A fourth Texas high-tech startup that received taxpayer dollars through Gov. Rick Perry’s signature economic development fund has filed for bankruptcy in the $194 million portfolio’s biggest bust yet.

The collapse of bioenergy producer Terrabon Inc., which was awarded $2.75 million in 2010 and was backed by large Perry political donors, raises questions about whether the state’s Emerging Technology Fund launched in 2006 could now be worth less than what taxpayers have put into it.