Effect of the nitrogenous source on the production of rhamnolipids by Pseudomonas sp, using diesel oil 2 as a substrate

Abstract

To evaluate the effect of the nitrogen source on the production of rhamnolipids by Pseudomonas sp using diesel 2 oil as substrate, an experimental design was carried out using a pure Pseudomonas sp culture isolated from active sludge from the Covicorti-Trujillo Water Treatment Plant. The evaluation system consisted of four Stirred tank bioreactors fed as follows: 0.98 Lt Davies Minimum Medium, with diesel 2 at 5% as carbon source, and as a source of nitrogen: urea, sodium nitrate, Ammonium sulfate and yeast extract (control) respectively. In all cases the C / N ratio was 10/100. 20 mL of Pseudomonas sp inoculum was added to each bioreactor at a concentration of approximately 9x108 cells / mL), and allowed to run at room temperature 20 + 2 ° C during 96 hours. It was observed that the higher production of rhamnolipids was obtained in the presence of ammonium sulphate as a nitrogen source (0.0593 mg %), followed by sodium nitrate (0.04118 mg %). The lowest production was obtained in the presence of urea (0.0260 mg %). The analysis of variance test indicates that there is a significant difference between the production of rhamnolipids in the different nitrogen sources compared to the yeast extract and among themselves (p = 0.000). It was concluded that the nitrogen source affects the production of rhamnolipids by Pseudomonas sp, and that the ideal nitrogen source for the production of rhamnolipids is ammonium sulfate, followed by sodium nitrate.