Continuous fermentation of d-xylose by immobilizedpichia stipitis comparison between cstr and cpfr

Applied Biochemistry and Biotechnology - The main purpose of this work was to compare the performance of two different kinds of reactors (CSTR and CPFR) in order to enhance the ethanol productivity...     

Lipase-catalyzed solvent-free transesterification of wood sterols

Eighteen commercial lipase preparations, either immobilized or crude enzyme powders, were screened for the transesterification of wood sterols. The reactions were carried out in a solvent-free system, at the optimum temperature of the enzyme preparations as reported by the manufacturer and at the pressure of 2 mbar, with 5 or 10% in weight of the enzyme relative to the wood sterol content of the reacting mixture. Methyl esters of sunflower fatty acids were used as transesterifying agent. Of all the enzymes assayed, only Lipase TL from Pseudomonas stutzeri PL-836 (Meito Sangyo) exhibited any significant transesterifying capacity, 85 and 95% of conversion after 2 and 8 h of reaction, respectively, when 10% in weight of enzyme was used.     

Microbial transformation of marine halogenated sesquiterpenes

The sesquiterpene pacifenol is one of the main constituents of the red alga Laurencia claviformis. Earlier work on the semisynthetic derivatives of pacifenol afforded a series of halogenated sesquiterpenes. The aim of the present work was to obtain new hydroxylated derivatives of halogenated sesquiterpenes by means of microbial transformation using Aspergillus niger, Gibberella fujikuroi and Mucor plumbeus. The best results were obtained with M. plumbeus. The microbiological transformation by M. plumbeus of pacifenol, and two semisynthetic derivatives, is described. The structures of the new compounds obtained were determined by spectroscopic means.     

Oxidative degradations of the side chain of unsaturated ent-labdanes. Part II

A route for the degradation of the side chain of ent-labdane derivatives has been devised, giving the useful synthon 2beta,12-dihydroxy-13,14,15,16,17-pentanor-ent-labdane-8-one (8). The use of this compound in the preparation of terpenylquinone derivatives shall be reported elsewhere. In addition we have synthesized the compound 2beta,12-diacetoxy-8beta,17-epoxy-13,14,15,16-tetranor-ent-labdane (10), which upon catalytic epoxide ring opening in alkaline or acid media gave rise in all cases to the formation of tricyclicc ompounds.     

New diterpenoids from Calceolaria polifolia

Four new and seven known diterpenes have been isolated from the dichloromethane extract of the aerial parts of Calceolaria polifolia. The structures of the new compounds were established by spectroscopic evidence.     

The incubation of 13α,17-dihydroxystemodane with Cephalosporium aphidicola

The biotransformation of 13α,17-dihydroxystemodane (3) with the fungus Cephalosporium aphidicola afforded 13α,17,18-trihydroxystemodane (4), 3β,13α,17-tri-hydroxystemodane (5), 13α,17-dihydroxy-stemodan-18-oic acid (6), 3β,11β,13α,17-tetra-hydroxystemodane (7), 11β,13α,17,18-tetrahydroxystemodane (8) and 3β,13α,17,18-tetra-hydroxystemodane (9). The hydroxylation at C-18 of the substrate points to a biosynthetically-directed transformation, because aphidicolin (2) is hydroxylated at this carbon. However, the C-3(β) and C-11(β) hydroxylations seem to indicate a xenobiotic biotransformation.     

Valorization of Artichoke Industrial By-Products Using Green Extraction Technologies: Formulation of Hydrogels in Combination with Paulownia Extracts

The integral valorization of artichoke bracts generated during industrial canning of artichoke was assessed. The extraction of bioactive compounds was addressed with pressurized hot water under subcritical conditions. The performance of this stage on the extraction of phenolics with antioxidant properties and the saccharidic fraction using conventional and microwave heating was compared. The microwave assisted process was more efficient than the conventional one regarding extraction yields of total solubles, and glucose and fructose oligomers and phenolics, because lower operational temperatures and shorter times were needed. Degradation of fructose oligomers was observed at temperatures higher than 160 °C, whereas the maximal phenolic content occurred at 220 °C. Both the extracts and the residual solids, obtained at conditions leading to maximum phenolics yields, were evaluated for the production of starch-based hydrogels, supplemented with Paulownia leaves’ aqueous extracts.     

Anaerobically treated wastewater in agricultural irrigation as an alternative for posttreatment in water-demanding zones

Agroindustries usually produce high amounts of wastewaters and are frequently located close to agricultural activities. Agricultural use of treated wastewaters therefore represents a unique opportunity to solve the problem of water supply for irrigation and disposal of treated water at the same time. This article is the result of collaborative work with the biggest Chilean pisco-(a distillated drink prepared from Muscatel wine) producing company at present. Experiments were conducted to establish anaerobic treatability of wastewaters and also irrigation properties of treated water. With the purpose of confirming laboratory results, a full-scale anaerobic plant was built, and treated water is being used to irrigate 3000 eucalypti. The results showed, at both laboratory and full scale, that anaerobic treatment is suitable for the treatment of pisco wastewater, and that nutrient content of treated water can be beneficial for plant growth, reducing the need for fertilizers.     

Diterpenoids from Calceolaria alba

Chemical examination of the petrol ether (60-80) extract of the aerial parts of Calceolaria alba R. et Pav., collected in Santa Juana, VIII Region, Chile, resulted in the isolation of 3 new diterpenoids. Their structures have been elucidated by a study of their physical and spectral data; in particular using 2 NMR spectroscopy (DEPT, 1H-1H, COSY, NOESY, HMQC and HMBC).     

Enzymatic hydrolysis of starch in a fixed-bed pulsed-flow reactor

Applied Biochemistry and Biotechnology - One of the most important problems in the design and operation of fixed-bed biological reactors is the control of the process rate by mass-transfer...