(594s) Bioconversion of Coffee Pulp by the Lignoculous Fungus Alternaria Alternata

1) Department of Chemical Engineering, University of Puerto Rico, Mayagüez Campus

2) Department of Civil and Environmental Engineering, University of Puerto Rico, Mayagüez Campus

E-mails: maria.sierra@upr.edu, monica.medina@upr.edu, erick.zorrilla@upr.edu, patricia.ortiz3@upr.edu

Efforts devoted to the efficient use of agro-industrial residues have increased, especially if their re-utilization contributes to the reduction of pollution problems associated with industrial processing. Coffee pulp is the main byproduct generated during the wet processing of coffee. To reduce the pollution from this process it is necessary to establish new treatments to bio-transform these wastes, which contain various toxic substances (e.g. caffeine and lignin). The presence of these substances limits their recycling potential and makes their management an environmental challenge. This study focuses on the identification and characterization of fungal strains that might be able to detoxify coffee processing wastes. Among the activities we screened for are decaffeination and delignification. We have identified Alternaria alternata as a potential candidate to degrade caffeine. This isolate was obtained from a ligniculous fungi collection provided by the Forest Products Laboratory in Madison, Wisconsin. A. alternata was evaluated in terms of caffeine degradation as carbon and nitrogen source. Under these conditions we observed a decrease in the caffeine content of 45.33% in a purified culture system. After addition of sucrose the caffeine concentration was reduced to 60.92%, in the same period of time (69 days). Analysis of solid-state fermentations of coffee pulp using Alternaria alternata demonstrated a significant removal of caffeine in 20 days, obtaining a 44.5% caffeine reduction. Analyses of dry weights of fermented coffee pulp coupled to ergosterol determinations confirmed fungal growth on the coffee pulp. In addition these analyses suggested that the fungus might be degrading the coffee pulp as well. This is the first report of the detoxification potential of A. alternata with respect to coffee-processing waste.