Identification of xanthans isolated from sugarcane juices obtained from scalded plants infected by Xanthomonas albilineans.

The exudate gum produced by Xanthomonas albilineans, a specific sugarcane pathogen, has been isolated from juices of diseased sugarcane stalks, hydrolyzed with hydrochloric acid, and the hydrolysate analyzed by capillary electrophoresis. Sucrose. cellobiose, mannose, glucose, glucose-1-P and glucuronic acid were identified as the major components of the polysaccharide isolated from diseased stalks. Juices from healthy stalks contained maltose instead of cellobiose. The chemical nature of this polysaccharide is discussed.

Changes in free and conjugated polyamines during starvation of sugarcane juices as analyzed by high-performance liquid chromatography.

Changes of the polyamines (PAs) titer in high- and mid-molecular-mass carbohydrates (HMMCs and MMMCs, respectively) obtained from sugarcane juices stored for 72 h at pH 5.2 or clarified at pH 8.0 have been studied. Cadaverine (CAD) is the most abundant free (S) PA in the MMMC fraction from juices at pH 5.2, whereas putrescine (PUT) was revealed as the main PA at pH 8.0. A slight increase in the free PUT titer can be noted at pH 5.2 for 72 h of juice starvation. PAs from MMMC were mainly conjugated to acid-insoluble (PH) molecules. Accumulation of PH-PAs with the time of starvation was especially significant for PUT and CAD. However, CAD has also been detected in the acid-soluble (SH) fraction and its concentration increases with the time of starvation at pH 5.2. The accumulation pattern of free and conjugated PAs from HMMCs is similar to that found for MMMCs although some differences can be observed. For instance, the increase in free PUT with the time at pH 8.0 was 2.7-times higher in the HMMC fraction than in the MMMC fraction. Conjugated PAs associated to acid-soluble macromolecules (SH fraction) achieved a level in HMMC fractions higher than that observed in the MMMC fraction. Moreover, the reported increase with time that was observed in PH-CAD from the MMMC fraction was not observed in the HMMC fraction, and, finally, the increase in PH-PUT with the time was lower for the HMMC fraction than for the MMMC fraction.

Purification and Partial Characterization of a Fructanase which Hydrolyzes Natural Polysaccharides from Sugarcane Juice.

A new sugarcane (Saccharum officinarum L.) fructanase which hydrolyzes both high molecular weight polysaccharides mid R:Fructose(4):Galactitol(5)mid R:(n) (SP) and moderate-sized carbohydrates mid R:Fructose(2):Galactitol(3)3mid R:(n) (MMWC) has been purified from sugarcane juice. The K(m) value has been estimated to be 33.7 micrograms per milliliter and 20 micrograms per milliliter for SP and MMWC, respectively. The optimal pH and temperature values are 6.0 and 30 degrees C, respectively. Purified protein has a pl value of 6.35 and a molecular weight of 13.2 kilodaltons. Fructanase activity appears to be Mn(2+)-dependent.