Transform the word in brackets so that it fits the sentence. He recycles as many (use) materials as possible.

The word 'use' needs to be transformed into its correct form to fit the sentence. The sentence structure 'as many ___ materials' requires a noun. The noun form of 'use' is 'usage'. However, in this context, referring to the materials themselves, the plural noun 'uses' is appropriate. Therefore, the transformed word is 'uses'.
He recycles as many uses materials as possible.