No abstract

Protein production by bacteria might be increased in stressful conditions such as in the presence of antimicrobial agents. Many studies proved that antibiotics or antimicrobial agents at low concentration are able to activate or repress gene transcription process in bacteria. However, there are still few studies on potential of natural antimicrobial compounds such as Cymbopogon essential oils acting as specific chemical signal that can trigger biological functions of bacteria. Therefore, this study aims to explore the potential of natural antimicrobial compound (Cymbopogon flexuosus and Cymbopogon nardus) at low concentration in regulating proteins production by Lactobacillus plantarum ATCC8014. The bacteria cells of L. plantarum ATCC8014 are exposed to Cymbopogon essential oils at low concentration in fermentation process for 48 hours at 37°C. SDS-PAGE analysis showed that a new intracellular protein with approximate size of 40 kDa was produced by L. plantarum ATCC8014 after being enhanced with C. nardus essential oil. Besides, the intracellular proteins, each with approximate size of 85 kDa, 45 kDa and 28 kDa synthesized by L. plantarum ATCC8014 prior to inducing with C. nardus or C. flexuosus were expressed differently. Some of the intracellular proteins were highly expressed and some of the proteins were repressed based on the intensity of protein bands appeared. Hence, L. plantarum ATCC8014 in the presence of Cymbopogon essential oils at low concentration could regulate the intracellular proteins production. The isolated protein also showed antimicrobial activity against selected Gram-positive and Gram-negative bacteria.

Proteins levels produced by bacteria may be increased in stressful surroundings, such as in the presence of antibiotics. It appears that many antimicrobial agents or antibiotics, when used at low concentrations, have in common the ability to activate or repress gene transcription, which is distinct from their inhibitory effect. There have been comparatively few studies on the potential of antibiotics or natural compounds in nature as a specific chemical signal that can trigger a variety of biological functions. Therefore, this study was focusing on the effect of essential oil from Cymbopogon flexuosus in regulating proteins production by Bacillus subtilis ATCC21332. The Minimum Inhibition Concentration (MIC) of the C. flexuosus essential oil on B. subtilis was determined by using microdilution assay, resulting 1.76mg/ml. The bacteria cells were further exposed to the C. flexuosus essential oil at concentration of 0.01 MIC for 72 h. The proteins were then isolated and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Proteins profile showed that a band with approximate size of 30 kDa was appeared for the treated bacteria with C. flexuosus essential oil. Thus, B. subtilis ATCC21332 in stressful condition with the presence of C. flexuosus essential oils at low concentration could induce the protein production. The isolated protein also showed antimicrobial activity against selected Gram-positive and Gram-negative bacteria.

Kalanchoe pinnata (synonym to Byrophyllum pinnatum) or commonly known as “Setawar” is a medicinal plant belongs to the Crassulaceae family. It is also known as “life plant” and “resurrection plant” due to its multiple roles in traditional medication. The therapeutic values of K. pinnata mostly lie on the presence of phytochemicals or plant active compounds which possess high potential as a natural antimicrobial agent source. Given the global health threat of antimicrobial resistance towards synthetic drugs, uncovering the natural sources as a novel drug is of crucial need. In this regard this review highlights the antimicrobial property of K. pinnata extract, the bioactive compound analysis of this plant extract and their mode of action against pathogenic microorganisms. The potent bioactive compounds extracted from K. pinnata plant could be further explored as an alternative medicine to the current synthetic antimicrobial drugs.

The sharing of COVID-19 sequences worldwide has allowed for comprehensive and real-time analyses of COVID-19 genomic diversity at regional levels. Temporal distribution of COVID-19 variants and lineages enables better infection control, surveillance, and facilitates policy making for public health. 417 sequences extracted from all COVID-19 cases in Negeri Sembilan of peninsular Malaysia from July 2021 until May 2022 were used for this study. Phylogenomics revealed a total of 20 circulating lineages, of which seven are still circulating. The majority (60.4%) of viruses in Negeri Sembilan are of GRA lineage with strong representation from the Malaysian lineage BA.1.1 (24.7%). A time series analysis showed a change in the dominating circulating lineage from AY.79 to BA.1.1, which correlated to the relaxing of lockdowns implemented by the Malaysian government. Several Malaysian sub-lineages (BA.2.40.1, BA.2.57 and BA.2.9) have emerged from April 2022 onwards. Evolutionary mutations of the sub-lineages also gave rise to novel single nucleotide polymorphisms (SNPs) in the spike proteins. Out of the 70 SNPs isolated from all samples,in silicoprediction revealed five novel SNPs that could cause functional defects to the spike protein, which are S221L, L226S, V826L, C1240F and C1243F. Structural modelling of the V826L showed that the L826 possibly confers an increase in protein flexibility within the S2 region of S protein, which supports ourin silicopredictions.