Piper nigrum, commonly known as black pepper, is one of the most important spice crops
with high demand by the world market. However, diseases like foot rot and stem blight
cause by Phytophthora capsici have become the important production constraints in black
pepper industry. The frequent application of toxic fungicides to counter the diseases in pepper
plantations has raised certain environmental issues. In order to mitigate the use of fungicides,
biological approach to control P. capsici has been suggested. In this study, endophytic bacteria
were isolated from six P. nigrum roots and screened for in vitro antagonistic activity against P.
capsici through dual culture, mycelial growth, spore germination and double plate assay. The
antagonism testing involved the secretion of volatile and diffusible bioactive compounds by
the endophytic bacteria. Out of 19 isolates tested, two isolates DB(2)7 and SB(2)6 produced
volatile bioactive compounds and these two isolates showed highest antagonism against P.
capsici mycelia with the percentage of inhibition up to 47.63% and 43.33%, respectively.
Diffusible compounds from isolates DB(2)7, DB(2)9 and SB(2)6 produced clear zones in spore
germination test with radii measurements of 10.0-17.0 mm. Three isolates with promising
antifungal activity were further characterised through 16S rDNA sequencing. The analysis
of their sequences via National Center for Biotechnology Information (NCBI) suggests close
identity towards Enterobacter cancerogenus, Enterobacter cloacae and Enterobacter asburiae.
This research study demonstrated that these endophytic bacteria isolates are potentially to be
used as biocontrol agent in pepper cultivation.
This study was conducted to detect the presence of Listeria monocytogenes (L. monocytogenes)
and screen for its antibiotic susceptibility characteristic from wildlife and water samples at
Kubah National Park, Sarawak, Malaysia. Samples collected were incubated and streaked on
selective medium PALCAM agar to confirm the presence of Listeria spp. before they were
further tested using molecular analysis. Specific Polymerase Chain Reaction (PCR) assay were
performed to target specific virulence gene, haemolysin gene, hlyA to further distinguish the
presence of this pathogenic bacteria in the samples. Overall, out of the 30 samples tested, 10
samples were confirmed as to contain L. monocytogenes strains and selected to subsequent
antibiotic susceptibility test. Susceptibility patterns to 10 antibiotics were investigated
among the L. monocytogenes strains. All strains were uniformly resistant to tetracycline and
erythromycin. On the other hand, all strains were sensitive to gentamycin and tobramycin. The
multiple antibiotic resistance shown by the strains in this study indicate the potential health
hazard associated with the possible transmission between wildlife and water to its surrounding
environment especially visitors and workers of Kubah National Park, Sarawak, Malaysia.