QCU THE STAR: Journal of Science, Engineering and Technology
2023, Volume 1, Issue 1, pages 1-15

Abstract.

The development of multi-drug resistant (MDR) pathogens caused by the overuse and misuse of antimicrobials is going to be the next pandemic, according to The World Health Organization (WHO). Thus, conducting studies on how the MDR pathogens spread should also be prioritized. For instance, microbes, a number of which are potentially antimicrobial resistant, spread among vegetables and other food products due to improper sanitation and handling. The lack of clean water and sanitation as well as inadequate infection prevention and control promotes their spread, some of which can be resistant to antimicrobial treatment. In this study, lettuce grown in the Philippines has been subjected to investigation to determine the presence of pathogenic microorganisms. Lettuce has become popular through the introduction of foreign delicacies such as salads, wraps, and samgyeupsal. Three samples were procured in different markets in Metro Manila: Marikina wet market, Farmers’ market Cubao, and Supermarket (Cubao). Bacteria from the lettuce were cultured in Eosin Methylene Blue Agar (EMB) for 24 h at 37°C, counted using the colony counter and analyzed using Independent Samples Kruskal-Wallis H Test at .05 Level of Significance. Gram staining was then performed for three colonies exhibiting different colors and were isolated and subcultured in nutrient broth to obtain pure culture. All samples were done in triplicates. The genomic DNA of the microorganisms were extracted using the xanthogenate method, and the specific DNA regions were amplified using 16S rRNA. DNA sequencing to identify the microbes at the species level. Results indicate that there is no significant difference between the number of colonies from the samples in the three markets. Moreover, three microbes namely Raoultella ornithinolytica (Marikina wet market), Acinetobacter pittii (Farmer’s market), and Acinetobacter soli (supermarket) match the results in BLAST (Basic Local Alignment Search Tool); hence, they were classified as biosafety level 2. Further investigation on the source of contamination is highly recommended.

Keywords: microorganisms, lettuce, genomic DNA, PCR, DNA sequence, Acinetobacter soli, Acinetobacter pittii, Raoultella ornithinolytica