Research work carried out by my team at Imperial College in the mid 80's showed that acids produced by bacteria are harmful to both steel and concrete.
Bacteria are a very powerful species originating billions of years before man and are essential to the existence of humans. But they are also very eco-friendly and turn harmful substances to natural harmless ones.
So there are no real horror stories for bugs. What the bacteria are trying to do is to transform steel to oxide or its natural ore. If, as the article suggests, steel will be replaced by concrete in due course, bacteria will have their own means of also returning this concrete to its original constituents.
Patrick Sullivan, visiting professor City University.