Coconut is a cash crop and it means subsistence for thousands of people in South Asia, particularly in Lanka, India, Philippines, Thailand and Malaysia. Philippines are probably the biggest producer of coconut in the world with almost 30% of fertile land planted with coconut.
Although biotechnology in coconuts has been focusing on molecular markers for genetic improvement of the coconut tree as well as for molecular detection of diseases, there are other interesting applications of biotechnology in coconuts and so this article will be concentrating more on those other aspects.
As compared to the impact of biotechnology on other vegetable oil crops, there is not much of research to show on coconuts. This is probably because, coconut is a difficult subject to study mainly due to the presence of increased lipid level and polysaccharides like galactomannan in the endosperm and polyphenols in the leaves. These substances make it difficult to get high quality DNA from the coconut plant which is a pre-requisite for any molecular biology oriented research. So the standard procedure is to extract DNA from the young leaves of the early emergent frond. This gives good quality enzyme digestible DNA.
The coconut tree is susceptible to several illnesses of bacterial, fungal, viral and phytoplasmal origin. For instance, biotechnology can be used to both detect and counter the Ganoderma butt rot disease which is of fungal origin. For detectection of Ganoderma disease, ELISA test with basidiocarp antiserum can be used, and if found positive, the pathogenicity could be stopped within a few months using Pseudomonas fluorescens and Trichoderma viride.
Coconut oil is generally extracted from coconut using copra-expeller method and this includes a stage where copra is smoke dried leading to the presence of aflatoxin which is toxic. To remove this substance, biological methods are being adopted like using the microorganisms (Flavobacterium aurantiacum, Rhizopus oryzae, and Tetrahymena pyriformis) that degrade aflatoxin.
But coconut oil can also be extracted now using a completely biotechnological route (that means not through copra-expeller method), although this method may not find favor with most coconut farmers who by and large have small plantations, and who do not have the expertise nor can bear the costs. This fermentation process involves the breaking of coconut milk emulsion by using microbial starter inoculums. These enzymes hydrolyze protein, carbohydrate and lipids in the coconut kernel. So what happens is, as a result of the fermentation, the coconut emulsion separates into oil in the top layer and into water along with carbohydrates in the lower layer. Although several microbial strains have been used for this purpose, the strain of Lactobacillus bulgaricus was found most effective as it only needed a starter concentration of 5% and gave highest yield as well. The advantage with coconut oil made by enzymatic route is that it contained more of lauric oil and it was more potent against inhibiting bacterial growth of Bacillus subtilis, Escherichia coli, Pseudomonas fluorescence and Salmonella. Research is also being conducted to develop enzymes that can restructure fatty acids such as lauric acid that are present in coconut oil.
Interestingly, in the distant future, biotechnology could perhaps challenge (not likely) the pre-emininence of coconut oil, because certain organisms such as moulds (Entomorphtora and Entomorphtora obscura) could even be programmed to make edible oils, though research in this area is very much nascent.
Plants are good for producing recombinant proteins which require a DNA sequence to be put into the plant genome either through biolistics, electroporation or using Agrobacterium tumefaciens. Now research has shown that coconut water which is sterile in nature expresses foreign DNA sequences adequately, which means it could be extrapolated to make recombinant proteins from recombinant DNA vectors.
Despite the abundance of rich germplasm of different coconut varieties, biotech research in coconut is very much retrograde. But as coconut trees are susceptible to pests and viral diseases like 'Cadang¬cadang' that has a high fatality rate, coconut cloning using in vitro culture techniques is an area of current research. However till date, somatic embryogenesis research with coconut hasn't produced many results and the coconut palm continues to be propogated by seed. Moreover, though coconut cloning is a possibility, it is also beset with problems like time taken by a coconut tree to grow.
Genetic engineering in coconuts has lagged, perhaps due to the lack of in vitro tissue culture system for studying coconuts, but interestingly as coconut water nuclei are naked and devoid of cell membranes, the possibility exists of micropropogating genetically engineered plant clones.
Coir extraction, bleaching and effluent disposal
Coir is a fibre that can be used to make exquisite floor mats and carpeting. Coir can be extracted from the outer peel or husk of the coconut. The coconut cut from a coconut tree is first hacked to remove the outer peel or husk to separate the nut. These husks are left soaked in small ponds for several days and biotechnology helps reduce this retting period by as much as three months with the use of bacterial cocktails such as "Coirrett" which also lessens pollution problems.
Earlier, bleaching of coir fibres was done using chemical agents, but now it can be done by bacterial and fungal cultures especially by using the enzyme xylanase of fungal origin. Other biotech agents that could be used for this purpose are ligninase and hemicellulase.
The stiffness of coir is on account of the high proportion of lignin and softening could be done by treating the raw fibre with Pseudomonas putida and Phanerocheate chrysosporium.
Biotechnology also has a role to play in effluent disposal connected to coir manufacturing. For example, white rot fungi that can be found growing on corn cob wastes and saw dust is useful in degrading coir effluents.
Perhaps biotechnology would help the coconut tree win the ongoing tussle with the palm tree from a utility point of view.
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