Friday, November 18, 2016

Bacteria Its Role In Formation Nata
Acetobacter xylinum bacteria are bacteria that play an active role in changing the fermentation into nata. This bacterium is the acetic acid bacteria. Systematics are as follows:

Division: Prothophyta
Class: Schizomycetes
Order: Pseudomonodales
Family: Pseudomonadaceae
Genus: Acetobacter
Species: Acetobacter xylinum
Nata-forming bacteria when grown in a medium containing sugar, can turn sugar into cellulose. Cellulose is formed in the medium in the form of yarns together with slimy polysaccharide to form a braid like textiles. In liquid medium, these bacteria form a solid mass and can reach a thickness of several centimeters. The bacteria itself caught up in the mass of fibrillar formed.

Synthesis of polysaccharides by these bacteria, is strongly influenced by the availability of nutrients and certain metal ions can catalyze or stimulate the activity of the bacteria. Increasing the concentration of nitrogen in substat can increase the amount of polysaccharides which are formed, while the bivalent ions such as Mg2 +, Ca2 + and other very necessary to control the extracellular enzymes work and form a bond with the polysaccharide.

Activation nata formation only occurs at pH 3.5 to 7.5 Klarisa. glacial acetic acid is added to the medium to lower medium pH optimum is 4.0. while the optimum temperature is at room temperature between 28-320 C.

Bacteria formation of nata belonged Acetobacter which has characteristics include Gram negative for the culture of the young and Gram positive cultures are old, obligate aerobic, in the acidic medium to form the stem, whereas in alkaline medium, oval, and do not form spores, unable to melt the gelatin, do not produce H2S, does not reduce nitrate and "thermal death point" at a temperature of 65-70 0 C.

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