(Peer Review) Structural Characteristics of Chitin and Chitosan Isolated from the Biomass of Cultivated Rotifer, Brachionus rotundiformis.

We characterized the molecular structure of chitin and chitosan isolated from the biomass of cultivated rotifer (B. rotundiformis). Chitin and chitosan are potential biomaterials for biotechnological industries due to their structural and functional characteristics. Zooplankton seems to be a better source of chitin, associated with the very low degree of calcification and sclerotization of the cuticles. Cultivation of local strain rotifer from North Sulawesi waters has been successfully conducted in a very simple medium with raw fish input without aeration in fiber tanks. This mass production technology has enabled to harvest 45-48 million individuals with estimated 5 to 48 g rotifer biomass in each production cycle. From this rotifer biomass, 4.6% chitin was extracted and 52.7% chitosan could be derived by deacetylation of chitin. Structural characteristics of the rotifer chitin and chitosan were discussed on the basis of the X-ray and infrared analysis data. X-ray analysis was done using X-Ray Defraction (XRD) with CuK radiation at a voltage of 40 kV and 30 m A. X-ray diffraction diagram of chitin indicated the molecular form at three strongest peaks, 8.1, 9.2 and 19 2θ, differed from that of chitosan at peaks, 9.6, 19.5 and 21.1. Christalinity of chitosan (47.06%), was higher than that of chitin (33.94%). Molecular structure of chitin, C18H26N2O10, where the hydroxyl group on the second carbon replaced by acetyl amide, was shown by the infrared spectra. In the infrared spectra, the rotifer chitin indicated the amide II band at 1558.48 cm, a typical one for marine chitin. A marked difference was observed for the amide I bands, at 1651.07 cm. Chitosan showed no amide band, but hydroxyl and amino bands at the ranged spectra up to 3500 cm. The yields of chitin isolated from rotifer biomass and its deacetylated products (chitosan) were relatively small and as a polymer of N-acetyl D-glucosamine, both molecules showed difference in specific functional groups. Chitin is composed of 2-acetamido-2-deoxy-D-glucose, while chitosan composed primarily of glucosamine, 2-amino-2-deoxy-D-glucose. Some treatments are necessary to confirm the molecular conformation and deacetylation behavior. Chitosan could be more accessible for structural modifications to develop biocompatible materials for pharmaceutical purposes.