Bacterial diversity and abundance of a creek valley sites reflected soil pH and season

The effect of environmental factors on bacterial and actinobacterial communities was assessed to predict microbial community structure in natural gradients. Bacterial and actinobacterial communities were studied at four sites differing in vegetation and water regime: creek sediment, wet meadow, dry meadow and deciduous forest located in a shallow valley. The vegetation structure was assessed by phytocoenological releves. T-RFLP and quantitative PCR were used to determine community composition and abundances. Significant relationships between bacterial community structure and selected soil traits at sites located relatively close to each other (within 200 m) were demonstrated. Both the quantity and structure of bacterial communities were significantly influenced by organic matter content, soil moisture and pH. Bacterial diversity was higher in summer, while that of actinobacteria increased in winter. The Simpson’s evenness E was significantly correlated with soil organic matter content. Soil pH had the greatest influence on bacterial community structure showing higher within-site variability in summer than in winter