With a length of 596 km in the country,
Siret River is one of the most important river in
the N -E of Romania. In the 5 km downstream
from the Bacau city, the Siret River collects
Bistrita River water. In this paper, were
determined quantitatively several groups of
bacteria with implications in the carbon cycle,
nitrogen cycle, sulfur cycle and
aerobic/anaerobic heterotrophic bacteria in 2009.
The water and sediment samples were
collected upstream and downstream of the Bacau
city from:downstream Basta village, Dragesti, the
Siret River near Bacau /CIC area, the Siret River
after the confluence with the Bistrita River and
upstream of the Racaciuni lake.
From the analysis performed was observed a
seasonal evolution for all groups of bacteria
analyzed with a maximum development in the
warm season. | 
