Who owns the copyright of the acquisition of an object or sample owned by a third party?
Copyright almost certainly isn't the correct legal basis here (IANAL, so take that with a grain of salt, but as comments have pointed out, data is not subject to copyright in many jurisdictions), so I would suggest dropping that part of your thinking. The issue is not whether you have copyright of something produced, but whether you were allowed to use the materials you were provided to produce publicly available data.
Usually when materials pass between entities, including between universities or between a private company and a university, they are subject to a Material Transfer Agreement (MTA). This is a contract that specifies what can and can't be done with provided materials.
In the absence of such an agreement, there may be some implied rights but it might be best to go ahead and secure an MTA after the fact, or at a minimum get some informal agreement that you can use to protect yourself. Otherwise, you're in a situation where you are at the mercy of those who may be upset by your actions, which could start an academic or legal dispute that you don't want to be involved in.
(note: I'm assuming there is something somewhat special about these materials such that you could not have obtained them from other sources)