Physical Factors and Reuse Affect the Production of Cholesterol Oxidase in Reactors Containing Calcium Alginate-Immobilized Rhodococcus equi No. 23

Abstract

Some physical factors including initial pH of medium, cultivation temperature and shaking speed as well as reuse affecting the production of cholesterol oxidase (CholOx) in reactors containing calcium alginate-immobilized cells of Rhodococcus equi No. 23 were investigated. Results revealed that the free cells showed the maximum CholOx in the culture with an initial pH of 5.0, while culture inoculated with immobilized cells exhibited a broad pH range, 6.0-9.0, for maximum CholOx production. The immobilized and free cells produced the maximum CholOx in the culture incubated at 30 and 25°C, respectively. The CholOx production decreased upon increasing the cultivation temperature. Increasing CholOx activity was also noted for both immobilized and free cells of R. equi No. 23 in the culture with increasing shaking speed. Under the optimal culture conditions, that were established, a higher maximum CholOx production of 0.94 unit/ml was found for immobilized R. equi No. 23 compared to that of 0.84 unit/ml for free cells after 48 h of cultivation. Furthermore, no gel leakage was noted after re-use of the calcium alginate-immobilized R. equi No. 23 for seven consecutive 48 h batch culture. The CholOx production in the seventh cycle was about 60.4% of that obtained in the first cycle.

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Cholesterol oxidase production from entrapped cells ofStreptomycessp.

“…Chang et al . observed that maximum COD was produced at 250 rpm from calcium alginate immobilized cells of R. equi .…”

“…Chang et al . investigated COD production by the immobilized cells of R. equi in Ca‐alginate beads and found that immobilized cells give maximum production at higher pH range (6.0–9.0) and temperature (30 °C).…”

“…Chang et al . studied on the production of COD in reactors containing calcium alginate‐immobilized R. equi and found that immobilized cells produced maximum enzyme in the 6.0–9.0 pH ranges. Buzas et al .…”