Studies on the growth of Lactobacillus reuteri, Bifidobacterium and Escherichia coli as affected by prebiotic extracted from citrus peel

Figures & data

Table 1. Treatment plan.

Treatment	Prebiotic concentration (g/100 mL)
Control	0
T1	1
T2	2
T3	3
T4	4
T5	5

Table 2. Description of milk fermentation model.

Codes	Description
L1	Lactobacillus reuteri
B1	Bifidobacterium
E1	E. coli
LbB1	Co-culture of L. reuteri and Bifidobacterium
E2	E. coli grown with co-culture of L. reuteri on MacConkey agar
E3	E. coli grown with co-culture of Bifidobacterium on MacConkey agar
E4	E. coli grown with co-culture of L. reuteri, Bifidobacterium on MacConkey agar
L2	L. reuteri grown with co-culture of E. coli on MRS agar
B2	Bifidobacterium grown with co-culture of E. coli on MRS agar
E5	E. coli grown with co-culture of L. reuteri on MRS agar
E6	E. coli grown with co-culture of Bifidobacterium on MRS agar
LbB2	E. coli grown with co-culture of L. reuteri, Bifidobacterium on MRS agar

Figure 1. FTIR transmittance spectra for citrus peel powder, insoluble and soluble fractions of citrus peel powder extracts.

Table 3. Characterization of prebiotic extracted from citrus peel.

Parameter	Results
Prebiotic Yield (%)	76.48 ± 3.60
Soluble Dietary Fiber (g/100 g)	64.82 ± 2.46
Insoluble Dietary Fiber (g/100 g)	11.66 ± 1.14
Total Flavonoid Content (mg QE/g)	14.28 ± 0.01
DPPH (%)	73.36 ± 0.09
ABTS (%)	89.14 ± 0.08
Water Holding Capacity (g/g)	7.79 ± 0.033
Oil Holding Capacity (g/g)	3.22 ± 0.008
Prebiotic activity score (L. reuteri)	1.54 ± 0.05
Prebiotic activity score (Bifidobacterium)	2.93 ± 0.05

Table 4. Mean squares for microbial growth affected by prebiotic as a function of time.

SOV	DF	L. reuteri	Bifidobacterium	Co-culture of probiotics
Treatments	5	1.997 × 10^18**	4.908 × 10^18**	6.121 × 10^20**
Time	3	3.494 × 10^16**	7.210 × 10^16**	3.866 × 10^18**
Treatment × Time	15	9.506 × 10^14NS	2.997 × 10^15**	8.681 × 10^16*
Error	48	7.278 × 10^14	5.444 × 10^14	4.347 × 10^16
Total	71

DF = Degree of Freedom; SOV = Source of Variation; NS = Not Significant

Figure 2. Growth of L. reuteri over the period of time at different concentrations of prebiotic.

Figure 3. Growth of Bifidobacterium over the period of time at different concentrations of prebiotic.

Figure 4. Growth of L. reuteri and Bifidobacterium in co-culture system over the period of time at different concentrations of prebiotic.

Figure 5. Growth of L. reuteri (L1), Bifidobacterium (B1), E. coli (E1) and co-culture of probiotic bacteria (LbB1) at different concentrations of prebiotic (spread plated on MRS and MacConkey agar).

Table 5. Mean squares for microbial growth affected by prebiotic in milk.

SOV	DF	L. reuteri	Bifidobacterium	E. coli	Co-culture of probiotics
Treatments	5	1.45832**	1.08650**	1.50932**	1.03825**
Error	6	0.00443	0.00027	0.00177	0.00762
Total	11

DF = Degree of Freedom; SOV = Source of Variation

Figure 6. Log CFU/mL of E. coli incubated with L. reuteri (E2), E. coli incubated with Bifidobacterium (E3), E. coli incubated with L. reuteri and Bifidobacterium (E4) at different concentrations of prebiotic (spread plated on MacConkey agar).

Table 6. Mean squares for microbial growth affected by prebiotic in milk grown on MacConkey agar.

SOV	DF	E. coli incubated with L. reuteri	E. coli incubated with Bifidobacterium	E. coli incubated with both probiotics
Treatments	5	0.19542**	0.26461**	0.01212*
Error	6	0.00530	0.00222	0.00298
Total	11

DF= Degree of Freedom; SOV= Source of Variation

Figure 7. Log CFU of L. reuteri incubated with E. coli (L2), Bifidobacterium incubated with E. coli (B2), L. reuteri and Bifidobacterium incubated with E. coli (LbB2) at different concentrations of prebiotic (spread plated on MRS agar).

Table 7. Mean squares for microbial growth affected by prebiotic in milk grown on MRS agar.

SOV	DF	L. reuteri incubated with E. coli	Bifidobacterium incubated with E. coli	L. reuteri and Bifidobacterium incubated with E. coli
Treatments	5	0.01145^NS	0.00473^NS	0.00643*
Error	6	0.00313	0.00119	0.00146
Total	11

DF= Degree of Freedom; SOV= Source of Variation; NS= Not Significant

Figure 8. Log CFU/mL of E. coli (E1), E. coli incubated with L. reuteri (E5), E. coli incubated with Bifidobacterium (E6) at different concentrations of prebiotic (spread plated on MRS agar).

Table 8. Mean squares for microbial growth affected by prebiotic in milk grown on MRS agar.

Source	DF	E. coli	E. coli grown with co-culture of L. reuteri	E. coli grown with co-culture of Bifidobacterium
Treatments	5	1.50932**	0.03435**	0.04759**
Error	6	0.00177	0.00092	0.00102
Total	11

DF= Degree of Freedom; SOV= Source of Variation

Data availability statement

Data will be shared upon request.