Bacterial communities associated with aquatic organisms in the floodwater of a Japanese paddy field estimated by RFLP pattern analysis

Abstract

Bacterial communities associated with crustacean (Tanycypris, Cladocera, Cyclopoida), Diptera (larvae of Cricotopus sp.), and roots of duckweed (Lemna paucicostata Hegelm) in the floodwater of a paddy field were analyzed based on the RFLP patterns of 16S rDNA. A larger number of RFLP bands was obtained from the bacterial communities in the floodwater and that associated with Cyclopoida than from the bacterial community associated with the other host organisms. The bacterial community associated with Tanycypris gave the smallest number of bands compared with the other habitats. DNA fragments common to Tanycypris, Cladocera, Cyclopoida, and Diptera and specific to the respective organisms were recognized. The RFLP pattern of the bacterial communities in the floodwater was markedly different from and more complex than those from aquatic organisms. The RFLP pattern of the bacterial community associated with Lemna roots was also specific. Cluster analysis and principal component analysis enabled to clearly separate the RFLP patterns of the bacterial communities associated with aquatic organisms from one another. The effect of sampling time on the bacterial communities was not appreciable compared to the effect of host organisms.