Porous chemical pretreated Saccharomyces cerevisiae was used as support, stabilizer, and reducing agent for the rapid green synthesis of gold nanocatalyst. Au nanoparticles (Au NPs) were generated through in-situ reduction of the absorbed Au(III) by the reductive functional groups of mannoproteins in yeast cell wall. The obtained spherical mono-dispersed Au NPs have an average particle diameter of 9.99±1.63nm as evidenced by TEM image, and exhibits excellent catalytic activity for the dechlorination of quinclorac to 8-quinoline-carboxylic acid...