MYCOLab Ai Logo - gold and army green

Impact of Oxalic Acid Consumption and pH on the In Vitro Biological Control of Oxalogenic Phytopathogen Sclerotinia sclerotiorum

Summary

Scientists studied how bacteria that eat oxalic acid can control a destructive plant fungus called Sclerotinia sclerotiorum. The fungus produces oxalic acid to damage crops, but when special bacteria consume this acid, they change the soil pH to become more alkaline, which the fungus cannot tolerate. This research shows that pH changes are just as important as removing the acid itself for controlling this pathogenic fungus in agriculture.

Background

Sclerotinia sclerotiorum is a destructive phytopathogenic fungus with a wide host range that uses oxalic acid as a virulence factor. Previous studies proposed oxalate-degrading bacteria as a biological control approach, but the differential effects of oxalic acid consumption and pH alkalinization on fungal growth have not been investigated.

Objective

To investigate the combined effects of oxalic acid consumption and pH alkalinization on biological control of S. sclerotiorum using oxalotrophic bacteria Cupriavidus necator and Cupriavidus oxalaticus, comparing wild-type and oxalate-deficient mutant strains across different media compositions.

Results

Oxalotrophic bacteria controlled S. sclerotiorum only in media where oxalic acid was produced (R2A/R2B), not in malt-based media (MA1/10). However, the oxalate-deficient mutant was also controlled on R2A, indicating oxalic acid consumption is not the sole biocontrol mechanism. Medium alkalinization, driven by bacterial metabolism and oxalic acid degradation, was critical for fungal growth control.

Conclusion

While oxalic acid consumption was initially proposed as the biocontrol mechanism, subsequent medium alkalinization is equally important for controlling S. sclerotiorum growth. The pH change—regardless of whether driven by oxalic acid consumption or ammonia production—is ultimately responsible for growth control, suggesting future studies should examine in planta pH modification mechanisms.
  • Published in:Journal of Fungi,
  • Study Type:In Vitro Experimental Study,
  • Source: PMID: 40137229, DOI: 10.3390/jof11030191
Scroll to Top