An in vitro investigation of the antimicrobial activity of oxifulvic acid
Key Findings
- Oxifulvic acid (coal-derived FA) tested against S. aureus, E. coli, P. aeruginosa, C. albicans
- MIC data provided for each organism
- Humic substances account for 50% of dissolved organic carbon in stream water
- Fulvic acids are 9-10× more abundant in water than humic acids
- Coal-derived FA designated 'oxifulvic' to distinguish from naturally occurring FA
A short but data-dense paper in the Journal of Antimicrobial Chemotherapy providing minimum inhibitory concentration (MIC) values for oxifulvic acid against four common pathogens. Published by the same research group (van Rensburg et al., University of Pretoria) who later produced the comprehensive 2015 anti-inflammatory review.
What Was Tested
Oxifulvic acid — a fulvic acid derived from coal rather than peat — was tested for antimicrobial activity against:
- Staphylococcus aureus (gram-positive; associated with skin infections, acne, dermatitis)
- Escherichia coli (gram-negative; common contaminant)
- Pseudomonas aeruginosa (gram-negative; opportunistic pathogen)
- Candida albicans (fungus; associated with skin and scalp conditions)
MIC values (the lowest concentration that prevents visible growth) were measured for each.
The Sourcing Distinction
The FA studied here is coal-derived, not peat-derived. The authors designate it “oxifulvic” to make this clear. Peat fulvic acids and coal fulvic acids share the same chemical class but differ in molecular detail depending on source geology and formation conditions. This paper’s MIC data is frequently cited in peat therapy literature as evidence for FA antimicrobial activity, but strictly speaking it demonstrates that oxifulvic acid has these properties — the parallel to peat-derived FA is chemically reasonable but not directly proven by this study.
Significance
This paper is the primary quantitative source for fulvic acid antimicrobial claims on this site. The MIC data makes the evidence concrete — not “has antimicrobial properties” but “inhibits growth at measurable concentrations.” Wollina 2009 and Ansorg 1978 provide the broader antimicrobial picture; van Rensburg 2000 provides the specific FA-focused MIC numbers.