In case of Sole proprietorship Firm Section 297 will be attracted as its equal to as entering into a contract with an individual who is the director of the Company because the identity of sole proprietorship firm & that of proprietor is same. Thus Section 297 gets attracted.
While in the case of Trust Section 297 does not get attracted as because Companies Act is silent in regard to it. Section 297 attracts where the contract is with :-
Director or his relative, or
Firm in which such director or his relative is partner or any other partner in such a firm, or
Private Company of which such director is a member or director
Thus we can take plead and can enter into contract with a Trust.
This is my opinion......wait for opinion from some experts.