The provisions of section 412.271 shall apply to cities operating under Optional Plan B except that orders shall be signed by the mayor and manager and no order shall be marked not paid for want of funds and except as otherwise provided in this section. Every resolution or motion authorizing a disbursement and every order shall specify the purpose for which the disbursement is made and indicate the fund from which it is to be paid. No order shall be issued until there is money to the credit of the fund from which it is to be paid sufficient to pay the order together with all then outstanding encumbrances upon the fund. The manager shall specify on each contract requiring the payment of money by the city the particular fund out of which the same is to be paid, and shall cause a suitable notation to that effect to be made on each such contract. The council may by ordinance make further regulations for the safekeeping and disbursement of the funds of the city.