Isolation and characterization of antimicrobial cyclic dipeptides from Pseudomonas fluorescens and their efficacy on sorghum grain mold fungi.
This study was aimed at isolation and characterization of natural antifungal compounds for grain mold, a key parasitic fungal disease of sorghum. Pseudomonas fluorescens strain isolated from rhizosphere of groundnut crop was selected as a source. Its biocontrolling ability was assessed by testing some biochemical attributes such as phosphate-solubilization, and HCN, NH3 , indole-3-acetic acid, and siderophore production. The strain showed positive result for all except indole-3-acetic acid, revealing its suitability for a further study. The antibiotic-sensitivity pattern of the strain against 43 antibiotics was also established, which showed resistance to 15 antibiotics. The efficacy of P. fluorescens strain against grain mold was identified by dual culture technique. Hundred percent inhibition was found against Fusarium moniliforme, an important causative agent of this disease. The strain was fermented for secondary metabolites and extracted with AcOEt. Chromatographic separation of the extract yielded four known compounds, cyclo(L-Pro-L-Phe) (1), cyclo(trans-4-hydroxy-L-Pro-L-Leu) (2), cyclo(trans-4-hydroxy-L-Pro-L-Phe) (3), and cyclo(Gly-L-Pro) (4), which were characterized by spectral analysis and optical rotation. The crude extract, a mixture of 2 and 3, and isolated 1 were proved to be significantly effective against grain mold fungi. This is the first report on production of these cyclic dipeptides by P. fluorescens and their antagonistic properties.
Department of Pharmacy, Birla Institute of Technology & Science - Pilani, Hyderabad Campus, Jawahar Nagar, Shameerpet, Hyderabad-500078, Andhra Pradesh, India (phone: +91-40-66303578). sajeli@hyderabad.bits-pilani.ac.in.
Ahil
A
Sajeli Begum
Shaik Ameer
SA
Basha
Govardhanam
G
Raghavendra
Mallela Venkata Nagesh
MV
Kumar
Yukthi
Y
Singh
Jagannath V
JV
Patil
Yuhei
Y
Tanemura
Yoshinori
Y
Fujimoto
D000935:Antifungal Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D004151:Dipeptides / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005670:Fusarium / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D010456:Peptides, Cyclic / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D011551:Pseudomonas fluorescens / Q000737:chemistry*; D013329:Structure-Activity Relationship
D000935:Antifungal Agents; D004151:Dipeptides; D010456:Peptides, Cyclic
Antifungal metabolites; Diketopiperazine; Peptides; Pseudomonas fluorescens; Sorghum grain mold