Page 191 - Demo

SECTION I: MOLECULAR GENETIC ENGINEERING AND BIOCHEMICAL TECHNOLOGY 195cultured in vitro according to the method of Skehan et al. (1990) [10]. The absorbance values were measured at 570 nm using a microplate reader and the cell viability (CS%) was calculated.CS% = (OD [sample] - OD [day 0])/ (OD [control] - OD [day 0]) x 100Identification of selected bacterial strains: The total DNA of selected bacterial strains was extracted according to the instructions of The NucleoSpin Soil Mini Kit for DNA (Macherey Nagel, Germany). The 16S rRNA gene of bacteria was amplified using primer pair 16SF: 5%u2019-AGA GTT TGA TCA TGG CTC A-3%u2019 and 16SR: 5%u2019-AAG GAG GTG ATC CAG CC-3%u2019 (Sigmaaldrich, USA) with thermal cycle: 94 oC for 3 minutes, 30 cycles (94 oC for 1 minute, 50 oC for 1 minute, 72 oC for 1 minute 30 seconds), the last cycle at 72 oC: 7 minutes and keeping the sample at 4 oC. PCR products were checked by electrophoresis on 1% agarose gel. Samples were sent for sequencing at FIRST BASE Malaysia according to Sanger sequencing principles. The obtained sequences were processed using Bioedit software and compared with the NBCI gene bank database using the BLAST program to find strains with high similarity to the research strain. The phylogenetic tree of the research strains was constructed using MEGA11 software.3. RESULTS3.1. Screening of antagonistic bacteria from Nai Lagoon sediment samplesBacteria were isolated from five sediment samples of Nai Lagoon using eight different media. The isolated bacterial colonies displayed diverse colors and morphologies across the media. Of these, the most diverse number of colonies were obtained on the three types of media MA, MI, and Gauze II, and the least