Biocatalytic synthesis of ethyl (R)-2-hydroxy-4-phenylbutyrate with a newly isolated Rhodotorula mucilaginosa CCZU-G5 in an aqueous/organic biphasic system

Bioresources and Bioprocessing

Table 1 Tolerance and asymmetric reduction of OPBE to ( R )-HPBE with R. mucilaginosa CCZU-G5 in different organic/aqueous biphasic systems

Organic solvent	Log P	Metabolic activity retention (%) ^a	Yield (%) ^b	ee (%) ^b
EtOAC	0.68	14.5 ± 0.6	11.3 ± 0.7	16.5
Butyl acetate	1.7	17.1 ± 0.7	14.3 ± 1.3	18.4
Benzene	2.0	17.5 ± 0.6	36.1 ± 1.1	45.5
Toluene	2.5	22.3 ± 0.7	44.1 ± 1.0	49.4
Cyclohexane	3.2	50.4 ± 1.3	53.1 ± 1.5	68.9
n-Hexane	3.5	67.2 ± 0.9	69.3 ± 0.5	>99.0
n-Heptane	4.0	70.5 ± 0.8	89.3 ± 0.4	>99.0
n-Octane	4.5	78.8 ± 0.7	90.3 ± 0.4	>99.0
Isooctane	4.6	80.1 ± 0.6	98.1 ± 0.3	>99.0
n-Hydride	5.1	92.2 ± 0.4	63.1 ± 0.3	>99.0
n-Decane	5.6	98.0 ± 0.4	52.8 ± 0.9	>99.0

^aMetabolic activity retention (R) of R. mucilaginosa CCZU-G5: 0.4 g wet cells suspended in 10 mL PBS buffer (0.1 M, pH 7.0) was mixed with 10 mL of different organic solvents incubated at 30°C and 180 rpm for 24 h. The cell suspension in PBS without any organic solvent was used as a control. Then the harvested cells were transferred to 10 mL of 20 g/L glucose and incubated at 30°C and 180 rpm for 4 h. ^bReaction conditions: 2.0 g wet cells suspended in 10 mL PBS buffer (0.1 M, pH 7.0) containing 1.0 g glucose was mixed with 10 mL of an organic solvent containing 2 mmol OPBE and incubated at 30°C and 180 rpm for 24 h.