Take a bus from the O.R. Tambo International Airport at Johannesburg, travel southwest for an hour, and you reach Drienfontein Consolidated Mines. A shaky iron elevator carries you down 4 km into the belly of the earth. Wander into one of those blind, hot, humid alleys where mining has been abandoned. From the cracks in the soggy, dark wall, collect a sample swab and seal it in a test-tube. If you are lucky, the sample might grow an unusual bacterium, Cupriavidus metallodurans.
Geochemist Gordon Southam of Western Ontario, Canada was lucky. When he put the newly grown bacteria into a solution of Auric chloride, his luck changed to surprise. Auric chloride, a laboratory catalyst used to accelerate many chemical reactions, is also a potent tissue toxin. Put a normal bacterium in a solution of Auric chloride and it would die instantly, but not Cupriavidus. Not just that, it thrived in the hostile chemical, and produced nano-particles of 24-carat gold (metallodurans = durable metal)
The South African superbug is not alone. From the complex maze of the Ashanti mines of Ghana came Delftia acidovorans. (acidovorans = acid eating). The depths of the choppy East China Sea off the Zhoushan archipelago turned out to be the home of Marinobacter pelagius (marinobacter = bacteria from sea); both bacteria essentially produce gold nuggets as a metabolic byproduct.
In case you hate the very thought of bugs but your wife is crazy about gold, here is a cleaner alternative. Take a piece of bismuth and expose it to a flow of electrons from a particle accelerator. The 83 protons of bismuth would take the blow, and eventually some of it would be left with 79 protons, producing pure gold. David Morrissey of the Lawrence Berkeley National Laboratory in California proved that metallic transmutation from bismuth to gold is possible. Just one little problem: the bugs produce just nano-particles, barely visible to the naked eye. And a particle accelerator costs a little over a trillion dollars.
People can do amazing things with gold. From crown to anklet, pendant to tooth-filling, the possibilities are endless and limitless. If you think upper-arm gold jewellery is limited to rings and bangles, ask your wife and she will tell you how difficult it is to survive without a bracelet, an armlet and an amulet.
But what Nobel laureate Ernest Rutherford did was beyond comprehension. In 1909, while working in the Manchester University laboratory, he shot a barge of electron through a gold plate, observed the path of the deflected electrons and proved the existence of a proton. He deserves credit for his genius in scientific terms, but I think we should thank his wife Mary Georgina Newton for allowing him to use ‘gold’ for target practice, be it with electron or whatever.
Mother earth is careful with her gold. Almost all of the earth’s gold remains in the core, far beyond the reach of her greedy children. The gold we dig up from the crust probably came from showers of asteroid that hit and bombarded the earth some four billion years ago. Till date humans have dug up 175,000 tons of it, with China leading the race. But when it comes to jewellery, India with an annual consumption of 975 tons beats many countries.
But the yellow metal is also winning the hearts of medical researchers worldwide and saving lives. Gold nano-particles can be shaped in different ways and glued to molecules, such as those of sulfur. A sulfur-coated gold nano-particle can be tagged to either a medicine or a dye or a radiotracer to detect a deranged cancer cell, or even programmed to destroy it. Gold has suddenly gained its sheen, transiting from fashion jewellery to medical formulary.
Since particle accelerators are beyond my budget, I should be looking out for a cheap ticket to South Africa. But after a recent crash of gold prices, my wife insists we wait. Hitherto unheard-
of infections such as chikungunya are emerging; a new desi gold-producing bacteria may not be an impossibility after all.
tinynair@gmail.com
