The Siret river is one the most important river from Romania. It is characterized by a rich microflora, who participating a degradation and mineralization of the organic matter.
For this study, the water samples were collected seasonally during 2008 and 2009 in the following locations: Ion Creanga aval Roman; upstream pig farm Basta village, Dragesti near the exploatation of the ballast, Siret village, Siret river area CIC (industrial zone), Siret river upstream Adjudul Vechi.
We proposed to determinated the the group of: the ammonifing, the denitrifing bacteria group and the aerobic and anaerobic heterotrophic microorganisms.
The analysis shows that the number of germs/ml of water sample varied at the same station from the experience date and one station to the other. These differences between stations, depending by the season and depending by the degree of the polution of the water. | 
