San Justo, Argentina
San Justo, Argentina

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Bakhtiari N.,Tarbiat Modares University | Mirshahi M.,Tarbiat Modares University | Babaeipour V.,Biochemical Engineering Group | Maghsoudi N.,Shahid Beheshti University of Medical Sciences
Iranian Journal of Biotechnology | Year: 2010

Expression of foreign proteins in E. coli is normally inhibited by exogenous production of acetate. To overcome this problem, various strategies have been proposed and tested to reduce the extent of acetate accumulation. Although these strategies can improve the outcome, the implementation of their proposed techniques is not practical. Because to achieve optimal results, it requires extremely tight control conditions and the actual cost is very high. Furthermore, a simple knockout mutation of the target metabolic pathway would not be appropriate because the acetate pathway plays an important physiological role in E. coli. In this study, we employed an antisense RNA strategy as an elaborated metabolic engineering tool to partially block biosynthesis of two major acetate pathway enzymes, acetate kinase (ACK) and phosphotransacetylase (PTA). The fragments of antisense cassette were cloned sequentially in pBluescriptsk+ and completed cassette subcloned in pLT10T3. The function of this cassette was evaluated with RT-PCR and ACK and PTA assay. The effect of cassette on cell physiology was monitored by determination of optical density, glucose consumption and acetate production. We found that the antisense method partially reduced mRNA levels of the target genes, lowered the concentration of acetate in culture media and increased growth rate and final cell density in antisense-regulated strain. This strategy could provide us with a useful, inexpensive and practical tool to achieve a large-scale protein production system.

Nisenbaum M.,Biochemical Engineering Group | Bouchet A.,Digital Processing Image Group | Guzman M.N.,Laser Laboratory | Gonzalez J.F.,Biochemical Engineering Group | And 4 more authors.
International Journal of Environment and Health | Year: 2014

The movement of the microorganisms towards a higher concentration of the chemical attractant is called positive chemotaxis and is involved in the efficiency of chemical degradation. Several studies are focused in this field related to genomics, and towards demonstrating chemotactic responses by bacteria, but there is little information related to the activity and morphology of their response. In this work, we use a recently reported dynamic speckle laser method, to process images and to distinguish motile surface patterns per area of colonisation by applying image processing techniques called fuzzy mathematical morphology (FMM). The images of bacterial colonies are usually surfaced, with vague edges and non-homogeneous grey levels. Hence, conventional image processing methods for shape analysis cannot be applied in these cases. In this paper, we propose the application FMM to solve this problem. The approach given was effective to segment, detect and also to describe colonisation patterns. Copyright © 2014 Inderscience Enterprises Ltd.

Strohle F.W.,Biochemical Engineering Group | Cekic S.Z.,Biochemical Engineering Group | Magnusson A.O.,Biochemical Engineering Group | Schwaneberg U.,RWTH Aachen | And 3 more authors.
Journal of Molecular Catalysis B: Enzymatic | Year: 2013

P450s catalyze a wide spectrum of stereo- and regioselective reactions like hydroxylations, epoxidations and dehydrogenations. Therefore biotransformations with P450s are of great relevance to organic synthesis. The use of isolated enzymes offers advantages over the use of whole cells. A key issue for catalytic applications of isolated P450s is the demand for a continuous electron supply to the heme-group. Mediator driven bioelectrocatalysis can help to overcome this problem. For mediator driven bioelectrocatalysis the identification of a suitable mediator is crucial for the fast development of an efficient electro enzymatic process. To this end we have developed a computational screening method based on using freely available software. Calculated electron transfer rates were compared with measured product formation rates. The novel in silico procedure allows a faster identification of suitable mediators for electrochemically driven P450 catalyzed reactions and can be used as screening tool. It may also lead to a massive reduction of experimental effort for the development of bioelectrochemical reaction systems in the future. © 2012 Elsevier B.V.

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