Agave-based alcoholic beverage companies generate thousands of tons of solid residues per year in Mexico. These agave residues might be used for biofuel production due to their abundance and favorable sustainability characteristics. In this work, agave leaf and bagasse residues from species Agave tequilana and Agave salmiana were subjected to pretreatment using the ammonia fiber expansion (AFEX) process. The pretreatment conditions were optimized using a response surface design methodology. We also identified commercial enzyme mixtures that maximize sugar yields for AFEX-pretreated agave bagasse and leaf matter, at ~ 6% glucan (w/w) loading enzymatic hydrolysis. Finally, the pretreated agave hydrolysates (at a total solids loading of ~ 20%) were used for ethanol fermentation using the glucose- and xylose-consuming strain Saccharomyces cerevisiae 424A (LNH-ST), to determine ethanol yields at industrially relevant conditions. Low-severity AFEX pretreatment conditions are required (100–120 °C) to enable efficient enzymatic deconstruction of the agave cell wall. These studies showed that AFEX-pretreated A. tequilana bagasse, A. tequilana leaf fiber, and A. salmiana bagasse gave ~ 85% sugar conversion during enzyme hydrolysis and over 90% metabolic yields of ethanol during fermentation without any washing step or nutrient supplementation. On the other hand, although lignocellulosic A. salmiana leaf gave high sugar conversions, the hydrolysate could not be fermented at high solids loadings, apparently due to the presence of natural inhibitory compounds. These results show that AFEX-pretreated agave residues can be effectively hydrolyzed at high solids loading using an optimized commercial enzyme cocktail (at 25 mg protein/g glucan) producing > 85% sugar conversions and over 40 g/L bioethanol titers. These results show that AFEX technology has considerable potential to convert lignocellulosic agave residues to bio-based fuels and chemicals in a biorefinery.
Phytochemicals are substances produced mainly by plants, and these substances have biological activity. In the pharmaceutical industry, plants represent the main source to obtain various active ingredients. They exhibit pharmacological effects applicable to the treatment of bacterial and fungal infections and also chronic-degenerative diseases such as diabetes and cancer. However, the next step in science is to find new ways to obtain it. In this chapter, we discuss about the main groups of phytochemicals, in addition to presenting two case studies. One of the most important secondary metabolites is currently Taxol, which is a natural compound of the taxoid family and is also known for its antitumor activity against cancer located in breasts, lungs, and prostate and is also effective with Kaposi’s sarcoma. Our case studies will be about Taxol, extracted from an unexplored plant species, and the production of Taxol by its endophytic fungi.
25 November 2008 in World Journal of Microbiology and Biotechnology