Process for continuously preparing bacterial cellulose

Details Process for continuously preparing bacterial cellulose Process for continuously preparing bacterial cellulose

1998-02-26

2000-10-17

Prats, Francisco

Chemistry: molecular biology and microbiology

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

Preparing compound containing saccharide radical

435 72, 536 56, 536126, 53612312, C12P 1904, C12P 1900, C08B 1500

Patent

active

061329983

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to a process for the production of cellulosic material (bacterial cellulose: "BC") at a high rate, which comprises using microorganisms capable of producing BC (cellulose-producing bacteria) while maintaining the concentration of the residual sugars in a culture broth at a specific level or less.


BACKGROUND ART

Since BC is edible, it is utilized in the food industry. BC's high dispersibility in water further provides it with a lot of industrial applications, 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 as an emulsion stabilizer.
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.
Owing to such structural and physical features of microfibrils, a homogenized BC has plenty of industrial applications 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 owing 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 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 cultivation 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 Laid-Open 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, there have been proposed a method for cultivating the cellulose-producing bacteria under a specific range of oxygen-transfer coefficient (K.sub.L a) (Japanese Patent Application Hei 7(1995)-31787), a method for cultivating the cellulose-producing bacteria while maintaining the concentration of carbon sources in a culture broth at a specific level or more (Japanese Patent Application Hei 7(1995)-267407) and a method for cultivating the cellulose-producing bacteria while maintaining the internal pressure within a fermentation tank at a specific level or more at a certain stage during the cultivation (Japanese Patent Application Hei 7(1995)-76408).
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.
An economical and high-yielding method for the production of bacterial cellulose is described in Japanese Patent Laid-Open Application Hei 8(1996)-33495, wherein the concentration of the bacterial cellulose in a culture medium is kept at a specif

REFERENCES:
Matsuoka et al, Biosci. Biotech. Biochem. 60(4): 575-579 (1996).
Toyosaki et al, J. Gen. Appl. Microbiol. 41:307-314 (1995).

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