OK heres an answer from the Certified Pro
IICRC Certified in WRT, ASD, AMRT, FSRT, OCT and more... here is your answer:
1) Don't touch it.
Reason is not one that you may expect.....99.9% sure you don't have liability coverage for the possible lawsuit you could incure. 99.9% of the P&P Contractors do not have Commercial Pollution Liability. 99.9% of General Liability Policies exclude Mold Coverage unless they offer an endorsement (for big $$) to add additional coverages to your base policy. But you don't have this endorsement since to be eligible you have to be certified.
2) Determining "cause of the mold" really is hard to know until the "finished product" is removed ie...drywall, panelling etc etc and by you telling the Service Company or Bank what the cause of mold is (by guessing) you subject yourself to payment of possible erroneous insurance claim costs. Example: you say that the reason is "no sump pump" but in truth this house was built in say 1980 and no mold formed till the bank acquired the home in 2010 so why was there never a mold problem before? Perhaps a shift in the ground caused a crack in the foundation thus a water leak? Problem is for all P&P Contractors is: until you live in the home and actually SEE what is causing the water intrusion you just don't know.
3) I strongly suggest that all contractors get training in mold with the pursuit of certification. There are many steps that has to be taken to get the certification before the mold qualifications are awarded but this can and is a very rewarding experience. YOU also will find out that YOU/US/ME/Everyone is hanging themselves out for possible litigation if you listen and follow the directions from these Service Companies. They will HANG YOU and not care since YOU are the professional.
Many States now require (and more every month) that if you treat any moldy area of 6sf or larger that you have to be certified. Due to this fact and the Service Companies wanting to collect/subrogate back to the insurance company for reimbursement they are required to use certified contractors. This has and is putting a heck of a strain on Service Companies since the "idiots in charge" don't know that they can't collect on Insurance without the proper certifications and thus the Contractors doing any mold work will be facing chargebacks over the next couple of years. We have seen this many times already.
Example: we bid out a mold home of approx 1100sf that came in at approx $16,000 to remediate properly (air scrubbers/containment zones/HEPA vac etc) and we lost the bid to another P&P contractor who was awarded the bid at $4200 (spray with bleach..big no no and painted the main level with kilz..another no no---)....2 months later the mold bloomed into the entire 2800sf of the home and we got the call again (bid fee of $750 approved) to bid and try to determine the cause....Cause was improper treatment. Bid to fix the improper treatment was $31,000. Guess who is paying the $31,000?
It is a very tricky field but with proper training and proper protocols can be very rewarding. Get training from the IICRC or the IAQ. Both researchable on the web.