Continuous Culture of Immobilized Streptomyces Cells for Kasugamycin Production

Abstract

Continuous cultures of immobilized Streptomyces kasugaensis, a kasugamycin producer, were carried out on Celite beads. When using a prototype separator for immobilized-cell separation and recycling, the continuous operation could not be sustained for an extended period as a result of an excessive loss of immobilized cells caused by the poor performance of the separator. Accordingly, the immobilized-cell separator was revised to provide better immobilized-cell settling and thus recycling into the reactor. In a subsequent culture using the revised separator, a stable operation was maintained for over 820 h with a high kasugamycin productivity. The kasugamycin productivity ranged from 9.8 to 16.1 mg/L/h, which was about 14- to 23-fold higher than that in a batch suspended-cell culture. When the original feeding medium concentration was doubled at the end of the continuous culture, the productivity became severely impaired for several reasons, which will be discussed. An excessive formation of free cells and loss of immobilized cells through the separator were also observed.

Functional expression of SCO7832 stimulates tautomycetin production via pathway-specific regulatory gene overexpression in Streptomyces sp. CK4412

“…operates at several layers of control. This involves a complex regulatory network in response to external stimuli, such as nutrient depletion, salt shock, oxidative stress and acidic pH shock [8,14,17,18,26]. Some of these aVect only one speciWc antibiotic production, whereas others aVect several antibiotic productions along with morphological diVerentiation, suggesting that the two processes share some elements of genetic control, while others are unique.…”

Gene-expression analysis of acidic pH shock effects on two-component systems in Streptomyces coelicolor

“…In one of our previous studies to investigate pH shock effects on secondary metabolites production, more than 7-fold enhancement in kasugamycin production in a bioreactor culture of S. kasugaensis was observed when an artificial pH drop and recovery was introduced [7,8]. In another case, it was found that an acidic pH shock caused earlier initiation of stationary phase, enhanced the biosynthesis of secondary metabolites, and activated the major metabolic pathways in surface grown cultures of S. coelicolor A3(2) [9].…”

Biocatalytic Desulfurization of Diesel Oil in an Air-Lift Reactor with Immobilized Gordonia nitida CYKS1 Cells

“…In this study, a cell immobilization method effective in achieving high cell or biocatalyst density (1,12) and a novel bioreactor design apt for dealing with a multiphase liquid mixture were proposed for the development of an efficient bioreactor system for diesel desulfurization. The performance of the newly developed immobilized-cell reactor system was investigated in a series of repeated batch experiments at various carbon source concentrations and oil-to-water phase ratios.…”