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Bacteria are an essential biotic component in freshwater environments. A group of 262 bacterial strains of freshwater environments from an altitudinal gradient in the Eastern Cordillera of Colombia was identified using the 16S rRNA gene sequence analysis. Hill numbers and related diversity indices were calculated to know the bacteria diversity in this collection and environments. In addition, the Bray–Curtis index was also calculated to know the differences in genera composition between sampled localities and their relationship with altitudinal gradient. The identified bacterial strains were grouped into 7 major phylogenetic groups (Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Flavobacteriia, Actinomycetes, Clostridia, and Bacilli), 38 genera, and 84 distinctive species. Diversity analysis based on Hill numbers showed that the diversity concerning bacteria inhabiting freshwater environments was consistently high. Dominant genera were Klebsiella, Serratia , and Pseudomonas , although other genera such as Bacillus, Lelliottia , and Obesumbacterium were well represented per locality. The highest bacterial diversity came from localities Cimitarra and El Carmen del Chucurí, while those originating from Santa Bárbara and Páramo del Almorzadero were relatively lower diverse. Differences in diversity were found to be mainly due to the spatial replacement of one genus by another and, to a lesser extent, to the loss or gain of taxa. [ABSTRACT FROM AUTHOR]

A total of 985 bacterial strains with different colony characteristics were isolated from the root of tree peony plants (variety 'Fengdan' and 'Lan Furong'); 69 operational taxonomic units were identified by amplified ribosomal DNA restriction analysis. Representatives of each group were selected for partial 16S rRNA gene sequencing and phylogenetic analysis. The major groups in the bulk soil, rhizosphere, and rhizoplane of Fengdan were Firmicutes (63.2%), Actinobacteria (36.3%), and Betaproteobacteria (53.0%), respectively. The major bacteria groups in the bulk soil, rhizosphere, and rhizoplane of Lan Furong were Actinobacteria (34.8%), Gammaproteobacteria (45.2%), and Betaproteobacteria (49.1%), respectively. In total, the bacterial isolates comprised 26 genera - 14 in the bulk soil, 14 in the rhizosphere, and 11 in the rhizoplane. The most common genus in the bulk soil of Fengdan and Lan Furong was Bacillus (49.6% and 32.6%, respectively), in the rhizosphere Microbacterium (21.1%) and Pseudomonas (42.0%), and in the rhizoplane Variovorax (53.0% and 49.1%, respectively). The results show that there are obvious differences in the bacterial communities in the three root domains of the two varieties, and the plants exerted selective pressures on their associated bacterial populations. The host genotypes also influenced the distribution pattern of the bacterial community. [ABSTRACT FROM AUTHOR]