Thermo Fisher Scientific Inc is emerging as the lead contender in Life Technologies Corp's auction, working on a bid that could value the genetic testing maker at as much as $12 billion, three people familiar with the matter said. Thermo Fisher, the world's largest maker of laboratory equipment, is considering a bid of between $65 and $70 per share for Life Tech and is interested in buying the entire company, two of the people said. It is expected to have a leg up over private equity bidders because it can squeeze more cost savings than a buyout firm can, as well as over rival trade buyers who may not want all of Life Tech or have not been as aggressive in their pursuit of the company so far, the three sources said.