, J.F. Shimp, L.C. Davis, L.E. Erickson, and J.C. Tracy Sound Production by Interfacial Effects in Airlift Reactors; J. Hua, T.-Y. Yiin, LA Glasgow, and L.E. Erickson Soy Yogurt Fermentation of Rapid Hydration Hydrothermal Cooked Soy Milk; P. Tuitemwong, L.E. Erickson, and D.Y.C. Fung Influence of Carbon Source on Pentachlorophenol Degradation by Phanerochaete chrysosportum in Soil; C.-Y.M. Hsieh, RK. Bajpai, and S.K. Banerji Cellular Responses of Insect Cells Spodopiera frugiperda -9 to Hydrodynamic Stresses; P.L.-H. Yeh and RK. Bajpa1 A Mathematical Model for Ripening of Cheddar Cheese; J. Kim, M. Starzak, G.W. Preckshoi, and R.K. Bajpai