title: A sulfuric-lactic acid process for efficient purification of fungal chitosan with intact molecular weight.
abstract: The most recent method of fungal chitosan purification, i.e., two steps of dilute sulfuric acid treatment, pretreatment of cell wall at room temperature for phosphate removal and extraction of chitosan from the phosphate free cell wall at high temperature, significantly reduces the chitosan molecular weight. This study was aimed at improvement of this method. In the pretreatment step, to choose the best conditions, cell wall of Rhizopus oryzae, containing 9% phosphate, 10% glucosamine, and 21% N-acetyl glucosamine, was treated with sulfuric, lactic, acetic, nitric, or hydrochloric acid, at room temperature. Sulfuric acid showed the best performance in phosphate removal (90%) and cell wall recovery (89%). To avoid depolymerisation of chitosan, hot sulfuric acid extraction was replaced with lactic acid treatment at room temperature, and a pure fungal chitosan was obtained (0.12 g/g cell wall). Similar pretreatment and extraction processes were conducted on pure shrimp chitosan and resulted in a chitosan recovery of higher than 87% while the reduction of chitosan viscosity was less than 15%. Therefore, the sulfuric-lactic acid method purified the fungal chitosan without significant molecular weight manipulation.
authors.affiliation: Department of Chemical Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran.
authors.forename: Mitra
authors.initials: M
authors.lastname: Naghdi
authors.affiliation: Department of Chemical Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran; Industrial Biotechnology Group, Institute for Biotechnology and Bioengineering, Isfahan University of Technology, Isfahan 84156-83111, Iran. Electronic address: Zamani.Akram@cc.iut.ac.ir.
authors.forename: Akram
authors.initials: A
authors.lastname: Zamani
authors.affiliation: Department of Chemical Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran; Industrial Biotechnology Group, Institute for Biotechnology and Bioengineering, Isfahan University of Technology, Isfahan 84156-83111, Iran.
authors.forename: Keikhosro
authors.initials: K
authors.lastname: Karimi
mesh_terms: D002473:Cell Wall / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry / Q000302:isolation & purification*; D005944:Glucosamine / Q000737:chemistry; D019344:Lactic Acid / Q000737:chemistry; D012233:Rhizopus / Q000737:chemistry*; D013464:Sulfuric Acids / Q000737:chemistry
chemical_list: D013464:Sulfuric Acids; D019344:Lactic Acid; D048271:Chitosan; D005944:Glucosamine
keywords: Alkali-insoluble material (AIM); Fungal cell wall; Fungal chitosan; Lactic acid; Rhizopus oryzae; Sulfuric acid