Monisha Joy Gomez

• BSc (Hons) Food & Human Nutrition
• Investigating the Presence of Pathogenic Bacteria in Conventional and Hydroponic Iceberg Lettuce in Singapore

Commercially-sold green leafy vegetables in Singapore are grown conventionally, hydroponically, and organically. In general, less bacteria is found on conventionally-grown vegetables due to the routine use of chemical pesticides to prevent microbial decay and to increase shelf-life. Furthermore, some bacteria are pathogenic and can cause foodborne illnesses when consumed. In this project, the bacterial profile of conventional and hydroponic iceberg lettuce samples in Singapore were investigated over 30 days. Specialised biochemical tests were conducted on single colony bacterial isolates to characterize the different strains observed. Conventional lettuce samples exhibited significant bacterial growth only after 3 weeks of purchase. This could be attributed to the chemical-intensive growth conditions of soil-based agriculture. On the other hand, the hydroponic variety consistently showed the growth of only 1 strain, Pseudomonas spp, throughout the 30-day period. Further biochemical analysis is needed to confirm the six different strains isolated from conventional lettuce.

Funding source: Newcastle University

Supervisor: Dr Saloni Kaur Dang