Cellulose-producing bacteria

#This invention relates to novel cellulose-producing bacteria including one producing cellulose having high degrees of polymerization, one producing a Bingham polysaccharide as a by-product, and one producing a small amount of water-soluble polysaccharide; a method for the production of cellulosic material (bacterial cellulose: "BC"), which comprises culturing these cellulose-producing bacteria; and bacterial cellulose thus obtained.

#Since the bacterial cellulose is edible as well as tasteless and odorless, it is utilized in the food industry. The homogenized bacterial cellulose's high dispersibility in water further provides it with many industrial applications, such as to maintain particle sizes of food, cosmetics or coating agents, to strengthen food materials, to maintain moisture, to improve stability of food, and to be used as low-calorie additives and an emulsion stabilizer.

#The bacterial cellulose is characterized by a sectional width of its fibrils which is smaller by two orders of magnitude than that of other kinds of cellulose such as those derived from wood pulp.

#FIG. 1 is a graph showing the stress curve of water-soluble polysaccharide produced by the cellulose-producing bacteria.

#FIG. 2 shows the distribution of the degree of polymerization of BC produced in the static culture.

#FIG. 3 shows the distribution of the degree of polymerization of BC produced in the flask culture.

#The present invention will be further illustrated according to the following examples.

#(1) NTG Treatment

#A Roux flask (750 ml volume) containing 100 ml of CSL-Fru medium was inoculated with BPR 2001 from glycerol stock, and incubated at 28.degree. C. for 3 days under static culture conditions. After the completion of the culture, the Roux flask was shaken vigorously to release the bacteria cells from the cellulose membrane. The culture was then sterilely filtered through a gauze to obtain a bacteria mixture as filtrate. The resulting bacteria mixture (2 ml) was inoculated into 20 ml of CSL-Fru medium in a flask (100 ml volume) containing 0.2% of cellulase (Meicelase P1; Meiji Seika Kaisha Ltd., Japan), and cultured at 28.degree. C. for 24 hours with shaking of 180 rpm. The culture (10 ml) was inoculated into 10 ml of CSL-Fru medium in a flask (100 ml volume) containing 0.2% of cellulase (Meicelase P1), and grown further for 3 hours under the same shaking conditions. The bacteria suspension was centrifuged at 5,000 rpm for 5 min. and the bacteria cells were washed with 50 mM acid buffer solution (pH 6.5). After the washing, the bacteria cells were resuspended into a phosphate buffer solution (20 ml). 4.5 ml of the resulting suspension was mixed with 0.5 ml of NTG solution (100 .mu.g/ml) and incubated at 30.degree. C. for 30 min. in an assist tube (20 ml volume) with shaking. As a control, a sterilized water (0.5 ml) was used instead of NTG solution. The bacteria cells were collected by centrifugation, and washed with CSL-Fru medium three times. After the washing, the bacteria cells were suspended into CSL-Fru medium (5 ml) containing 0.2% cellulase and cultured at 30.degree. C. for overnight with shaking in order to fix the mutation. 0.1 ml of the suspension was transferred onto a CSL-Fru plate for the measurement of the number of living cells. The same amount of 30% glycerol was added to the culture, and 1 ml of the resulting mixture was transferred into each vial tube for cryopreservation. The survival ratio under the above conditions was about 0.24%