UNIVERSITÉ PAUL CÉZANNE, AIX MARSEILLE III - IMEP

Résultats et discussion. Chapitre 3: Evaluation des facteurs de croissance
substrate on polyphenol removal. These results are in accordance with previous findings
demonstrating that high content of N had a negative effect of the degradation of procyanidins
by Aspergillus fumigatus (Contreras-Dominguez, 2006). Our results, demonstrating decrease
of pH in the substrate without supplement after the incubation period, are comparable to those
obtained on oak-wood sawdust substrates (Philippoussis et al., 2003), and they confirm
previous observations stating that a low pH value of the substrate is probably a prerequisite
for primordia formation (Kalberer 1995).
Spawn inoculation size was found an important factor that affects the mycelial growth.
Compared to the straw, spawn is a relatively expensive item. Using the lowest inoculation
size possible without sacrificing the mushroom yield would give the best economics. The
spawn size is defined as the weight ratio of spawn to substrate on a fresh weight basis. The
optimum spawn size depends on the type of substrate, mushroom species, spawn quality, and
the cultivation conditions. Among the two spawn size (10 and 20%) tested, the 10% spawn
size resulted in significantly lower mycelial biomass than the other size. The mycelial
biomass at the 10% size was 37.5% lower than at the 20% size for the substrate without
supplement. The mycelial growth at the 10% size showed contamination by green and black
moulds during cultivation of the L.edodes Le119 strain. Therefore, based on these results, it
would be recommended that at least 10% spawn level be used to achieve a colonization of the
substrate by L. edodes without any mould contamination.
5. Conclusion
The growth of L. edodes Le119 on SOS using different mixture allowed us to
determine the optimal formulation which was OTL (20%) + OC (30%) + OMW (50%)
allowing mycelial biomass production of 16,24 mg.g -1 of substrate dry weight. The nutriments
added to the substrate which negative effect and spawn size which positive effect were the
main parameter that affected the growth of L. edodes Le119 on optimal SOS. Thus, the
optimal condition of growth of L. edodes Le119 on SOS are the following; SOS composition
(20% of OTL, 30% of OC and 50% of OMW), initial pH of 5, temperature of incubation
25°C, aeration flow 20 mL.min -1 , inoculum age of 10 days, inoculum size 10%, 70% of
particle size between 2 and 0.8 mm mixed with 30% of particle size less than 0.8 mm and
with addition of nutrients.
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