plant surface microbiology.pdf

600
Giang Huong Pham et al.
days with a gradual decrease in fresh and dry biomass after prolong incubation.
Linear growth of the fungus on different solidified agar media is represented
in Table 3. On modified Melin-Norkrans (MMN) medium sparsely
running hyaline hyphae on the agar surface were seen, while on Potato Dextrose
Agar deep furrows with strong adhesion to the agar surface were apparent.
This sharp mode of growth was not observed when fortified with malt
extract and normal aspergillus medium. In contrast to aspergillus medium,
shaking conditions on MMN broth medium invariably inhibited the growth.
The explanation for this observation is not known. Fungal growth acidifies
the medium within 10 days to pH 4.4. Buffered medium prevented the reduction
of pH (Table 4). 2-(N-morpholine) ethane sulfonic acid (MES) in the
range of 25–100 mM was used.
6 Carbon and Energy Sources
Fig. 6. An overall view of P.
indica grown on solidified
aspergillus medium. Inset
shows enlarged view of a small
portion. On an agar concentration
of 2 % w/v concentric rings
often appeared (arrows) indicating
the rhythmic growth of
the fungus. The black arrows
point on the regions with slow
growth and high amount of
chlamydospores, the white
arrows point on thin mycelial
mats resulting from fast growth
of the hyphae
Individual sugars were uniformly added to the minimal broth at a rate of 1.0 %
(w/v) in all treatments.They were included in the medium separately after sterilization.
In all the sugar-supplied media, growth was better than the control
(Table 5). There were not many changes in the growth except for rafinose and
fructose.There were no changes in the color of the mycelium.Good growth was
recorded in media containing maltose followed by xylose, sucrose, rhamnose,
arabinose, glucose, lactose and mannose, respectively. The final pH was not
altered significantly, but was lower than that of the control (Table 5).
In a further study, fungal growth was best when glucose (1 % w/v) was
used as a carbon source as compared to sucrose, and followed by fructose. A