Figure 2.9
1.2
1
0.8
0.6
0.4
% Cellulose
0.2
0
Effect of Initial pH on Cellulose Content (%)
pH 4.6
pH 5.5
pH of Culture Medium
36
Bacterial Cellulose
Figure 2.9
Cellulose. content. (%). in. BNC. tubes. cultured. at. pH. 4.6. and. 5.5.. Data. are. presented. as. the.
. average ± standard.deviation..Four.replicates.in.each.group.
Cellulose Content
The.initial.pH.of.the.culture.medium.affects.the.cellulose.content.in.the.BNC.
tubes..The.cellulose.content.was.calculated.by.dividing.the.dry.weight.of.the.
BNC.tube.by.the.wet.weight.of.the.BNC.tube:
.Cellulose.content.(%).=.(dry.weight.BNC.tube/wet.weight.BNC.tube).×.100.
We.investigated.the.effect.of.the.initial.pH.of.the.growth.media.and.found.
that.the.cellulose.content.increases.during.the.cultivation.period.for.both.pH.
4.6.and.pH.5.5..At.day.7,.when.the.tubes.were.harvested,.the.highest.cellulose.
content.was.shown.to.be.in.the.BNC.tubes.cultured.at.pH.5.5.(see.Figure 2.9).
influence of Oxygen Availability on Tube Formation
Oxygen.availability.in.the.medium.during.culture.in.a.tube.bioreactor.can.
be.measured.using.an.oxygen.probe..This.bioreactor.is.identical.to.the.tube.
bioreactor.with.the.exception.of.a.side.tube.that.allows.for.insertion.of.an.
oxygen. probe.. A. needle. oxygen. probe. and. a. Microx. TX3. microfiber. optic.
oxygen.transmitter.were.used.for.the.measurements..Oxygen.measurements.
showed.that.oxygen.passes.through.the.silicon.tubing.and.the.level.increases.
in.the.medium,.but.it.drops.rapidly.to.a.few.percent.due.to.the.consumption.
of. oxygen. by. the. bacteria. (see. Figure 2.10).. The. decrease. was. surprisingly.
fast.(within.10.hours)..During.this.time.the.number.of.bacteria.increases,.but.
no.cellulose.layer.is.yet.visible..The.oxygen.level.then.remains.around.2%.
for.the.rest.of.the.culture.time,.which.is.usually.7.days..The.cellulose.tube.is.
visible.after.1.day.and.continues.to.be.formed.until.day.4,.where.no.further.
increase.in.thickness.can.be.observed.
1.2
1
0.8
0.6
0.4
% Cellulose
0.2
0
Effect of Initial pH on Cellulose Content (%)
pH 4.6
pH 5.5
pH of Culture Medium
36
Bacterial Cellulose
Figure 2.9
Cellulose. content. (%). in. BNC. tubes. cultured. at. pH. 4.6. and. 5.5.. Data. are. presented. as. the.
. average ± standard.deviation..Four.replicates.in.each.group.
Cellulose Content
The.initial.pH.of.the.culture.medium.affects.the.cellulose.content.in.the.BNC.
tubes..The.cellulose.content.was.calculated.by.dividing.the.dry.weight.of.the.
BNC.tube.by.the.wet.weight.of.the.BNC.tube:
.Cellulose.content.(%).=.(dry.weight.BNC.tube/wet.weight.BNC.tube).×.100.
We.investigated.the.effect.of.the.initial.pH.of.the.growth.media.and.found.
that.the.cellulose.content.increases.during.the.cultivation.period.for.both.pH.
4.6.and.pH.5.5..At.day.7,.when.the.tubes.were.harvested,.the.highest.cellulose.
content.was.shown.to.be.in.the.BNC.tubes.cultured.at.pH.5.5.(see.Figure 2.9).
influence of Oxygen Availability on Tube Formation
Oxygen.availability.in.the.medium.during.culture.in.a.tube.bioreactor.can.
be.measured.using.an.oxygen.probe..This.bioreactor.is.identical.to.the.tube.
bioreactor.with.the.exception.of.a.side.tube.that.allows.for.insertion.of.an.
oxygen. probe.. A. needle. oxygen. probe. and. a. Microx. TX3. microfiber. optic.
oxygen.transmitter.were.used.for.the.measurements..Oxygen.measurements.
showed.that.oxygen.passes.through.the.silicon.tubing.and.the.level.increases.
in.the.medium,.but.it.drops.rapidly.to.a.few.percent.due.to.the.consumption.
of. oxygen. by. the. bacteria. (see. Figure 2.10).. The. decrease. was. surprisingly.
fast.(within.10.hours)..During.this.time.the.number.of.bacteria.increases,.but.
no.cellulose.layer.is.yet.visible..The.oxygen.level.then.remains.around.2%.
for.the.rest.of.the.culture.time,.which.is.usually.7.days..The.cellulose.tube.is.
visible.after.1.day.and.continues.to.be.formed.until.day.4,.where.no.further.
increase.in.thickness.can.be.observed.