Use of waste canola oil as a low-cost substrate for rhamnolipid production using Pseudomonas aeruginosa

Rhamnolipids are glycolipid biosurfactants that are primarily produced by Pseudomonas aeruginosa that have gained a great deal of interest for their numerous industrial applications and environmentally friendly properties. In this study, we explored the potential of waste canola oil as a low-cost and environmentally friendly substrate for the production of rhamnolipids by P. aeruginosa. Four different 2(3) full factorial designs were used to assess the effect of three independent factors on rhamnolipid production, including carbon source (canola oil and waste canola oil), nitrogen source [(NH(4))(2)SO(4) and NaNO(3)] and production time (7 and 14 days). The highest observed yield was 3585.31 ± 66.24 mg/L when P. aeruginosa was cultured for 14 days with 3% v/v waste canola oil and 4 g/L of NaNO(3). The nitrogen source proved to be a crucial factor, as the use of NaNO(3) rather than (NH(4))(2)SO(4) led to a 30-fold increase in production yield. The observed yield when waste canola oil was used was similar to, and even slightly higher than, that obtained using canola oil. Our results showed that waste canola oil has great potential for use as a carbon source for rhamnolipid production by P. aeruginosa, thus paving the way for the development of a low-cost, efficient, and environmentally friendly bioprocess for the production of rhamnolipids. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13568-019-0784-7) contains supplementary material, which is available to authorized users.