Figure 2.5
 
Increase
FHK
Lactate
Fructose
F6P
PGI
G6PD s
inhibition
Pentose
phosphate
pathway
pyruvate
LDH
Ethanol
G6P
acetaldehyde
ADH
PGM
acetate
ALDH
G1P
UGP
acetyl­CoA
UDPG
Cellulose
synthase
BC
ATP
increase
TCA
cycle
Activation
CO 2 + H 2 O
27
Effect of Cultivation on BNC Biomaterials
Figure 2.5
Effect. of. ethanol. on. bacterial. cellulose. production. in. continuous. culture. from. fructose..
Adapted.from.Naritomi.et.al..(1998).
components.of.the.growth.medium.will.increase.the.BNC.production.rate.
and. yield. and. are. often. used. by. the. bacteria. as. energy. sources,. not. as. a.
substrate.for.BNC.production..Compounds.that.increase.the.production.of.
water-soluble.extracellular.polysaccharides.will.probably.affect.the.cellulose.
network,.since.the.assembly.of.the.cellulose.chains.is.affected.by.the.interference.of.water-soluble.extracellular.polysaccharides..Other.compounds.in.
the.growth.media.can.have.an.effect.on.the.enzymes.that.are.involved.in.the.
pathway.where.BNC.is.produced..The.presence.of.a.rapidly.utilized.. carbon.
source. in. the. growth. media. can. lead. to. higher. adenosine-5′-triphosphate.
(ATP).production,.and.ATP.has.an.inhibitory.effect.on.the.enzyme.glucose6-phosphate.dehydrogenase.(Figure 2.5).
Lactate
The.addition.of.lactate.to.the.growth.media.increases.the.cellulose.production.in.G. xylinus.since.it.is.linked.to.the.respiratory.chain..Lactate.generates.
energy.and.does.not.act.as.an.extra.substrate.for.cellulose.production..This.
extra.energy.source.provided.by.lactate.increases.the.concentration.of.. bacteria.
(i.e.,.biomass).during.the.early.stages.of.cultivation,.resulting.in.increased.BNC.
production..Adding.more.lactate.to.the.growth.media.will.result.in.an.increase.
in.ATP.production..A.correlation.between.a.high.ATP.level.and.a.high.specific.