Cold environment represent a large part of the Earth’s biosphers. It has been shown that bacteria activity can allow such species to be active, for example spore formation, pigmentation and production of enzyme active at low temperature. Two ecosystems were selected to characterize of cultivable bacteria in part of southwestern Alps (dry and wet meadows) which are close geographically but different in plant vegetation and period snow covering, therefore we have a hypothesized two different ecosystems in bacterial diversity.We collected our samples at October 2006 and isolated the bacteria by using different source of carbon (TSA, PYG and extracted soil) and different temperature (25°C, 4°C). enumeration was performed by CFU. 89 isolates are selected for PCR and sequencing. The results are analysed by RDPII and NCBI and MEGA 3.1. Our results demonstrated high phylogenetic diversity in the form of four major lineages of the bacteria domain (Actinobacteria, CFB, Firmicute and Proteobacteria). In dry and wet meadow 43% and 30% of isolates are corresponding to Actinobacteria, respectively. Because at this season, soil contain subtract complex (like polymers) for degrading. So date of sampling is an important factor for to dominant a group of bacteria. We identified 10 genera in dry and 22 genera in wet meadow from different bacteria groups. Results demonstrated that there is higher diversity in wet meadow particularity at genera level. Because in wet meadow, there are easy source of carbon for bacterial growth. In wet meadow, there is condition temporal optimum, because don’t exist high variation temperature.

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