I am soon starting a project, in which I aim at isolating bacteria from the muccus of Aiptasia ( a model organism for corals). I do not have a lot of experience in this field and I hope to get some technical tips and tricks. I will have three different strains of Aiptasia and try to obtain bacterial isolates from all of the three. The obtained colonies will be subjected to whole genome sequencing in order to determine the exact strain that was isolated (16S rRNA sequencing would not be enough for that). Is there a robust control, to exclude that the bacteria originated from the surrounding water and not from the muccus of Aiptasia? Thank you in advance.