Antifungal potential of non-ribosomal peptide producing Serratia surfactantfaciens (S31) and Alcaligenes pakistanensis (S33) isolated from the Solanum lycopersicum rhizosphere

Non-ribosomal peptide (NRP) producing bacteria confer promising alternatives for control of plant pathogens. In the current study Serratia surfactantfaciens (S31) and Alcaligenes pakistanensis (S33) were isolated from the rhizosphere of Solanum lycopersicum. The main aim of the study was to explore the antifungal potential of these novel strains, to characterize the synthesized NRPs and determine their antibiosis mechanisms and influence on plant growth. To screen the strains for their antifungal potential, dual assays were performed against the plant pathogens Aspergillus niger , A . flavus , A . fumigatus and Fusarium oxysporum. When screened for quantitative results regarding enzyme production, A . pakistanensis exhibited a zone of 38.50±4.95 mm for pectinase whereas S . surfactantfaciens showed a zone of 23.0±2.82 mm for cellulase. Antifungal assays showed prominent zones of growth inhibition of the phytopathogens using both bacterial cultures and cell-free supernatants. Genetic analysis revealed the presence of various NRP genes in the bacterial genomes, which were further confirmed by structural analysis. In vivo experimentation showed higher seedling vigour and plant growth parameters when grown in autoclaved as compared to non-autoclaved soil for the applied treatments. • Rhizobacteria and cell-free supernatants exhibit better plant growth parameters. • Lipopeptides confer promising alternatives for control of phytopathogens. • Novel bacteria hold potential to reform agriculture.