Colony morphology on Congo red-supplemented agar was used to detect the formation of fimbriae in colonies. LB agar without NaCl consists of 10 g/L tryptone (Merck, Germany), 6 g/L technical agar (Oxoid, UK), and 5 g/L of yeast extract (HiMedia Laboratories Pvt. Ltd, India) was supplemented with 0.04 g/L Congo red (Sigma Aldrich Inc., Germany). Then, | wL of the overnight culture was inoculated into congo red agar and incubated at 25°C for 5 days (Abdullah et al., 2017). Their colony morphologies were observed at day 3 and 5. The morphotypes observed were red, dry and rough (rdar) and smooth and white morphotype (saw). Rdar morphotypes able to form multicellular communities and their colonies were dark red colour, with a rough surface and undulated margins. While saw morphotypes showed Colony morphology on Congo red-supplemented Kacang Botol (Psophocarpus tetragonolobus) Table 1. Prevalence of Congo Red morphotypes of Escherichia coli and Salmonella spp. Congo red supplemented agar used to visualize curli and cellulose production in the colonies. Rdar colonies isolate producing both curli fimbriae and cellulose as an extracellular matrix component. Table 2 and 3 show rdar morphotype was expressed by 18 (78.3%) isolates of E. coli (SMDS2, SMDS4, WMDS, SMKGI1, SMKG2, SMKG3, SMKG4, SMKB2, SMKB4, SMKBS, SMKB8, SMK2, SMK3, SMU2, SMT4, WMSK4, WMSK7 and WMPP2) and rdar morphotypes absent in all Salmonella enterica. Verma et al. (2018) reported that rdar morphotype characterized by both expressions of curli fimbriae and cellulose production was identified in 28 isolates (38.3%) of E. coli isolated from fresh vegetables and fruits samples. Table 3. Gram stain, colony morphology and biofilm formation on the air-liquid interface of Salmonella spp. Table 2. Gram stain, colony morphology and biofilm formation on the air-liquid interface of Escherichia coli *Morphotypes on Congo Red agar (rdar) red, dry and rough, intermediate and (saw) smooth and white; "Phenotype on air-liquid interface: (-) the complete absence of pellicle — lack of ability to produce biofilm; (+) formation of very thin pellicle — weak biofilm producer; (++) formation of thin pellicle — moderate biofilm producer, (+++) formation of strong and thick pellicle — strong biofilm producer. Table 4. Screening of biofilm formers of Escherichia coli Table 5. Screening of biofilm formers of Salmonella spp. Figure 3. The Biofilm Formation of £. coli strains. The Biofilm formation was calculated by using formula; Biofilm Formation (BF) BF = AB — CW; AB, stained attached bacteria; CW, stained control wells. *Value more than 0.30 indicate strong biofilm. Figure 4. The Biofilm Formation of Salmonella spp. strains. The Biofilm formation was calculated by using formula; Biofilm Formation (BF) BF = AB — CW; AB, stained attached bacteria; CW, stained control wells. *Value more than 0.30 indicate strong biofilm. Figure 5. Representative agarose gel analysis of PCR assay targeting csgA gene in Escherichia coli (EC) and Salmonella spp. (S) isolates. Lane 1 and 5: 100 bp DNA ladder, Lane 2: Negative control, Lane 3: Sample 14/EC, Lane 4: Sample 1/S. Table 6. Correlation between colony morphotypes and biofilm production of E. coli
