Isolation and identification of bacteria associated with Anabaena from upland soils in northeast China

Abstract:

[Background] Anabaena distribute widely in agricultural soils and have the ability of fixing-carbon and fixing-nitrogen. Clarifying the relationship between cyanobacteria and their associated bacteria is beneficial to improve the function of Anabaena in agricultural soils. [Objective] To isolate associated bacteria with Anabaena sp. PCC7120 from different upland soils in northeast China, to taxonomically identify the associated bacteria, to speculate the function of associated bacteria, and to provide data support for clarifying the relationship between soil cyanobacteria and their associated bacteria. [Methods] Isolation from cultured plate, PCR-DGGE and cloning-sequencing were used to obtain and analyze 16S rRNA gene sequences of associated bacteria with Anabaena sp. PCC7120 from different upland soils and to determine their taxonomic position. [Results] PCR-DGGE profiles showed there are different quantity and type of associated bacteria with Anabaena sp. PCC7120 from 14 upland soils in northeast China. PCR cloning-sequencing result showed that 37 sequences of associated bacteria were obtained, and 36 sequences were identified at species level. The associated bacteria mainly belong to Sphingopyxis, Variovorax, Flavobacterium, Rhodococcus, and these bacteria were suspected with the functions of adapting oligotrophic condition, enriching trace elements, removing toxins. [Conclusion] There are different quantity and type of associated bacteria with Anabaena sp. PCC7120 from upland soils in northeast China. These associated bacteria were mainly members of Sphingopyxis, Variovorax, Flavobacterium and Rhodococcus.

Key words:Upland black soil, Cyanobacteria, Associated bacteria, Isolation, Identification