The T refers to the information that the strain is the "Type strain" of the species mentioned. This means that when the species was named, this is one of the strains used to characterize that species...for instance, there will be many strains of a given species within a culture collection that vary slightly. The type strain is the 'true' strain. To truly determine if a strain represents a new species, it needs to be compared with the most similar Type strains. If you see a strain number followed by "NT", it means "Neotype strain." This means that the original type strain is no longer viable or in a collection, and so this strain now replaces the original type strain.
When a strain is followed by "= XXXXX" it means this exact strain has been deposited in other culture collections under those IDs. The number refers to the exact strain, while the alphabet characters refer to the specific culture collection. I believe BBC represents the Biotec culture collection, while JCM represents the Japanese culture collection. If you were to request the three specific strains mentioned above, from the three different culture collections, they would all represent the same tissue.