Nowadays, the foodborne outbreaks associated with fresh produces, including ulam, are increasing worldwide. The biofilm formation or bacterial attachment to plant surface is the initial step towards the contamination in fresh produce. The biofilm phenotype of bacteria grown on congo red agar is termed as red, dry and rough (rdar) morphotype. The binding of congo red dye with both biological proteins and inert surfaces is due to the presence of curli fimbriae and cellulose as the main extracellular components. The objective of this study was to determine the rdar morphotypes, biofilm ability and the role of csgA gene of Escherichia coli and Salmonella spp. isolated from ulam or Malaysian herbs. A total of 29 isolates, including 23 E. coli and 6 Salmonella spp. were analyzed for their ability to produce biofilm by colony morphology test, microtiter plate biofilm assay and qualitative biofilm test (pellicle formation). The presence of the csgA gene of E. coli was identified by PCR, which demonstrated the potential gene that able to produce curli fimbriae. Results revealed that 16 (69.6%) E. coli isolates were categorized as strong biofilm producers, 2 (8.7%) as moderate biofilm producers, 3 (13%) as weak biofilm producers, whereas 2 (8.7%) as negative biofilm producers (did not produce biofilm). While 4 (66.7%) Salmonella spp. isolates were identified as strong biofilm producers, 1 (16.7%) as moderate biofilm producers and 1 (16.7%) as negative biofilm producers. Majority of the E. coli strains (69.6%) were identified as strong biofilm producers and able to express rdar morphotypes. The ability of the of E. coli and Salmonella spp. isolates to form biofilm reveals the ability of these isolates to persist on the fresh vegetables and become hosts for the disease transmission to humans or/and animals.

Although vegetables are considered to be an essential part of a healthy diet, studies have shown that they can also represent a hazard for human health as they are usually eaten raw and receive minimal treatment. In recent years, vegetables are among the food groups associated with higher rates of recurrence and are the leading cause of enteric diseases. There is a colossal amount of data available on fresh produce worldwide; however, limited data are available regarding the microbiological quality of ulam in Malaysia. In fact, cross -contamination that occurs during minimal processing of ulam has not yet been studied. Therefore, the aim of this study was to evaluate the microbiological quality and the occurrence of Escherichia coli and Salmonella in ulam. A total of 32 samples of ulam were randomly collected from wet markets and supermarkets in Kuala Terengganu, Malaysia. The samples were analysed for enumeration of aerobic mesophilic bacteria, coliforms, yeast and moulds, Bacillus cereus, Listeria monocytogenes and detection of Escherichia coli and Salmonella. In this study, the microbiological quality of ulam were in the range of 6.36-8.83; 4.14-7.48; 0-8.16; 3.94-6.45 log10 CFU/g for aerobic mesophilic bacteria, coliforms, Salmonella and yeast and moulds, respectively. Escherichia coli and Salmonella were detected in 3.13% and 9.4% of ulam samples, respectively. The findings from the study are intended to provide insight into the potential health risks associated with the consumption of ulam. The strong interdisciplinary approach by various agencies and development of safe agricultural systems will ensure the delivery of safe vegetables to the end-users