Temperature Shifts for Extraction and Purification of Zygomycetes Chitosan with Dilute Sulfuric Acid

• The temperature-dependent hydrolysis and solubility of chitosan in sulfuric acidsolutions offer the possibility for chitosan extraction from zygomycetes mycelia andseparation from other cellular ingredients with high purity and high recovery. In this study,Rhizomucor pusillus biomass was initially extracted with 0.5 M NaOH at 120 °C for20 min, leaving an alkali insoluble material (AIM) rich in chitosan. Then, the AIM wassubjected to two steps treatment with 72 mM sulfuric acid at (i) room temperature for10 min followed by (ii) 120 °C for 45 min. During the first step, phosphate of the AIM wasreleased into the acid solution and separated from the chitosan-rich residue bycentrifugation. In the second step, the residual AIM was re-suspended in fresh 72 mMsulfuric acid, heated at 120 °C and hot filtered, whereby chitosan was extracted andseparated from the hot alkali and acid insoluble material (HAAIM). The chitosan wasrecovered from the acid solution by precipitation at lowered temperature and raised pH to8-10. The treatment resulted in 0.34 g chitosan and 0.16 g HAAIM from each gram AIM.At the start, the AIM contained at least 17% phosphate, whereas after the purification, thecorresponding phosphate content of the obtained chitosan was just 1%. The purity of thischitosan was higher than 83%. The AIM subjected directly to the treatment with hotsulfuric acid (at 120 °C for 45 min) resulted in a chitosan with a phosphate impurity of 18.5%.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Industriell bioteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Industrial Biotechnology (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Kemiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Chemical Engineering (hsv//eng)

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

Rhizomucor pusillus

sulfuric acid

fungal chitosan

phosphate release

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