plant surface microbiology.pdf

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Giang Huong Pham et al.
Fig. 18. Laccase activity in P. indica. The fungus was grown for 5 days on Aspergillus
medium, then a small hole (arrow) was cut into the agar at the border of the growing
mycelial mat. Three drops (30 ml) of ABTS were added. Green coloration appeared and
was monitored at different time intervals. The evolution of the coloration is given with
time, but the coloration was immediately obtained after a few seconds. Snowflake indicates
the fungal growth
Table 5. Cell wall degrading enzymes from P. indica
Compound Detection Possible enzymes Important for
the degradation of
ABTS + Laccase Lignin
Ferulic acid + Ferulase Lignin
Vanillin – Monoxygenase Lignin
Tannin – Phenoloxidase Phenols
Starch + Amylase Plant storage polysaccharides
Cellulose + Cellulase Cellulose
Gelatine + Protease Proteins
Pectin + Pectinase Pectin
Lipid + Lipase Fat
Xylan + Xylanase Hemicellulose
Chitin + Chitinase Chitin
cf. Bütehorn (1999) and Varma et al. (2001)
(after 20 min) of incubation, i.e., up to 0.058 mmol ml –1 min –1 , and declined to
0.041 mmol ml –1 min –1 after 80 min of incubation.
Fungal hyphae entered the cells randomly through the cell wall. It seems
the entry was facilitated by the combined action of wall degrading enzymes
and mechanical pressure.
Under normal conditions AMF do not invade vascular systems and the aerial
parts of their hosts. Despite heavy root colonization this is also true for P.
indica and S. vermifera, although these fungi were able to produce heavy
amounts of cell wall-degrading enzymes.