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D. Lahiri et al.
Fig. 3 Effect of treatment of A. cepa on the biofilm formation of B. cereus
Fig. 4 Effects of treatment with ethanolic extract of A. cepa on the quorum sensing activity of oral
isolates
3.3 Effect of Treatment on Quorum Sensing
Since quorum sensing (QS) used to play critical role in regulating biofilm formation,
the concentration of acyl homoserine lactone (AHL), the autoinducer molecule in
QS could be used as a marker. It was observed that there was a marked diminution
(around 50%) in the concentration of AHL in both the working strains after being
treated with extracts of A. cepa and azithromycin (Fig. 4). However, the extract of A.
cepa was found to be more effective than azithromycin in inhibiting AHL dependent
quorum sensing.
3.4 Effect of Treatment on Viability and Revival
of the Biofilm Forming Bacterial Cells
It was observed that the count of sessile bacterial cells from the biofilms of B. cereus,
treated with herbal compounds and antibiotics showed marked reduction with time.
This reduction was higher in extract-treated cells than those of antibiotic-treated cells.
It was observed that the viability of bacterial cells showed a marked reduction of 9.3%