Growth inhibition of pathogenic microorganisms by Pseudomonas protegens EMM-1 and partial characterization of...

Area of Science:

• Microbiology
• Biochemistry
• Plant Pathology

Background:

• The search for novel antimicrobials is crucial due to rising multidrug resistance.
• Pseudomonas species are known producers of bioactive compounds with antimicrobial properties.
• Rhizosphere bacteria can influence plant health and disease resistance.

Purpose of the Study:

• To isolate and identify a novel bacterial strain with antimicrobial properties from the maize rhizosphere.
• To characterize the antimicrobial compounds produced by the identified strain.
• To evaluate the efficacy of the strain and its compounds against pathogenic bacteria and fungi.

Main Methods:

• Phylogenetic analysis using 16S rDNA, rpoB, rpoD, and gyrB gene sequences for bacterial identification.
• Antimicrobial activity screening using double-layer agar assays.
• Extraction and partial purification of inhibitory substances.
• Physicochemical characterization of the active compounds (molecular weight, thermal stability, pH stability, protease sensitivity).

Main Results:

• Pseudomonas protegens EMM-1 was identified, possessing genes for antimicrobial compound synthesis (2,4-DAPG, pyoluteorin, bacteriocins).
• The strain effectively inhibited multidrug-resistant clinical isolates (Klebsiella, Streptococcus) and phytopathogenic fungi (Aspergillus, Botrytis, Fusarium).
• Partially purified compounds showed activity against Streptococcus sp. and Microbacterium sp., with molecular weight between 3-10 kDa, thermal stability up to 60°C, activity across pH 3-9, and protease sensitivity.

Conclusions:

• Pseudomonas protegens EMM-1 is a promising source of novel antimicrobial compounds.
• The characterized inhibitory substances, likely proteinaceous, demonstrate potential for combating human and plant pathogens.
• Further research into these natural compounds could lead to new therapeutic and agricultural applications.