Continuous culture of Bacillus popilliae was achieved for the first time in a small chemostat. Initially, variable cell yields during steady-state chemostat growth led to a re-examination of growth rates in batch cultures. B. popilliae NRRL B-2309 and a wild strain were both found to be natural mixtures of three substrains characterized by different growth rates and colony morphologies and vary...

It has been known for many years that small fractions of persister cells resist killing in many bacterial colony-antimicrobial confrontations. These persisters are not believed to be mutants. Rather it has been hypothesized that they are phenotypic variants. Current models allow cells to switch in and out of the persister phenotype. Here, a different explanation is suggested for persistence, na...

The cybernetic framework developed by Ramkrishna and co-workers has been expanded to include the effects of cellular maintenance energy requirements on biomass levels in slow-growing, carbon-substrate-limited cultures. A simple structured model, based on the existence of distinct key enzymes for growth and maintenance functions, is presented. Comparisons of the model with experimental data for ...

Recombinant alkaline polygalacturonate lyase (PGL) production by recombinant Pichia pastoris GS115 was selected as a model to study as a continuous culture strategy for enhancing heterologous protein production based on controlling methanol feeding (CCCM culture) or on dual carbon source feeding (CCCD culture). Using the CCCM process with a dry cell weight of 75 g/L regulated by controlling met...

The activation of caspases represents a crucial turning point during a batch or a fed-batch culture of mammalian cells. It not only affects the quantity but also the quality of the recombinant glycoprotein produced. In this study, the activation of various caspases, the release of intracellular sialidase and the changes in sialylation pattern of a recombinant product, erythropoietin (EPO), in t...

mathematical modeling and simulation of microbial polyhydroxybutyrate (phb) production process is beneficial for optimization, design, and control purposes. in this study a batch model developed by mulchandani et al., [1] was used to simulate the process in matlab environment. it was revealed that the kinetic model parameters were estimated off the optimal or at a local optimal point. therefore...

Fed-batch culture strategy is often used for increasing production of heterologous recombinant proteins in Escherichia coli. This study was initiated to investigate the effects of dissolved oxygen concentration (DOC), complex nitrogen sources and pH control agents on cell growth and intracellular expression of streptokinase (SK) in recombinant E. coli BL21(DE3). Increase in DOC set point from 3...

The production of lipids by oleaginous yeast and fungi becomes more important because these lipids can be used for biodiesel production. To understand the process of lipid production better, we developed a model for growth, lipid production and lipid turnover in submerged batch fermentation. This model describes three subsequent phases: exponential growth when both a C-source and an N-source ar...

Dynamic changes of physiological bioprocess parameters, e.g. a change in the specific growth rate μ, are frequently observed during industrial manufacturing as well as bioprocess development. A quantitative description of these variations is of great interest, since it can bring elucidation to the physiological state of the culture. The goal of this contribution was to show limitations and issu...

The principal objective of this study was to evaluate the kinetics of dihydroxyacetone production by Gluconobacter frateurii CGMCC 5397 under different oxygen volumetric mass transfer coefficient (kLa) conditions in submerged bioreactors using biodiesel-derived crude glycerol as the carbon source. kLa is a key fermentation parameter for the production of dihydroxyacetone. Cultivations were cond...