from indigenous fermented foods and human gut ... - Thapar University

Table 3.1 Isolation of Lactobacillus from different sources
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Chapter III Material and methods
S. No. Source name Number of
samples examined
1 Mango pickle 100
2 Garlic–chilli pickle 100
3 Chilli pickle 100
4 Fermented rice (Bhaati jaanr) 50
5 Fermented mustard (Kharoli) 50
6 New born babies meconium 36
Total samples 436
3.3.4 Carbohydrate Fermentations
Isolates were characterized according to their fermentation ability to ferment eight
different carbohydrates. All reactions were performed by using 96-well microtitre plates
containing fermentation medium with different sugars, namely Glucose, Sorbitol, Mannitol,
Lactose, Maltose, Mannose, Galactose and Arabinose. Active cells and sugar solutions were
prepared separately. For preparation of active cells; isolates were activated in 10 ml MRS
medium and incubated at 37°C for 24 h followed by centrifugation for 10 min at 10,000 rpm.
Pellets obtained were washed twice with saline and resuspended in MRS broth without
glucose, containing pH indicator bromothymol blue (0.01 g/l). The sugar solutions were
prepared at a final concentration of 10% (w/v) after filter sterilization with sterile 0.22 µm
membrane filters (Millipore TM , India).
After preparative steps, following procedure was applied: 40 μl of sugar solutions
were pipetted into each well followed with addition of 160 μl of suspended cells, giving the
final sugar concentration of 2%. All the reactions were performed in triplicates. Positive and
negative controls were used to indicate any contamination. Suspended cells (160 μl) and
glucose (40 μl) solution were used as positive control while suspended cells (200 μl) alone
were used as negative control. After overnight incubation at 37°C, the turbidity and the color