Limonene inhibites the growth of resistant e. coli and pseudomonas aeruginosa

Saeedeh Ghiasvand,1,* Ali shalilian,2 Firoozeh alavian,3

1. Department of Biology,faculty of science Malayer University
2. Department of Biology,faculty of science Malayer University
3. Faculty of science,Farhangian University Tehran, Iran



Through the last decades, by developing new antibiotics for microorganisms, the resistance of bacteria developed too. therefore, new compounds should be use for antibiotics to have greater effect on microorganism and infections. plants have always been a good secondary and sometimes primarily participants in antibiotics and in last decade the use of herbal drugs are growing worldwide. herbs and natural compounds could be a good help in making and developing recombinant this study, we investigate the antibacterial properties of citrus essence (limonene). its main constituents are 51% linal acetate, 35% linalool and camphor. bacteria used for this study are e. coli and pseudomonas aeruginosa hospital variant. the bacteria were gathered from malayer hospital and were resistant to variety of antibiotics.


Bacteria were incubated in nutrient broth , overnight and in 37 ̊c. then cultivate in nutrient agar media with wells which have already been filled with limonene. after 24 hours the diameter of inhibition region were measured. for synergism effect of the limonene the prepared bacteria were added to nutrient agar media and then the antibiotic disks and limonene were added to the media and after 24 hours the diameter of inhibition region were measured.


Limonene inhibited the growth of e. coli with 10mm inhibited region diameter, pseudomonas aeruginosa with 11mm inhibited region diameter. synergism results showed that if the limonene was added to media with antibiotics, the bacteria are more inhibited and the inhibition region is greater therefore the antibiotic is more useful with limonene. the limonene inhibited e. coli 15mm more than penicillin disk itself, and limonene inhibited pseudomonas aeruginosa 3mm more than penicillin disk itself.


Based on these results, limonene could be a useful compound of new antibiotics. our developed antibiotics and drugs need herbal substitute for greater effect and less harm for health of human kind.


limonene, hospital bacteria, resistance, recombinant drugs, herbal compounds.