Publications by Henri Kornmann

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The influence of residual ethanol on metab. of food grade Gluconacetobacter xylinum I 2281 was investigated during controlled cultivations on 35 g/l glucose and 5 g/l ethanol. Bacterial growth was strongly reduced in the presence of ethanol, which is unusual for acetic acid bacteria. Biomass accumulated only after complete oxidn. of ethanol to acetate and carbon dioxide. In contrast, bacterial growth initiated without delay on 35 g/l glucose and 5 g/l acetate. It was found that acetyl CoA was activated by t

A novel in situ product removal (ISPR) method that uses microcapsules to ext. inhibitory products from the reaction suspension is introduced into fermn. technol. More specifically, L-phenylalanine (L-phe) was transformed by Saccharomyces cerevisiae to 2-phenylethanol (PEA), which is inhibitory toward the yeast. In order to continuously remove PEA from the vicinity of the cells, the reaction suspension was brought into contact with capsules of 2.2-mm diam. that had a hydrophobic core of di-Bu sebacate and an

Bacterial exopolysaccharides (EPS) have unique rheol. properties due to their high purity and regular structure. Thus, the food industry frequently uses EPS as thickening, gelling or stabilizing agents. The strain Gluconacetobacter xylinus I 2281 is capable of producing with a very high yield a new sol. EPS named gluconacetan, which is composed of rhamnose, glucose, mannose and glucuronic acid. Growth of these bacteria presents many features that represent a real challenge for both monitoring and control. H

A partial least-squares calibration model, relating mid-IR spectral features with fructose, ethanol, acetate, gluconacetan, phosphate and ammonium concns. has been designed to monitor and control cultivations of Gluconacetobacter xylinus and prodn. of gluconacetan, a food grade exopolysaccharide (EPS). Only synthetic solns. contg. a mixt. of the major components of culture media have been used to calibrate the spectrometer. A factorial design has been applied to det. the compn. and concn. in the calibration

An in-situ, mid-IR sensor was used to monitor the major analyte concns. involved in the cultivation of Gluconacetobacter xylinus and the prodn. of gluconacetan, a food-grade exopolysaccharide. To predict the analyte concns., three different sets of std. spectra were used to develop calibration models, applying partial least-squares regression. It was possible to build a valid calibration model to predict the 700 spectra collected during the complete time course of the cultivation, using only 12 spectra coll

Over the past decade the interest for bioprocess monitoring using non-invasive IR spectroscopic sensors has increased considerably. This is mainly due to their rapid simultaneous multi-analyte detn. ability, in-situ sterilizability, and low need for maintenance during operation. Most of the components in culture media absorb in the MID-IR region. The complex spectra obtained can be deconvoluted using numerical methods such as Partial Least-Squares. In order to do this, a calibration model for each component

The influence of substrate compn. on the yield, nature, and compn. of exopolysaccharides (EPS) produced by the food-grade strain G. xylinus I-2281 was investigated during controlled cultivations on mixed substrates contg. acetate and either glucose, sucrose, or fructose. Enzymic activity anal. and acid hydrolysis revealed that 2 EPS, gluconacetan and levan, were produced by G. xylinus. In contrast to other acetic acid strains, no exocellulose formation has been measured. Considerable differences in metaboli

In order to reduce the large calibration matrix usually required for calibrating multiwavelength optical sensors, a simple algorithm based on the addn. in process of new stds. is proposed. A small calibration model, based on 14 stds., is periodically updated by spectra collected online during fermn. operation. Concns. related to these spectra are reconciled into best-estd. values, by considering carbon and oxygen balances. Using this method, fructose, acetate, and gluconacetan were monitored during batch fe

Henri Kornmann

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Influence of residual ethanol concentration on the growth of Gluconacetobacter xylinus I 2281

xxvel type of in situ extraction: Use of solvent containing microcapsules for the bioconversion of 2-phenylethanol from L-phenylalanine by Saccharomyces cerevisiae

Adaptive control of a G. xylinus fed-batch fermentation using in situ mid-IR spectroscopy

Monitoring and control of Gluconacetobacter xylinus fed-batch cultures using in situ mid-IR spectroscopy

Methodology for real-time, multianalyte monitoring of fermentations using an in-situ mid-infrared sensor

Experimental versus simulated calibration mdels for in situ FTIR monitoring of bioprocesses

Influence of nutritional factors on the nature, yield, and composition of exopolysaccharides produced by Gluconacetobacter xylinus I-2281

Real-time update of calibration model for better monitoring of batch processes using spectroscopy

Monitoring and control of exopolysaccharides production by "Gluconacetobacter xylinus" I-2281 using in situ mid-infrared spectroscopy

Etude de l'extraction du phenylethanol par des capsules d'alginate contenant le solvant. Application à la biotechnologie

Real-time adaptation of partial least squares calibration model used in on-line monitoring of bioprocess by mid-infrared spectroscopy