Microbial cellulose, in the Philipp

Microbial cellulose, in the Philippines known as nata de
coca, is used in sweetened form as dessert, as an ingredient
in food products and cosmetics, and as an additive in the
manufacture of cloth, high grade papers, and membrane
materials (1, 2). It is produced at the surface of coconut
water and other suitable media by a gram-negative rod-
shaped bacterium, Acetobacter xylinum (3). The fermen-
tation is carried out in static cultures at 30°C in acidic
pH from 3.5 to 7.0. As the organism is obligate aerobic,
it is thought that cellulose is produced at the air/liquid
interface, where the cells can obtain oxygen (4). In static
cultures, substrates have to be transported entirely by
diffusion, and as carbon sources are generally available,
the oxygen supply isMicrobial cellulose, in the Philippines known as nata de
coca, is used in sweetened form as dessert, as an ingredient
in food products and cosmetics, and as an additive in the
manufacture of cloth, high grade papers, and membrane
materials (1, 2). It is produced at the surface of coconut
water and other suitable media by a gram-negative rod-
shaped bacterium, Acetobacter xylinum (3). The fermen-
tation is carried out in static cultures at 30°C in acidic
pH from 3.5 to 7.0. As the organism is obligate aerobic,
it is thought that cellulose is produced at the air/liquid
interface, where the cells can obtain oxygen (4). In static
cultures, substrates have to be transported entirely by
diffusion, and as carbon sources are generally available,
the oxygen supply is considered as the limiting factor for
growth and cellulose production. Moreover, diffusion
rates will be reduced gradually due to the formation of
cellulose at the surface. To date, there is no information
available concerning the oxygen concentration in the
medium or the changes in the local oxygen concentration
during fermentation. However, it is quite likely that sub-
stantial concentration profiles will develop. considered as the limiting factor for
growth and cellulose production. Moreover, diffusion
rates will be reduced gradually due to the formation of
cellulose at the surface. To date, there is no information
available concerning the oxygen concentration in the
medium or the changes in the local oxygen concentration
during fermentation. However, it is quite likely that sub-
stantial concentration profiles will develop.