Table I
Physiological and biochemical features of 11 isolated strains.
| Characteristic | WDS | WDS-7 |
|---|---|---|
| Glucose gas production | − | − |
| Gelatin | 3 | − |
| Nitrate reduction | − | − |
| Catalase | − | − |
| Arginine hydrolysis | − | − |
| Motile | − | − |
| H2S production | − | − |
| Indole | − | − |
| 15°C growth test | − | − |
| 45°C growth test | + | + |
| Arabinose | 3 | − |
| Cellobiose | 7 | − |
| Esculin | 5 | − |
| Fructose | + | + |
| Gluconate | 4 | − |
| Lactose | 9 | + |
| Mannose | 6 | + |
| Mannitol | 1 | − |
| Sorbitol | − | − |
| Melezitose | − | − |
| Melibiose | 5 | − |
| Raffinose | 3 | − |
| Rhamnose | − | − |
| Salicin | 6 | − |
| Glucose | + | + |
| Sucrose | 8 | + |
| Trehalose | 6 | − |
| Xylose | − | − |
| Ribose | − | − |
| Maltose | 8 | − |
[i] WDS – WDS-2, WDS-3, WDS-4, WDS-8, WDS-9, WDS-10, WDS-11, WDS-15, WDS-18, WDS-20; 10 isolates
[ii] + – positive or weakly positive reaction
[iii] – – negative reaction
[iv] number – the number of positive reactions
Table II
Adhesion rate to HT-29 cells of 11 isolated LAB strains.
Table III
Tolerance to artificial simulated gastrointestinal conditions of six isolated LAB strains.
| Strains | Artificial simulated gastric juice, 3 h, survival rate (%) | Artificial simulated intestinal juice, 5 h survival rate (%) |
|---|---|---|
| WDS-3 | 81.34 ± 4.40b | 70.56 ± 4.49b |
| WDS-4 | 77.45 ± 3.66ab | 62.36 ± 3.06ab |
| WDS-7 | 78.99 ± 3.98ab | 67.81 ± 3.57ab |
| WDS-9 | 76.95 ± 2.03ab | 66.19 ± 3.48ab |
| WDS-10 | 70.94 ± 4.27a | 60.04 ± 1.25a |
| WDS-18 | 71.29 ± 2.13a | 60.75 ± 5.17a |
| LGG | 84.72 ± 4.96b | 77.75 ± 4.25c |
Table IV
Antioxidant capacities of six isolated LAB strains.
| Strains | Antioxidant capacities (%) | ||
|---|---|---|---|
| DPPH scavenging activity | ABTS+ scavenging activity | Superoxide anion scavenging activity | |
| WDS-3 | 19.32 ± 1.24ab | 52.35 ± 2.47b | 41.31 ± 2.64a |
| WDS-4 | 31.04 ± 1.71c | 65.20 ± 2.38d | 49.72 ± 1.63b |
| WDS-7 | 30.15 ± 2.24c | 68.31 ± 1.50d | 48.92 ± 1.36b |
| WDS-9 | 18.09 ± 1.78a | 40.78 ± 1.43a | 40.77 ± 1.85a |
| WDS-10 | 22.08 ± 1.61b | 49.01 ± 1.72b | 41.94 ± 1.69a |
| WDS-18 | 32.00 ± 2.71c | 56.97 ± 1.68c | 48.68 ± 1.33b |
| LGG | 21.32 ± 1.13ab | 51.94 ± 2.04b | 40.12 ± 1.07a |
Fig. 1
Antibacterial activity of six isolated LAB strains. a–c) Different letters represent statistical significance (p < 0.05).
Fig. 2
Phylogenetic tree constructed based on the 16S rRNA gene sequence of Lactobacillus delbrueckii ssp. indicus WDS-7 strain.
Fig. 3
SEM images of Lactobacillus delbrueckii ssp. indicus WDS-7 strain. A) SEM image of numerous bacteria located at random, B) SEM image of a single cell.
Fig. 4
Growth curve and acid production curve of Lactobacillus delbrueckii ssp. indicus WDS-7 strain.
Table V
The cell survival rates after heat treatment of Lactobacillus delbrueckii ssp. indicus WDS-7 strain.
| Strains | Temperature (°C) | |||
|---|---|---|---|---|
| 50 | 60 | 70 | 80 | |
| WDS-7 | 91.81 ± 7.43% | 12.38 ± 2.33%* | ≈ 0% | 0% |
| LGG | 83.38 ± 7.32% | 4.79 ± 0.93% | ≈ 0% | 0% |
Table VI
Biofilm formation by Lactobacillus delbrueckii ssp. indicus WDS-7 strain.
| Strains | Biofilm formation | |
|---|---|---|
| Glass | Plastic | |
| WDS-7 | + | ++ |
| LGG | + | + |
[i] + and ++ represent mild biofilm producer (0.1 < OD590 < 0.2) and strong biofilm producer (OD590 > 0.2), respectively
Fig. 5
EPS production activity of Lactobacillus delbrueckii ssp. indicus WDS-7 strain.
* – represents the statistical significance (p < 0.05).
Table VII
Antibiotic susceptibility of Lactobacillus delbrueckii ssp. indicus WDS-7 strain.
| Strains | Antibiotic susceptibility | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Metronidazole | Chloramphenicol | Streptomycin | Kanamycin | Ampicillin | Gentamicin | Tetracycline | Erythromycin | Rifampicin | Ciprofloxacin | Doxycycline | Vancomycin | |
| WDS-7 | R | S | R | R | S | R | I | S | S | I | S | R |
| LGG | R | S | R | R | S | R | S | S | S | S | S | R |
[i] R, I, and S represent resistance, intermediate susceptibility, and susceptibility to the antibiotic, respectively
Table VIII
Enzyme production by Lactobacillus delbrueckii ssp. indicus WDS-7 strain.
| Enzyme | Strains | |
|---|---|---|
| LGG | WDS-7 | |
| Alkaline phosphatase | 1 | 1 |
| Esterase | 2 | 1 |
| Esterase lipase | 1 | 2 |
| Lipase | 0 | 0 |
| Leucine arylamidase | 2 | 4 |
| Valine arylamidase | 3 | 2 |
| Cystine arylamidase | 1 | 0 |
| Trypsin | 0 | 0 |
| α-Chymotrypsin | 0 | 0 |
| Acid phosphatase | 2 | 0 |
| Naphthol-AS-BI-phosphohydrolase | 2 | 2 |
| α-Galactosidase | 1 | 3 |
| β-Galactosidase | 2 | 4 |
| β-Glucuronidase | 0 | 0 |
| α-Glucosidase | 2 | 2 |
| β-Glucosidase | 1 | 0 |
| N-Acetyl-b-glucosaminidase | 0 | 0 |
| α-Mannosidase | 0 | 0 |
| α-Fucosidase | 1 | 0 |
| Control | 0 | 0 |
[i] 0: 0 nmol, 1: 5 nmol, 2: 10 nmol, 3: 20 nmol, 4: 30 nmol, 5: 40 nmol