Sheet n°252 - October 2006
© IRD/Esther Katz
S
ugar-cane bagasse is a
fibrous waste-product of
the sugar refining industry,
along with ethanol vapour.
Part of the great volume of
this waste produced is recycled as a raw material for
paper manufacture, but the
industrial processing required
for delignification and bleaching of the resulting paper
pulp can be damaging for
the environment. Seeking to
overcome these drawbacks,
IRD researchers (UMR 180)
and INRA (UMR 1163) (1),
working jointly within IFRBAIM (Biotechnologies AgroIndustrielles de Marseille),
have elaborated a new bioprocess that transforms the
bagasse into paper pulp and
also produces an industrially
useful enzyme, laccase. The
process is based on the metabolism of a filamentous fungus
which, when raised in culture
on bagasse in the presence of
ethanol, produces this enzyme. Laccase breaks down
the lignin in the cane waste,
changing the latter into paper
pulp. Preliminary laboratory
trials show that this integrated
bioprocess can be adapted to
other potential fibre-yielding
materials, opening up promising applications for the paper
industry.
Developing uses for sugar-cane
bagasse: biotechnology applied
to the paper industry
Sugar cane for sale at Tiacolula market, Mexico.
The principal raw material used for manufacturing paper pulp is wood. However,
growing demand in the paper industry, at
a time of dwindling forest resources, have
compelled the sector to turn to other sources of raw materials, such as cereal straw,
reeds, bamboo or sugar-cane bagasse. This
residue, obtained after crushing of the cane,
is already used as a source of paper-making
fibres in producer countries (in South America
and India for example, where it represents
20 % of the paper production). The industry
absorbs 10% of the world bagasse production.
This material offers several advantages: rapid
growth of the sugar-cane plant, widespread
cultivation, lower energy and bleaching chemical requirements for bagasse refining. Such a
process is also a convenient means of usefully
clearing this voluminous sugar refinery waste
product: indeed, one tonne of refined sugar
results in two tonnes of bagasse.
However, whatever the raw material used,
paper pulp has to undergo processing stages
of delignification and bleaching to turn it into
high-strength and durable paper. In some
countries the chemical processing involved still
entail the use of chlorine, dangerous for both
health and the environment (2).
Research scientists from the IRD and INRA
studied an alternative, biologically based, solution. Laboratory experimentation enabled them
to develop a non-polluting process, which at
the same time yields a delignifying enzyme,
laccase, from a culture of a filamentous fungus
and effectively recycles the sugar-cane bagasse. Its principle lies in the specific metabolic
characteristics of this fungus, Pycnoporus cinnabarinus, which produces laccase naturally.
This enzyme breaks down the lignin in the
fibres of bagasse used as substrate in these
trials, transforming this waste product, after
>>
Institut de recherche pour le développement - 213, rue La Fayette - F-75480 Paris cedex 10 - France - www.ird.fr
CONTACTS :
RICHARD AURIA
IRD UR 180, IFR 86 de biotechnologie Agro-Industrielle
de Marseille, ESIL,
Université de Provence et de
la Méditerranée, Marseille
Tel : +33 (0)4 91 82 85 68.
rauria@esil.univ-mrs.fr
JEAN-CLAUDE SIGOILLOT
INRA UMR 1163
Université de Provence
et de la Méditerranée de
Biotechnologie des champignons filamenteux, ESILGBMA, same address.
Tel : +33 (0)4 91 82 86 23.
jcs@esil.univ-mrs.fr
PRESS OFFICE:
+33 1 48 03 75 19 ;
presse@paris.ird.fr
INDIGO BASE, IRD PICTURE LIBRARY
+33 1 48 03 78 99 ;
indigo@paris.ird.fr
REFERENCES:
JUAN CARLOS MEZA,
JEAN-CLAUDE SIGOILLOT,
ANNE LOMASCOLO, DAVID
NAVARRO AND RICHARD AURIA
– New Process for fungal
Delignification of Sugar-Cane
Bagasse and Simultaneous
Production of Laccase in
a Vapor Phase Bioreactor,
Journal of Agricultural and
Food Chemistry, 2006, 54, p.
3852-3858. DOI : 10.1021/
jf053057j
JUAN CARLOS MEZA, ANNE
LOMASCOLO, LAURENCE
CASALOT, JEAN-CLAUDE
SIGOILLOT, RICHARD AURIA
- Laccase production by
Pycnoporus cinnabarinus
grown on sugar-cane bagasse : Influence of ethanol
vapours as inducer, Process
Biochemistry, 2005, 40 p.
3365-3371.
KEY WORDS
SUGAR-CANE BAGASSE,
BIOTECHNOLOGY,
INDUSTRIALLY APPLICABLE
ENZYME,
PYCNOPORUS CINNABARINUS,
PAPER INDUSTRY.
P. cinnabarinus naturally sythesizes only
small amounts of laccase when it grows on
bagasse. It is necessary to add volatile agents
such as ethanol, in order to increase production of the enzyme under these conditions (3).
Ethanol was chosen as a laccase-inducer in
this study because of its abundance, its low
toxicity and low production cost. The research
team moreover showed that if it was put into
the system by forced convection at a rate of 7
g of ethanol per m3 (concentration equivalent
to 3° of alcohol in the liquid phase), laccase
production increased, to a maximum level (90
U per g of dry bagasse support). This amounts
to 45 times the yield obtained without ethanol.
Moreover, it appeared that little or no ethanol introduced was consumed by the fungus
which preferentially uses other sources of carbon, resulting from the bagasse (saccharose)
or put in with the substrate (maltose, yeast
extracts and so on). It can therefore be recycled in the system or eliminated in a second
system associated with it (4).
Replication of the fermentation trials at a
larger scale, in an 18 litre bioreactor, confirmed the efficiency of the laccase production
obtained using bagasse and ethanol (90 000 U
per kg of dry bagasse after 30 days, representing the quantity needed for processing, without
input of fungus, an extra 4 kg of bagasse). This
bioprocess resulted in a 50% saving in energy
consumption required for paper pulp refining,
compared with that recorded for refining pulp
from bagasse that had not been biologically
treated. Another benefit came in the form of a
© INRA/Instituto de Microbiología de Pekín, China.
Sheet n°251 - Octobre 2006
For futher information
mechanical refining, into paper pulp. As the
lignin progressively disappears, the pulp obtained becomes bleached. This pulp can be used
as it is to make cardboard, but it must undergo
additional treatment using hydrogen peroxide
in order to yield paper for printed and writing.
35% improvement in the paper’s mechanical
characteristics (tensile strength and tear resistance) without appreciable loss of material.
The results as a whole emphasize the potential for applications of this bioprocess in the
paper industry. Retrieval of the laccase at the
end of the cycle, after washing and pressing
of the bagasse, allows additional quantities
of the substrate to be processed and, in this
way, raise the profitability of the operation.
Furthermore, this process can be adapted to
the processing of other raw materials (wood,
cereals). Investigation of the use of methanol
as laccase inducer can, similarly, be envisaged
as a way of recycling this compound, which
constitutes one of the main pollutants emitted
by the paper industry.
(1) Each of these teams is a partner of the
Universities of Provence and the Mediterranean
They are grouped together within the research
entity IFR 86-BAIM.
(2) In Europe, however, the paper industry is
turning increasingly towards completely chlorine-free processes.
(3) Lomascolo et al.- Overproduction of laccase
by a monokarryotic strain of Pycnoporus cinnabarinus, using ethanol as inducer, J. Appl.
Microbiol. 2003, 94, p. 1-7.
(4) Other research conducted by the IRD,
working jointly with the UAM (Autonomous
University of Mexico) of Mexico City and the
ICIDEA (Cuban Institute of Research on Sugarcane derivatives) of Cuba, have shown that a
yeast, Candida utilis, can be used to produce
biomass on the bagasse. It can thus provide a
protein-rich feed for animals, while eliminating
ethanol in the process (air pollution removal).
See the scientific bulletin n°155, May 2002,
on line on www.ird.fr/fr/actualites/fiches/2002/
fiche155.htm.
Marie Guillaume-Signoret - IRD
Translation : Nicholas Flay
White wood rot fungus of the genus
Pycnoporus.
Marie Guillaume - Signoret, coordinatrice
Délégation à l’information et à la communication
Tél. : +33(0)1 48 03 76 07 - fax : +33(0)1 40 36 24 55 - fichesactu@paris.ird.fr