Abstract
The solid state fermentation (SSF) is increasingly being used for the production of high value-added products using agro-food wastes as substrate. In fact, these residues which are available in large quantities and at low cost, have usable nutrients for the microorganism growth and seem to reproduce the natural habitat of filamentous fungi. In recent years, there have been significant additions to the science and engineering knowledge of SSF. Unlike systems SmF (Submerged Fermentation), the SSF are still able to achieve a high degree of development, mainly because of the problems associated with the beds solids, such as poor mixing of the materials and heat transfer.
For this reason, we have been further studied the efficiency of the fermentation process through mechanical treatments of extrusion of the substrate (SSF dynamics), able to promote the availability of substrate, the exchange of oxygen on the surface, the activity produced and the recovery enzyme. In the presence of this process, was observed an increase on the production of several enzyme activities. In the third week of fermentation of grape stalks, the caffeoyl and feruloyl esterase showed a considerable increase of almost 3 and 4 times (respectively), with respect to the values obtained previously in static SSF.
To increase the enzymatic activities produced by Pleurotus ostreatus in dynamic SSF (cellulase, xylanase, laccase, pectinase and arylesterase (caffeoyl esterase and feruloyl esterase)), we evaluated the effect of the mixes of agro-food wastes as substrates (grape stalks, grape seeds, and wheat bran) already previously used individually.
The different enzymatic production by the P. ostreatus probably depends on the different chemical-physical composition of the substrates. Furthermore was noted that in the mixes of vegetable matrix, the different substrates can act both as inducers that as inhibitors of certain classes enzymatic, in relation to the specificity of each individual matrix. One of the examples is the presence of grape seeds or stalks in the mix, which seem to counteract the inductive action of the wheat bran in the synthesis of cellulase and xylanase.
