Scheppen van ruimte : systeeminnovaties voor duurzame voedselproductie, jaarverslag 2004

Ruimte wordt in toenemende mate een schaars goed. Zowel nationaal als mondiaal is er sprake van een gevecht om deze schaarse ruimte. Er zijn claims vanuit diverse hoeken waaronder landbouw, natuur en recreatie, energieproductie, stedelijke ontwikkeling en waterberging. Duurzame voedselproductie kan niet los gezien worden van duurzaam ruimtegebruik. Het programma Scheppen van Ruimte wil aan dit proces een bijdrage leveren. Het bestrijkt bewust een breed terrein van onderzoek vanuit de gedachte dat er geen unieke oplossing bestaat, maar dat de toekomst veelvormig zal zijn. Systeeminnovaties zijn daarom nodig om het ruimteconflict tussen de verschillende functies te verzachten. De voedselproductie-functie moet ruimte scheppen voor andere functie

Vaccination of carp against SVCV with an oral DNA vaccine or an insect cells-based subunit vaccine

We recently reported on a successful vaccine for carp against SVCV based on the intramuscular injection of a DNA plasmid encoding the SVCV glycoprotein (SVCV-G). This shows that the intramuscular (i.m.) route of vaccination is suitable to trigger protective responses against SVCV, and that the SVCV G-protein is a suitable vaccine antigen. Yet, despite the general success of DNA vaccines, especially against fish rhabdoviruses, their practical implementation still faces legislative as well as consumer's acceptance concerns. Furthermore, the i.m. route of plasmid administration is not easily combined with most of the current vaccination regimes largely based on intraperitoneal or immersion vaccination. For this reason, in the current study we evaluated possible alternatives to a DNA-based i.m. injectable vaccine using the SVCV-G protein as the vaccine antigen. To this end, we tested two parallel approaches: the first based on the optimization of an alginate encapsulation method for oral delivery of DNA and protein antigens; the second based on the baculovirus recombinant expression of transmembrane SVCV-G protein in insect cells, administered as whole-cell subunit vaccine through the oral and injection route. In addition, in the case of the oral DNA vaccine, we also investigated the potential benefits of the mucosal adjuvants Escherichia coli lymphotoxin subunit B (LTB). Despite the use of various vaccine types, doses, regimes, and administration routes, no protection was observed, contrary to the full protection obtained with our reference i.m. DNA vaccine. The limited protection observed under the various conditions used in this study, the nature of the host, of the pathogen, the type of vaccine and encapsulation method, will therefore be discussed in details to provide an outlook for future vaccination strategies against SVCV

In silico-guided engineering of Pseudomonas putida towards growth under micro-oxic conditions

BackgroundPseudomonas putida is a metabolically versatile, genetically accessible, and stress-robust species with outstanding potential to be used as a workhorse for industrial applications. While industry recognises the importance of robustness under micro-oxic conditions for a stable production process, the obligate aerobic nature of P. putida, attributed to its inability to produce sufficient ATP and maintain its redox balance without molecular oxygen, severely limits its use for biotechnology applications.ResultsHere, a combination of genome-scale metabolic modelling and comparative genomics is used to pinpoint essential O2-dependent processes. These explain the inability of the strain to grow under anoxic conditions: a deficient ATP generation and an inability to synthesize essential metabolites. Based on this, several P. putida recombinant strains were constructed harbouring acetate kinase from Escherichia coli for ATP production, and a class I dihydroorotate dehydrogenase and a class III anaerobic ribonucleotide triphosphate reductase from Lactobacillus lactis for the synthesis of essential metabolites. Initial computational designs were fine-tuned by means of adaptive laboratory evolution.ConclusionsWe demonstrated the value of combining in silico approaches, experimental validation and adaptive laboratory evolution for microbial design by making the strictly aerobic Pseudomonas putida able to grow under micro-oxic conditions