Δ′-Dehydrogenation of steroids byArthrobacter simplex immobilized in calcium polygalacturonate beads

Abstract

Arthrobacter simplex ATCC 6946 (viable cells) was immobilized in a calcium polygalacturonate gel. The trapped cells were used for repeated batchwise bioconversion of steroids. Reichstein's compound S and hydrocortisone were dehydrogenated introducing a double bond between C1 and C2 of ring A. The products 1-dehydro S and prednisolone, respectively, were identified by high pressure liquid chromatography. Steroid dehydrogenase activity increased in the system when an artificial electron acceptor, such as menadione (vitamin K3) was present in the reaction mixture. An airlift-type reactor was used to bioconvert up to 90% of substrate in 15 min, under optimal conditions. The gel entrapped cell preparations were used for repeated batch bioconversion during 30 days; 69 batch bioconversions for Reichstein's compound S were performed during 15 days of operation of the reactor. The operational stability of the process and the feasibility of repeated batch bioconversions was shown to be comparable to similar processes.

Removal of heavy metals using different polymer matrixes as support for bacterial immobilisation

“…For Ca-alginate and Ca-pectate, the bacterial inoculum was immobilised under aseptic conditions, using the method described by Escamilla et al [30] and Montes and Magana [31] with some modifications. The inoculum [OD = 1 (610 nm), which represented a fresh weight of 74 mg for 1C2, 108 mg for 1ZP4 and 128 mg for EC30, in a volume of 100 ml] was adjusted in a volumetric cylinder to 1:1 inoculum/polymer ratio by using alginic acid (Sigma) or polygalacturonic (Sigma) 4% (w/v) concentrated.…”

Substrate Carriers for C-1(2)-Dehydrogenation of 6-Methylene Androstenedione to Exemestane by Growing and Immobilized Arthrobacter Simplex Ncim 2449

“…The stability of C-1(2)-dehydrogenase activity of A. simplex cells immobilized in Ca-polygalacturonate [34], Ca-alginate [35], k-carrageenan beads, and polyurethane foam [36] has been shown against a variety of steroid substrates. The present work indicated the use of growing and Ca-alginate immobilized A. simplex cells as an environment-friendly alternative for 1(2)-dehydrogenation of 6-MeAD to exemestane.…”

Study and Mathematical Modeling of the Production of Propionic Acid by Propionibacterium acidipropionici Immobilized in a Stirred Tank Fermentor

“…P. acidipropionici was grown in dilution bottles with culture medium with 6.0 g/L of yeast extract for 60 h. The microorganism was harvested by centrifugation, to obtain a suspension with 14.0 g/L of biomass. The immobilization technique used was entrapment on calcium polygalacturonate beads (21). This suspension was mixed with a solution of ethanol and polygalacturonic acid (Sigma) at 4% v/v and 8% w/v, respectively, with a pH of 8.0.…”