Display of a thermostable lipase on the surface of a solvent-resistant bacterium, Pseudomonas putida GM730, and its applications in whole-cell biocatalysis.
BACKGROUND
Whole-cell biocatalysis in organic solvents has been widely applied to industrial bioprocesses. In two-phase water-solvent processes, substrate conversion yields and volumetric productivities can be limited by the toxicity of solvents to host cells and by the low mass transfer rates of the substrates from the solvent phase to the whole-cell biocatalysts in water.


RESULTS
To solve the problem of solvent toxicity, we immobilized a thermostable lipase (TliA) from Pseudomonas fluorescens on the cell surface of a solvent-resistant bacterium, Pseudomonas putida GM730. Surface immobilization of enzymes eliminates the mass-transfer limitation imposed by the cell wall and membranes. TliA was successfully immobilized on the surface of P. putida cells using the ice-nucleation protein (INP) anchoring motif from Pseudomonas syrinage. The surface location was confirmed by flow cytometry, protease accessibility and whole-cell enzyme activity using a membrane-impermeable substrate. Three hundred and fifty units of whole-cell hydrolytic activity per gram dry cell mass were obtained when the enzyme was immobilized with a shorter INP anchoring motif (INPNC). The surface-immobilized TliA retained full enzyme activity in a two-phase water-isooctane reaction system after incubation at 37 degrees C for 12 h, while the activity of the free form enzyme decreased to 65% of its initial value. Whole cells presenting immobilized TliA were shown to catalyze three representative lipase reactions: hydrolysis of olive oil, synthesis of triacylglycerol and chiral resolution.


CONCLUSIONS
In vivo surface immobilization of enzymes on solvent-resistant bacteria was demonstrated, and appears to be useful for a variety of whole-cell bioconversions in the presence of organic solvents.
Jung
Heung-Chae
HC
National Research Laboratory of Microbial Display, GenoFocus, Inc., 461-58 Jeonmindong, Yusong, Daejeon 305-811, Republic of Korea. hcjung@kribb.re.kr
Kwon
Seok-Joon
SJ
Pan
Jae-Gu
JG
D020816:Amino Acid Motifs; D001426:Bacterial Proteins; D001709:Biotechnology / Q000379:methods*; D002384:Catalysis; D002462:Cell Membrane / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D004800:Enzymes, Immobilized; D005285:Fermentation; D005434:Flow Cytometry; D006358:Hot Temperature; D006868:Hydrolysis; D008049:Lipase / Q000096:biosynthesis*; D009795:Octanes / Q000737:chemistry; D000069463:Olive Oil; D010666:Phenylpropionates / Q000737:chemistry; D010938:Plant Oils / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D015202:Protein Engineering / Q000379:methods*; D016958:Pseudomonas putida / Q000201:enzymology*; D011994:Recombinant Proteins; D012997:Solvents; D013237:Stereoisomerism; D013379:Substrate Specificity; D013696:Temperature; D013997:Time Factors; D014280:Triglycerides / Q000737:chemistry; D014867:Water / Q000737:chemistry
D001426:Bacterial Proteins; D004800:Enzymes, Immobilized; D009795:Octanes; D000069463:Olive Oil; D010666:Phenylpropionates; D010938:Plant Oils; D011994:Recombinant Proteins; D012997:Solvents; D014280:Triglycerides; D014867:Water; C017568:4-nitrophenyl propionate; D008049:Lipase; C428386:thermostable lipase; C045798:2,2,4-trimethylpentane