P. smilacis, produced increases in tensile, tear and/or burst indices.Hormonema
sp. again showed the best results and was the only fungus which enhances the three
properties compared to control:indices.N. australepresented good outcomes in
relation to delignification yield, also increased tensile and burst indices. Other
authors have found similar results: 8% increase in tensile and 12% in burst indices
and an 8% decrease in tear index after pre-treated black pine withC. subvermis-
pora, (Gulsoy and Eroglu 2011 ). Mechanical properties as tensile and burst indices
are associated with bond ability amidfibers, whereas tear index is correlated with
the degradation offibers. Those pre-treated pulps that present less lignin content can
present a greater bonding amid cellulose-to-cellulose that could improve the
strength in the handsheets (Ismail et al. 2005 ).
12.4.3 Effect of Fungal Pre-treatments on Mechanical
Pulping
Fungal pre-treated chips with the endophytes and the saprophytic fungi were sub-
jected to mechanical pulping (Fig.12.5) (Martín-Sampedro et al.2015a). After
mechanical pulping of pre-treated chips, the pulps presented higher refining degree
compare to an untreated pulp (48° SR), especially the one pre-treated with
Hormonemasp. (69° SR). Gulsoy and Eroglu ( 2011 ) reported easierfibrillation in
pine pulp pre-treated withC. subvermisporathan control pulp; this enhancement was
related to a higher production by fungus. As well, time reductions in refining to obtain
a givenfibrillation degree was observed inEucalyptus tereticornispulp pre-treated
withC. subvermispora(Bajpai et al. 2001 ) and hornbeam withP. chrysosporium
(Kasmani et al. 2012 ). The easier beating of fungal pre-treated pulps to obtain target
wetness imply less energy consumption (Gulsoy and Eroglu 2011 ).
A reduction in kappa number of 8 points and 1.4% in Klason lignin was found
when chips were pre-treated withHormonemasp. This endophyte can modify
lignin and also, remove it from the wood. Other authors have also observed kappa
number reductions in pulps pre-treated with fungi and subjected to
chemo-mechanical pulping (Singh et al. 2013 ).
Enhanced mechanical properties were found in all fungal pre-treated pulps,
except forUlocladiumsp. According to Ferraz et al. ( 2008 ), fungal pre-treatment
produces a double effect, a deep short period depolymerization of lignin and also an
increase of the water saturation point due to the oxalate esterification on the
polysaccharides chains mediated by the fungus. Both changes could influence the
fiber bonding, and then, the physical properties of the wood and the pulp obtained
after mechanical pulping. Handsheets obtained from pulp pre-treated with
Hormonemasp. provided the highest tensile and burst indices increases of 28% in
tensile, 16% in tear, and 44% in burst indices, compared with an untreated sample.
whereas when using the reference fungusTrametessp. I-62 increments of 23, 17,
and 12% were obtained, for the same properties. Ramos et al. ( 2001 ) and Singh
12 Potential of Lignin-Degrading Endophytic Fungi... 275