Chemistry: molecular biology and microbiology – Micro-organism – per se ; compositions thereof; proces of... – Fungi
Patent
1997-12-30
2000-02-01
Redding, David A.
Chemistry: molecular biology and microbiology
Micro-organism, per se ; compositions thereof; proces of...
Fungi
4352625, 435913, 435911, C12N 114, B09B 300
Patent
active
060201843
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the biodegradation of polyorganosiloxanes (POS) and in particular of polydimethylsiloxanes (PDMS). It also relates to a screening method which makes it possible to select microscopic fungi of use in the context of the biodegradation process.
Until now, silicones were generally regarded as being non-biodegradable.
This state of affairs is today an obstacle to the use of silicones.
Contrary to all expectations, the Inventors have found that, under specific conditions, it is possible to degrade PDMSs with the help of certain microscopic fungi belonging in particular to the genera Phanaerochete and Aspergillus and that this teaching can be extended to POSs in general.
Mention may more particularly be made of P. sordida and P. chrysosporium, as well as of a recently isolated Aspergillus strain, known as Aspergillus sydowii BJS 94, deposited on Feb. 22, 1996 at the CNCM (Collection Nationale de Culture de Microorganismes [National Collection of Microorganism Cultures] of the Pasteur Institute, 28 Rue de Dootour Roux, F-78724 Paris Cedex 15, France) under the reference I 1679. Aspergillus sydowii BJS 94 is a filamentous fungus which can degrade glucose and was cultured on malt agar (with 50 g/l malt and 20 g/l agar) from spores. This deposit was made under the Budapest Treaty and all restrictions imposed by the depositor on the availability to the public of the deposited biological material will be irrevocably removed upon the granting of a patent
The subject of the present invention is thus a process for the biodegradation of POSs, in particular of PDMSs, wherein the POSs are brought into contact with at least one microscopic fungus, preferably in the presence of at least one cosubstrate, the microscopic fungus being selected in particular from the family of the Corticiacea, preferably from the genus Phanaerochaete, or from the genus Aspergillus, the preferred fungi being selected from the group composed of P. sordida, P. chrysosporium and A. sydowii BJS 94.
These fungi are freely available from the collections indicated above and in the examples.
The cosubstrate is preferably a source of carbon and of energy which is readily assimilable by the fungus. It is in particular a carbohydrate or a mixture of carbohydrates and very particularly sugar, preferably glucose or sucrose.
According to a first embodiment, preferred in the case of the members of the Phanaerochete genus, of the process according to the invention, the process can be carried out in a medium deficient in nitrogen and preferably, in this case, at an acidic pH, preferably between pH 4.5 and pH 6.
According to a second embodiment of the invention, the process can be carried out in a medium which is not deficient in nitrogen and preferably, then, at a pH in the region of neutrality.
pH in the region of neutrality is understood to mean in particular a pH of between 6.5 and 7.5, preferably of between 6.7 and 7.3 and more preferably of the order of 7.
The process according to the invention can be carried out in a stationary culture but it is preferable, however, to carry it out in an agitated culture with PDMS concentrations preferably ranging up to 5000 mg/l, in particular from 100 to 5000 mg/l, preferably from 250 to 500 mg/l.
Inoculation can be carried out using spores, mycelium or a mixture of both.
Another subject of the present invention, which has for the first time proved that POSs can be degraded by a microscopic fungus, is a screening method which makes it possible to select other microscopic fungi capable of degrading POSs, in particular PDMSs, under the conditions of the invention.
This screening method consists in bringing POS, preferably PDMS, into contact with a candidate microscopic fungus, preferably in the presence of a cosubstrate as defined above.
The screening method can comprise, in addition, a preliminary test which makes it possible to preselect candidates. This preliminary test consists in evaluating the ability of the candidates to grow on POS, preferably PDMS, as sole carbon source.
REFERENCES:
patent: 5085998 (1992-02-01), Lebron et al.
patent: 5342779 (1994-08-01), Matsumura et al.
Bilai, V.I., "Certain features of microbiological destruction of organosilicon films on swollen perlite"; Dopov. Akad. Nauk Ukr. RSR, Ser. B, vol. 4, pp. 322-324, 1978.
Chemical Abstracts, vol. 101, No. 17, Oct. 22, 1984, Columbus, Ohio, Abstract No. 147501, Milstein, Oleg et al, "Biodegradation of carbon-14 labeled synthetic lignin polymer by Aspergillus species".
Baud-Grasset Frederic
Palla Jean-Claude
Redding David A.
Rhone-Poulenc Chimie
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