A new study has found that a bioactive compound in olive mill wastewater may have potential for use in the development of biopesticides, Olive Oil Times wrote.
Published on the Plant Stress website, the study highlighted the potential commercial application of oligogalacturonides in providing a new revenue source for olive oil producers, as well as contributing to environmental sustainability, the 7 May report said.
In the study, researchers from the Sapienza University of Rome and the Italian National Agency for New Technologies, Energy and Sustainable Economic Development identified pectin-derived oligogalacturonides with a degree of polymerisation between 10 and 17 in olive mill wastewater that could trigger a plant’s immune system and be used in the development of biopesticides, Olive Oil Times wrote.
Oligogalacturonides trigger a plant’s immune system via the cell wall, activating defence responses and resistance against some pathogens.
This was the first time the molecules had been separated from olive mill wastewater, the report said.
Using transgenic Arabidopsis seedlings, the researchers confirmed that the extracted oligogalacturonides triggered the expected defence responses, including increased calcium ions, which were intracellular messengers critical in plant defence signalling pathways, Olive Oil Times wrote.
Olive mills in the Mediterranean basin produce an estimated 30bn litres/year of wastewater, which are considered a significant environmental pollutant, with most countries banning it from being dumped without being treated, according to the report.
The wastewater is very acidic, with high concentrations of recalcitrant compounds including lignins and tannins, which require significant amounts of oxygen to biodegrade.
However, the wastewater also contained a wide range of valuable phenolic compounds with proven antimicrobial properties, although the effect of this liquid waste as a plant elicitor of defence responses had yet to be investigated, the researchers wrote.
In the study, oligogalacturonides were separated from the olive mill wastewater using tangential-flow membrane filtration.
“Tangential-flow membrane filtration is a powerful tool in bioprocessing, allowing the separation and concentration of active biomolecules into specific molecular pools, such as proteins, sugars and secondary metabolites,” the researchers wrote.
“By using complex mixtures for filtration, tangential-flow membrane filtration effectively removes impurities while retaining the desired molecules.”
The researchers said the method did not require a chemical solvent and was scalable from a laboratory setting, allowing large-scale olive mills to use it.
Oligogalacturonides have been approved in commercial plant protection products recognised by the European Union, which has set a target to reduce synthetic pesticide use by 50% by 2030, Olive Oil Times wrote.
According to market research by Industry Research Reports, the global biopesticide market was valued at US$6.1bn (€5.6bn) in 2023 and is estimated to reach US$11.5bn (€10.1bn) by 2030.
