Influence of medium composition on the cephalosporin C production with a highly productive strain Cephalosporium acremonium

Production of cephalosporin C using crude glycerol in fed-batch culture of Acremonium chrysogenum M35

In this study, cephalosporin C production by Acremonium chrysogenum M35 cultured with crude glycerol instead of rice oil and methionine was investigated. The addition of crude glycerol increased cephalosporin C production by 6-fold in shake-flask culture, and also the amount of cysteine. In fed-batch culture without methionine, crude glycerol resulted only in overall improvement in cephalosporin C production (about 700%). In addition, A. chrysogenum M35 became highly differentiated in fed-batch culture with crude glycerol, compared with the differentiation in batch culture. The results presented here suggest that crude glycerol can replace methionine and plant oil as cysteine and carbon sources during cephalosporin C production by A. chrysogenum M35.

Quantitative metabolic flux analysis revealed uneconomical utilization of ATP and NADPH in Acremonium chrysogenum fed with soybean oil

A metabolic network was constructed for the Acremonium chrysogenum cultivation fed with soybean oil. Metabolic flux analysis indicated that the shift from exponential growth to rapid cephalosporin C (CPC) formation was accompanied by 1.63- and 5-fold carbon flux enlargement in TCA cycle and glyoxylate by-pass, respectively. The flux via pentose phosphate pathway branch was little affected during the rapid CPC formation period; the contributory explanation was that 35.6% of NADPH was consumed in the dissimilation of fatty acids. Estimation of NADPH, ATP generation, and consumption demonstrated that, with soybean oil as carbon source in rapid CPC formation phase, the NADPH consumed in fatty acid catabolism was fourfold greater than that used in the CPC biosynthesis-relevant part; simultaneously, more than 90% energy spent was not directly related to the CPC formation. Therefore, the improvement of CPC production yield through optimization of the NADPH, ATP generation, and consumption was put forward.

Progress in monitoring, modeling and control of bioprocesses during the last 20 years

The paper gives a review on the recent development of bioprocess engineering. It includes monitoring of product formation processes by flow injection analysis, various types of chromatographic and spectroscopic methods as well as by biosensors. The evaluation of mycelial morphology and physiology by digital image analysis is discussed also. It deals with advanced control of indirectly evaluated process variables by means of state estimation/observer, with the use of structured and hybrid models, expert systems and pattern recognition for process optimization and gives a short report on the state of the art of metabolic flux analysis and metabolic engineering.

On-line and off-line monitoring of the production of cephalosporin C by Acremonium chrysogenum

Process monitoring of cephalosporin C formation by Acremonium chrysogenum in laboratory investigations is considered. The goal of these investigations is the identification of bottlenecks in the biosynthesis and the improvement of the process performance. Based on reports of other research groups and own experience the key parameters were selected, which influence the process performance. They are: dissolved oxygen and pH values. In addition the concentrations of biomass, DNA, glucose and reducing sugars (glucose, maltose, maltotriose and oligosaccharides), methionine, other nitrogen sources (ammonium ion, other amino acids), organic acids, phosphate, sulfate, dissolved organic carbon, proteins, product and precursors in the cell free cultivation medium are monitored. In addition the intracellular concentrations of RNA, DNA, proteins, amino acids as well as the activities of the enzymes of the biosynthesis of cephalosporin C are determined. The influence of these parameters on the biosynthesis is discussed.

The inhibitory mechanisms of glucose and carbon dioxide on the biosyntheses of penicillins and cephalosporins

The inhibitory mechanism of glucose and CO2 on the biosyntheses of penicillins and cephalosporins is discussed in the present paper. 6-aminopenicillanic acid (6-APA) is considered to be an intermediate product, and the reaction between 6-APA and glucose may play an important role in the yield and rate of biosyntheses of beta-lactam antibiotics. According to this hypothesis the experimental phenomena taking place in biosynthesis of penicillin and cephalosporin, such as the inhibition by glucose and carbon dioxide and the reduction of the yield, can be satisfactorily explained. The stability of 6-aminopenicillanic acid (6-APA) in bicarbonate solution, the reaction of 6-APA with sugars, the determination of the concentration of the 6-APA-sugar compound and the effect of these reactions on the biosynthesis of penicillin G are investigated to present evidences for this hypothesis.

Fermentation monitoring and process control

During the past year, several papers describing the potential of new sensor devices for application in real bioprocesses have been published. Biosensors, optical sensors, and immunosensors are all gaining in importance. At present, the development of correct/adequate interfacing of biosensors to bioprocesses is the major limitation on progress. On the basis of new analytical data, a more precise modeling and control of fermentations can now be performed. Recent research efforts attest to the increasing importance of this area in biotechnology.

Cephalosporin C production by a highly productive Cephalosporium acremonium strain in an airlift tower loop reactor with static mixers

The production of cephalosporin C (CPC) and its precursors penicillin N (PEN N), deacetoxycephalosporin C (DAOC) and deacetylcephalosporin C (DAC), with a highly productive strain of Cephalosporin acremonium, was investigated in an 80-1 airlift tower loop reactor with four static mixer modules (Type SMV, Sulzer) (ATLRM) on a complex medium containing 50 g l-1 peanut flour (PF). The most important key parameters such as glucose concentration and cell mass concentration were monitored during a fed-batch cultivation process. The concentrations of products CPC, PEN N, DAOC an DAC were determined on line by HPLC. The influences of four motionless mixers on the dissolved oxygen concentration (DOC), oxygen transfer rate, the cell growth and the CPC production, as well as the reactor performance, were evaluated. The results were compared with the performance of an airlift tower loop reactor (ATLR) without static mixers as well as with a stirred tank reactor (STR). A comparison of cultivations in the ATLRM and ATLR with 50 g l-1 PF indicates that the obtained maximal CPC concentration and the (CPC + DAC + DAOC) concentration were 7% and 22% higher in the ATLRM (4.96 and 7.46 g l-1) than in the ATLR (4.63 and 6.13 g l-1) respectively. The maximal CPC volumetric productivity in the ATLRM (55.1 mg l-1 h-1) was also considerably higher than that in the ATLR (48.5 mg l-1 h-1). The specific power input was reduced from 2.36 to 1.5 kW m-3, the specific productivity pertaining to the power input was improved from 1.96 to 3.31 g W-1. On the other hand, cultivation in the ATLRM had a lower maximum CPC concentration and volumetric productivity than those in STR (7.2 g l-1 and 71.2 mg l-1 h-1) with the same medium due to the lower shear stress levels and the lower specific power input (1.5 vs. 3.0 kW m-3); but the specific power imput-based yield coefficient was in the ATLRM (3.31 g W-1) higher than in the STR (2.40 g W-1). By increasing the amount of PF, it was possible to enhance the CPC concentration and volumetric productivity in the STR. However, the performance of the ATLRM was limited to using a medium containing maximal 50 g l-1 PF because of the high viscosity of the medium, the limited energy input and thus the limited oxygen supply.