A new green technology for direct production of low molecular weight chitosan

Low molecular weight chitosan (LMW-chitosan) in the molecular range 5–10 kDa was firstly prepared directly from the Absidia coerulea mycelia. To improve the LMW-chitosan production, the solid-state fermentation media were optimized to investigate the influence of substrate and supplemental medium components on LMW-chitosan production. The LMW-chitosan was obtained after treatments with 2% NaOH and 10% acetic acid. Maximal LMW-chitosan production was 6.12 g/kg substrate. Gel permeation chromatography combined with laser light scattering gave a Mw of 6.4 kDa with Mw/Mn of 1.09. FT-IR, X-ray diffraction and 13 C NMR spectra of the product showed typical peak distributions the same as those of standard chitosan which confirmed the extracted product to be chitosan-like. The method provided a new, simple and green technology to produce LMW-chitosan directly.