There is, appropriately enough, a biblical quality to Craig Venter's account of the genesis of his quest to create life "from scratch". He dates his mission to 1968 when he was working in the frontline medical corps of the US army in Vietnam during the Tet offensive. He had tried, and mostly failed, to save hundreds of men from dying – it was M*A*S*H without jokes – and he felt he'd had enough of the horror of life. A champion swimmer, he determined to swim out into the South China Sea and not swim back. In the beginning, then, this mythology goes, the biologist was in the middle of the ocean, "surrounded by venomous sea serpents", preparing to meet his genome. It took a shark circling to wake him out of this suicidal fantasy.

"For a moment," he wrote in his 2007 autobiography, "I was angry that the shark had disrupted my plan. Then I became consumed with fear. What the fuck was I doing? I wanted to live…" Venter struck out for shore, now miles behind him, and when he arrived there it was if he had been reborn, like Crusoe, into a new fate: "I lay on the sand, naked, for what felt like hours. I was exhausted and relieved. I wanted my life to mean something; I wanted to make a difference. I felt pure; I felt energised."

For the last 40 years, that pure energy has driven Craig Venter to extraordinary heights. ("A doctor can save maybe a few hundred lives in a lifetime," he told his brother as he embarked on his scientific career, with a characteristic mix of hubris and chutzpah. "A researcher can save the whole world.")

Venter first came to international attention as the "rogue" biologist who attached himself to the painstaking $5bn, 15-year programme to decode the human genetic blueprint, "the book of life" Human Genome Project and announced to anyone who would listen he could do it much more quickly and much more cheaply with private capital (the distinguished scientists leading the global initiative were, he insisted, "the Liars Club": habitual fibbers about costs and deadlines).

He caused further outrage when he said he would not only beat that establishment club to the solution but patent the results. He eventually – arguably – made good the first part of that boast but, under pressure from President Clinton, gave up on the latter and agreed a joint declaration of the triumph with the official team in the millennium year, losing a fortune in the process. (Asked how he felt to have deciphered human life, Venter, who had designs on being "the first billionaire biochemist", replied: "Poorer.")

Not content with what was widely considered the landmark scientific achievement of our age, however, Venter then decided he would solve the crisis of climate change and ecological meltdown by discovering a biologically engineered source of energy. He set sail on his $15m yacht Sorcerer II on an unending voyage with the mission, along the way, "to put everything that Darwin missed into context" and map the whole world's genetic components. He dipped buckets into the Sargasso Sea and sent millions of primordial microbial lifeforms back to his labs for decoding.

As a development of that ongoing effort, last week Venter announced in the pages of Science magazine that his research team had – by putting together a living and replicating bacterium from synthetic components, inserting a computer-generated genome into a cell – "created life" in the laboratory for the first time. The experiment suggested the possibility of creating bacteria to perform specific functions: as producers of fossil fuels or medicines.

Venter, now 63, is nothing if not a showman and the publication of this revelation and the subsequent press conferences, have polarised opinion in ways with which he has long been familiar. Some authorities, and several newspaper leader writers, have claimed him as our Galileo or our Einstein; others have been notably underwhelmed.

Freeman Dyson, the physicist, captured the full range of academic sentiment in this dry appraisal: "This experiment is clumsy, tedious, unoriginal. From the point of view of aesthetic and intellectual elegance, it is a bad experiment. But it is nevertheless a big discovery… the ability to design and create new forms of life marks a turning point in the history of our species and our planet."

Venter's ego and his preference to turn to corporations rather than research foundations as funding partners (Exxon Mobil is a $600m sponsor of his energy experiments) do not tend to endear him to the academic establishment. Steve Jones, professor of genetics at University College London, and a perennial voice of reason, offered me this verdict on the biologist's latest headlines.

"It's very easy to mock Venter," Jones suggests. "When he first appeared, people just kind of sneered at him. But they stopped sneering when they saw his brilliance in realising that the genome was not a problem of chemistry but a problem of computer power. I don't think anybody can deny that that was a monumental achievement and he has been doing fantastically interesting things subsequently with marine life. Having said that, though, the man is clearly a bit of a prick and one with a serial addiction to publicity."

Jones is sceptical about the hyperbole of breathless headlines. "The idea that this is 'playing God' is just daft. What he has done in genetic terms would be analogous to taking an Apple Mac programme and making it work on a PC – and then saying you have created a computer. It's not trivial, but it is utterly absurd the claims that are being made about it."

Stewart Brand, the ecological visionary and creator of the Whole Earth Catalog, is more persuaded. Brand has got to know Venter over the last couple of years through John Brockman's Edge initiative which brings together the world's pioneering minds. What differentiates Venter from many of his peers, Brand believes, is that he is not only a brilliant biologist, but also a brilliant organisational activist. "A lot of people can think big but Craig also has the ability to fund big: he doesn't wait for grants, he just gets on and finds a way to do these things. His great contribution will be to impress on people that we live in this vast biotic of microbes. What he has shown is that microbial ecology is now where everything is at."

Brand once suggested that "we are as gods and we might as well get good at it". That statement has gained greater urgency with climate change, he suggests. "Craig is one of those who is rising to the occasion, showing us how good we can be."

On the publication of his autobiography, Venter also brought out another book, one that contained the six billion characters of his own genome. It was the first full catalogue of a single individual's genetic code and it revealed several secrets about Venter's inherited traits, notably a predisposition to heart disease and to Alzheimer's. What it has not so far rendered, however, is the chemical clue to his most vital characteristic: impatience.

The greatest scientists have shared the understanding that there is so much to do and so little time in which to do it. A decade ago, Venter was plagued by the sense that "as a civilisation, we know far less than 1% of what will be known about biology, human physiology and medicine. My view of biology is: we don't know shit". In the years since, he has perhaps done more that any man who has ever lived to add to that raw information. He did this initially by being the first to see that "the analogue world of biology" had to be transformed by the "digital world of the microchip". He is now, it is said, the largest private user of computer power in the world.

Just as he found his vocation in the sea, so he returns to it constantly for inspiration. He was a high school dropout, a prototype beach bum. "I was a surfer as a kid, I was a surfer in Vietnam, I am still a surfer," he likes to say. When a writer for Wired magazine caught up with him in French Polynesia a couple of years ago, Venter was wandering the shoreline, naked, fishing items of interest out of the water. At the time, he described his scientific quest by gesturing to the ocean: "We're just trying to figure out who fucking lives out there." Of the billions of answers to that particular question, Venter himself has now added another one: Mycoplasma mycoides J Craig Venter Institute-syn1.0. Life has his name on it.