Evaluation of the biocontrol efficacy of a Serratia marcescens strain indigenous to tea rhizosphere for the management of root rot disease in tea

Abstract

The aim of the present study is to evaluate plant growth promoting and biocontrol efficacy of a Serratia marcescens strain ETR17 isolated from tea rhizosphere for the effective management of root rot disease in tea. Isolated bacterial culture ETR17 showed significant level of in vitro antagonism against nine different foliar and root pathogens of tea. The phenotypic and molecular characterization of ETR17 revealed the identity of the bacterium as Serratia marcescens. The bacterium was found to produce several hydrolytic enzymes like chitinase, protease, lipase, cellulase and plant growth promoting metabolites like IAA and siderophore. Scanning electron microscopic studies on the interaction zone between pathogen and antagonistic bacterial isolate revealed severe deformities in the fungal mycelia. Spectral analyses (LC-ESI-MS, UV-VIS spectrophotometry and HPLC) and TLC indicated the presence of the antibiotics pyrrolnitrin and prodigiosin in the extracellular bacterial culture extracts. Biofilm formation by ETR17 on polystyrene surface was also observed. In vivo application of talc-based formulations prepared with the isolate ETR17 in tea plantlets under green house conditions revealed effective reduction of root-rot disease as well as plant growth promotion to a considerable extent. Viability studies with the ETR17 talc formulation showed the survivability of the isolate up to six months at room temperature. The sustenance of ETR17 (concentration of 8-9x108 cfu g-1) in the soil after the application of talc formulation was recorded by ELISA. Safety studies revealed that ETR17 did not produce hemolysin as observed in pathogenic Serratia strains. The biocontrol strain reported in this study can be used for field application in order to minimize the use of chemical fungicides for disease control in tea gardens.

Pyrrolnitrin Biosynthesis From Rhizospheric Serratia Spp. With Antifungal Activity and Binding Interactions of PrnF With Ligands

“…There were a total of 1461 positions in the nal dataset. Of these, Serratia marcescens was reported earlier for PRN production (Purkayastha et al 2018). The occurrence of extracellular PRN from other rhizobacterial species were reported for the rst time in this study.…”

Screening of bacterial isolates related to olive orchard pests in Tunisia using 16S ribosomal RNA and evaluation of their biotechnological potential

“…In addition, Dhar Purkayastha et al . () have presented the evaluation of plant growth promoting and biocontrol efficacy of a S. marcescens strain isolated from tea rhizosphere for the effective management of Rhizoctonia root rot disease in tea.…”

Rhizosphere Community Selection Reveals Bacteria Associated With Reduced Root Disease

“…Serratia plymuthica is a ubiquitous gramnegative bacterium, most frequently associated with plants and used as a broad-spectrum biocontrol agent because it produces antimicrobial compounds [67][68][69] and was successfully developed as a commercial product called Rhizostar (produced by E-nema GmbH Raisdorf, Germany). Recently Serratia marcescens was found to produce several hydrolytic enzymes and showed antagonistic activity against eight fungal pathogens of tea [70]. In contrast, genera Bacillus, Duganella and Lysobacter were more highly abundant in the rhizosphere soil without AG8 infection.…”