Journal of Biotechnology & Biomaterials
Open Access

Abstract

A biomatrix made of agro-industrial rice residues (straw and husks) and sunflower seed hulls and mycelium of the medicinal fungi Ganoderma lucidum as bio-adherent microorganism was obtained and studied. Those lignocellulosic raw materials have a low density which in terms of transportation set a real problem for an environmental friendly disposal; indeed in countries lacking of an adequate legislation, producers usually burn those materials in the open field or in ovens. Fortunately, in the last years lot of work has been made by scientists and technologists in order to obtain high value products from this kind of residues. One approach is to produce biodegradable matrixes by using different environmentally friendly adhesives. Here the mycelium of Ganoderma lucidum becomes the adhesive material through solid-state fermentation. Under controlled conditions, the fungal mycelium produces a tight net around and into the available lignocellulosic particles to build a considerable mechanical strength once the cultivated unit is dehydrated. This mechanical property taken together with the low weight of the resulting biomatrix justifies to deep into the study of other physical properties particularly in units of this biomatrix obtained in templates designed for specific applications. Results of mycelium growth analysis on different substrate formulations showed a good growth performance on substrates based on agro-industrial rice residues that contained 57-69% straw, 25-30% husk, 5-10% rice bran and 0-1% olive oil or in sunflower based substrates that contained 100% sunflower seed hulls. Mechanical properties of compression and flexion were evaluated at different packaging densities of substrates. Analyses showed no differences in the mechanical properties between 0.3-0.5 g/cm3 densities. However the two main substrates differed in the response of those variables. Biomatrix made of sunflower seed hulls resisted higher pressures while the one obtained with agro-industrial rice materials exhibited a higher elasticity. These attributes evoke the properties of high and low density polystyrene materials respectively. Since that G. lucidum mycelium can bind all the substrate particles that completely fill the container, different biomatrix shapes can be obtained for different uses example for plant pot containers, panels, packaging pieces and cuboids or cylindrical blocks. It is important to note that, as white rot fungi, G. lucidum function in nature is to biotransform plant materials with high-lignin content, the resulting material could then be exposed to other microorganisms, the so called “secondary decomposers”. Regarding to the biomatrix its imbibition with water allows the secondary decomposers start to grow quickly which is an advantageous trait when considering their final disposal in municipal garbage allocations. Indeed, the biodegradation caused by fungi reduces the time required to their decomposition in comparison with the original substrates (rice straw and husks and sunflower seed hulls). The biomatrix could be applicable in land farming or bioremediation of contaminated soils. Alternatively, the matrix could carry anti-pollutant microorganisms and even seeds of bioremediation plants species. Current projects in our institutions are focused into the development of horticultural plant pots that are able to be biodegraded following the transplant of seedling and in obtaining panels for acoustic and thermal isolation.

Biography

Email:

pablop@criba.edu.ar