The　objective　of　this　study　was　to　investigate　the　fundamental　question　of　biofilm　formation.　First,　a　drum　biofilm　reactor　was　introduced.　The　drums　were　coated　with　three　porous　substrates　(cotton　rope,　canvas,　and　spandex),　respectively.　The　relationships　among　the　substrate,　extracellular　polymeric　substances　(EPS),　and　adhesion　ratio　were　analyzed.　Second,　a　plate　biofilm　reactor　(PBR)　was　applied　by　replacing　the　drum　with　multiple　parallel　vertical　plates　to　increase　the　surface　area.　The　plates　were　coated　with　porous　substrates　on　each　side,　and　the　nutrients　were　delivered　to　the　cells　by　diffusion.　The　influence　of　nitrogen　source　and　concentration　on　compositions　of　EPS　and　biofilm　formation　was　analyzed　using　PBR　under　sunlight.　The　results　indicated　that　both　substrate　and　nitrogen　were　critical　on　the　EPS　compositions　and　biofilm　formation.　Under　the　optimal　condition　(glycine　with　concentration　of　1　g　l(-1)　and　substrate　of　canvas),　the　maximum　biofilm　productivity　of　54.46　g　m(-2)　d(-1)　with　adhesion　ratio　of　84.4　%　was　achieved.