Twenty six isolates of endophytic fungi were
obtained from surface sterilized healthy leaf and twig
tissues of adult trees of 17 species of Lithocarpus sp.
naturally growing on Doi Sutep - Pui National Park in
Chiang Mai. Healthy plant was washed in running water and
surface sterlization was performed by immersion sequence
ethanol, sodium hypochlorite and ethanol. The surface
sterlized plant material was then placed onto 2% malt
extract agar plus 0.03% Rose Bengal supplemented with
streptomycin sulfate to suppress bacterial growth. All
plates were kept at 3dc for 5-7 days depending on growth
rates of fungi which emerged. The purification was done
by transfering individual hypha tip to Potato Dextrose
agar (PDA) and incubated for 3-4 days. The purified
mycelium was kept in PDA slant at room temperature.
Production of some metabolites by endophytic fungi
Twenty six isolates were cultured in basal medium
containing four kinds of carbon sources namely xylan,
inulin, CMC and locust bean gum. Three pieces of
mycelium mats (0.5 x 0.5 cm) were transfered to 3 ml of
the basal medium and incubated on a reciprocal shaker at
room temperature for 4 days.
Assay for antibacterial activity
The test bacteria (Staphylococcus aureus and
Pseudomonas aeruginosa) was cultured in nutrient broth
(NB) and shaked on a rotary for 24 hour at room
temperature. Then, 100 microliter of cell suspension was
spreaded onto nutrient agar plate. Filter paper disc
impregnanted with endophytic fungi's culture fluid was
placed on the agar plate and incubated at 37 C for 18 hours.
The endophytic isolates showing a zone of inhibition
greater or equal to 8 mm were selected and kept in nutrient
agar slants.