Chitosan activates resistance against pathogens after exposure production of chitosans from shrimp shells for applications in plant disease protection (CARAPAX)

Grunddaten zu diesem Projekt

Art des Projektes: EU-Projekt koordiniert an der Universität Münster
Laufzeit: 19.03.2001 - 31.03.2005

Beschreibung

The CARAPAX project convened a consortium of experts from Academia and Industry to evaluate the potential of speciality chitosans with known and defined physico-chemical properties to be used as novel, environment-friendly, and consumer-safe plant disease protectants. In the past, chitosans had been reported to protect plants from disease by inhibiting microbial growth and by inducing plant disease resistance mechanisms. However, convincing protection had been achieved in some but not all previous studies, and reliable results had only been obtained when ca. 40 kg of chitosan had been applied per hectare. We hypothesised that this lack of reliability observed with feasible application doses was due to batch-to-batch differences in commercial chitosans, and due to a lack of basic understanding of structure/function relationships of chitosans. The CARAPAX project, therefore, aimed at developing reproducible procedures for the isolation of high quality chitin from shrimp shells and squid pen, and for the conversion of chitin into speciality chitosans with known degrees of polymerisation (DP) and degrees of acetylation (DA). These CARAPAX chitosans were then analysed for their physico-chemical properties, and tested for their antimicrobial and plant disease inducing activities. Based on our results, selected chitosans were finally tested for their potential as novel plant protectants.The physico-chemists in our consortium optimised the procedures for the extraction of chitin from shrimp shells and squid pen, and for the conversion of chitin into chitosans with different DP and DA. These technologies were successfully transferred from the lab to the commercial chitin/chitosan producer of the consortium. Using these well characterised chitosans, we have been able to confirm the basic assumption of the CARAPAX project, namely the strong dependency of the biological activities of partially acetylated chitosans from their physico-chemical properties, and we defined a general law of behaviour describing this dependency. Based on this knowledge, we were able to reduce the amount of chitosan required to achieve reliable plant disease protection from 40 kg ha-1 to 160 g ha-1 which is similar to the amount required of modern chemical fungicides. However, the efficacy of the chitosans is not yet good enough to begin formulating a commercial product. Research strategies for the further improvement of the performance of chitosan as a plant protectant have been identified and are being pursued in follow-up projects.The results of the CARAPAX project also have direct implications for the use of chitosans in other life science applications such as in medicine and pharmacy, food protection and cosmetics. We anticipated that all of these bioactivities of chitosans will strongly depend on their physico-chemical properties. Methods to produce well characterised chitosan polymers and oligomers have been optimised or developed during the CARAPAX project so that follow-up projects investigating these alternative high-end uses of quality chitosans have been started (e.g. NanoBioSaccharides).Three years after the end of the CARAPAX project and based on the basic knowledge gained from our results, one of the chitosan producers of our consortium, Dr. Gillet, has started marketing his first chitosan-based plant protectant for wheat, groundnut, and pearl millet in Gujarat in North India where his chitosan producing company is located. This seed dressing reliably increases yields of harvest for resource poor farmers by a minimum of ca. 25 %, thus securing food production and rural incomes. Registration as a plant strengthener in Europe, however, failed due to changed European legislation which discontinued the category of plant strengtheners leaving only plant protectants - which are far too costly to register for anyone but big pharma.

Stichwörter: biopolymer; polysaccharide; chitosan; plant protection