SSF and bioproducts
The background of GICOM in Composting offers a consolidated and solid base to further develop the bioprocessing of organic solid wastes under the new paradigm of waste-to-feedstock or waste-to-product through Solid-State Fermentation (SSF). The Group started to work in this new research line in 2010 and explores how a broad range of valuable products can be obtained from very diverse wastes such as oil-refining wastes, cow hair from leather industry or orange peels. So far we have succesfully produced: enzymes (lipase, protease, cellulase), biosurfactants and biopesticides. We are working further to get biofuels and other chemical compounds. The options appear infinite. That’s why SSF currently receives increasing attention by academia. However the main challenge remains being the process scale-up. Our research in this field is based on a reliable, easily scalable SSF process, based on our knowledge on Composting which is successfully undertaken at field scale. Simultaneouslly, we focus both in the production of novel products and their use in environmental applications or green chemical processes.
At the GICOM group we have explored the production of biosurfactants by bioconversion of food industry waste by solid state fermentation. Specifically, we have studied the production of sophorolipids, a glycolipid with multiple applications in environmental resortation, agriculture, cleaning or personal hygiene products, and the cosmetics industry, among others. This compound can be produced by fermentation of substrates rich in oils and / or sugars. For example, filter cake from the edible oil refining industries (sunflower, corn, etc.) has an enormous potential as a source of hydrophobic carbon for the yeast Starmerella bombicola, one of the best known producer of these biosurfactants. Production from urban or industrial waste hydrolysates has also been shown to be viable. By optimizing process conditions and selecting laboratory-scale media, we achieved promising productivity of approximately 3 g of SL per liter per day. The process has been successfully scaled-up to an actual volume of 60 liters. In order to develop this process on a commercial scale, we are improving the procedures for recovering SLs from the solid matrix and exploring advanced operation and process control strategies for successful scaling-up. In addition, we are conducting economic and environmental feasibility studies of the process. The developed process can be extrapolated to the production of other glycolipid biosurfactants produced by yeasts on analogous carbon sources.
Biocontrol agents can totally or partially replace traditional chemical pesticides, they are effective on a considerable number of pests, without having harmful effects on humans, animals or the ecosystem. Some of these biopesticides are of microbial origin, produced by bacteria and fungi. These microorganisms can grow, under controlled conditions, on solid substrates through solid state fermentation. This allows to use waste materials as a substrate, reducing the production cost and becoming a way for waste valorization.
Examples of biopesticides are: Bacillus thuringiensis that is a bacteriathat produces an endotoxin that affects the digestive tract of the larvae of some pest insects. Beauveria bassiana is an entomopathogenic fungus with lethal effects on numerous pests while Trichoderma harzianum has shown fungicidal effects. All three microorganisms are currently marketed as the basis of different biopesticide products.
The Composting Research Group (GICOM) works with Bacillus thuringiensis, Beauveria bassiana and Trichoderma harzianum using waste from various sources to produce both, a compound with a biopesticidal effect and/or a liquid extract with these properties. We are working with substrates such as agro-industrial waste (rice husk, waste fibers from vegetable drinks production derived from rice or soy, bagasse from beer production), as well as pruning waste and organic fraction of municipal waste from selective collection systems. The process was successfully carried out on a semi-pilot scale, in 22L reactors in the case of fungi and up to 290L in the case of bacteria.
In the context of improving sustainable agriculture, biostimulants play a promising role. Biostimulant is a product that stimulates plant growth, by improving the following characteristics: nutrient use efficiency, tolerance resistance to biotic and abiotic stress, and availability of confined nutrients in the soil or rhizosphere. A wide range of substances as well as microorganisms can be utilized as biostimulants. Among them, the fungus Trichoderma strains, have been predominantly used as biostimulants for their capacity to control the fungal phytopathogens and improving plant tolerance against abiotic stresses.