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Substances naturelles en Polynésie française

 | 
Jean Guezennec
, 
Christian Moretti
, 
Jean-Christophe Simon

Part one. Synopsis and Recommendations

French Polynesia’s biodiversity assets

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TERRESTRIAL PLANT RESOURCES

  • 1 Bioprospecting: exploiting, extracting and screening or sorting biological diversity and indigenous (...)

1French Polynesia’s primary flora is relatively poor, with only some 900 species, and is therefore more vulnerable than introduced species. But 62% of its species are endemic, owing to insularity, the islands’ wide geographical scatter and their extensive north-south spread. For 80-90% of endemic plants there is no bibliographical reference pointing to scientific study. Between them, these two facts obviously mean that there is ample scope for bioprospecting1.

2Apart from local uses and a few clearly identified marketable resources, the origin features of French Polynesia’s flora have not been explored to any great extent. Very few local species have been adopted for economic use.

3This observation suggests two avenues to explore:

  • How can new species with commercial potential be identified and selected?

  • How can income from the species already exploited be increased?

Approach and method of the expert group review

4There is no proven, unanimously recognised method for determining which are the exploitable plant resources in a given region.

5Nor, to our knowledge, is there any synoptic table or database of the relevant information on French Polynesia’s exploitable plant resources, apart from books on local uses of plants.

6The experts’ work goes some way to filling the gap.

7The panel opted for an approach that starts from the biological resource, which was possible thanks to the relatively reliable botanical data available for French Polynesia. The main stages in the process were as follows:

  • Despite the relatively small number of native species, we were not able to analyse the scientific literature on all of them. We therefore made a critical analysis of the available scientific knowledge and worked out a preselection method to identify potentially exploitable plant substances.

  • As this is a vulnerable island flora with a high rate of endemism, a preliminary correlation of criteria was necessary, taking botanical originality as the primary criterion for inclusion and ecological status as the primary criterion for exclusion: vulnerability is clearly a criterion for exclusion because vulnerable species cannot reasonably be regarded as “potentially exploitable” without endangering the resource itself, and hence biodiversity.

  • This brought the number of species to consider down to 430. We then applied an additional set of exclusion/selection criteria to this group. Below is a simplified synoptic table of these criteria.

Source: paper by Moretti and Florence (see CD-ROM).
Note 15. IUCN list: since 1994, the IUCN (International Union for the Conservation of Nature and Natural resources) has been developing a classification of plant and animal species into five categories, from which risks to biodiversity can be measured: extinct (EX), critically endangered (CR); endangered (EN); vulnerable (VU); low risk (LR); data deficient (DD).
Note 16. This criterion does not apply to Tahitian vanilla (Vanilla tahitensis), which is a specifically Polynesian variety. It is therefore included in the selected species list.

8Using this set of exclusion/selection criteria, 78 species were chosen for examination. A data sheet has been drawn up for each one, using the model shown below. These can be used to compare the data (such as exists) with the various experts’ comments:

9The experts collectively defined three main groups, classing each species in one or other:

    • 2 For easier consultation, the data sheets for this group are reproduced in the paper edition of the (...)

    Group 1 – Shortlist of species already exploited or potentially exploitable2;

  • Group 2 – Species whose economic use is possible in the medium term, but which would first require R&D work;

  • Group 3 – Non-priority species that meet the experts’ selection criteria but for which no proposals can be made on possible R&D directions, for lack of significant bibliographical data.

10For species classed in Groups 1 and 2, the experts give their opinion on the possible directions for research, development and utilisation. Two points should be made here:

  • A comparison of groups 1 and 2 shows that the information available varies widely from species to species; our suggestions vary accordingly in their degree of refinement.

  • Most species in group 2 are in the IUCN’s vulnerable categories.

11To conclude, although potential economic uses for very few of the species studied have been clearly identified, the experts’ work provides French Polynesia with a preliminary checklist of relevant information on exploitable resources. This is an original contribution, both in the method adopted and the final output.

12However, attention must be drawn to the following facts:

  • As already stated, French Polynesia’s plant biodiversity has not yet been studied sufficiently and its potential therefore remains inadequately assessed. In this connection the catalogue of useful species drawn up as part of the expert group review (Flore utile de la Polynésie française, appended to the paper by Moretti and Florence on the CD-ROM) is a valuable instrument. It brings together the available data on useful plants mentioned in reference works, with their taxonomic status checked and updated. Apart from the taxonomic updating, this data pack contains new or updated data on geographical distribution and availability, including the accessibility, abundance and structure of current populations.

  • The selection method adopted here has doubtless allowed some useful species to slip through the net because they did not meet the criteria used, particularly that of endemism. We know this applies to some introduced species that have escaped from crops; several of these, especially varieties of Quinquina, are of significant economic interest. Moretti and Florence draw attention to this genus in their paper, but it could not be included in the final list using our set of criteria.

MARINE RESOURCES

Introduction

13Marine organisms hold an immense store of potentially useful molecules which has so far been studied only partially and unevenly, and is still less exploited. The best catalogued groups are corals and molluscs – known indicators of marine biodiversity – and algae. Spongiae and micro-organisms have been studied far less.

14To date, an estimated 500,000 marine, animal and plant species have been identified, but fewer than 5% have been studied for their chemical and biochemical properties. The scientific literature is steadily producing new discoveries of bioactive marine metabolites. Analysis has shown that the likelihood of finding such metabolites in marine organisms is far higher than with land organisms: 10 per 10,000 compared to 1 per 10,000.

15But because marine substances are rarely used in traditional medicines, there are no ethno-pharmacological references to guide the search for useful molecules in this ocean of possibilities (ranging from bacteria to sharks!).

16Given the current low level of inventoried knowledge on marine resources and their utilization potential, there was no basis for taking an overall approach and drawing up data sheets as was done for land plants (see paper by Guézennec and Débitus on CD-ROM). Below we briefly introduce the main types of organism and outline their utilisation prospects in major economic sectors.

Different types of marine resource

Fishery by-products

17The main uses of fishery by-products are in health applications, mainly of omega-3 and omega-6 unsaturated fatty acids, which have potential uses in human nutrition, cardio-vascular medicine and oncology.

18Fishery by-products are also being explored to find specific fats.

19Broadly speaking, research in this field is at a far more “pure research” level than the work on other types of marine molecule.

Seaweed

20Uses of seaweeds are relatively little-known to the general public, although they are used in many consumer products. Internationally, seaweeds are mainly (70%) used in the food and feed sector, principally in the Asian food market. The market in food seaweed is worth 4 billion dollars a year in the United States. While the main users are Asian countries, food use of seaweed is growing in the West, especially in the market for food supplements and health foods.

21Utilisation of seaweed in food is growing fast and has a promising future. French Polynesia, as already mentioned, has excellent research assets and tools in this field. The University of French Polynesia has a large seaweed collection, the Institut Louis-Malardé another, and a recent doctoral thesis provides a synthesis of work on Polynesian seaweeds and their potential uses in different sectors, from environmental management to cosmetics.

Micro-organisms

22The term “micro-organisms” is used here to cover micro-algae, fungi, bacteria, archaebacteria and cyanobacteria.

23French Polynesia has some particularities in this field owing to its geographical position and the presence of specific ecosystems such as the “kopara ponds”; a doctoral thesis on kopara is under way.

24Micro-organisms are a source of many molecules with real potential in biotechnology, particularly biodegradable polymers, polysaccharides, enzymes and secondary metabolites (see Table 7, p. 235).

25The considerable progress made in molecular biology in recent years now makes it possible, and above all easier, to study microbial ecosystems. But as many studies have shown, only 0.1 to 1% of microbial species found in marine ecosystems can be studied using conventional laboratory techniques such as culturing on more or less selective media. This means that a very high proportion of microbial metabolites of biotechnological interest may defy attempts to study them. And yet marine micro-organisms could prove to be the main source of new biotechnologically useful molecules in the next few decades. It can be said that one of the main challenges for biotechnology research on marine micro-organisms is to develop methods for identifying, characterising and analysing the “non-culturable” ones.

26For the reasons stated, it seems impossible, and indeed pointless, to list the microbial species present in Polynesian ecosystems, both because there are so many of them, and because such a list might well not be representative. It is generally recognised that only a very small percentage of microbial species are culturable and hence identifiable using conventional taxonomic methods, and that the very notion of a culture medium implies selection of some species and exclusion of others. The same can be said of the use of these micro-organisms in biotechnology, as synthesising useful metabolites can depend on manipulating their growth and fermentation conditions. In short, to use a micro-organism in industry or even study it scientifically, one must be able to culture it.

27In the light of this, the best way forward with micro-organisms would be to focus on conservation and building up of collections which would provide the basis for subsequent action towards utilisation in biotechnology.

Potential uses

28There are many potential applications for marine resources; they can be a source of new models, new products or new processes for a number of industries. Their diversity and their adaptation to atypical or extreme conditions open up new prospects for developing new bioactive molecules. There is now a lively interest in them, as reflected in the growing number of patents connected with the biological activity of products derived from marine organisms (mainly invertebrates so far).

29In terms of economic uses, whatever the marine resource concerned, there are some fields that seem to match both economic and social demand:

  • The environment and the search for “clean technologies” (“green chemistry”) to replace existing technologies that are more polluting, less specific, less effective or more costly.

  • Cosmetology/dermo-cosmetology, a field that is constantly looking for innovative or original substances, whether in terms of their history or their physical-chemical properties and efficacy. Despite many uncertainties including questions of official regulation, this sector often looks like the best niche to aim for when looking for short-term economic uses. This view may be better founded in some cases than in others.

  • The food and feed industries in the broad sense, which are looking for new texturing molecules that can adapt to new market constraints.

  • Synthetic and hemisynthetic chemistry, which are looking for new molecules or precursors.

  • The health sphere, which is looking for molecules – sometimes narrowly targeted – that are highly specific, effective or active, to develop substitutes for existing molecules that are in one way or another undesirable owing to their origins. With the recent discovery of unconventional pathogens, bioactive marine compounds could present a major advantage over the use of animal-based compounds such as heparine and hyaluronic acid.

Utilisation strategies

30The scale of marine biodiversity, and the current state of knowledge, make it delicate if not impossible at this stage to favour one channel over another for economic utilisation. The first step will have to be a multidisciplinary study of the flora and fauna of different biotopes.

31The conditions for such uses would also vary widely depending on how the extracts are obtained. One determining factor for exploiting a new product is the ease and cost-effectiveness with which it can be obtained. There are three ways to obtain sufficient quantities of such products: extracting and purifying primary or secondary metabolites from macro- or microorganisms, synthesis, and hemisynthesis, which is a compromise between these two, taking a natural precursor and converting it. Though rarely impossible, synthesis and hemisynthesis can be complicated; they are not always cost-effective for industrial purposes. Producing active molecules by biotechnology is therefore a promising method in economic terms. It may involve using natural environments to farm molecule-producing organisms – e.g. sponges, ascidiae, gorgoniae, algae – or, particularly with microorganisms such as cyanobacteria, micro-algae, fungi and bacteria, biotechnology solutions such as fermentation and photobioreactors.

32For all these reasons, building up collections coupled with a solid marine chemistry component seems to be the most relevant short- and mediumterm step towards economic utilisation. The conditions required for this work are well within the reach of French Polynesia and will be set out in the following Section.

Anmerkungen

1 Bioprospecting: exploiting, extracting and screening or sorting biological diversity and indigenous knowledge to discover commercially valuable genetic or biochemical resources.

2 For easier consultation, the data sheets for this group are reproduced in the paper edition of the review (Annex 1).

Abbildungsverzeichnis

Bildunterschrift Source: paper by Moretti and Florence (see CD-ROM).Note 15. IUCN list: since 1994, the IUCN (International Union for the Conservation of Nature and Natural resources) has been developing a classification of plant and animal species into five categories, from which risks to biodiversity can be measured: extinct (EX), critically endangered (CR); endangered (EN); vulnerable (VU); low risk (LR); data deficient (DD).Note 16. This criterion does not apply to Tahitian vanilla (Vanilla tahitensis), which is a specifically Polynesian variety. It is therefore included in the selected species list.
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