**4.3 Organic acids**

Some *Y. lipolytica* strains are good candidates for the reduction of the pollution potential of OMWW and for the production of enzymes and metabolites such as lipase and citric acid (Lanciotti et al. 2005). *Y. lipolytica* strain ACA-DC 50109 demonstrated efficient growth on media containing mixtures of OMWs and commercial glucose. In nitrogen-limited diluted and enriched with high glucose quantity OMWW, a noticeable amount of total citric acid was produced. The ability of *Y. lipolytica* to grow on relatively high phenolic content OMWs based media and produce in notable quantities citric acid, make this non-conventional yeast worthy for further investigation (Papanikolaou et al. 2008).

The biochemical behavior and simultaneous production of valuable metabolites such as lipase, citric acid (CA), isocitric acid (ICA) and single-cell protein (SCP) were investigate by *Y. lipolytica* DSM 3286 grown on various plant oils as sole carbon source. Among tested plant oils, olive oil proved to be the best medium for lipase and CA production. The *Y. lipolytica* DSM 3286 produced 34.6 ± 0.1 U/ml of lipase and also CA, ICA and SCP as byproduct on olive oil medium supplemented with yeast extract. Urea, as organic nitrogen, was the best nitrogen source for CA production. The results of this study suggest that the two biotechnologically valuable products, lipase and CA, could be produced simultaneously by this strain using renewable low-cost substrates such as plant oils in one procedure (Darvishi et al. 2009).

In the other study, a total of 300 yeast isolates were obtained from samples of agro-industrial wastes, and M1 and M2 strains were investigated for their ability to produce lipase and

62.8) were accumulated in cultures with OMWW or polymeric pigment. Furthermore, modified manganese-dependent peroxidases were observed mainly in OMWWsupplemented cultures. Laccase was more stable to the effect of OMWW toxic components and was accumulated in monomeric aromatic-supplemented cultures, suggesting a more important role than manganese-dependent peroxidases in OMWW detoxification. Alternatively, MnPA accumulated in cultures containing the polymeric pigment seemed to be more essential than laccase for degradation of this recalcitrant macromolecule by *P.* 

Enzyme laccase, produced by fungus *Pycnoporus coccineus*, is responsible for OMWW decolorization and decrease COD and phenolic compounds. The highest laccase level was 100 000 U/l after 45 incubation-days. The enzyme was stable at pH 7, at room temperature and showed a half-life of 8 and 2 h at 50 and 60°C, respectively (Jaouani et al. 2005). In order to decolourise OMWW efficiently, production and differential induction of ligninolytic enzymes by the white rot *Coriolopsis polyzona*, were studied by varying growth media composition and/or inducer addition (Jaouani et al. 2006). The production of lignin peroxidase (LiP), manganese peroxidase (MnP) and lipases by *Geotrichum candidum* were performed in order to

Sequential batch applications starting with adapted *Trametes versicolor* FPRL 28A INI and consecutive treatment with *Funalia trogii*, possible to remove significant amount of total phenolics content and higher decolorization as compared to co-culture applications. Also highest laccase and manganese peroxidase acitivities were obtained with *F. trogii* (Ergul et

Some *Y. lipolytica* strains are good candidates for the reduction of the pollution potential of OMWW and for the production of enzymes and metabolites such as lipase and citric acid (Lanciotti et al. 2005). *Y. lipolytica* strain ACA-DC 50109 demonstrated efficient growth on media containing mixtures of OMWs and commercial glucose. In nitrogen-limited diluted and enriched with high glucose quantity OMWW, a noticeable amount of total citric acid was produced. The ability of *Y. lipolytica* to grow on relatively high phenolic content OMWs based media and produce in notable quantities citric acid, make this non-conventional yeast

The biochemical behavior and simultaneous production of valuable metabolites such as lipase, citric acid (CA), isocitric acid (ICA) and single-cell protein (SCP) were investigate by *Y. lipolytica* DSM 3286 grown on various plant oils as sole carbon source. Among tested plant oils, olive oil proved to be the best medium for lipase and CA production. The *Y. lipolytica* DSM 3286 produced 34.6 ± 0.1 U/ml of lipase and also CA, ICA and SCP as byproduct on olive oil medium supplemented with yeast extract. Urea, as organic nitrogen, was the best nitrogen source for CA production. The results of this study suggest that the two biotechnologically valuable products, lipase and CA, could be produced simultaneously by this strain using renewable low-cost substrates such as plant oils in one procedure

In the other study, a total of 300 yeast isolates were obtained from samples of agro-industrial wastes, and M1 and M2 strains were investigated for their ability to produce lipase and

control the decolourisation and biodegradation of OMWW (Asses et al. 2009).

worthy for further investigation (Papanikolaou et al. 2008).

*flavido-alba*. (Ruiz et al. 2002).

al. 2010).

**4.3 Organic acids** 

(Darvishi et al. 2009).

citric acid. Identification tests showed that these isolates belonged to the species *Y. lipolytica*. M1 and M2 strains produced maximum levels of lipase on olive oil, and high levels of citric acid on citric acid fermentation medium (Mafakher et al. 2010).

The highest oxalic acid quantity (5 g/l) was obtained by the strain *Aspergillus* sp. ATHUM 3482 on waste cooking olive oil medium. For strain *Penicillium expansum* NRRL 973 on this medium sole organic acid detected was citric acid with maximum concentration achieved 3.5 g/l (Papanikolaou et al. 2011).
