ABSTRACT
Plant growth promoting rhizobacteria (PGPR) are strains of naturally occurring soil bacteria that live in close vicinity to the plant's rhizosphere region which possess the capability to augment host growth. This study was conducted to isolate and identify potential PGPR isolates indigenous to Metroxylon sagu, Rottb. rhizosphere. These potential isolates were characterised based on their beneficial plant growth promoting (PGP) properties and identified by molecular analysis via 16S rDNA sequencing. A total of 18 isolates were successfully isolated, out of which five isolates were tested, and designated as (S1A, S2B, S3A, S3C and S42). Among the five isolates, two isolates (S2B and S3C) were found to produce high levels of indole-3-acetic acid (2.96 µg/mL and 10.31 µg/mL), able to fix nitrogen and show significant activity in phosphate solubilisation. The analysis of their sequences via National Center for Biotechnology Information (NCBI) suggested their close identity towards Lysinibacillus sphaericus and Bacillus thuringiensis. It can be concluded that the isolated PGPR possesses beneficial PGP attributes. It can be implied that the isolated PGPR are potential to be used as inoculant biofertilisers, beneficial for Metroxylon sagu, Rottb. growth. Hence, further studies need to be done to evaluate the effectiveness of the beneficial microbes towards sago seedlings growth, under pot experiment.
Rizobakteria penggalak pertumbuhan tumbuhan adalah sejenis bakteria tanah yang hidup berdekatan rizosfera tumbuhan dan mempunyai impak berfaedah ke atas pertumbuhan tanaman. Kajian ini telah dijalankan untuk melakukan pengasingan dan pengecaman PGPR, daripada rizosfera Metroxylon sagu, Rottb. Bakteria endofit diasing berdasarkan ciri-ciri penggalak tumbuhan yang kemudiannya dipilih untuk pengenalpastian secara biologi molekul melalui 16S rDNA sequencing. Sebanyak 18 bakteria berjaya diasingkan, dan lima jenis bakteria dipilih berdasarkan ciri-ciri penggalak tumbuhan dan dilabelkan sebagai S1A, S2B, S3A, S3C dan S42. Di antara kelima-lima bakteria tersebut, dua bakteria (S2B dan S3C) dijumpai mempunyai kemampuan untuk menghasilkan kadar indole-3-acetic acid (IAA) yang tinggi (2.96 µg/mL dan 10.31 µg/mL), mempunyai kemampuan mengikat gas nitrogen serta menunjukkan aktiviti yang memberangsangkan dalam mengurai fosfat. Hasil analisis biologi molekul melalui NCBI menunjukkan identiti terdekat kedua-dua bakteria tersebut cenderung kepada Lysinibacillus sphaericus dan Bacillus thuringiensis. Melalui hasil penyelidikan ini, dapat dirumuskan bahawa PGPR yang telah diasingkan daripada rizosfera Metroxylon sagu, Rottb., mempunyai ciri-ciri penggalak tumbuhan dan berpotensi untuk digunakan sebagai inokulan biobaja, berfaedah kepada pertumbuhan Metroxylon sagu, Rottb. Maka, kajian selanjutnya perlu dilakukan untuk menilai keberkesanan mikrob ke atas pertumbuhan benih sagu, melalui eskperimen dalam pasu.
ABSTRACT
BACKGROUND: Staphylococcus aureus is a major human pathogen, especially methicillin-resistant S. aureus (MRSA), which causes a wide range of hospital and community-acquired infections worldwide. Conventional testing for detection of MRSA takes 2-5 days to yield complete information of the organism and its antibiotic sensitivity pattern. RESULTS: The present study focused on the development of a pentaplex PCR assay for the rapid detection of MRSA. The assay simultaneously detected five genes, namely 16S rRNA of the Staphylococcus genus, femA of S. aureus, mecA that encodes methicillin resistance, lukS that encodes production of Panton-Valentine leukocidin (PVL), a necrotizing cytotoxin, and one internal control. Specific primer pairs were successfully designed and simultaneously amplified the targeted genes. The analytical sensitivity and specificity of the pentaplex PCR assay was evaluated by comparing it with the conventional method. The analytical sensitivity of the pentaplex PCR at the DNA level was found to be 10 ng DNA. The analytical specificity was evaluated with 34 reference staphylococci and non-staphylococcal strains and was found to be 100%. The diagnostic evaluation of MRSA carried out using 230 clinical isolates, showed 97.6% of sensitivity, 99.3% of specificity, 98.8% of positive predictive value and 98.6% of negative predictive value compared to the conventional method. The presence of an internal control in the pentaplex PCR assay is important to exclude false-negative cases. CONCLUSION: The pentaplex PCR assay developed was rapid and gave results within 4 h, which is essential for the identification of Staphylococcus spp., virulence and their resistance to methicillin. Our PCR assay may be used as an effective surveillance tool to survey the prevalence of MRSA and PVL-producing strains in hospitals and the community.