Upotreba patočnog ulja, nusproizvoda prehrambene industrije u biotehnologiji - Kinetički model enzimske esterifikacije izoamilnog alkohola s oleinskom kiselinom pomoću lipaze B iz plijesni Candida antarctica

Fusel oil is a by-product of distilleries, its main component is i-amyl alcohol, which can form ester compounds. Esterification of oleic acid and i-amyl alcohol by Candida antarctica lipase B (Novozym 435 preparation) in n-heptane solvent was studied in this work. Ping-pong bi-bi mechanism (inhibition phenomena taken into account) was applied as a complex kinetic model. The parameters of the model were determined by numerical methods. It was found that four-parameter model fitted well with the experimental results and described properly the enzymatic reaction.Patočno je ulje („fusel oil“) nusproizvod destilacije, a njegov je glavni sastojak izoamilni alkohol čijom esterifikacijom nastaju esteri. U ovom je radu ispitana esterifikacija oleinske kiseline s izoamilnim alkoholom u n-heptanu pomoću lipaze B izolirane iz kvasca Candida antarctica (preparat Novozym 435). Primijenjen je složeni kinetički model ping-pong bi-bi mehanizma, pri čemu je uzeta u obzir pojava inhibicije. Parametri modela određeni su numeričkim metodama. Utvrđeno je da je za rezultate pokusa i opis enzimske reakcije najprikladniji model sa 4 parametra

Investigating the specific role of external load on the performance versus stability trade-off in microbial fuel cells

The performance and behavior of microbial fuel cells (MFCs) are influenced by among others the external load (Rext). In this study, the anode-surface biofilm formation in MFCs operated under different Rext selection/tracking-strategies was assessed. MFCs were characterized by electrochemical (voltage/current generation, polarization tests, EIS), molecular biological (microbial consortium analysis) and bioinformatics (principal component analysis) tools. The results indicated that the MFC with dynamic Rext adjustment (as a function of the actual MFC internal resistance) achieved notably higher performance but relatively lower operational stability, mainly due to the acidification of the biofilm. The opposite (lower performance, increased stability) could be observed with the static (low or high) Rext application (or OCV) strategies, where adaptive microbial processes were assumed. These possible adaptation phenomena were outlined by a theoretical framework and the significant impact of Rext on the anode colonization process and energy recovery with MFCs was concluded

Bioelectrochemical treatment of municipal waste liquor in microbial fuel cells for energy valorization

Microbial fuel cells (MFCs) are recognized as promising applications to produce bioelectricity by utilizing various waste materials. In this study, dual-chamber microbial fuel cells were employed for energy valorization of an untested substrate, the liquid fraction of pressed municipal solid waste (LPW). This by-product is potentially applicable as a substrate in MFCs because of its high organic matter content. In the course of the experiments, the anodic biofilm response and energy production efficiency have been investigated by experimental design approach, taking substrate and fresh inoculum - mesophilic anaerobic sludge (MAS) - addition into account as factors. It was observed that reinoculation could result in a negative effect on the energy production, especially at low substrate (LPW) dosing levels. However, when the LPW to fresh MAS ratio in the anode chamber exceeded a particular value, the biofilm-associated electrical utilization dominated against the degradation in the bulk phase. Furthermore, the results indicated that the highest energy yields (8-9Jg-1δCODd-1) could be attained at the lowest input COD concentrations. The maximal and average COD removal efficiencies were 94% and 87%, respectively, which indicate the excellent biodegradability of LPW. As for COD removal rate, 1.2-1.9kgCODm-3d-1 could be reached. © 2015 Elsevier Ltd

Effectiveness of a Peptide-rich Fraction from Xenorhabdus budapestensis Culture against Fire Blight Disease on Apple Blossoms

Erwinia amylovora is one of the most frequently occurred plant pathogenic bacterium. It causes necrosis and blight symptoms on host plants and it lead to considerable yield losses throughout the world on apple trees. There is no effective chemical treatment is currently available against fire blight. The purpose of the present study was to search a new, alternative control method. The evaluation of the plant protection potential of an enriched fraction of Xenorhabdus budapestensis cell-free conditioned media was investigated. Purified samples were tested in vitro and in planta against the phytopathogenic bacterium. A reproducible method for isolation of a peptide-rich fraction from Xenorhabdus cell-free conditioned media was established. The process resulted in 400 mg of dry sample prepared from three litres of Xenorhabdus cell culture. Significant correlation was found between the concentration of the purified preparation and the induced inactivation zones against Erwinia amylovora Ea1 in agar diffusion test method. The minimum inhibitory concentration and minimum bactericidal concentration of the purified fraction against Ea1 strain were 8 ;g/mL and 16 ;g/mL, respectively. In planta experiments were tested on an apple cultivar (‘Watson Jonathan’) susceptible to fire blight. The effective range of concentration was 62-200 μg/mL, while treatment with 300 μg/mL and larger amounts caused necrotic symptoms on the petals of flowers. Current study pointed to the effectiveness of the compounds produced by X. budapestensis against fire blight. The development of a commercially applicable formulation of these compounds would allow growers to effectively control fire blight in apple and pear orchards

Application of Ionic Liquids in the Utilization of the Agricultural Wastes: Towards the One-Step Pre-Treatment and Cellulose Hydrolysis

Cheap, renewable lignocellulosic materials are relevant to the future of biofuel production. Wood and agricultural wastes (e.g. straw, corn stover) provide a raw material source that cannot be used for human consumption, thus biofuels from such sources do not threaten the food supply. The aim of the work was to carry out the pre-treatment and hydrolysis of lignocellulosic material in the same ionic liquid solvent (1-n-butyl-3- methyl-imidazolium-chloride, [Bmim]Cl), using ground wheat straw and a mixture of corn (Zea mays) leaf and stover, as substrates. Our measurements show that it is possible to achieve an acceptable glucose content from the cellulose by applying Cellic® CTec2 and Cellic® HTec2 enzyme complexes

Fermentative hydrogen production by conventionally and unconventionally heat pretreated seed cultures: a comparative assessment

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