Restriction fragment length polymorphism analysis of pce-amplified nifH sequences from wetland plant rhizosphere communities

摘要

We describe a method to assess the community structure of N_2-fixing bacteria in the rhizosphere. Total DNA was extracted from the macrophytic plants Spartina alterniflora and Sesbania macrocarpa root zones by nead beating and was purified by CsCl-EtBr gradient centrifugation. The average DNA yield was 5.5 μg g~-1 of soil and was of sufficient purity for PCR Amplification of nifH. [α-~32P]dCTP was incorporated into the PCR products were restriction digested.