Convert a string into an OWLAxiom object

Question

Is it possible to convert a string into an OWLAxiom object using OWLAPI?

For example, if I have this code below:

String axiom_str = axiom.toString();
String newAxiom_str = axiom_str.replaceAll(oldClass.getIRI().toString(), newClass.getIRI().toString());

Is it possible to create an OWLAxiom object bases on the newAxiom_str? What I want to achieve is to convert the newAxiom_str into an OWLAxiom object. Is there any way so?

Thank you in advance

I am obviously using OWLAPI. I tried using OWLObjectVisitorEx but I didn't have a efficient result...