BEHIND the hype and hoopla about creating artificial life forms and the ethical concerns it raises lies a more fundamental question. Why do it at all?
Craig Venter and his colleagues say that their artificial microbe, or others like it, could one day be engineered to produce hydrogen for fuel, break down carbon dioxide to reduce global warming, or help clean up toxic dumps. But experts told 快猫短视频 that such efforts would be misguided, and possibly even wasted.
Take biological methods for producing hydrogen. It would probably be more practical to fine-tune microbes that are already fairly good at it. Bruce Logan of Pennsylvania State University recently showed how to make ordinary garden soil bacteria produce more hydrogen as they ferment sugar.
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Now his team is working on genetically engineering the bacterium Clostridium acetobutylicum to make it better at producing hydrogen. 鈥淲e don鈥檛 understand the regulation of hydrogen production in those microbes, so to try and recreate that in another [artificial] microbe is maybe premature,鈥� says Logan.
Then there is the idea of using microorganisms to generate hydrogen by splitting water. Some natural organisms can already do this: for instance, when light shines on the green alga Chlamydomonas reinhardtii in the absence of CO2 it starts splitting water into hydrogen and oxygen. It is unclear whether Venter鈥檚 artificial life forms would do the job as well, let alone better.
Several factors limit the efficiency of such organisms. The oxygen that C. reinhardtii produces eventually shuts down the very enzyme responsible for splitting water. Also, the alga鈥檚 photosynthetic machinery quickly becomes saturated, which means that brighter light does not increase the amount of hydrogen it produces.
鈥淲e are facing fundamental chemical and thermodynamic barriers,鈥� says Laurens Mets, an expert in hydrogen-producing microorganisms at the University of Chicago. 鈥淚 don鈥檛 see [the artificial microbe] as a breakthrough against the major hurdles.鈥�
Even if Venter鈥檚 group does figure out mechanisms that will surmount these problems, the knowledge might be better used to improve synthetic techniques rather than in creating a microbe. 鈥淚f you are smart enough to genetically engineer [artificial microbes] around these barriers, it means you are also smart enough to do it without the living organism,鈥� Mets says.
Both Logan and Mets doubt whether artificial microbes would be good at mopping up toxic spills or waste dumps. Genetically engineered bacteria don鈥檛 survive long in soil, so the artificial microbes may not stand a chance. 鈥淵ou really need to find bacteria that exist in that environment and then manipulate them in some way to derive the outcome that you want,鈥� says Logan.
Moreover, communities of different species of bacteria are much better at bioremediation than one species alone. 鈥淵ou are talking about metabolic pathways that exchange intermediates between organisms,鈥� says Mets. 鈥淚t鈥檚 a kind of a multicellular attack on [the environment]. Understanding one microbe is probably not going to be enough.鈥�