What is the best approach in adding projects on a Domain Driven Design DDD having multiple databases?

Solution Projects:

• API - contains controller and exposes API
• Application - contains specific business rule only applied for the an API
• Common - contains constants
• Domain - it contains the entities which uses the onion architecture of DDD
• Infrastructure - handles external API transactions
• Persistence - Domain to Database configuration and mappings

I have a set of projects in my solution (see above), however, the whole solution transacts to only 1 database. Now, I have a plan to integrate another database, What is the best approach in adding projects on a Domain Driven Design DDD having multiple databases?

Initially, I'm thinking of adding another pesistence project but I'm thinking it will require domains. I'm not sure if it is right to mix the domains mapped with different databases. Can someone tell me how to approach this?