Process for the production of bacterial cellulose

Details Process for the production of bacterial cellulose Process for the production of bacterial cellulose

1997-08-07

2000-01-25

Lankford, Jr., Leon B.

Chemistry: molecular biology and microbiology

Micro-organism, tissue cell culture or enzyme using process...

Preparing compound containing saccharide radical

4352521, 435822, 435823, 536 56, C12P 1904, C12N 120, C08B 100

Patent

active

060177403

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to a process for the production of cellulosic material (bacterial cellulose: "BC"), which comprises using microorganisms capable of producing the BC (cellulose-producing bacteria) while maintaining the internal pressure within a fermentation tank at a certain level or above, or maintaining CO.sub.2 pressure in a gas phase at a certain level or less.


BACKGROUND ART

Since the BC is edible, it is utilized in the food industry. The BC's high dispersibility in water further provides it with a lot of industrial utility value, such as to maintain viscosity 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 BC 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.
Due to such structural and physical features of microfibrils, a homogenized BC has plenty of industrial utility as a strengthening agent for polymers, especially hydrophilic polymers. Products prepared by solidification of the homogenized BC in the form of a lump or paper show a high elastic modulus in tension due to the above feature, and are therefore expected to have excellent mechanical properties for use in various kinds of industrial materials.
Methods for the production of the BC are described in, for example, Japanese Patent Laid-Open Application Sho 62(1987)-265990, Japanese Patent Laid-Open Application Sho 63(1988)-202394 and Japanese Patent Publication Hei 6(1994)-43443.
As a nutrient medium suitable for the culture of the cellulose-producing bacteria, Schramm/Hestrin medium is known, which contains carbon source, peptone, yeast extract, sodium phosphate and citric acid (Schramm et al., J. General Biology, 11, pp.123-129, 1954). Further, it has been found that the productivity of the BC is increased by the addition of an accelerator for the cellulose production such as inositol, phytic acid and pyrroloquinoline quinone (PQQ) (Japanese Patent Publication Hei 5(1993)-1718; Mitsuo TAKAI, Japan TAPPI Journal, Vol.42, No.3, pp.237-244), carboxylic acid or their salts (Japanese Patent Application Hei 5(1993)-191467; Japanese Patent Laid-Open Application Hei 7(1995)-39386), invertase (Japanese Patent Application Hei 5(1993)-331491; Japanese Patent Laid-Open Application Hei 7(1995)-184677) and methionine (Japanese Patent Application Hei 5(1993)-335764; Japanese Patent Laid-Open Application Hei 7(1995)-184675) into such a nutrient medium. Furthermore, a method for cultivating the cellulose producing bacteria under the specific range of oxygen-transfer coefficient (K.sub.L a) condition has been proposed (Japanese Patent Application Hei 7(1995)-31787).
The bacteria may be generally cultured in any known culture conditions such as static culture, shaken culture, and aerated and agitated culture, and in any known culture operation methods such as batch fermentation, fed batch fermentation, repeated batch fermentation and continuous fermentation.
Means for agitation include impellers (agitating blades), air-lift fermenters, pump-driven recirculation of the fermenter broth and any combination of these means.
The impellers include gate-shape impellers, turbine impellers, double helical ribbon impellers and screw impellers.
The productivity in the culture of bacteria has been generally improved by the increment of the inner pressure within the fermentation tank, followed by the increment of an oxygen-supply into a culture medium.
The above advantage may be contributed to the increment of a partial pressure of O.sub.2 in the gas phase (air bubbles), which will cause the increment of oxygen-transfer according to the following formula: state with the partial pressure of oxygen in the air bubbles;
However, the effect of the internal pressure within the fermentation tank on the BC production has not yet been clarified.
In the prior BC production methods, accumulation

REFERENCES:
patent: 4863565 (1989-09-01), Johnson et al.
patent: 5079162 (1992-01-01), Ben-Bassat et al.
Watanabe et al. Biosci. Biotech. Biochem. vol. 59(1), pp. 65-68, 1995.
Toyosaki et al. Biosci. Biotech. Biochem. vol. 59(8), pp. 1498-1502, 1995.
Kouda et al. J. Ferm. Bioeng. vol. 84(2), pp. 124-127, 1997.

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