Plant growth promoting endophyte Burkholderia contaminans NZ antagonizes phytopathogen Macrophomina phaseolina through melanin synthesis and pyrrolnitrin inhibition

• Published in: PloS one Vol. 16; no. 9; p. e0257863
• Main Authors: Zaman, Nazia R., Chowdhury, Umar F., Reza, Rifath N., Chowdhury, Farhana T., Sarker, Mrinmoy, Hossain, Muhammad M., Akbor, Md. Ahedul, Amin, Al, Islam, Mohammad Riazul, Khan, Haseena
• Format: Journal Article
• Language: English
• Published: San Francisco Public Library of Science 30.09.2021; Public Library of Science (PLoS)
• Subjects: Acetic acid; Annotations; Antibiotics; Antifungal agents; Bacteria; Bioactive compounds; Biochemistry; Biological control; Biology and Life Sciences; Burkholderia contaminans; Catechol; Chromatography; Cytotoxicity; Endophytes; Fungi; Fungicides; Gene clusters; Genes; Genetic aspects; Genomes; Growth (Plants); High-performance liquid chromatography; Indoleacetic acid; Jute; Laboratories; Liquid chromatography; Liquid culture; Macrophomina phaseolina; Mass spectrometry; Medicine and Health Sciences; Melanin; Metabolites; Microorganisms; Molecular biology; Pathogens; Phenols; Physical Sciences; Phytopathogenic fungi; Plant growth; Properties; Proteins; Pyrrolidine; Research and Analysis Methods; Scientific imaging; Secondary metabolites; Seeds; Synthesis; Tyrosinase; Virulence; Bangladesh; India
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0257863

The endophytic bacterium Burkholderia contaminans NZ was isolated from jute, which is an important fiber-producing plant. This bacterium exhibits significant growth promotion activity in in vivo pot experiments, and like other plant growth-promoting (PGP) bacteria fixes nitrogen, produces indole acetic acid (IAA), siderophore, and 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity. B . contaminans NZ is considered to exert a promising growth inhibitory effect on Macrophomina phaseolina , a phytopathogen responsible for infecting hundreds of crops worldwide. This study aimed to identify the possibility of B . contaminans NZ as a safe biocontrol agent and assess its effectiveness in suppressing phytopathogenic fungi, especially M . phaseolina . Co-culture of M . phaseolina with B . contaminans NZ on both solid and liquid media revealed appreciable growth suppression of M . phaseolina and its chromogenic aberration in liquid culture. Genome mining of B . contaminans NZ using NaPDoS and antiSMASH revealed gene clusters that displayed 100% similarity for cytotoxic and antifungal substances, such as pyrrolnitrin. GC-MS analysis of B . contaminans NZ culture extracts revealed various bioactive compounds, including catechol; 9,10-dihydro-12’-hydroxy-2’-methyl-5’-(phenylmethyl)- ergotaman 3’,6’,18-trione; 2,3-dihydro-3,5- dihydroxy-6-methyl-4H-pyran-4-one; 1-(1,6-Dioxooctadecyl)- pyrrolidine; 9-Octadecenamide; and 2- methoxy- phenol. These compounds reportedly exhibit tyrosinase inhibitory, antifungal, and antibiotic activities. Using a more targeted approach, an RP-HPLC purified fraction was analyzed by LC-MS, confirming the existence of pyrrolnitrin in the B . contaminans NZ extract. Secondary metabolites, such as catechol and ergotaman, have been predicted to inhibit melanin synthesis in M . phaseolina . Thus, B . contaminans NZ appears to inhibit phytopathogens by apparently impairing melanin synthesis and other potential biochemical pathways, exhibiting considerable fungistatic activity.