Integrated foam fractionation for heterologous rhamnolipid production with recombinant Pseudomonas putida in a bioreactor

Abstract

Heterologeous production of rhamnolipids in Pseudomonas putida is characterized by advantages of a non-pathogenic host and avoidance of the native quorum sensing regulation in Pseudomonas aeruginosa. Yet, downstream processing is a major problem in rhamnolipid production and increases in complexity at low rhamnolipid titers and when using chemical foam control. This leaves the necessity of a simple concentrating and purification method. Foam fractionation is an elegant method for in situ product removal when producing microbial surfactants. However, up to now in situ foam fractionation is nearly exclusively reported for the production of surfactin with Bacillus subtilis. So far no cultivation integrated foam fractionation process for rhamnolipid production has been reported. This is probably due to excessive bacterial foam enrichment in that system. In this article a simple integrated foam fractionation process is reported for heterologous rhamnolipid production in a bioreactor with easily manageable bacterial foam enrichments. Rhamnolipids were highly concentrated in the foam during the cultivation process with enrichment factors up to 200. The described process was evaluated at different pH, media compositions and temperatures. Foam fractionation processes were characterized by calculating procedural parameter including rhamnolipid and bacterial enrichment, rhamnolipid recovery, YX/S, YP/X, and specific as well as volumetric productivities. Comparing foam fractionation parameters of the rhamnolipid process with the surfactin process a high effectiveness of the integrated foam fractionation for rhamnolipid production was demonstrated.Electronic supplementary materialThe online version of this article (doi:10.1186/s13568-016-0183-2) contains supplementary material, which is available to authorized users.

High titer heterologous rhamnolipid production

“…Therefore, the putative generation of polysaccharides as byproducts should be mainly addressed. Another approach will be the combination of the strategy presented here using fed-batch processing, with in situ product removal by foam fractionation (Beuker et al 2016) and thus avoiding the necessity of chemical antifoaming agents. This could lead to a further enhanced semi-continuous process.…”

“…P. putida KT2440 with plasmid pSynPro8oT_ rhlAB producing mono-rhamnolipids was used as described in Beuker et al (2016). …”

One‐step bioconversion of hemicellulose polymers to rhamnolipids with Cellvibrio japonicus: A proof‐of‐concept for a potential host strain in future bioeconomy

“…cellulosa ) was obtained from the National Collection of Industrial Food and Marine Bacteria NCIMB (Aberdeen, UK) listed under strain number 10,462. For expression of genes rhlAB required for rhamnolipid biosynthesis plasmid pSynPro8oT carrying a tetracycline resistance was used as described previously (Beuker, Steier, et al, ).…”

Influence of the Process Parameters on the Foam Fractionation Treatment of Olive Mill Wastewater

“…In an industrial scale, these technologies have drawbacks because they are too expensive to have a wide application, are ine ective in meeting stringent e uent standards, and could result in a huge amount of sludge [15,[17][18][19][20]. A method with high throughput, low costs for operation, and a simple plant concept should be employed to eliminate costly separation steps, particularly in the early stages when large matrix problems can be expected [21][22][23].…”

“…The foam fractionation of ions is similar to ion otation, but uses an excess of surfactant or a proper frother to produce stable foam [18][19][20]25]. During foam fractionation, gas bubbles are introduced into a liquid, which contains surface-active substances [26].…”