Flocculant and chemical properties of a polysaccharide from Pullularia pullulans.
An extracellular polysaccharide, PP-floc, was synthesized from glucose by Pullularia pullulans (or Aureobasidium pullulans) in a pilot plant batch fermentor containing 175 liters of culture medium. At 58 h of fermentation, the concentration of PP-floc was 1.03 g/100 ml, giving a 25.8% conversion of initial glucose to polysaccharide. The flocculant activity of the culture medium increased during the fermentation process and reached its maximum at 50 h of culture age. Less PP-floc (0.33 lb/ton of slimes [approximately 149.7 g/0.907 t]) was required to give the same flocculant activity as a synthetic polymer of acrylamide, Separan NP-10 (0.5 lb/ton of slimes [approximately 226.8 g/0.907 t]), at all temperatures from 25 to 100 C. The degree of inactivation of PP-floc and Separan NP-10 at elevated temperatures was almost identical, and they were completely inactivated at about the same temperature (80 C). PP-floc also gave better compaction of slimes than Separan NP-10 at all temperatures tested. PP-floc was soluble in water and its specific optical rotation was [alpha](D) (25) + 194 degrees in water (c, 0.4). PP-floc contained 83.3% carbohydrate, 3.2% protein, and 8.1% water. Glucose was found to be the principal sugar monomer with traces (>5%) of galactose and mannose present. Structural studies on the fractions of purified polysaccharide by methylation and by periodate oxidation techniques prove that PP-floc is linear and composed of alpha-(1 --> 4) and alpha-(1 --> 6) glucopyranosyl units in the approximate ratio of 2:1. The action of pullulanase on crude PP-floc suggested the ordered arrangement of two consecutive alpha-(1 --> 4)-linked glucopyranosyl units flanked by alpha-(1 --> 6)-linked glucopyranose residues.
D002241:Carbohydrates / Q000032:analysis; D002854:Chromatography, Paper; D003470:Culture Media; D005285:Fermentation; D005427:Flocculation; D005656:Fungal Proteins / Q000032:analysis; D005690:Galactose / Q000032:analysis; D005947:Glucose / Q000032:analysis / Q000378:metabolism; D008358:Mannose / Q000032:analysis; D008745:Methylation; D003904:Mitosporic Fungi / Q000032:analysis* / Q000254:growth & development / Q000378:metabolism; D010504:Periodic Acid; D011134:Polysaccharides / Q000032:analysis* / Q000096:biosynthesis / Q000302:isolation & purification / Q000494:pharmacology; D013696:Temperature
D002241:Carbohydrates; D003470:Culture Media; D005656:Fungal Proteins; D011134:Polysaccharides; D010504:Periodic Acid; D005947:Glucose; D008358:Mannose; D005690:Galactose