Can fungi survive completely independent of other life?

All fungi I'm aware of (like humans) are heterotrophs (meaning they can't make their own food from raw materials) but must consume something that is (or was) living to survive.

From OP:

> Sunshine and seawater. That’s all a new, futuristic-looking greenhouse needs to produce 17,000 tonnes of tomatoes per year in the South Australian desert

> The $200 million infrastructure makes the seawater greenhouse more expensive to set up than traditional greenhouses, but the cost will pay off long-term, says Saumweber. Conventional greenhouses are more expensive to run on an annual basis because of the cost of fossil fuels, he says

From the #1 google result for "cost of a ton of tomatoes" http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=15889:

> Processors agreed to pay growers $83 per ton in 2014, up from $70 per ton last year.

So assuming 100% profit margins (ie the tomatoes grow themselves, no human labor needs to be paid, nothing needs repairing or replacing, tomatoes deliver themselves to processing plants, etc, etc), the 17,000 tonnes produced would yield ~$1.4M annually. That's an awful (0.7%) annual return on $200M. Much less than you could get by investing the $200M in an index fund.

Which is to say there's a 0% chance it will "pay off in the long-term".