The chitosan yield of zygomycetes at their optimum harvesting time

Fungi are a promising alternative source of chitosan. Fungi can be manipulated to give chitosan of more consistent and desired physico-chemical properties compared to chitosan obtained from crustacean sources. Chitosan was extracted from the mycelia of Rhizopus oryzae USDB 0602 at various phases of growth. The growth phase which produced the most extractable chitosan was determined to be the late exponential phase. In contrast to previous work on the screening of chitosan from fungal sources, mycelia of the fungi used in this study were harvested at their late exponential growth phase instead of at a fixed incubation time. The amount of extractable chitosan varied widely among the fungal strains. Gongronella butleri USDB 0201 was found to produce the highest amount of extractable chitosan per ml of substrate, followed by Cunninghamella echinulata and Gongronella butleri USDB 0428. However, in terms of yield of chitosan per unit mycelia mass, C. echinulata was the best strain among all fungi in the experiment. Therefore, besides G. butleri USDB 0201, C. echinulata can also be considered to be used in the commercial production of chitosan.