SAO PAULO--(BUSINESS WIRE)--Fitch Ratings has downgraded Tonon Bioenergia S.A's (Tonon) foreign and local currency Issuer Default Ratings (IDRs) to 'RD' from 'C'. At the same time, Fitch has affirmed at 'C/RR4' the ratings on the USD300 million senior unsecured notes due 2020 and the USD230 million senior secured notes due 2024 issued by Tonon's fully-owned subsidiary Tonon Luxembourg S.A. The senior unsecured notes due 2020 were transferred to Tonon Luxembourg from Tonon. A full list of rating