Proceedings e report - Firenze University Press

DEGRADATION OF MELANIN AND BIOCIDES BY LIGNINOLYTIC FUNGI
able to oxidise the majority of the available HBT (inhibitive competition of reduced forms of HBT
was prevented), and the oxidation of melanin was more successful than in any of the other
combinations of reagents. A thorough visual inspection of treated melaninised paper samples did not
reveal any significant damage to the integrity of paper that might have happened as a consequence of
the treatment, regardless of the procedure employed.
dL (%)
10
8
6
4
2
0
Melaninised paper samples treated with
different reagents
buffer buffer +
5mM HBT
buffer +
laccase
132
buffer +
laccase +
1mM HBT
Reaction solutions
buffer +
laccase +
5mM HBT
Fig. 1: Treatment of melaninised paper samples with different reaction solutions at elevated air pressure (dL – a
change of lightness; error bars indicate standard deviation of ten parallel samples)
Fungal growth rates in the presence of biocides
The fungal growth in the presence of biocides was compared to the control media. Lindane showed no
statistically significant adverse effect on the fungal growth and in the case of P. ostreatus also
promoted its growth in comparison to the controls. The same was with PCB, which promoted the
growth not only of P. ostreatus but also of T. versicolor. PCP is reflected as typical fungicide in lower
obtained fungal dry masses. They are about 50 % lower in all the tested fungi with an exception of T.
versicolor, where obtained dry mass yields was surprisingly comparable to the controls (Fig. 2).
Dry mass weight [g]
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
control
lindane
PCB-153
NaPCP
H. fragiforme G. trabeum P. ostreatus T. versicolor
Fungus
Fig. 2: Dry mass yields of fungal species grown in liquid medium with 30 µM final concentrations of lindane,
PCB or PCP, and in control medium without biocide
3.2. Biodegradation of biocides
Among selected white-rot fungi, P. ostreatus showed the highest efficiency in degrading lindane and
PCB. Other two white rot fungus C. purpureum and H. fragiforme, and a brown rot G. trabeum were
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00