Rahman, Norhaswani Abd
(2014)
The effects of quercus infectoria gall
extract on the morphology of gram-positive
bacteria, gram-negative
bacteria and yeast.
Project Report.
Universiti Sains Malaysia.
(Submitted)
Abstract
The gall extract from Q. infectoria is well known to have a broad spectrum of
activity against Gram-positive bacteria, Gram-negative bacteria and yeast. However, studies on identifying and comparing the antimicrobial mechanisms of phytochemicals in the Q. infectoria gall extract are still limited and not well
established. The aims of this study were to determine the antimicrobial activity of
methanolic 0. infectoria gall extract against Gram-positive, Gram-negative and yeast
strains, and also to study the effects of the gall extract on the cell morphology of the
tested strains. Antimicrobial activity of gall extract was screened using disc diffusion
method against Gram-positive bacteria (S. agalactiae), Gram-negative bacteria (P.
vulgaris) and yeast (C. albicans). Minimum inhibitory concentration (MIC) was
determined using twofold serial microdilution technique at concentrations ranging
between 0.01 mg/mL and 5.00 mg/mL (for bacteria) and between 0.02 mg/ml and
12.00 mg/ml (for yeast). Minimum bactericidal concentration (MBC) and minimum
fungicidal concentration (MFC) were determined by subculturing the wells plate
which showed no apparent growth or turbidity onto the agar plates. Morphological
changes of treated cells (IxMlC and 4xMIC) were then observed under scanning
electron microscope (SEM). A higher antimicrobial activity was observed against C.
albicans in this study. Based on the MBC to MIC ratio or MFC to MIC ratio, the extract was considered as bactericidal and fungicidal against the tested strains.
Morphological changes were observed in all treated cells but more distinct at 4xMIC
under SEM. This preliminary study provides scientific information to the effect of
gall extract on the bacterial and fungal morphology suggesting its antimicrobial
mechanism on the cell wall and membrane integrities.
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