Study Finds Potential for Olive Mill Wastewater in Biopesticides

Summary

Researchers have iden­ti­fied pectin-derived oli­gogalac­tur­onides in olive mill waste­water that can trig­ger a plan­t’s immune sys­tem and be used in the devel­op­ment of biopes­ti­cides. The study high­lights the poten­tial com­mer­cial appli­ca­tion of these com­pounds, which could pro­vide a new rev­enue source for olive oil pro­duc­ers and con­tribute to envi­ron­men­tal sus­tain­abil­ity in agri­cul­ture.

A recent study pub­lished in Plant Stress sug­gests that a bioac­tive com­pound in olive mill waste­water may have com­mer­cial appli­ca­tion in devel­op­ing biopes­ti­cides. 

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 poly­mer­iza­tion between ten and 17 in the olive mill waste­water.

Oligogalacturonides trig­ger a plant’s immune sys­tem via the cell wall, acti­vat­ing defence responses and resis­tance against some pathogens. The mol­e­cules had not pre­vi­ously been sep­a­rated from olive mill waste­water.

Using trans­genic Arabidopsis seedlings, the researchers con­firmed that the extracted oli­gogalac­tur­onides trig­gered the expected defense responses, includ­ing increased cal­cium ions, which are intra­cel­lu­lar mes­sen­gers crit­i­cal in plant defense sig­nal­ing path­ways. 

The study is part of researchers’ ongo­ing efforts to add value to olive oil pro­duc­tion byprod­ucts, espe­cially olive mill waste­water. An esti­mated 30 bil­lion liters of waste­water are pro­duced annu­ally by olive mills in the Mediterranean basin.

While olive pomace byprod­ucts are con­sid­ered easy to recy­cle, they are widely used in the food indus­try, pro­duc­ing olive pomace oil and renew­able energy. Olive mill waste­water presents more chal­lenges.

The waste­water is highly acidic with high con­cen­tra­tions of recal­ci­trant chem­i­cal sub­stances, includ­ing lignins and tan­nins, which require sig­nif­i­cant amounts of oxy­gen to biode­grade.

Therefore, olive mill waste­water is con­sid­ered a sig­nif­i­cant envi­ron­men­tal pol­lu­tant, with most coun­tries pro­hibit­ing it from being dumped with­out being treated.

“On the other hand, olive mill waste­water con­tains a wide range of valu­able phe­no­lic com­pounds with proven antimi­cro­bial prop­er­ties (e.g., flavonoids, hydrox­ytry­rosol, oleu­ropein) and olive mill waste­water by-prod­ucts are effec­tive as biopes­ti­cides against dif­fer­ent micro­bial pathogens,” the researchers wrote.

“However, the effect of this liq­uid waste as a plant elic­i­tor of defense responses has not yet been inves­ti­gated,” they added.

Using tan­gen­tial-flow mem­brane fil­tra­tion, the researchers sep­a­rated the oli­gogalac­tur­onides from the olive mill waste­water.

“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,” they added.

The researchers high­lighted how the method does not require a chem­i­cal sol­vent and is scal­able from a lab­o­ra­tory set­ting, allow­ing large-scale olive mills to employ it. They added that the find­ings could pro­vide a new source of rev­enue for olive oil pro­duc­ers. 

Oligogalacturonides have been approved in com­mer­cial plant pro­tec­tion prod­ucts rec­og­nized by the European Union, which has set a tar­get to reduce syn­thetic pes­ti­cide use by 50 per­cent by 2030.

According to mar­ket research from Industry Research Reports, the global biopes­ti­cide mar­ket was val­ued at $6.1 (€5.6) bil­lion in 2023 and is esti­mated to reach $11.5 (€10.1) bil­lion by 2030. 

“The oli­gogalac­tur­onide-enriched frac­tion, described in the present work, is suit­able to be employed as a novel bio-pes­ti­cide, con­tribut­ing to enhance both envi­ron­men­tal and eco­nomic sus­tain­abil­ity of the olive oil indus­try,” the researchers wrote. 

“We pave the way for field exper­i­ments with plants of agro­nomic inter­est for exploita­tion of these by-prod­ucts as sus­tain­able nat­ural phyto-pro­tec­tants in the con­trol of pathogens caus­ing dev­as­tat­ing dis­eases of eco­nom­i­cally impor­tant crops accord­ing to a cir­cu­lar econ­omy per­spec­tive in agri­cul­ture,” they added.