, the highest (R)HPBA production was detected at pH 6.five (Fig. 3A).Figure four. Time course of extremely optically pure (R)-HPBA production from OPBA beneath optimal circumstances. (A) Biotransformation employing entire cells of E. coli DF as a biocatalyst and formate for cofactor regeneration. (B) Biotransformation working with entire cells of E. coli D2 as a biocatalyst and glucose for cofactor regeneration. ( ), OPBA; (m), (R)-HPBA; ( ), ee. doi:ten.1371/journal.pone.0104204.gNPLOS 1 | plosone.org(R)-2-Hydroxy-4-Phenylbutyric Acid ProductionTable 3. Comparison of lately reported processes for (R)-HPBA or (R)-HPBE production via bio-reduction.Productivity (mM h21) 1.7 1.1 5.0 0.Biocatalyst Complete cells of Candida boidinii CIOC21 Entire cells of Bacillus pumilus Phe-C3 Entire cells of Candida krusei SW2026 Saccharomyces cerevisiae pretreated with a-phenacyl chloride Saccharomyces cerevisiae pretreated with a-phenacyl chloride Lyophilized cells of E. coli BL21/ pCgKR two and lyophilized GDH powders Whole cells of E. coli BL21 coexpressing IolS and GDH Complete cells of E. coli BL21 coexpressing IolS and GDHD-LDHProduct (mM) 20 29.six 79.five four.ee ( ) 99 97.1 97.4Co-substrate 5 glucose two glucose five glucose -References [27] [28] [26] [29]167.3.87.1.5 ethanol (v/v)[30]140..27 glucose[10]50 16003.eight 132.1 38.99.five 99.5 .99.3.six glucose 20 glucose 2.2 ammonium formate[31] [11] [15]from Staphylococcus epidermidis and FDH from Candida boidinii*Partially purified D-LDH (EC 1.1.1.28) and whole cells of Candida boidinii ATCC 32591 containing FDH* Complete cells of E. coli BL21 coexpressing YiaE and GDH* Entire cells of E. coli DF*56.49.ND0.8 sodium formate[12]100 71.four.two 47.98 .three.six glucose 0.five sodium formate[1] This study*Substrates had been OPBA.14871-41-1 site Substrates from the other processes had been OPBE.2-Chloro-5-methoxypyridin-4-amine In stock ND represents no data.PMID:33620301 doi:10.1371/journal.pone.0104204.tTo determine the impact of the OPBA concentration, reactions with eight distinct OPBA and sodium formate concentrations (25, 50, 75, 100, 125, 150, and 175 mM) have been performed at pH six.5 and 37uC for 30 min. The highest (R)-HPBA production was detected when 75 mM OPBA was utilized (Fig. 3B). The impact of your biocatalyst concentration was also investigated to ascertain the optimal range. The biotransformation was performed with 75 mM OPBA, 75 mM sodium formate, 200 mM phosphate buffer (pH 6.five), and entire cells of E. coli DF at six different concentrations (1, three, 5, six, 7, and eight g DCW l21). When the reactions have been performed to approximate 80 theoretical yield, the highest distinct productivity was observed at a biocatalyst concentration of 6 g DCW l21 (Table two).Production of (R)-HPBA beneath optimal conditionsOn the basis on the results presented above, an optimal bioconversion method for production of optically pure (R)-HPBA from OPBA was developed. Biotransformation was conducted at 37uC in 200 mM phosphate buffer (pH 6.five) with 6 g DCW l21 complete cells of E. coli DF because the biocatalyst. As shown in Fig. 4A, 71.8 mM (R)-HPBA with a high enantiomeric purity (ee .99 , Fig. S2) was obtained from 73.four mM OPBA in 90 min. When entire cells of E. coli D2 only expressing D-nLDHY52L/F299Y were applied as the biocatalyst, and glucose was added for NADH regeneration, only 44.7 mM (R)-HPBA was produced having a yield of 60.9 after 360 min (Fig. 4B). Quite a few biocatalysts have been applied inside the enantioselective production of (R)-HPBE and (R)-HPBA through bio-reductionPLOS One | plosone.org[1,12,26?8]. Compared with (R)-HPBE production processes, the product concentra.
