New Methods to Remove Rhizoplane Bacterial DNA of Banana

The aim of this study was to evaluate the effects of different surface sterilization protocols on retained rhizoplane bacterial DNA of banana. Viable rhizoplane bacteria and bacterial DNA copies of banana roots were treated with four sterilization agents: 75% ethanol and sodium hypochlorite solution (5% available chlorine), chlorine dioxide (0.2%), peroxyacetic acid (0.4%), and formaldehyde (36%) with different incubation times. Retained viable bacteria and bacterial DNA of banana roots treated were compared based on viable count, and qPCR and MPN-PCR methods. Root treatments with peroxyacetic acid (0.4%) and formaldehyde (36%) for 5 min could remove most (99.9999%) of viable rhizoplane bacteria. Chlorine dioxide (0.2%), peroxyacetic acid (0.4%), and formaldehyde (36%) could remove 99.9% of bacterial DNA segments of 16S rRNA gene, whereas, formaldehyde (36%) could remove 99.99% of whole 16S rRNA genes of rhizoplane bacteria. The surface sterilization protocol that included incubation with formaldehyde (36%) for 9 min and further treatment with 0.1 mol l-1 NaOH for 10 min might be an effective sterilization method to remove rhizoplane bacterial rRNA genes in the study of endophytic bacterial communities of banana roots.