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Web End = Bioprocess Biosyst Eng (2016) 39:13651374 DOI 10.1007/s00449-016-1612-y
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Effect of nitrogen and/or oxygen concentration on poly (3-hydroxybutyrate) accumulation by Halomonas boliviensis
Mara Garca-Torreiro1 Thelmo A. Lu-Chau1 Juan M. Lema1
Received: 18 December 2015 / Accepted: 19 April 2016 / Published online: 28 April 2016 Springer-Verlag Berlin Heidelberg 2016
Abstract The behaviour of Halomonas boliviensis during growth in fed-batch culture under different kind of nutrient restrictions was examined. The metabolic switch between growth and accumulation phase is determined by the limitation in one or more essential nutrient for bacterial growth. The aim of this study was to test the effect of applying limitations of a essential nutrient, such as nitrogen, and the inuence of different O2 concentrations on poly(3-hydroxybutyrate) (PHB) production during the accumulation phase. Single limitations of nitrogen and oxygen provoke PHB accumulations of 45 and 37 % (g g-1), respectively, while N limitation with low O2 supply causes the highest PHB accumulation of 73 %. The characterization of the PHB production with the strain H. boliviensis would allow a better optimization of the process and enrich the knowledge about the PHB production from strains different than Cupriavidus necator.
Keywords Polyhydroxyalkanoates Nitrogen Oxygen
Nutrient limitation Halomonas boliviensis
Introduction
Nutrient limitation is one of the most powerful tools to force microbial cultures to perform in a dened way. It is well known that nutrients availability highly inuences cell
composition and metabolism [1]. As a matter of fact, nutrients constraint is usually applied to induce or optimise the formation of microbial products. For this reason, the study of limitations in such cultures is of high pertinence to biotechnology. Polyhydroxyalkanoates (PHA) are a good example of microbial product whose synthesis is usually induced by a nutrient limitation. Plastic like properties of PHA, biodegradability and biocompatibility, increased the industrial interests of this product.
Bacterial PHA are polyesters produced as energy and carbon storage material, in the form of intracellular granules, when the carbon source is in excess and another nutrient is limiting. Several types of nutrients deciency are used to induce PHA production, i.e., nitrogen [2], phosphorous [3], sulphur, magnesium [4] or oxygen [5, 6].
PHA microbial producers can be classied in three different types, based on their PHA production...