Authors: Zubair Aslam Muhammad Yasir Hwan Sik Yoon Che Ok Jeon Young Ryun Chung
Publish Date: 2013/12/19
Volume: 51, Issue: 6, Pages: 747-756
Abstract
Bacterial diversity in the rice rhizosphere at different rice growth stages managed under conventional and notillage practices was explored using a culturebased approach Actinobacteria are among the bacterial phyla abundant in the rice rhizosphere Their diversity was further examined by constructing metagenomic libraries based on the 16S rRNA gene using actinobacterial and streptomycetespecific polymerase chain reaction PCR primers The study included 132 culturable strains and 125 clones from the 16S rRNA gene libraries In conventional tillage there were 38 Proteobacteria 22 Actinobacteria 33 Firmicutes 5 Bacteroidetes and 2 Acidobacteria whereas with notillage management there were 63 Proteobacteria 24 Actinobacteria 6 Firmicutes and 8 Bacteroidetes as estimated using the culturedependent method during the four stages of rice cultivation Principal coordinates analysis was used to cluster the bacterial communities along axes of maximal variance The different growth stages of rice appeared to influence the rhizosphere bacterial profile for both cultivation practices Novel clones with low similarities 89–97 to Actinobacteria and Streptomyces were retrieved from both rice fields by screening the 16S rRNA gene libraries using actinobacterial and streptomycetespecific primers By comparing the actinobacterial community retrieved by culturedependent and molecular methods it was clear that a more comprehensive assessment of microbial diversity in the rice rhizosphere can be obtained using a combination of both techniques than by using either method alone We also succeeded in culturing a number of bacteria that were previously described as unculturable These were in a phylogenetically deep lineage when compared with related cultivable genera
Keywords: