PhD CASE AWARD at Huddersfield University

Paul Williams paul at
Tue Sep 14 17:52:05 EST 1999

Optimisation of the Bio - processing  Factors Involved with large scale
Microbial Biotransformations to enable them to be carried out Economically
in  Continuous Mode.

Ciba Speciality Chemicals - CASE AWARD                          14-Sep-99

Ph D CASE Studentship aims:

Nitrilase catalyses the direct conversion of aliphatic and aromatic nitriles
to their corresponding carboxylic acids without producing the intermediate
amide. The broad substrate specificity of nitrilase offers the possibility
of their use in the production of commodity chemicals. The University of
Huddersfield in collaboration with Ciba Speciality Chemicals have isolated
a novel Rhodococcus species with high activities of an unusual nitrilase).

Continuous operation of the microbial biotransformation of acrylonitrile to
acrylamide and  to ammonium acrylate by a whole cell biocatalyst offers
several advantages over batch operation but is a much more complex process,
involving additional processes and more refined monitoring and control. As a
continuous process, the biocatalyst must be retained within the reaction
environment in an immobilised state or separated from the mixture of  the
biotransformation  substrate/product outflow stream and recycled. Retention
of the biocatalyst within the reaction environment  can be achieved by
immobilisation of the biocatalyst within a support matrix. Polyacrylamide is
one example of  such a matrix. Alternatively, the biotransformation reactor
vessel could incorporate a cross- flow filtration unit to maintain contact
of the biocatalyst with the substrate from which  only the product stream is
removed. The biocatalyst, as a whole cell, could be recycled from the
outflow stream to the reaction vessel (containing the substrate)  if it is
first separated from the outflow stream by centrifugation; a process that
can be assisted by prior flocculation of the whole cells.

The choice of method for continuous operation will depend on the bioreaction
and the nature of the biocatalyst involved. In this work the whole cell
biocatalysed conversion of acrylonitrile to acrylamide and to ammonium
acrylate will be used as model bioreactions. The Biotechnology Centre has a
great deal of experience of these bioreactions carried out under batch
conditions. The objective of the work will be to assess the suitability of
the various continuous modes of operation outlined above for both
bioreactions and to draw general conclusions regarding the technical and
economic features of each.

The 3 year PhD CASE studentship will begin October/November and requires a
minimum IIii classification in one of the  relevant areas  - Biochemical
Engineering, Microbiology, Biochemistry, Engineering.  If you are interested
in this PhD CASE award (University funded) please send  a covering letter
and CV immediately to:
Dr Paul Williams,
Biotechnology Centre,
Applied Sciences,
Huddersfield University,

Tel:01484 473139
Email: paul.williams at

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