Full Length Research Paper

Inhibition of dehydrogenase activity in pathogenic bacteria isolates by aqueous extracts of Musa paradisiaca (var Sapientum)

Alisi C. S.¹*, Nwanyanwu C. E.², Akujobi C. O.² and Ibegbulem C. O.¹

¹ Department of Biochemistry, Federal University of Technology Owerri.

²Department of Industrial Microbiology, Federal University of Technology Owerri.

*Corresponding author: E-mail: chinwealisi@yahoo.com. Tel: +234 80 3869 3868.

Accepted 30 May, 2008

Inhibition of dehydrogenase activity in pathogenic bacteria isolates by aqueous extract from the unripe fruit peels (called the bark) and leaves of Musa paradisiaca var sapientum were investigated via dehydrogenase assay using 2,3,5-triphenyl tetrazolium chloride (TTC) as the electron acceptor. Pure cultures of Staphylococcus and Pseudomonas species were exposed to varied concentrations of the extract [0 – 2000 µg/ml]. The extracts exhibited concentration dependent response against the tested organisms. Dehydrogenase activities (mg Formazan/mg cell dry weight/h) in the Gram-positive Staphylococcus sp. and Gram-negative Pseudomonas sp. were 1.125 ± 0.056 and 0.740 ± 0.040, respectively, and were progressively inhibited in the pure cultures. Threshold inhibitory concentrations (IC₅₀) of M. paradisiaca bark extract were 143.5 and 183.1 µg/ml against Staphylococcus and Pseudomonas species, respectively, while the threshold inhibitory concentrations (IC₅₀) of M. paradisiaca leaf extract were 401.2 and 594.6 µg/ml, respectively. The IC₁₀₀ of the leaf extract against Staphylococcus and Pseudomonas species were 1850 and 2000 µg/ml respectively, while the bark could not completely inhibit the organisms at the tested concentrations. The bark and leaves of M. paradisiaca may be an available source of raw material for the production of chemotherapeutic agents against pathogenic bacteria.

Key words: Musa paradisiaca, dehydrogenase activity, pathogenic bacteria..