Esters Rhizopus oryzae

Immobilisation of an Acetobacter aceti strain in calcium alginate resulted in improvement of the operational stability, substrate tolerance and specific activity of the cells and 23 g phenylacetic acid was produced within 9 days of fed-batch cultivation in an airlift bioreactor [133]. Lyophilised mycelia of Aspergillus oryzae and Rhizopus oryzae have been shown to efficiently catalyse ester formation with phenylacetic acid and phenylpropanoic acid and different short-chain alkanols in organic solvent media owing to their carboxylesterase activities [134, 135] (Scheme 23.8). For instance, in n-heptane with 35 mM acid and 70 mM alcohol, the formation of ethyl acetate and propylphenyl acetate was less effective (60 and 65% conversion yield) than if alcohols with increased chain lengths were used (1-butanol 85%, 3-methyl-l-butanol 86%, 1-pentanol 91%, 1-hexanol 100%). This effect was explained by a higher chemical affinity of the longer-chain alcohols, which are more hydrophobic, to the solvent. 

The use of extracellular lipases of microbial origin to catalyze the stereoselective hydrolysis of esters of 3-acylthio-2-methylpropionic acid in an aqueous system has been demonstrated to produce optically active 3-acylthio-2-methyl-propionic acid [41-43], The synthesis of the chiral side chain of captopril by the lipase-catalyzed enantioselective hydrolysis of the thioester bond of racemic 3-acetylthio-2-methylpropionic acid (15) to yield 5 -(-)-(15) has been demonstrated [44], Among various lipases evaluated, lipase from Rhizopus oryzae ATCC 24563 (heat-dried cells), BMS lipase (extracellular lipase derived from the fermentation of Pseudomonas sp. SC 13856), and lipase PS-30 from Pseudomonas cepacia in an organic solvent system (l,l,2-trichloro-l,2,2-tri-fluoroethane or toluene) catalyzed the hydrolysis of thioester bond of undesired enantiomer of racemic (15) to yield desired S-(-) (15), R-(+)-3-mercapto-2-methylpropionic acid (16) and acetic acid (17) (Fig. 8A). The reaction yield of... 

Li et al. (2007) reported the use of dry biomass, Rhizopus oryzae (R. oryzae) IF04697, whole cell-catalyzed methanolysis of soybean oil for biodiesel (methyl ester) in rm-butanol system. Changing one separate factor at a time (COST), live-level-four-factor Central Composite Design (CCD) were used to evaluate the effects of synthesis conditions, such as tert-butanol to oil volume ratio, methanol to oil molar ratio, water content, and dry biomass amount. Biodiesel yields of 72% were obtained under the optimal conditions using the proposed model for prediction. 

One of the reactions catalyzed by esterases and lipases is the reversible hydrolysis of esters (Figure 1 reaction 2). These enzymes also catalyze transesterifications and the asymmetrization of meso -substrates (Section 13.2.3.1.1). Many esterases and lipases are commercially available, making them easy to use for screening desired biotransformations without the need for culture collections and/or fermentation capabilities. As more and more research has been conducted with these enzymes, a less empirical approach is being taken due to the different substrate profiles amassed for various enzymes. These profiles have been used to construct active site models for such enzymes as pig liver esterase (PLE) (EC 3.1.1.1) and the microbial lipases (EC 3.1.1.3) Pseudomonas cepacia lipase (PCL), formerly P.fluorescens lipase, Candida rugosa lipase (CRL), formerly C. cylindracea lipase, lipase SAM-2 from Pseudomonas sp., and Rhizopus oryzae lipase (ROL) [108-116]. In addition, x-ray crystal structure information on PCL and CRL has been most helpful in predicting substrate activities and isomer preferences [117-119]. 

Table 11.1-15. Lipase-catalyzed enantiomer-differentiating hydrolysis of esters of racemic acyclic secondary alcohols in aqueous solution (CCL Candida cylindracea lipase, PSL Pseudomonas sp. lipase, PFL Pseudomonas fluorescens lipase, PAL Pseudomonas aeruginosa lipase, ASL Alcaligenes sp. lipase, ANL Aspergillus niger lipase, PCL Pseudomonas cepacia lipase, ROL Rhizopus oryzae lipase,...

Dhake, K. P., K. M. Deshmukh, Y. P. Patil, R. S. Singhal, and B. M. Bhanage. 2011. Improved Activity and Stability of Rhizopus Oryzae Lipase via Immobilization for Citronellol Ester Synthesis in Supercritical Carbon Dioxide. Journal of Biotechnology 156 (1) 46-51. 

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