ABSTRAKPenelitian ini bertujuan untuk mengetahui pengaruh bakteri probiotik terhadap jumlah koloni TSA, penelitian meliputi pembuatan media TSA dan isolasi bakteri air tambak. Media TSA ditimbang sebanyak 20 g dan ditambahkan KCL 0,375 g dan MgSO4 3,47 g , Nacl 9,2 g dan aquadest 500 ml, sterilisasi menggunakan autoclave pada suhu 121 derajat celcius selama 15 menit, inokulasi sampel air tambak dilakukan pengenceran menggunakan larutan Nafis (Natrium fisiologis) 0,9 ml dan sampel 0,1 ml bakteri probiotik bacillus 0,1 ml diencerkan pada cawan petri yang berisi media TSA di ratakan menggunakan pengaduk try angel lalu diinkubasi 24 jam, dan bakteri dapat dihitung jumlah koloninya. Semakin banyak diencerkan maka semakin banyak juga koloni yang tumbuh dan jumlahnya semakin banyak.Kata kunci: Jumlah koloni, Bakteri probiotik, TSA, Air tambak.ABSTRACTThis study aims to determine the effect of probiotic bacteria on the number of TSA colonies. Research includes the manufacture of TSA media and the isolation pf pond water bacteria. TSA media was weighed as much as 20 g and added 0,375 g, KCl and MgSO4 3,47 g , Nacl 9,2 g and 500 ml of distilled water, sterilized using an autoclave at 121ÂșC for 15 minutes. Inoculation of pond water samples was diluted using 0,9 ml of physiological sodium solution and a sample of 0,1 ml of probiotic bacteria Bacillus sp 0,1 ml was diluted in a petri dish containing TSA media, averaged using a try angel stirrer and then incubated for 24 hours. And bakteria, the number of colonies can be counted, the more they are diluted, the more colonies will grow and the number will increase.Keywords : Number of colonies, probiotic bakteria, TSA, Pond water.