Konjak

Mannans have been found in some kinds of plants such as endosperms of copra and ivory palm nuts, guar beans, locust beans, coffee beans and roots of konjak Amorphophallus konjac). Most of these saccharides are used only in the food and feed processing industries. Recently, it has been reported that manno-oligosaccharides are useful as one of the best growth factors for Bifidobacterium sp. and Lactobacillus... 

Bacillus sp. AM-001 was cultivated aerobically under various conditions, and activities of P-mannanase in the culture broth and P-mannosidase extracted from the cells treated with 0.1% Triton X-100 were monitored. Both enzymes were formed when the bacterium was grown under alkaline conditions in the presence of optimal concentrations of 0.5% Na2C03 or 0.5-1.0% NaHCOa. Various carbohydrates were also tested and the best carbohydrate for enzyme production was konjak powder (1%... 

Alkaliphilic Bacillus sp. AM-001 was aerobically grown to the early stationary phase at 37°C in alkaline medium (pH 9.0) containing 1% konjak mannan. Total chromosomal DNA obtained by the method of Saito and Miura( 14) was digested with Hindlll restriction enzyme. And 2 to 4 kbp DNA fraction of chromosomal DNA was collected by 1% agarose gel electrophoresis. The plasmid pUC19 was digested with Hindlll and then dephosphorylated with bacterial alkaline phosphatase. After the... 

E, co/i JMlOl (pMAH3) was grown aerobically in LB broth for 24 h at 37°C. The P-mannanase activity was located mainly in the periplasmic (53%) and intracellular (43%) fractions. No induction of the enzyme could be detected in the presence or absence of mannan, such as konjak, locust bean and copra, in the growth medium. 

E. B. Larson), and the glucomannans of wheat-stem rust urediospores (with N. Prentice and L. S. Cuendet) and Konjak flour (with H. S. Srivastava). 

The only commercially important glucomannan is konjak gum also known as konjak mannan. Konjak flour is obtained from the starchy tubers of the plant Amorphophallus konjac (Araceae), grown in subtropical to tropical eastern Asia (Japan, China and Indonesia). 

The basic structure of konjak gum polysaccharides is represented by formula 4-144. The dominating sequences are composed of one, two and five molecules of mannose and one and two molecules of glucose. The ratio of mannose and glucose is around 1.6 and the acetyl groups content is about 15%. The average molecular weight is high, around 6000 kDa. 

Konjak mannan dissolves in water to give highly viscous dispersions, which are pseudoplastic systems. Heating with a small... 

The association of chains and the formation of locust gum gel and the formation of a mixed gel of locust gum with xanthan gum, where the molecules form double helical structures, is shown schematically in Figure 7.27. Like locust gum galactomannan, glucomannan of xanthan gum also forms gels with glucomannan of konjak gum. 

A number of polysaccharides which yield D-glucose and D-mannose on hydrolysis have been described. The flour extracted from the conns of Amorphophattus konjak, which is used as a food in the Far East, contains a glucomannoglycan(2 3), konjakmannan. The molecule has a (i - -4)-linked main chain, with branches linked (i - 3), and has lo-ii residues per terminal unit. Glucomannoglycans have been found in other AmorphophdUus species, and in the seeds of some Iris species. 

Mannans of legume seeds (guar, carob galacto-mannans, konjak mannans) are constituents of native food in India, Japan and Pakistan. - Guar gum or - locust bean gum are widely used as stabilizers... 

---