BACKGROUND Tyrosinase is a bifunctional enzyme that catalyzes both the hydroxylation of monophenols to o-diphenols (monophenolase activity) and the subsequent oxidation of the diphenols to o-quinones (diphenolase activity). Due to the potential applications of tyrosinase in biotechnology, in particular in biocatalysis and for biosensors, it is desirable to develop a suitable low-cost process fo...

This work utilizes both insights obtained from experimental work and kinetic modeling to develop an optimization strategy for high-solids cellulose saccharification, which presents a problem for the operation of stirred tank reactors (STRs) at insoluble solids levels greater than ~15%. In this work, a previously developed model for enyzmatic hydrolysis of cellulose was modified to consider the ...

An algorithm using feedforward neural network model for determining optimal substrate feeding policies for fed-batch fermentation process is presented in this work. The algorithm involves developing the neural network model of the process using the sampled data. The trained neural network model in turn is used for optimization purposes. The advantages of this technique is that optimization can ...

The production of 1,4-dihydroxy-2-naphthoic acid (DHNA) was investigated using a fed-batch culture of Propionibacterium freudenreichii ET-3. DHNA is a precursor of menaquinone (MK) and is transformed to MK by combination with an isoprenoid unit. We found that ET-3 stopped MK production and increased DHNA production in an anaerobic fed-batch culture by maintaining the lactose concentration at ap...

We carried out the first simulation on multi-stage continuous high cell density culture (MSC-HCDC) to show that the MSC-HCDC can achieve batch/fed-batch product titer with much higher productivity to the fed-batch productivity using published fermentation kinetics of lactic acid, penicillin and ethanol. The system under consideration consists of n-serially connected continuous stirred-tank reac...

Current industry practices for large-scale mammalian cell cultures typically employ a standard platform fed-batch process with fixed volume bolus feeding. Although widely used, these processes are unable to respond to actual nutrient consumption demands from the culture, which can result in accumulation of by-products and depletion of certain nutrients. This work demonstrates the application of...

BACKGROUND Saccharomyces cerevisiae BY4741 is an auxotrophic commonly used strain. In this work it has been used as host for the expression and secretion of human interleukin-1beta (IL1beta), using the cell wall protein Pir4 as fusion partner. To achieve high cell density and, consequently, high product yield, BY4741 [PIR4-IL1beta] was cultured in an aerated fed-batch reactor, using a defined m...

This paper is focused on a comprehensive study of neural network (NN) model based predictive control (MPC), as an operation strategy for a fed-batch sugar crystallizer. The process is divided into four subsequent control loops and for each of them an individual NN-based MPC is designed. The operation is tested for a number of scenarios and is compared with alternative (linear and batch nonlinea...

There are relatively few industrial applications of process systems to the specialty batch process industry (as compared to bulk continuous or even bulk batch process industry). However, inherent flexibility of these processes can be exploited to increase productivity and product quality. This study is based on a real industrial example of fed-batch polymerisation of ethylene oxide with a base ...

The random nature of transgene integration harbours various pitfalls for development of production cell lines including clonal variation in expression level and growth characteristics. The CEMAX system is an expression system for targeted integration of expression cassettes via DNA double-strand break induced homologous recombination. Stable high producers are available within 4 weeks without t...