natural-products-in-plant-pest-management

276 S. HettiarachiFragments of DNA can be cloned using artificial bacterial chromosome(BAC) vectors. These are designed to carry larger fragments than those producedby PCR techniques. Rondon (2000) used this technique and revealed agreat deal of information on phylogenetic, physical and functional propertiesof the metagenome. Some of the clones showed antibacterial and nucleaseactivity and the DNA sequences governing these characteristics were foundto be different from those already known. This directly supports the idea thatunculturable organisms provide a source of novel genes. Other functionsobserved were the production of amylase and lipase and hemolysis.13.4 ConclusionThe search for natural products has been rekindled with realization of thevast biological diversity and genetic diversity that make biological systemsan unlimited resource. Furthermore, the global society is demanding naturalproducts and rejecting synthetic chemicals for all possible uses, includingfood and additives, drugs, cosmetics and so on. Although plants and animalshad been a source of such products from ancient times, the horizons nowhave widened and continue to expand, particularly with the development ofmodern biotechnological tools. Man was unaware that he was exploitingmicroorganisms as they are invisible to the naked eye. Some products becomeredundant over time, as is the case for antibiotics for which resistance hasdeveloped in target (and non-target) organisms. Further new diseasesemerge, new lifestyles demand new products, and biotechnology is neededto satisfy those demands. As new tools in biotechnology have been found,one can expect that the trend will continue. Exploring and exploiting newresources will be feasible in the future, as evidenced by metagenomics innew product formation which harness the biosynthetic capability ofunculturable microorganisms. However, with all of these developments, thenumber of bioproducts that have already conquered the market is not encouraging.Therefore, there is a need for more intensive research on optimizingproduction of already identified bioproducts, with simultaneous researchefforts on new product formation. It can also be noted that technology transferis not occurring effectively, because the already available technologiesremain in the laboratories where they were generated without reaching theindustrial fermenters or industrial-scale farms.ReferencesAlfermann, A.W. and Petersen, M. (1995)Natural product formation by plant cellbiotechnology: results and perspectives.Plant Cell, Tissue and Organ Culture 43,199–205.Arakawa T., Yu, J., Chong, D.K.X., Hough, J.,Engen, P.C. and Langridg, W.H.R. (1998)A plant-based cholera toxin B subunit–insulin fusion protein protects againstthe development of autoimmune diabetes.Nature Biotechnology 16, 934–938.Berlin, J. (1984) Plant cell cultures—a futuresource of natural products? Endeavour 8,5–8.