Aerobic　granular　sludge　(AGS)　could　be　cultivated　from　only　flocs　(called　normal　granulation　(NG)　process)　or　mixture　of　flocs　and　crushed　AGS　(called　enhanced　granulation　(EG)　process),　which　might　lead　to　different　system　performances　such　as　granulation　speed　and　pollutants　removal　efficiencies.　However,　the　differences　of　mechanisms　between　NG　and　EG　processes　at　microbial　community　level　are　still　unknown.　In　this　study,　the　NG　and　EG　processes　were　implemented　successively　in　a　pilot-scale　sequencing　batch　reactor　(SBR)　with　certain　amounts　of　additional　carbon　sources.　Illumina　MiSeq　sequencing　and　quantitative　PCR　were　applied　to　investigate　the　dynamics　of　bacterial　communities　during　NG　and　EG　processes　and　explore　the　possible　explanations　for　faster　EG　process.　The　results　showed　that　significant　distinctions　in　bacterial　diversities　and　community　structures　were　observed　between　NG　and　EG　processes.　The　major　contributor　to　NG　process　was　bacterial　communities　with　32.04%　contribution.　While　EG　process　was　more　dependent　on　the　interactions　(73.16%　contribution)　between　the　bacterial　communities　and　environmental　variables　(operational　parameters　and　self-adaptive　variable).　EG　process　had　higher　relative　abundances　of　functional　bacteria　than　NG　process.　Glycogen　accumulating　organisms　(GAOs)　related　bacteria　with　a　total　relative　abundance　of　maximum　65.43%　might　be　mainly　responsible　for　the　faster　EG　process.　This　study　provided　microbial　insights　for　practical　application　of　AGS　technology　that　inoculating　crushed　AGS　might　be　an　effective　way　to　cultivate　AGS.　(C)　2019　Elsevier　B.V.　All　rights　reserved.