Lentinula edodes removes phenols from olive-mill wastewater: impact on durum wheat (Triticum durum Desf.) germinability.

Olive-mill wastewater (OMW) exhibits highly phytotoxic properties, mainly due to phenols. A valuable option for OMW disposal is its agricultural use provided that phytotoxic effects are removed. The present investigation was aimed at evaluating the efficacy of the lignin-degrading fungus Lentinula edodes in achieving OMW detoxification. Germinability experiments on durum wheat showed that OMW phytotoxicity was significantly reduced by L. edodes cultures. Germinability on undiluted and twofold diluted OMW from fungal cultures was 34+/-5% and 57+/-6%, respectively, while on related incubation controls it was almost completely suppressed. These results suggest that fungal cultures of L. edodes would decrease the phytotoxicity of this waste.

Reduction of the phenolic components in olive-mill wastewater by an enzymatic treatment and its impact on durum wheat (Triticum durum Desf.) germinability.

Olive-mill wastewater (OMW), an effluent of olive oil extraction process, is annually produced in huge amounts in olive growing areas. An interesting option for its disposal is the spreading on agricultural land, provided that phytotoxic effects are neutralized. The objective of the present investigation was to evaluate the potential of an enzyme-based treatment in removing OMW phytotoxicity. To this aim, germinability experiments on durum wheat (Triticum durum Desf. cv. Duilio) were conducted in the presence of different dilutions of raw or enzyme-treated OMW. OMW treatment with laccase resulted in a 65% and 86% reduction in total phenols and ortho-diphenols respectively, due their polymerization as revealed by size-exclusion chromatography. Raw OMW exerted a significant concentration-dependent inhibition on the germinability of durum wheat seeds which was evident up to a dilution rate of 1:8. When the effluent was treated with a fungal laccase, germinability was increased by 57% at a 1:8 dilution and by 94% at a 1:2 dilution, as compared to the same dilutions using untreated OMW. The treatment with laccase also decreased the mean germination time by about 1 day as compared to untreated controls. These results show that germinability inhibition due to OMW can be reduced effectively using fungal laccase, suggesting that phenols are the main determinants of its phytotoxicity.