Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Developing uses for sugar-cane bagasse: biotechnology applied to the paper industry

14.11.2006
Sugar-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 IFR-BAIM (Biotechnologies Agro-Industrielles 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.

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 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.

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 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.

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 Sugar-cane 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 | alfa
Further information:
http://www.ird.fr/fr/actualites/fiches/2006/fas252.pdf

More articles from Agricultural and Forestry Science:

nachricht Six-legged livestock -- sustainable food production
11.05.2017 | Faculty of Science - University of Copenhagen

nachricht Elephant Herpes: Super-Shedders Endanger Young Animals
04.05.2017 | Universität Zürich

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

How herpesviruses win the footrace against the immune system

26.05.2017 | Life Sciences

Water forms 'spine of hydration' around DNA, group finds

26.05.2017 | Life Sciences

First Juno science results supported by University of Leicester's Jupiter 'forecast'

26.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>