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susceptible at a concentration of 0.02mg/ml. It was observed that the callus extract of

Pongamia pinnata in methanol inhibited S. aureus with the inhibition zone of 26mm at
0.1mg/ml concentration which was quite high amongst all the tested bacteria. At 0.1mg/ml

concentration B. subtilis was also inhibited with a 20mm zone of inhibition. E. coli and K.
pneumoniae were less affected compared to the other two pathogens tested. Based on the

present study it is observed that P. pinnata callus extract is more effective against gram-
positive strains. The callus extracts of P. pinnata in diethyl ether did not show any

antibacterial activity against any of the pathogens tested up to the concentrations of

0.08mg/ml (Table 4A.5). However, at 0.1mg/ml concentration zone of inhibition was
observed in K. pneumoniae and S. aureus cultures.Taraquzzaman et

al. (2014) observed that there was no significant activity with methanol extract of

Pterospermum semisagittatum against gram-positive and gram-negative bacterial
cultures. Contrary to this several reports are suggesting the methanol extracts have

antibacterial properties. Kachhawa et al. (2012 b) reported that Pterocarpus marsupium, a
member of the family Leguminosae, showed potent antibacterial activity with methanolic

extract against E. coli. Kamraj et al. (2012) reported significant antimicrobial activity of
Acacia karroo with methanolic extract. Pongamia pinnata, methanolic extracts of seed as

well as callus had shown potent antibacterial activity against gram-negative and gram-

positive bacteria. Hence, the seeds and callus of both plants can be a good source of
antimicrobial agents.

Photoplate 4A.5 Effect of methanolic seed Extract of P. pinnata on E. coli

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Photoplate 4 A.6 Effect of methanolic seed extract of pinnata on B. Subtilis

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