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Bioconversion
Terms modified by Bioconversion Selected AbstractsEnhanced bioavailability of a new thiazolidine derivative FPFS-410, an antidiabetic and lipid-lowering drug, after oral administration of its hydroxypropyl-,-cyclodextrin complex to bile duct-cannulated ratsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2006Takumi Hara Abstract The effect of bile acids on bioavailability of FPFS-410 (2-(N -Cyanoimino)-5-{(E)-4-styrylbenzylidene}-4-oxothiazolidine) after oral administration of the drug and its 2-hydroxypropyl-,-cyclodextrin (HP-,-CyD) complex was investigated. The complexation with HP-,-CyD increased the oral bioavailability of FPFS-410 in normal rats in a HP-,-CyD concentration-dependent manner, compared with that of drug alone. In bile duct-cannulated rats, bile acid concentrations in pylic serum and biliary were decreased to 18% and 14% of sham-operated rats, respectively. After oral administration of the HP-,-CyD complex, the plasma levels of FPFS-410 were lower in bile duct-cannulated rats than in sham-operated rats up to 1 h, however, this order reversed from 2 to 12 h. The plasma levels of M1, a dominant metabolite of FPFS-410 in rats, significantly decreased until 2 h after administration of the complex in bile duct-cannulated rats, compared with in sham-operated rats. Bioconversion of FPFS-410 to M1 and CYP3A2 expression in the liver was markedly lowered by bile duct-cannulation. Bile duct-cannulation did not, however, affect the serum levels of estradiol. These results suggest that bile acids have a pivotal role for bioavailability of FPFS-410 after oral administration of the FPFS-410 complex with HP-,-CyD through CYP3A2 activity in liver of rats. © 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 95: 1771,1782, 2006 [source] Bioconversion of naltrexone and its 3-O-alkyl-ester prodrugs in a human skin equivalentJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 4 2005Dana C. Hammell Abstract The purpose of this study was to compare the percutaneous absorption and bioconversion of naltrexone (NTX), naltrexone-3-O-valerate (VAL), and naltrexone-3-O-(2,-ethylbutyrate) (ETBUT) in a human skin equivalent model (EpiDermÔ) and in fresh human skin in vitro. NTX diffusion and metabolism to 6-,-naltrexol (NTXol) were quantitated and compared in the EpiDermÔ and in excised fresh human skin. VAL and ETBUT diffusion and bioconversion studies were also completed in EpiDermÔ. Naltrexone bioconverted to levels of 3,±,2% NTXol in the EpiDermÔ and 1,±,0.5% in fresh human skin. VAL hydrolyzed rapidly in the EpiDermÔ and mainly (93,±,4%) NTX was found in the receiver compartment, similar to human skin. More intact ETBUT permeated the EpiDermÔ tissue compared to VAL, and only 15,±,11% NTX was found in the receiver. Significantly higher fluxes of NTX and the prodrugs were observed with the EpiDermÔ compared to human skin. A similar flux enhancement level was observed for VAL, compared to NTX base, in the EpiDermÔ and the human skin. Metabolically active human epidermal models like EpiDermÔ are useful as an alternative experimental system to human skin for prediction of topical/transdermal drug/prodrug bioconversion. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:828,836, 2005 [source] Bioconversion of 3,-acetoxypregna-5,16-diene-20-one to androsta-1,4-diene-3,17-dione by mixed bacterial cultureLETTERS IN APPLIED MICROBIOLOGY, Issue 2 2002S. Patil Aims:,To isolate a bacterium capable of degrading 3,-acetoxypregna-5,16-diene-20-one (16-DPA) to androsta-1,4-diene-3,17-dione (ADD) and to decipher the biodegradation pathway. Methods and Results:,Isolation on mineral salt agar containing 16-DPA as sole carbon source yielded two bacteria identified as Pseudomonas diminuta and Comamonas acidovorons. These bacteria failed to degrade 16-DPA individually in pure cultures but converted 16-DPA to ADD in a mixed culture. The intermediates accumulated during the bioconversion were identified as pregna-4,16-diene-3,20-dione and pregna-1,4,16-triene-3,20-dione. Conclusions:,The degradation pattern of 16-DPA by mixed bacterial culture revealed the reaction sequence as (i) cleavage of C-3 acetyl function, (ii) dehydrogenation at C-1 and C-2 positions and (iii) cleavage of C-17 side-chain. Significance and Impact of the Study:,The present work opens a new approach towards the production of a female sex hormone precursor and elucidates the biodegradation pathway of 16-DPA by mixed bacterial culture. [source] Influence of Dietary Fat on ,-Carotene Absorption and Bioconversion into Vitamin ANUTRITION REVIEWS, Issue 4 2002Judy D. Ribaya-Mercado Sc.D. Dietary fat facilitates the utilization of carotenoids and, based on serum ,-carotene or retinol responses following ingestion of meals containing carotene and fat sources, it has been reported that the amount of fat required in a meal may be minimal (,3-5 g). However, the dietary fat requirement for optimal carotene utilization in humans cannot be fully ascertained without longer-term dose-response studies that measure the changes in vitamin A body stores in response to varying levels of dietary fat. In humans, vitamin A body stores can be determined by use of stable isotope-dilution methods. Animal studies have shown that although the level of dietary fat has no effect on serum vitamin A concentrations of animals fed ,-carotene, higher liver vitamin A concentrations were found in those that ingested higher fat levels. Other factors that might influence the relationship of fat intake and ,-carotene utilization include the type of fat ingested, physicochemical properties of the carotenoid source, amount of carotene ingested, whether fat and ,-carotene sources are provided in the same meal, the presence of helminthic infections, age, and vitamin A status. [source] Sulfur Deficiency Changes Mycosporine-like Amino Acid (MAA) Composition of Anabaena variabilis PCC 7937: A Possible Role of Sulfur in MAA BioconversionPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2010Shailendra P. Singh In the present investigation we show for the first time that bioconversion of a primary mycosporine-like amino acid (MAA) into a secondary MAA is regulated by sulfur deficiency in the cyanobacterium Anabaena variabilis PCC 7937. This cyanobacterium synthesizes the primary MAA shinorine (RT = 2.2 min, ,max = 334 nm) under normal conditions (PAR + UV-A + UV-B); however, under sulfur deficiency, a secondary MAA palythine-serine (RT = 3.9 min, ,max = 320 nm) appears. Addition of methionine to sulfur-deficient cultures resulted in the disappearance of palythine-serine, suggesting the role of primary MAAs under sulfur deficiency in recycling of methionine by donating the methyl group from the glycine subunit of shinorine to tetrahydrofolate to regenerate the methionine from homocysteine. This is also the first report for the synthesis of palythine-serine by cyanobacteria which has so far been reported only from corals. Addition of methionine also affected the conversion of mycosporine-glycine into shinorine, consequently, resulted in the appearance of mycosporine-glycine (RT = 3.6 min, ,max = 310 nm). Our results also suggest that palythine-serine is synthesized from shinorine. Based on these results we propose that glycine decarboxylase is the potential enzyme that catalyzes the bioconversion of shinorine to palythine-serine by decarboxylation and demethylation of the glycine unit of shinorine. [source] A novel microplate-based screening strategy to assess the cellulolytic potential of Trichoderma strainsBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2010Stefano Cianchetta Abstract Bioconversion of lignocellulosic biomass to fuel requires a hydrolysis step to obtain fermentable sugars, generally accomplished by fungal enzymes. An assorted library of cellulolytic microbial strains should facilitate the development of optimal enzyme cocktails specific for locally available feedstocks. Only a limited number of strains can be simultaneously assayed in screening based on large volume cultivation methods, as in shake flasks. This study describes a miniaturization strategy aimed at allowing parallel assessment of large numbers of fungal strains. Trichoderma strains were cultivated stationary on microcrystalline cellulose using flat bottom 24-well plates containing an agarized medium. Supernatants obtained by a rapid centrifugation step of the whole culture plates were evaluated for extracellular total cellulase activity, measured as filter paper activity, using a microplate-based assay. The results obtained were consistent with those observed in shake-flask experiments and more than 300 Trichoderma strains were accordingly characterized for cellulase production. Five strains, displaying on shake-flasks at least 80% of the activity shown by the hyper-cellulolytic mutant Trichoderma Rut-C30, were correctly recognized by the screening on 24-well plates, demonstrating the feasibility of this approach. Cellulase activity distribution for the entire Trichoderma collection is also reported. One strain (T. harzianum Ba8/86) displayed the closest profile to the reference strain Rut-C30 in time course experiments. The method is scalable and addresses a major bottleneck in screening programs, allowing small-scale parallel cultivation and rapid supernatant extraction. It can also be easily integrated with high-throughput enzyme assays and could be suitable for automation. Biotechnol. Bioeng. 2010;107: 461,468. © 2010 Wiley Periodicals, Inc. [source] Bioconversion of Linoleic Acid into Conjugated Linoleic Acid by Immobilized Lactobacillus reuteriBIOTECHNOLOGY PROGRESS, Issue 3 2003Sun-Ok Lee Lactobacillus reuteri was immobilized on silica gel to evaluate the bioconversion of linoleic acid (LA) into conjugated linoleic acid (CLA), consisting of cis -9,trans -11 and trans -10,cis -12 isomers. The amount of cell to carrier, the reaction time, and the substrate concentration, pH, and temperature for CLA production were optimized at 10 mg of cells/(g of carrier), 1 h, 500 mg/L LA, 10.5, and 55 °C, respectively. In the presence of 1.0 mM Cu2+, CLA production increased by 110%. Under the optimal conditions, the immobilized cells produced 175 mg/L CLA from 500 mg/L LA for 1 h with a productivity of 175 mg/(L·h) and accumulated 5.5 times more CLA than that obtained from bioconversion by free washed cells. The CLA-producing ability of reused cells was investigated over five reuse reactions and was maximal at pH 7.5, 25 °C, and 1.0 mM Cu2+. The total amount of CLA by the combined five reuse reactions was 344 mg of CLA/L reaction volume. This was 8.6 times higher than the amount obtained from reuse reactions by free washed cells. [source] Mixed Culture Bioconversion of 16-Dehydropregnenolone Acetate to Androsta-1,4-diene-3,17-dione: Optimization of ParametersBIOTECHNOLOGY PROGRESS, Issue 2 2003Tushar Banerjee Bioconversion of 16-dehydropregnenolone acetate (16-DPA) to androsta-1,4-diene-3,17-dione (ADD), an intermediate for the production of female sex hormones, by mixed culture of Pseudomonasdiminuta MTCC 3361 and Comamonas acidovorans MTCC 3362 is reported. Various physicochemical parameters for the bioconversion of 16-DPA to ADD have been optimized in shake flask cultures. Nutrient broth inoculated with actively growing co-culture proved ideal for bacterial growth and bioconversion. A temperature range of 35,40 °C was most suitable; higher or lower temperatures adversely affected the bioconversion. Dimethylformamide below 2% concentration was the most suitable carrier solvent. Maximum conversion was recorded at 0.5 mg mL,1 16-DPA. A pH of 5.0 yielded a peak conversion of 62 mol % in 120 h incubation period. Addition of 9,-hydroxylase inhibitors failed to prevent further breakdown of ADD to nonsteroidal products. 16-DPA conversion in a 5 L fermenter followed a similar trend. [source] ChemInform Abstract: Bioconversion of Substituted Styrenes to the Corresponding Enantiomerically Pure Epoxides by a Recombinant Escherichia coli Strain.CHEMINFORM, Issue 7 2001Silvana Bernasconi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Indices for bioavailability and biotransformation potential of contaminants in soilsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2004Washington J. Braida Abstract Bioavailability is an important consideration in risk assessment of soil contaminants and in the selection of appropriate remediation technologies for polluted sites. The present study examined the bioavailability and biodegradation potential of phenanthrene with respect to a pseudomonad in 15 different soils through separate measurements of mineralization, transformation, and desorption to a polymeric infinite sink (Tenax®) after 180-d sterile pre-equilibration with phenanthrene. Fractions strongly resistant to desorption and mineralization at long times were evident in all cases. After correcting for bioconversion (moles mineralized per mole transformed) determined in aqueous particle-free soil extracts, a correlation was found between the biotransformation-resistant fraction and the Tenax desorption-resistant fraction. Indices are proposed to assess bioavailability (BAt) and biotransformation potential (BTPt) of a compound in a soil based on parallel desorption and degradation studies over a selected period t. The BAt is the ratio of moles biotransformed to moles desorbed to an infinite sink, and it reflects the biotransformation rate relative to the maximal desorption rate. Values of BA30 (30-d values) ranged from 0.64 (for dark gray silt loam) to 1.12 (Wurtsmith Air Force Base [AFB] 2B, Oscoda, MI, USA). The BTPt is the ratio between moles biotransformed and moles of contaminant remaining sorbed after maximal desorption. The BTPt provides an indication of the maximum extent of biotransformation that may be expected in a system, assuming desorption is a prerequisite for biodegradation. Values of BTP30 ranged between 0.3 (Wurtsmith AFB 1B) and 13 (Mount Pleasant silt loam, NY, USA). The combination of BAt and BTPt provides insights regarding the relationship between physical availability (desorption) and biological processes (biotransformation kinetics, toxicity, other soil factors) that occur during biodegradation and are suggested to represent the remediation potential of the chemical. The BA30 values less than 0.9 and BTP30 values less than five indicate poor potential for site remediation. [source] Preventing biofilm formation: promoting cell separation with terpenesFEMS MICROBIOLOGY ECOLOGY, Issue 3 2007Carla C.C.R. De Carvalho Abstract Both carveol and carvone were effective in dispersing Rhodococcus erythropolis cells that were being stimulated to aggregate by the presence of organic solvents. The two terpenes influenced the fatty acid composition of the cell membrane, decreasing the percentage of fatty acids with more than 16 carbon atoms, and thus cell hydrophobicity, and also the degree of saturation of the fatty acids. In the presence of 250 ,mol of terpene, the volume of biofilm was reduced by one third in comparison with biofilms in the absence of terpenes. The percentage of aggregated cells was also found to depend on carvone concentration during the bioconversion of carveol to carvone, in a membrane reactor. The extent of cell aggregation decreased from 90% to 10% when carvone concentration reached ca. 48 mM in the organic phase. [source] Separation and characterization of the 1,3-propanediol and glycerol dehydrogenase activities from Clostridium butyricum E5 wild-type and mutant DJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2001H. Malaoui H. MALAOUI AND R. MARCZAK. 2001. Aims:,Clostridium butyricum E5 wild-type and mutant E5-MD were cultivated in chemostat culture on glycerol in order to compare the properties of two key enzymes of glycerol catabolism, i.e. propanediol and glycerol dehydrogenase. Methods and Results:,These two enzymes, which belong to the dha regulon, were separated by gel filtration. Both dehydrogenase activities displayed similar properties, such as pH optimum values, specificity towards physiological substrates and dependence on Mn2+. Both strains accumulate glycerol at high levels. Conclusion:,The mutant D strain contained a propanediol dehydrogenase activity which had a low affinity for its physiological substrate, leading to the conclusion that this strain would seem more resistant to the toxic effect of 3-hydroxypropionaldehyde than the wild-type. Significance and Impacts of the study: These properties make Cl. butyricum mutant D strain the best candidate so far to be used as a biotechnological agent for the bioconversion of glycerol to 1,3-propanediol. [source] Kinetics and thermodynamics of glucoamylase inhibition by lactate during fermentable sugar production from food wasteJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2010Xiao Qiang Wang Abstract BACKGROUND: Glucoamylase hydrolysis is a key step in the bioconversion of food waste with complicated composition. This work investigated the effect of lactate on glucoamylase from Aspergillus niger UV-60, and inhibition mechanisms of glucoamylase by lactate during food waste hydrolysis. RESULTS: For 125 min hydrolysis of food waste (10%, dry basis), reducing sugars produced in the absence of lactate were 15%, 26% and 56% more than those produced in the presence of 24 g L,1 lactate at 60, 50 and 40 °C, respectively. Kinetic study showed that the type of glucoamylase inhibition by lactate was competitive, and Km (Michaelis-Menten constent), Vmax (maximum initial velocity), KI (inhibition constant) were 103.2 g L,1, 5.0 g L,1 min,1, 100.6 g L,1, respectively, for food waste hydrolysis at 60 °C and pH 4.6. Lactate also accelerated glucoamylase denaturation significantly. Activation energy of denaturation without inhibitor was 61% greater than that of denaturation with inhibitor (24 g L,1 lactate). Half-lives (t1/2) without inhibitor were 7.6, 2.7, 2.6, 1.7 and 1.2 times longer than those with inhibitor at temperature 40, 45, 50, 55 and 60 °C, respectively. CONCLUSION: These results are helpful to process optimization of saccharification and bioconversion of food waste. Copyright © 2010 Society of Chemical Industry [source] Strain isolation and optimization of process parameters for bioconversion of glycerol to lactic acidJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2009An-An Hong Abstract BACKGROUND: The crude glycerol from biodiesel production represents an abundant and inexpensive source which can be used as raw material for lactic acid production. The first aim of this investigation was to select a strain suitable for producing lactic acid from glycerol with a high concentration and productivity. The second aim was to obtain the optimum fermentation conditions, as a basis for large-scale lactate production in the future. RESULTS: Eight bacterial strains, which could aerobically convert glycerol to lactic acid, were screened from soil samples. One of the strains, AC-521, which synthesized lactic acid with a higher concentration, was identified based on its 16S rDNA sequences and physiological characteristics. These results indicated that this strain was a member of Escherichia coli. The optimal fermentation conditions for Escherichia coli AC-521 were 42 °C, pH 6.5, 0.85 min,1 (KLa). CONCLUSION:Escherichia coli AC-521 suitable for producing lactic acid from glycerol with high concentration and productivity was identified. After 88 h of fed-batch fermentation, both the lactic acid concentration and glycerol consumption reached maximum, giving 85.8 g L,1 of lactic acid with a productivity of 0.97 g L,1 h,1 and a yield of 0.9 mol mol,1 glycerol. Copyright © 2009 Society of Chemical Industry [source] Lactic acid fermentation of food waste using integrated glucoamylase productionJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2009Xiao Qiang Wang Abstract 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 [source] Multiparameter models for performance analysis of UASB reactorsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 8 2008C M Narayanan Abstract BACKGROUND: UASB (upflow anaerobic sludge blanket) bioreactors have the distinct advantage that they do not demand support particles and provide a high rate of bioconversion even with high strength feedstocks. Although apparently simple in construction, the performance analysis of these reactors involves a high degree of mathematical complexity. Most simulation models reported in the literature are rudimentary in nature as they involve gross approximations. In the present paper, two multiparameter simulation packages are presented that make no simplifying assumptions and hence are more rigorous in nature. RESULTS: The first package assumes the sludge bed to be a plug-flow reactor (PFR) and the sludge blanket to be an ideal continuous stirred tank reactor (CSTR). The second package equates the reactor to a plug flow dispersion reactor (PFDR), the axial dispersion coefficient however being a function of axial distance. The three phase nature of the sludge blanket has been considered and the variation of gas velocity in the axial direction has been taken into account. Three different kinetic equations have been considered. Resistance to diffusion of substrate into sludge granules has been accounted for by incorporating appropriately defined effectiveness factors. The applicability of simulation packages developed has been ascertained by comparing with real-life data collected from industrial/pilot plant/laboratory UASB reactors. The maximum deviation observed is ± 15%. CONCLUSIONS: Although the software packages developed have high computational load, their applicability has been successfully ascertained and they may be recommended for design and installation of industrial UASB reactors and also for the rating of existing installations. Copyright © 2008 Society of Chemical Industry [source] Effects of organic matter and initial carbon,nitrogen ratio on the bioconversion of volatile fatty acids from sewage sludgeJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2008Xiaoling Liu Abstract BACKGROUND: The biodegradable organic matter and the initial carbon,nitrogen ratio can be substantially different in different batches of sewage sludge, which results in a difference in the acidification efficiency of sludge. Using sewage sludge from three different sources, batch tests were performed to analyze the relationship between volatile fatty acids (VFAs) and consumed organic matter, and to investigate the effects of initial carbon,nitrogen (C/N) ratio on the acidification efficiency of sludge. RESULTS: Maximum yields of 152.1 ± 3.5 mg total VFAs-COD per gram volatile solid (VS) added and 22.4 ± 1.2 mg butyric acid-COD g,1 VS added were obtained from the sludge with the highest initial C/N ratio. Statistical analysis indicated that protein was the major substrate for the produced VFAs. The sludge with the least initial C/N ratio (5.01) had the least yield, and only acetic acid, which was also mainly related to protein, was detected. CONCLUSION: The initial carbon,nitrogen ratio was one of the most important factors influencing the distribution patterns of VFAs and the yield of total VFAs produced from sewage sludge. A high C/N ratio could not only improve the yield of total VFAs but also enhance the yield of butyric acid. Copyright © 2008 Society of Chemical Industry [source] The use of hybrid anaerobic solid,liquid (HASL) system for the treatment of lipid-containing food wasteJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2005Olena Stabnikova Abstract The hybrid anaerobic solid,liquid (HASL) system was a modified two-phase anaerobic digester developed for bioconversion of food waste. The aim of this study was to estimate the feasibility of the HASL system for the treatment of food waste with a high content of lipids. The presence of lipids in food waste increased the energy value of nutrients but could inhibit growth of methanogens. The positive effect of lipids on the performance of anaerobic digestion dominated when the contents of lipids were in the range from 20 to 30% of total solids of food waste. Lipid contents of 40% diminished the production of volatile fatty acids in the acidogenic reactor as well as biogas production and the concentration of total bacteria and methanogens in the methanogenic reactor. Therefore, the HASL system can be used for the treatment of lipid-containing food wastes if the lipid content is below 40% of total solids. Copyright © 2005 Society of Chemical Industry [source] Pretreatment of barley husk for bioethanol productionJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2005Beatriz Palmarola-Adrados Abstract This paper reports on the optimization of steam pretreatment of barley husk for high pentose and hexose recovery in the subsequent enzymatic hydrolysis step, as well as high ethanol yield, following simultaneous saccharification and fermentation. The parameters optimized in the steam pretreatment step were residence time (5,15 min), temperature (190,215 °C), and concentration of the acid catalyst (0 or 0.5% H2SO4). A microwave oven was employed for screening of the optimal conditions to obtain the highest sugar yield following combined pretreatment and enzymatic hydrolysis. The final optimization of the pretreatment prior to enzymatic hydrolysis was performed on a larger scale, in a steam pretreatment unit. Simultaneous saccharification and fermentation was carried out following steam pretreatment on 5 and 10% dry matter steam-pretreated slurries. Fermentability tests were performed to determine the effect of by-products (ie furfural and 5-hydroxymethyl furfural) in the bioconversion of glucose to ethanol by baker's yeast. The maximum glucose yield, 88% of the theoretical, was obtained following steam pretreatment with 0.5% H2SO4 at 200 °C for 10 min. Under these conditions, a sugar to ethanol conversion of 81% was attained in simultaneous saccharification and fermentation. Copyright © 2004 Society of Chemical Industry [source] Biotransformation of benzaldehyde to L -phenylacetylcarbinol (L -PAC) by Torulaspora delbrueckii and conversion to ephedrine by microwave radiationJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2002Vilas B Shukla Abstract In a 5,dm3 stirred tank reactor, bioconversion of 30,g benzaldehyde by cells of Torulaspora delbrueckii yielded 22.9,g of pure L -phenylacetylcarbinol (L -PAC). Facile functional group transformation of 4.5,g of L -PAC to 2-(methylimino)-1-phenyl-1-propanol by exposure to microwave irradiation for 9,min resulted in 2.48,g of product. Conversion of 4.8,g of 2-(methylimino)-1-phenyl-1-propanol to 3.11,g of ephedrine was achieved by exposure to microwaves in a reaction time of 10,min. The identity of all the products was confirmed by 1H NMR and FT-IR analysis. © 2002 Society of Chemical Industry [source] Extractive bioconversion in a four-phase external-loop airlift bioreactorAICHE JOURNAL, Issue 7 2000Lidija Sajc The integration of biosynthesis and product separation can increase the productivity of immobilized plant cells in airlift bioreactors. Extractive bioconversion of anthraquinones was studied in an external-loop airlift bioreactor consisting of a riser, a downcomer, and two horizontal sections, while containing alginate-immobilized Frangula alnus cells, a continuous aqueous phase (nutrient solution), dispersed solvent phase (n-hexadecane or silicone oil), and gas bubbles. A simple mathematical model was developed to describe the cocurrent liquid-liquid extraction in the riser section of the bioreactor and to rationalize the measured product concentrations in the aqueous and solvent phase. The model equations were solved analytically in a dimensionless form and used to study the effects of flow conditions, solvent properties, product formation rate, droplet size, and contactor length on the extraction efficiency and product concentration profiles in the continuous and dispersed phase. [source] Enzymes involved in the bioconversion of ester-based prodrugsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2006Bianca M. Liederer Abstract Enzymes are essential for the activation of many prodrugs. In this review, the most important enzymes (e.g., paraoxonase, carboxylesterase, acetylcholinesterase, cholinesterase) involved in the bioconversion of ester-based prodrugs will be discussed in terms of their biology and biochemistry. Most of these enzymes fall into the category of hydrolytic enzymes. However, nonhydrolytic enzymes, including cytochrome P450s, can also catalyze the bioconversion of ester prodrugs and thus will be discussed here. Other factors influencing the ability of these enzymes to catalyze the bioconversion of ester-based prodrugs, particularly species and interindividual differences and stereochemical and structural features of the prodrugs, will be discussed. © 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 95:1177,1195, 2006 [source] Bioconversion of naltrexone and its 3-O-alkyl-ester prodrugs in a human skin equivalentJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 4 2005Dana C. Hammell Abstract The purpose of this study was to compare the percutaneous absorption and bioconversion of naltrexone (NTX), naltrexone-3-O-valerate (VAL), and naltrexone-3-O-(2,-ethylbutyrate) (ETBUT) in a human skin equivalent model (EpiDermÔ) and in fresh human skin in vitro. NTX diffusion and metabolism to 6-,-naltrexol (NTXol) were quantitated and compared in the EpiDermÔ and in excised fresh human skin. VAL and ETBUT diffusion and bioconversion studies were also completed in EpiDermÔ. Naltrexone bioconverted to levels of 3,±,2% NTXol in the EpiDermÔ and 1,±,0.5% in fresh human skin. VAL hydrolyzed rapidly in the EpiDermÔ and mainly (93,±,4%) NTX was found in the receiver compartment, similar to human skin. More intact ETBUT permeated the EpiDermÔ tissue compared to VAL, and only 15,±,11% NTX was found in the receiver. Significantly higher fluxes of NTX and the prodrugs were observed with the EpiDermÔ compared to human skin. A similar flux enhancement level was observed for VAL, compared to NTX base, in the EpiDermÔ and the human skin. Metabolically active human epidermal models like EpiDermÔ are useful as an alternative experimental system to human skin for prediction of topical/transdermal drug/prodrug bioconversion. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:828,836, 2005 [source] Methyl esters of N -(dicyclohexyl)acetyl-piperidine-4-(benzylidene-4-carboxylic acids) as drugs and prodrugs: A new strategy for dual inhibition of 5,-reductase type 1 and type 2JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2005Martina Streiber Abstract Steroid 5,-reductase (5,R) inhibitory potency of three N -(dicyclohexyl)acetyl-piperidine-4-(benzylidene-4-carboxylic acids) and their corresponding methyl esters was monitored for type 2 isoenzyme in a benign prostatic hyperplasia cell free preparation and for type 1 isoenzyme in DU145 cells and in a cell free assay. The hydrolytic stability of the esters and their bioconversion to the corresponding acids was assessed in aqueous buffered solution (pH 7.4) and in selected biological media having measurable esterase activities. The carboxylic acids 1, 2, and 3 with high type 2 inhibitory potencies displayed only little type 1 inhibition. The esters 1a, 2a, and 3a, originally designed as prodrugs to enhance cell permeation, proved to be potent type 1 inhibitors and are therefore acting as drugs themselves. They are stable in buffered salt solution (pH 7.4), Caco-2 cells, and human plasma, whereas all esters are cleaved into the corresponding acids in benign prostatic hyperplasia tissue homogenate. Methyl esters, applied as hydrolytically stable precursor drugs to facilitate cell permeation, will yield the corresponding carboxylic acids as type 2 inhibitors after hydrolysis in the target organ. The esters themselves,stable in human plasma and Caco-2 cells,are acting as potent drugs toward 5,R type 1. Thus, dual inhibition of 5,R type 1 and type 2 can be achieved by applying a single parent compound. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:473,480, 2005 [source] Analysis of carotenoids in ripe jackfruit (Artocarpus heterophyllus) kernel and study of their bioconversion in ratsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2005UG Chandrika Abstract Vitamin A deficiency is of public health importance in Sri Lanka. Carotenoids are a significant source of provitamin A. The objective of this study was to analyse the carotenoid composition of jackfruit (Artocarpus heterophyllus sinhala: Waraka) kernel using MPLC and visible spectrophotometry and to determine the bioavailability and bioconversion of carotenoids present in jackfruit kernel by monitoring (i) the growth and (ii) levels of retinol and carotenoids in the liver and serum of Wistar rats provided with jackfruit incorporated into a standard daily diet. Carotenoid pigments were extracted using petroleum ether/methanol and saponified using 10% methanolic potassium hydroxide. Six carotenoids were detected in jackfruit kernel. The carotenes ,-carotene, ,-carotene, ,-zeacarotene, ,-zeacarotene and ,-carotene-5,6-epoxide and a dicarboxylic carotenoid, crocetin, were identified, corresponding theoretically to 141.6 retinol equivalents (RE) per 100 g. Our study indicated that jackfruit is a good source of provitamin A carotenoids, though not as good as papaya. Serum retinol concentrations in rats supplemented with jackfruit carotenoids were significantly higher (p = 0.008) compared with the control group. The same was true for liver retinol (p = 0.006). Quantification was carried out by RP-HPLC. These results show that the biological conversion of provitamin A in jackfruit kernel appears satisfactory. Thus increased consumption of ripe jackfruit could be advocated as part of a strategy to prevent and control vitamin A deficiency in Sri Lanka. Copyright © 2004 Society of Chemical Industry [source] Bioconversion of 3,-acetoxypregna-5,16-diene-20-one to androsta-1,4-diene-3,17-dione by mixed bacterial cultureLETTERS IN APPLIED MICROBIOLOGY, Issue 2 2002S. Patil Aims:,To isolate a bacterium capable of degrading 3,-acetoxypregna-5,16-diene-20-one (16-DPA) to androsta-1,4-diene-3,17-dione (ADD) and to decipher the biodegradation pathway. Methods and Results:,Isolation on mineral salt agar containing 16-DPA as sole carbon source yielded two bacteria identified as Pseudomonas diminuta and Comamonas acidovorons. These bacteria failed to degrade 16-DPA individually in pure cultures but converted 16-DPA to ADD in a mixed culture. The intermediates accumulated during the bioconversion were identified as pregna-4,16-diene-3,20-dione and pregna-1,4,16-triene-3,20-dione. Conclusions:,The degradation pattern of 16-DPA by mixed bacterial culture revealed the reaction sequence as (i) cleavage of C-3 acetyl function, (ii) dehydrogenation at C-1 and C-2 positions and (iii) cleavage of C-17 side-chain. Significance and Impact of the Study:,The present work opens a new approach towards the production of a female sex hormone precursor and elucidates the biodegradation pathway of 16-DPA by mixed bacterial culture. [source] Meeting Requirements for Vitamin ANUTRITION REVIEWS, Issue 11 2000Clive E. West Ph.D., D.Sc. When the intake of foods or pharmaceutical preparations containing sufficient nutrients of adequate bioavailability are consumed, nutrient requirements are met and optimal nutritional status is maintained. Recent studies have shown that the basis for describing vitamin A activity of carotenoids overestimates the bioavailability of provitamin A carotenoids and their bioconversion to retinol (vitamin A). It is therefore proposed that instead of 6 pg from a mixed diet, 21 ,g ,-carotene are required to provide 1 ,g of retinol or 1 RE (retinol equivalent) of vitamin A. Based on this assumption and on data from food balance sheets, estimates of daily per capita vitamin A intake expressed in RE in Africa, South America, and Asia are reduced from 895, 599, and 667, respectively, to 371, 372, and 258, respectively. Such intakes are well below the recommended daily intake of 600 RE for adult males. A new combination of approaches will therefore have to be used to combat vitamin A deficiency rather than that used up until now. [source] Sulfur Deficiency Changes Mycosporine-like Amino Acid (MAA) Composition of Anabaena variabilis PCC 7937: A Possible Role of Sulfur in MAA BioconversionPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2010Shailendra P. Singh In the present investigation we show for the first time that bioconversion of a primary mycosporine-like amino acid (MAA) into a secondary MAA is regulated by sulfur deficiency in the cyanobacterium Anabaena variabilis PCC 7937. This cyanobacterium synthesizes the primary MAA shinorine (RT = 2.2 min, ,max = 334 nm) under normal conditions (PAR + UV-A + UV-B); however, under sulfur deficiency, a secondary MAA palythine-serine (RT = 3.9 min, ,max = 320 nm) appears. Addition of methionine to sulfur-deficient cultures resulted in the disappearance of palythine-serine, suggesting the role of primary MAAs under sulfur deficiency in recycling of methionine by donating the methyl group from the glycine subunit of shinorine to tetrahydrofolate to regenerate the methionine from homocysteine. This is also the first report for the synthesis of palythine-serine by cyanobacteria which has so far been reported only from corals. Addition of methionine also affected the conversion of mycosporine-glycine into shinorine, consequently, resulted in the appearance of mycosporine-glycine (RT = 3.6 min, ,max = 310 nm). Our results also suggest that palythine-serine is synthesized from shinorine. Based on these results we propose that glycine decarboxylase is the potential enzyme that catalyzes the bioconversion of shinorine to palythine-serine by decarboxylation and demethylation of the glycine unit of shinorine. [source] Translational and transcriptional analysis of Sulfolobus solfataricus P2 to provide insights into alcohol and ketone utilisationPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 3 2007Poh Kuan Chong Abstract The potential of Sulfolobus solfataricus P2 for alcohol or ketone bioconversion was explored in this study. S. solfataricus was grown in different concentrations (0.1,0.8% w/v) of alcohols or ketones (ethanol, iso-propanol, n -propanol, acetone, phenol and hexanol) in the presence of 0.4% w/v glucose. Consequently, the addition of these alcohols or ketones into the growth media had an inhibitory effect on biomass production, whereby lag times increased and specific growth rates decreased when compared to a glucose control. Complete glucose utilisation was observed in all cultures, although slower rates of glucose consumption were observed in experimental cultures (average of 14.9,mg/L/h compared to 18.9,mg/L/h in the control). On the other hand, incomplete solvent utilisation was observed, with the highest solvent consumption being approximately 51% of the initial concentration in acetone cultures. Translational responses of S. solfataricus towards these alcohols or ketones were then investigated using the isobaric tags for relative and absolute quantitation (iTRAQ) technique. The majority (>80%) of proteins identified and quantified showed no discernable changes in regulation compared to the control. These results, along with those obtained from transcriptional analysis of key genes involved within this catabolic process using quantitative RT-PCR and metabolite analysis, demonstrate successful alcohol or ketone conversion in S. solfataricus. [source] (,)- epi -Inosose-2ACTA CRYSTALLOGRAPHICA SECTION C, Issue 12 2000Hiroyuki Hosomi The structure of the title compound, C6H10O6, was determined to confirm the position of the keto group in the molecule prepared enantioselectively by a bioconversion from myo -inositol. There are two independent molecules showing similar geometry. [source] | ||||||||||||||||||||||||||||