microbiological effects of olive mill waste addition to substrates for pleurotus pulmonarius cultivation . cristina soler-rives Ana garcia-rosado,isabel polonia gemma junca- blanch francisco R marin Harin J wichers . department of functional ingredients, agro technology and food innovations bornsesteeg 596708 pd wagenigen. the netherlands escola superior agraria de santarem (esds sector) de engenharia Agro-alimentar quinta do galinheiro S. pedro 2000-014 santarem portugal Universidad Autonoma de madrid (uma) Unit of food science and technology Ctra de colmenar Km 15 ,28049 Madrid Spain.
Received 11 November accepted 25 October 2005
Available online 7 december 2005
when olive mill wastes (omws) and vegetation waters (vws) obtained during the manufacture of olive oil were added as substrate supplements for the cultivation of pleurotus the material modified of the mushroom and the endemic microbiota of the substrate in particular the mushroom-pathogenic bacterium Pseudomonas tolaasii which is responsible for bacterial blotch disease in mushroom
vw addition to substrates at up to 30% (v/w) did not interfere with mycelial growth but inhibited
fruit body formation.supplementation at up to 10% did not inhibit pinhead appearance and reduced
Ps. tolaasii-related symptoms .
in an attempt to identify the compounds responsible for the observed reduction of symptoms of acidic basic or enzymic hydrolysis of oleuropein together with OMW ethyl acetate extracts and several single compounds were studied.
omw ethyl acetate extracts and hydroxytyrosol inhibited Ps tolaasii Growth but did not show bactericidal activity only 4-methylcatechol and catechol were effective as bactericides against Ps tolaasii (minimum biocidal concentration 5 and 10 mM, respectively). such concentrations were not reached if the wastes were added at 10% v/w at such levels growth of the bacteria will only be inhibited not eliminated completely
olive oil wastes are harmful to environment in the mediterranean region. they are phytotoxic and they are resistant to degradation by the natural soil microbiota (Ramos -cormenzana et al..1995).
the traditional olive oil pressing system (a three-phase continuous centrifugation system)generates two types of waste an olive press-cake (opc) and a black liquid effluent-olive oil wastewater or vegetation waters (vw). OPC is a fibrous lignocellulosic solid waste generally used as fuel. vw is a pollutant containing a high level of phytotoxic phenolic compounds. many uses have been
proposed for this waste e.g. as fertiliser or soil conditioner as growth medium for edible mushrooms (zervakis et al .,1996)
or algae for production of biopolymers (polysac-charide and biodegradable plastics); for biogas production; or as a source of biopharmaceuticals ( ramos-cormenzanaet al .,1995;cegarra et al .,1996) have all been suggested.