Amazon's genetic gold

Scientists decode genome of a bacterium with medical and industrial uses

Published: Wednesday 15 October 2003

Amazing collection: the <i>Chr (Credit: Amazonia)a bacterium commonly found in the Amazon rainforest promises to be a new source of ecofriendly plastic and life-saving medicines, if scientists who cracked its genetic code are to be believed. A consortium of 100 scientists, working for the Brazil National Genome Project, sequenced the genome of Chromobacterium violaceum. They accidentally hit upon the industrial and pharmaceutical potential of the microorganism, which is otherwise linked to fatal infections.

Discovered for the first time at the fag end of the 19th century, C violaceum is one of the most versatile and adaptable microorganisms; hence it dominates a variety of ecosystems in tropical and subtropical regions. The research on C violaceum started some 30 years ago, was intended to tackle its adverse affects. But subsequently, the scientists turned their attention to its beneficial properties. In 1978, they stumbled upon a pigment called violacein, which can cure certain skin diseases. In December 2000, Brazilian scientists also unravelled that the pigment has therapeutic properties against several kinds of cancer, tuberculosis, as well as the deadly chagas -- a tropical disease that attacks the vital organs and is caused by Trypanosoma cruzi, a protozoan. The disease plagues many parts of Latin America.

The find prompted the Brazilian ministry of science and technology to make the bacterium the target of the first project of the Brazil National Genome Project, which involved some 25 laboratories located in Brazil. The decoding, recently completed, shows that the organism contains a repertoire of genes that have many potential medical and business applications.

Apart from the gene sequence that codes for the violacein, the scientists have identified some other useful genetic materials. Prominent among them are the genes that order proteins to naturally break down gold, act as potential biocontrol agents against insects and fungi and fight arsenic pollution. There are several other genes that code for proteins that synthesise compounds with antibiotic properties and phenazine -- a substance known to have properties to arrest the replication of tumour cells.

The Brazilian scientists also isolated genes that have the capacity to synthesise polyhydroxyalkanoate polymer, which has physical properties similar to propylene -- the building blocks of ubiquitous plastic. This makes the bacterium an important renewable source of biodegradable plastic.

The find is yet another success story of Brazilian science, which broke new grounds in genomic research by networking dozens of institutions which are otherwise vying with one another. Today, Brazil is said to be one of the most advanced countries in the field of genetic research. In July 2000, Brazil took the scientific world by surprise when it published the genetic map of the Xillela fastidiosa, a bacterium that attacks orange trees. Brazil has even contributed to bioinformatics -- a branch indispensable to genetic research. One of its well-known achievements is the development of Orestes -- Open Reading Frame Expressed-sequence Tags -- a strategy that enables faster and better identification of new genes.

By sequencing the entire genome of the C violaceum, the Brazilian teams hope to fully understand the biology of the small bug. "This is an attempt to find out how an organism can be harnessed to make products that may be healthier for us and safer for the environment," says Andrew J Simpson, head of Laboratory of Cancer Genetics at the Ludwig Institute of Cancer in Sao Paulo, who coordinated the study.

The sequencing of more such similar, free-living tropical bacteria could lead to "the production of industrially useful genes, enzymes, and secondary metabolites, which would benefit...the biotechnological and pharmaceutical industries in the developing world; it would also provide a stimulus to preserve ecosystems where these organisms are found," the authors conclude.

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