Abstract:
Endophytic fungi isolated from Cyperaceae family plants are known to assist the host
against biotic stresses including microbial attacks. Accordingly, endophytic fungi of
Cyperus species are a judicious target for investigating their ability to produce antimicrobial
agents. The current study was designed to isolate the endophytic fungi of two Cyperus
species and evaluate their antibacterial producing potential. For the isolation of endophytic
fungi, the leaves and roots of two healthy plants, C. bulbosus and C. alternifolius, were
surface sterilized using standard procedure and the plant materials were next cut into small
segments and were placed on five types of media, potato dextrose agar (PDA), malt agar
extract (ME), malt peptone dextrose agar extract (MEA), starch yeast peptone agar extract
(SYP) and yeast peptone dextrose agar extract (YPD). Fungi emerging from the host
tissues were transferred onto new PDA dishes and sub culturing was done until pure
cultures were obtained. After incubating for 2-3 weeks each fungal culture was extracted
with ethyl acetate and the extracts were tested against Staphylococcus aureus, Bacillus
cereus, Pseudomonas aeruginosa, Escherichia coli and Salmonella enterica at 400,
200,100 μg/disc using agar disc diffusion assay.
Eleven and ten endophytic fungi were isolated from C. bulbosus and C. alternifolius
respectively. Nine endophytes were isolated using YPD medium while five, four, three and
two endophytic fungi were isolated from PDA, SYP, MEA and ME media respectively. At
400 μg/disc concentration, of the isolated endophytic fungi, nine from C. bulbosus and eight
from C. alternifolius inhibited at least one bacterium tested. At this concentration, three
extracts (02 from C. alternifolius and 01 from C. bulbosus) were active to both Gram positive
and Gram negative bacteria. Furthermore, 11 and 10 endophytic fungal extracts showed
activity against Gram positive S. aureus and B. cereus while 09, 05 and 06 showed activity
against P. aeruginosa, E. coli and S. enterica respectively. At 200 and 100 μg/disc
concentrations, eight endophytic fungal extracts were active for the tested pathogens. This
screening revealed that Cyperus spp. are hosts to a number of endophytic fungi producing
antimicrobial agents and that further research may result in potential antimicrobial drug
leads.
