SAN FRANCISCO (AP) – A TV report says California transportation officials are investigating whether microscopic organisms are attacking critical welds on the submerged foundation of a tower on the new San Francisco-Oakland Bay Bridge. While engineers tell KNTV there’s no immediate concern about the bridge failing, an underwater survey found pockets of accelerated corrosion on welds that bind massive piles that hold up the foundation. Experts say the corrosion suggests something besides simple rust is eating away at the steel. Caltrans says it’s looking into whether microorganisms are feeding on the metal. KNTV reported Friday that the problem could potentially endanger the projected 150-year lifespan of the $6.4 billion structure. The revelation is the latest in a string of problems that have dogged the project – including cost overruns, flawed welds, broken bolts and pitted cables.