Molecular microbial and chemical investigation of the bioremediation of two-phase olive mill waste using laboratory-scale bioreactors

Abstract

Two-phase olive mill waste (TPOMW) is a semisolid effluent that is rich in contaminating polyphenols and is produced in large amounts by the industry of olive oil production. Laboratory-scale bioreactors were used to investigate the biodegradation of TPOMW by its indigenous microbiota. The effect of nutrient addition (inorganic N and P) and aeration of the bioreactors was studied. Microbial changes were investigated by PCR-temperature time gradient electrophoresis (TTGE) and following the dynamics of polar lipid fatty acids (PLFA). The greatest decrease in the polyphenolic and organic matter contents of bioreactors was concomitant with an increase in the PLFA fungal/bacterial ratio. Amplicon sequences of nuclear ribosomal internal transcribed spacer region (ITS) and 16S rDNA allowed identification of fungal and bacterial types, respectively, by comparative DNA sequence analyses. Predominant fungi identified included members of the genera Penicillium, Candida, Geotrichum, Pichia, Cladosporium, and Aschochyta. A total of 14 bacterial genera were detected, with a dominance of organisms that have previously been associated with plant material. Overall, this work highlights that indigenous microbiota within the bioreactors through stimulation of the fungal fraction, is able to degrade the polyphenolic content without the inoculation of specific microorganisms.

Bioremediation and biovalorisation of olive-mill wastes

“…By using laboratory-scale bioreactors, it was shown that the genetic potential of the indigenous microbiota was able to metabolise polyphenolic compounds present in TPOMW under aerobic conditions, through the stimulation of the fungal fraction by nutrient supplementation (N and P), and it was also observed that predominant fungi identified by polymerase chain reaction (PCR)-temperature time gradient electrophoresis included members of the genera Penicillium, Candida, Geotrichum, Pichia, Cladosporium and Ascochyta (Morillo et al 2008a). Moreover, it was demonstrated that, compared to the inoculation of a single-strain (or consortium) approach, indigenous microorganisms could have a broader range of different biodegrading activities and thus sterilisation of the substrate is not necessary.…”

“…Moreover, it was demonstrated that, compared to the inoculation of a single-strain (or consortium) approach, indigenous microorganisms could have a broader range of different biodegrading activities and thus sterilisation of the substrate is not necessary. The amendment with nutrients to alter the C/N ratio allowed the microbial activity and the phenolic content reduction to be significantly improved during aerobic biodegradation of either OMWW (El Hajjouji et al 2008) or TPOMW (Morillo et al 2008a). Apart from changing the structure of the microbial communities involved in the bioremediation of OMWs, the addition of nutrients can also modify the pattern of degrading enzymes production by specific microorganisms.…”

Evaluation of “alperujo” composting based on organic matter degradation, humification and compost quality

“…AL is a very wet and pasty lignocellulosic material, difficult to handle and transport, which includes potentially pollutant compounds such as phenols and fats. Apart from the treatments to recover its residual oil (second centrifugation, and drying followed by chemical extraction), several methods have been considered for AL disposal (Aragón and Palancar 2001; Borja et al 2006;Miranda et al 2007;Morillo et al 2008;Rincón et al 2008), including physical, chemical and biological processes. Amongst the last of these, composting is increasingly considered a good way of improving profits and the viability of the olive oil production process, and much research work has been carried out in the recent decades to recycle the organic matter and nutrient contents of olive-mill wastes by composting, as noted in Azbar et al (2004) and Roig et al (2006).…”

Complete Valorization of Olive Mill Wastewater through an Integrated Process for Poly-3-hydroxybutyrate Production

“…This high COD value represents a hidden source of value, as all the chemicals can be separated from the waste stream and residual organic content used as raw-material for bio-polymers production. Olive oil is mainly produced in the Mediterranean countries, although other producers, such as Argentina, Australia and Chile, are facing the toxic effects of OMW [9]. The major olive oil producing countries are Spain, Italy, and Greece, with a production of 1,150, 560, and 370 thousand tons annually, respectively, followed by Tunisia and Turkey, with an annual production of 160 thousand tons each [10].…”