Paper360 - July/August 2013 - (Page 26)
Next Generation Enzymes for
the Paper and Pulp Industry
Enzymes have long been part of the paper making process, but
next generation enzymes use less energy, increase efficiency
and operate at wider pH ranges
ext generation enzymes use
genetic engineering to optimize the action of enzymes.
The first step is the search for
a gene that will produce the
desired enzyme. High speed
robots scan for genes using an assay that
indicates the presence of the desired gene.
The process is known as High Throughput
Robotic Screening or HTRS (Figure 1).
Once a desired gene is located, it is
extracted and inserted into a host organism
to reproduce millions of copies of the cell containing the gene. Host organisms are single
cell organisms that with genetic manipulation can be turned into little enzyme/protein
factories. There are a variety of host organisms including Yeast, Chinese Hamster
Ovaries, Viral Vectors, and Fungi such as
C1—a proprietary fungal expression system
Hosts are where research companies differ
in their approach. While some companies
extract the desired gene and insert it into a
test host organism and produce laboratory
quantities for further examination, others
work directly with the commercialization
host organism to ensure that the desired gene
Figure 1. Vial P shows a positive assay.
can be expressed on a commercial scale. This
is an important difference because often the
products produced by test hosts require further manipulation to make them suitable for
the commercial host.
While working with the host organisms, genes that inhibit the production of the desired protein or enzyme are
removed to optimize the production of the
Once a host strain is produced in sufficient quantities, it is inserted into large
industrial fermentation vessels to produce
the desired enzyme.
NEXT GENERATION ENZYMES AND
Wood pulp fibers in a raw state contain both
crystalline fibrils and less ordered cellulose
structures on the surface. Endoglucanases
help strip these fibrils from the surface of the
wood and attack the less ordered structures
that are to some extent degraded. Mild to
moderate beating increases fibrillation on the
fiber surface increasing fiber-to-fiber interactions and yielding a stronger pulp (Figure 2).
An improved next-generation endoglucanase interacts with cellulose in such a way
that it facilitates degradation to the fiber wall
structure allowing the pulp to be mechanically refined using lower energy input. The
endoglucanase is also capable of hydrolyzing
the small fibrils, or fines, that are released
from the fiber wall without consuming the
more ordered cellulose structures composing
the bulk of the fiber. This effect can improve
drainage when pulp reaches the paper
machine, which may have a positive effect
on productivity due to potential increases
in paper machine speed.
The next-generation endoglucanase is
also highly flexible—operating within wider
temperature and pH ranges making it more
adaptable in existing pulp mill processes.
Dosage also is highly flexible yielding higher
tensile strength than other cellulases (see
Fig. 3). Typical cellulase enzymes often must
be confined to a narrow dosage range or reaction time as overdose effects might occur if
applied improperly due to excess degradation
of the fiber wall prior to refining.
Following initial screening and industrial fermentation scale up, next generation
enzymes go through extensive laboratory
and mill trials to determine optimal dosage
and effect under process-specific conditions.
MILL TRIAL RESULTS
Trial 1: Multi-liner board, Southeast
Asia, 500 TPD capacity. The endoglucanase product was applied to the bottom layer
of a multi-liner board at dosages ranging
from 90-160 g/mT. As a result of successful
treatment, machine speed was increased by
9 percent which in turn increased production
by 44 TPD.
Trial 2: Six-ply coated and uncoated
paper, 400 TPD capacity. The multi-ply
paper was composed of a bleached eucalyptus
top layer, an ONP bottom layer, and recycled
Table of Contents for the Digital Edition of Paper360 - July/August 2013
Over the Wire . . . News Summary
Ready for Print 2.0?
Eldorado Brasil Begins Operations in the Pulp Industry
Newark’s Frank Papa on Leadership and Innovation
Tissue Mill Dewaters Pulp with Innovative Disc Filter
TAPPI Journal Summaries
Next Generation Enzymes for the Paper and Pulp Industry
The Best Resources for Your Best Resources
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Paper360 - July/August 2013