meliorators

/ˈmiːliəˌreɪtərz/
noun
  1. People or things that make something better; improvers.
    • In the company, the new software was seen as one of the key meliorators of workflow efficiency.
    • Community meliorators worked together to reduce pollution in the local river.
    • The volunteers acted as meliorators, cleaning up the park and planting new trees.