Submitted to: Biocatalysis and Agricultural Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2016
Publication Date: 8/8/2016
Citation: Solaiman, D., Ashby, R.D., Crocker, N.V. 2016. Genetic construction of recombinant Pseudomonas chlororaphis for improved glycerol utilization. Biocatalysis and Agricultural Biotechnology. doi: 10.1016/j.bcab.2016.08.011.
Interpretive Summary: Pseudomonas chlororaphis is a USDA ARS patent nonpathogenic bacterium useful for the fermentative production of antimicrobial biobased surfactants called rhamnolipids. Production costs could be reduced by using low-cost surplus industrial waste-streams. One such waste stream is the bioglycerol byproduct generated in the production of biodiesel fuel. This study reports the successful genetic engineering (GE) of the Pseudomonas chlororaphis to result in improved strain capable of consuming the glycerol substrate at a faster rate, thus cutting down on the production time and therefore making the bioprocess more cost-friendly. This GE strain is thus potentially useful for production of a lower cost antimicrobial biosurfactant for sanitary washing of food and nonfood products and equipment.
Technical Abstract: The objective of this study is to improve by genetic engineering the glycerol metabolic capability of Pseudomonas chlororaphis which is capable of producing commercially valuable biodegradable poly(hydroxyalkanoate) (PHA) and biosurfactant rhamnolipids (RLs). In the study, glycerol uptake facilitator or aquaglyceroporin gene (glpF) and glycerol kinase (glpK) gene were PCR-cloned from E. coli, inserted into a shuttle vector pBS29P2gfp, and expressed in P. chlororaphis by a Pseudomonas promoter P2. The P. chlororaphis recombinants were then tested for cell growth and glycerol metabolism in chemically defined medium containing 0.5 and 1.0 % glycerol. The simultaneous expression of glpF and glpK resulted in an increased rate of glycerol metabolism for cell growth of P. chlororaphis. In conclusion, the recombinant P. chlororaphis that grows more efficiently in glycerol is expected to improve the techno-economics of PHA and RL production using surplus bioglycerol byproduct stream from biodiesel production.