UNIVERSITÉ PAUL CÉZANNE, AIX MARSEILLE III - IMEP

1. Introduction
Résultats et discussion. Chapitre 3: Evaluation des facteurs de croissance
The importance of olive oil mill industry in Mediterranean countries is well known, as
well as the serious problems that olive mill factories have in disposing their by-products
(Cayuela et al., 2006, Altieri and Esposito 2008). Commonly, olive mills produce residual
solids, the olive cake (OC) which make up a fibrous lignocellulosic waste and generally used
as fuel (Ait Baddi et al., 2009); and a black liquid effluent, the olive mill wastewater or
(OMW), which is a strong pollutant mainly due to its high phenolic content and organic load
(Mekki et al., 2007). In addition, it has been estimated that each olive tree could produces 25
kg leaves and twigs per year (Fayed et al., 2009).
In the past, several investigations were carried out to select microorganisms (notably
fungi) capable of eliminating the inhibitory effects of those substances and of converting the
initial waste either directly into a useful end-product or by making it susceptible to further
physicochemical and biological treatments (Jaouani et al., 2003; Lakhtar et al., 2009). Among
Basidiomycotina in particular, white-rot fungi belonging to the genus Pleurotus and Lentinula
were selectively tested for their ability to decompose the lignin and are among the most
efficient producers of lignocellulosic enzymes (Elisashvili et al., 2008). In addition, they can
be cultivated on a large lignocellulosic substrates transforming them into food and feed
(Zhang et al., 1995).
Lentinula edodes (Berk.) Pegler (shiitake) is the second most popular edible
mushroom in the world because of its flavor, taste and quality ((Tsai et al., 2009)). In
addition, L. edodes is one of the best known and the best characterized mushrooms used for
medicinal purposes (Hadar and Dosoretz 1991; Hirasawa et al., 1999; Hatvani 2001; Gu and
Belury 2005; Israilides et al., 2008; Shen et al., 2009). Owing to L. edodes characteristic,
different substrate formulations have been developed in different countries, depending on
their readily available raw material. Agricultural wastes such as oak, cereal straw, corn cobs,
sugarcane bagasse are used alone or in combination with other wastes in L. edodes cultivation
(Sunchez et Royse 2001; Philippoussis et al., 2003; Kalmis et Sargin 2004; Özçelik and
Peksen 2007; Philippoussis et al., 2007). However, for the first time, the use of mixture of
olive cake, olive twigs and leaves supplemented with OMW is reported.
To determine the parameters affecting biomass production of L. edodes and
polyphenol removal from OMW, with the intention to optimize the conditions of solid state
fermentation, the set of factors influencing the growth of L. edodes on olives residues was
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