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.

Oxirane-immobilized Lentinula edodes laccase: stability and phenolics removal efficiency in olive mill wastewater.

Immobilization of Lentinula edodes laccase on Eupergit C increased pH, thermal and proteolytic stability with slight modifications in laccase oxidation efficiency. Immobilized laccase proved to be efficiently stable in removing olive mill wastewater phenolics.

Production and isolation of chitosan by submerged and solid-state fermentation from Lentinus edodes.

A method for the laboratory-scale production and isolation of chitosan (polyglucosamine) by liquid and solidstate fermentation from Lentinus edodes was developed. The yields of isolated chitosan were 120 mg/L of fermentation medium under liquid fermentation conditions and 6.18 g/kg of fermentation medium under solid-state fermentation conditions. The latter method, which gives up to 50 times yields than other chitosan production methods from fungi, provides a new flexible and easily scaledup procedure for the production of low acetylation degree chitosan.

Isotactic polypropylene biodegradation by a microbial community: physicochemical characterization of metabolites produced.

From a selective enrichment culture prepared with different soil samples on starch-containing polyethylene we isolated four microaerophilic microbial communities able to grow on this kind of plastic with no additional carbon source. One consortium, designated community 3S, was tested with pure isotactic polypropylene to determine whether the consortium was able to degrade this polymer. Polypropylene strips were incubated for 5 months in a mineral medium containing sodium lactate and glucose in screw-cap bottles. Dichloromethane crude extracts of the cultures revealed that the weight of extracted materials increased with incubation time, while the polypropylene sample weight decreased. The extracted materials were characterized by performing chromatographic and spectral analyses (thin-layer chromatography, liquid chromatography, gas chromatography-mass spectrometry, infrared spectrometry, nuclear magnetic resonance). Three main fractions were detected and analyzed; a mixture of hydrocarbons at different degrees of functionalization was found together with a mixture of aromatic esters, as the plasticizers usually added to polyolefinic structures.