Fungal Glucosamine: Production, Purification, and Characterization

A novel method was developed for production, recovery, and purification of fungal glucosamine. Fungal glucosamine is a good candidate for replacement of glucosamine obtained from shellfish wastes. Mycelium of the Rhizopusoryzae was treated with hot sodium hydroxide solution to obtain the fungal cell wall skeleton. Phosphates were removed from the cell wall by cold dilute sulfuric acid treatment. Phosphate free cell wall, containing mainly chitin and chitosan, was hydrolyzed by hydrochloric acid to produce glucosamine. The dissolved glucosamine was recovered from acid solution through a cold filtration step followed by an acid evaporation. The crude glucosamine was purified through dissolution in distilled water, decolorization, and evaporation stages. The obtained glucosamine crystals demonstrated high purity according to FTIR and DTA analyses. The yield of glucosamine was also optimized changing the acid concentration, reaction temperature, and time. Acid concentration, as well as the acid concentration-temperature and temperature-time interactions exhibited the most significant effects on glucosamine yield. The optimal temperature, time, and acid concentration giving the highest product yield were70 °C, 3.5 h, and 12 M (or 110 °C , 6h, and 6M), respectively. At these conditions 0.52g pure glucosamine was obtained from each gram of the fungal cell wall. This corresponds to 90.7% of theoretical yield which could be obtained by hydrolysis of the chitin and chitosan present in the cell wall of R. oryzae.