Soil protein as a potential antimicrobial agent against methicillin -resistant Staphylococcus aureus

Area of Science:

• Microbiology
• Biochemistry
• Natural Product Discovery

Background:

• Antibiotic resistance is a growing global health threat due to widespread antibiotic misuse.
• There is an urgent need for novel antibacterial agents to combat resistant pathogens.

Purpose of the Study:

• To investigate the antibacterial potential of soil-derived proteins against methicillin-resistant Staphylococcus aureus (MRSA).
• To characterize the mechanism of action and safety profile of the identified protein extract.

Main Methods:

• Protein extraction from forest soil samples with varying management histories.
• Antibacterial activity assays, including Minimum Inhibitory Concentration (MIC) and IC50 determination.
• Microscopy (optical and fluorescent) and comet assay for mechanism of action studies.
• Quantitative Polymerase Chain Reaction (qPCR) to assess gene expression.
• Hemolytic assay for toxicity evaluation.
• Ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) for protein identification.

Main Results:

• A protein extract (C3) from intensively managed forest soil demonstrated significant antibacterial activity (98% growth inhibition) against MRSA.
• The extract exhibited a Minimum Inhibitory Concentration (MIC) of 30 μg/g and an IC50 of 15.0 μg/g dry soil.
• C3 induced bacterial cell wall disruption and genotoxicity, down-regulated the mecA resistance gene, and showed no hemolytic toxicity to human red blood cells.
• UHPLC-MS identified 144 proteins in C3, predominantly from Gram-negative bacteria.

Conclusions:

• Soil protein extracts, particularly C3, possess potent, non-toxic antibacterial properties against MRSA.
• The findings support the development of novel, natural-source antibacterial agents to address antibiotic resistance.
• This research highlights the potential of soil microbiomes as a source for new antimicrobial therapies.