. 2023 Feb 22;54(2):1035–1046. doi: 10.1007/s42770-023-00920-8

Table 4.

Biofilm formation potential, curli expression phenotype, and identification of rpoS gene in E. coli isolated from pasteurized milk obtained from two producers from Mato Grosso, Brazil

Week	Isolate ID	Biofilm formation (A_570nm)	*Biofilm classification	**Curli expression	rpoS gene
4	^AA19C6	0.09 ± 0.01	Absent	Rdar	+
	^AA20C3	0.17 ± 0.02	Weak	Rdar	+
	^AA20C6	0.21 ± 0.05	Weak	Rdar	+
5	^AA21C1	0.12 ± 0.01	Weak	Rdar	+
	^AA22C1	0.14 ± 0.04	Weak	Rdar	+
	^AA24C1	0.29 ± 0.06	Moderate	Rdar	-
	^AA25C2	0.08 ± 0.001	Absent	Rdar	+
1	^BB01C3	0.09 ± 0.01	Absent	Rdar	+
	^BB02C1	0.13 ± 0.02	Weak	Rdar	-
	^BB03C4	0.09 ± 0.01	Absent	Intermediate	-
	^BB04C1	0.30 ± 0.02	Moderate	Saw	-
	^BB05C2	0.09 ± 0.004	Absent	Rdar	-
2	^BB06C5	0.22 ± 0.09	Moderate	Rdar	+
	^BB07C2	0.10 ± 0.01	Absent	Rdar	+
	^BB08C3	0.12 ± 0.02	Weak	Rdar	+
	^BB10C2	0.10 ± 0.01	Absent	Rdar	+
3	^BB11C1	0.14 ± 0.04	Weak	Intermediate	+
	^BB12C1	0.11 ± 0.01	Absent	Rdar	-
	^BB13C1	0.11 ± 0.02	Absent	Rdar	+
	^BB14C1	0.10 ± 0.01	Absent	Rdar	-
	^BB15C1	0.09 ± 0.01	Absent	Saw	+
4	^BB16C2	0.11 ± 0.02	Absent	Rdar	+
	^BB17C1	0.17 ± 0.03	Weak	Rdar	+
	^BB18C2	0.09 ± 0.01	Absent	Intermediate	+
	^BB19C1	0.09 ± 0.005	Absent	Saw	+
	^BB20C3	0.20 ± 0.06	Weak	Rdar	+
5	^BB21C1	0.11 ± 0.01	Absent	Rdar	-
	^BB22C1	0.13 ± 0.02	Weak	Intermediate	+
	^BB23C2	0.22 ± 0.03	Weak	Rdar	-
	^BB24C2	0.12 ± 0.01	Weak	Rdar	-
	^BB25C1	0.16 ± 0.002	Weak	Rdar	-

*The biofilm classification was obtained based on the cutoff optical density (ODc; 0.11) of two independent replicates, with each plate containing duplicate samples: nonbiofilm (OD_strain < ODc), weak biofilm (ODc < OD_strain < 2xODc), moderate biofilm (2 × ODc < OD_strain < 4 × ODc), and strong biofilm (4 × ODc < OD_strain < 8 × ODc). **Colony characteristics on Congo red agar after 4 days of incubation, comprising rdar (curli-positive colonies), intermediate (medium characteristics), or observed (negative colonies). Presence or absence of rpoS gene (involved in curli/cellulose control in stress conditions) [48]