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Biodegradation of polymeric substrates

The project encompasses a complex solution for biologically removing solid wastes consisting of natural and synthetic polymers. The r & d of this bioremediation is based on using microbial capability to colonise solid wastes.

Biodegradation of pollutants is a natural process by which unwanted organic chemicals in the environment are converted to simpler compounds, mineralised and redistributed through elemental cycles such as the carbon, nitrogen and sulphur cycles. Biodegradation of polymers (in comparison with non-polymeric pollutants) is an emerging field much needed in respect of unwanted environmental pollution by natural and synthetic polymeric materials, frequently accompanied by low molecular xenobiotics. The various aspects of cellulose as a (natural, polymeric) main pollutant are considered in view of its lack of toxicity on the one hand and its recalcitrant durable nature on the other. The microbial degradation of cellulosics is discussed, and the contrast between its success in handling cellulose waste versus its failure to cope with man-made refuse is described. Research carried out in the past decade has demonstrated that cellulolytic organisms are provided with cell surface multifunctional multi-enzyme conglomerates (cellulosomes), which are capable of solubilising cellulosic substrates. However, for the progress in establishing efficient biotechnology for a tailor-made solubilisation of cellulose wastes, the applicable knowledge about the intriguing properties of cellulolytic microorganisms, their many enzymatic components, their substrate targeting mechanism, etc., is still missing. Furthermore, the technological R & D must meet the fundamental limitations of such biotechnologies, i.e. very complex interaction between biotic factors, including the specific properties of cellulolytic microflora, cell responses to the effect of stressors, morphogenetic specificity of cellulolytic microorganisms, versatility of their (key) biochemical activities, etc. as well as cellulose composition, especially its complexity with hemicellulose and lignin, and abiotic factors such as molar mass, crystalinity and chemical modification of this polymer, and finally the physicochemical properties of technological environments. The purpose-built reactor design and technology set up is another field of this R & D. Biodegradation of synthetic polymers offers a similar survey of topics. In both cases, the application of immobilised degradative microflora is judged as a general innovative element of these environmental technologies. In this context, the innovative element of this project is technological employment of cell populations of the aforementioned microbial degraders in the form of natural biofilm and the application of additives increasing the polymeric pollutant bioavailability. The complex development of technologically applicable degradative microflora capable of reproducibly colonising the surface of a carrier or solid polymeric waste will be based on knowledge obtained about how bacterial and fungal cells adjust their biochemistry and behaviour to live as 3D multi-cellular consortia, and what triggers cause the suspended microbial cell to colonise a solid surface and adjust to a sedentary, multi-cellular existence. Moreover, to achieve this it is also necessary to solve tasks connected with biological, physico-chemical and engineering aspects of biofilm use in environmental biotechnology. Furthermore, any development in the field of the biodegradation of polymeric pollutants must focus on the mode of applying the biodegrader(s) engaged, which represents a wide range of possibilities for process upgrading and tailor-made implementation of appropriate treatments. In general the project intends paying close attention to all biological and engineering aspects of technological efficiency, technological drawbacks and technological (environmental) impacts. An international cooperation programme was therefore set up and aimed at R & D in these fields of research: 1) Phenotype analysis and characterisation of selected bacterial and fungal strains applicable in a biofilm based degradation of polymeric substrates, i.e. cellulose waste and selected synthetic polymers used in the healthcare sector and mostly modified by an antimicrobial finishing treatment; 2) Analysis and elucidation of factors triggering and affecting the formation and function of multi-cellular consortia of biodegraders; 3) Development of strain mixtures combining the capacity to degrade polymeric and low molecular substrates as a blended pollutant; 4) Biochemical characterisation of the enzyme systems determining given degradative activity; 5) Development of methodology for monitoring and visualising the process of biodegradation; 6) Immobilised-cell bioreactor design to be used in continuous biodegradable processes; 7) Experimental approaches verifying the effect of additives affecting the bioavailability of model polymeric substrates to be degraded; 8) Functional analysis of long-term viable biocatalysts; 9) Methodology to elucidate the efficiency of a polymeric substrate bioconversion into proteins; 10) The carrier material choice; 11) Technology set up if immobilised and suspended biodegraders are applied. Thus future work should address all (mostly missing) physiological, biochemical and technological aspects for technological functions and properties of bacterial and fungal degraders of key polymeric pollutants. The intention of the project is to develop a complex experimental approach that combines laboratory-based techniques with field-based relevance. Keywords: polymeric wastes, polymeric biodegradation, polymer finishing.
Acronym: 
BIOPOLS
Project ID: 
3 654
Start date: 
01-01-2006
Project Duration: 
36months
Project costs: 
1 980 000.00€
Technological Area: 
Biotreatment / Compost / Bioconversion
Market Area: 
Water, sewerage, chemical and solid waste treatment plants

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