Antimicrobial activity of some macrophytes from Lake Manzalah (Egypt)

The antimicrobial activities of aqueous and organic solvents (chloroform, ethanol and methanol) extracts of four plants Ceratophyllum demersum L., Eichhornia crassipes, Potamogeton crispus and Potamogeton pectinatus were tested in vitro against seventeen different microorganisms including Gram-positive and Gram-negative bacteria and fungi. Nine of these identified organisms were obtained from different sources, Bacillus subtilis 1020, Bacillus cereus 1080, Staphylococcus aureus, Erwinia carotovora NCPPB 312, Candida albicans, Candida tropicalis, Aspergillus niger, Fusarium oxysporum and Penicillium italicum. The other eight organisms were isolated from Manzalah lake water and identified using API 20E strip system (BioMereux). One hundred pathogenic bacterial isolates representing eight genera were identified to species level. These organisms are Escherichia coli (20%), Pseudomonas aeruginosa (16%), Klebsiella pneumoniae (14%), Salmonella colerasuis (13%), Shigella sp. (11%), Serratia liquefaciens (10%), Proteus vulgaris (9%) and Brenneria nigrifluens (7%). The extracts of all tested plants demonstrated antimicrobial activity against the used organisms. The efficiency of the extracts varied with, solvent used in the extraction as well as plant species and the part of plant used. The aqueous extract appeared to be the highly effective extract against all tested organisms especially Fusarium oxysporum causing inhibition zone 48 +/- 0.01 mm, Pseudomonas aeruginosa 59 +/- 0.02 mm and Salmonella cholerasuis 55 +/- 0.01 mm when using P. crispus, P. pectinatus and C. demersum, respectively. Ethanol extracts of C. demersum, P. crispus and E. crassipes root showed antimicrobial activities against all tested organisms except Aspergillus niger. At the same time the extract of P. pectinatus had no effect also on Fusarium oxysporum and the extract of E. crassipes leaves have no effect on Penicillium italicum. On using chloroform extracts Escherichia coli, Aspergillus niger and Penicillium italicum showed resistance. Comparing the effect of different plants extracts C. demersum appeared to be the most effective followed by P. pectinatus. Furthermore, the extracts of E. crassipes leaves being more effective than that, of its roots. Elemental analysis were also takes place in water and plant samples and the results revealed the presence of Mn and Pb in higher concentration in P. pectinatus (Mn 603 +/- 4.243 ppm and Pb 44 +/- 2.828 ppm), at the same time the highest values of Fe 1680 +/- 2.2 ppm, Zn 31.5 +/- 2.1 ppm and Cu 26.5 +/- 2.1 ppm were recorded for C. demersum. Comparing the two parts of E. crassipes (leaves and roots), the roots have the highest values of all studied metals.