Cellulose pellicle production and L-galactosidase
activity
The di¡erence in the pellicle thickness for both strains,
ITz3 and ITDI 2.1, is shown in Table 1. The amount of
cellulose produced by strain ITz3 was approximately 28-
fold higher in PYSL compared to ITDI 2.1. This means
that the mutant strain synthesises cellulose roughly 90
times more than the wild-type in lactose-based medium.
In the routinely used PYSS medium, the di¡erence in cellulose
production between the two strains was 40% in 2%
sucrose and none in 4% sucrose. In whey substrate, the
mutant strain maintained its ability to produce the same
amount of cellulose as in PYSL. This result implies that
the cellulose-synthesising genes and enzymes, as well as
other metabolic and replication machinery of the organism,
were not noticeably a¡ected by the insertion. Further,
the insertion of the lacZ gene enabled the modi¢ed strain
to produce signi¢cantly higher amounts of cellulose with
lactose as a source of carbon. This was the major factor,
which predisposes the mutant strain’s ability to grow and
produce cellulose with lactose as the carbon source. At
this point, it should be emphasised that the ability of the
modi¢ed strain, ITz3, to grow in lactose with the corre