ANTIMICROBIAL ACTIVITIES OF INDIGENOUS BLACK SOAP FORTIFIED WITH EGGSHELL POWDER ON SOME SELECTED SKIN PATHOGENS

Abstract

Antimicrobial activities of indigenous black soaps on the following skin associated pathogens: Staphylococcus aureus, Staphylococcus epidermidis Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Trichophyton rubrum, Candida albicans, Staphylococcus aureus ATCC-25923, Staphylococcus epidermidis ATCC-12228, Pseudomonas aeruginosa ATCC-27853 Escherichia coli ATCC-25922, Klebsiella pneumoniae ATCC-11930, and Candida albicans ATCC-10261 were investigated using agar diffusion method. Black soap was prepared with ashes from dried cocoa pod husks by saponification (hot method) and then fortified with brown and white eggshell powder at 20g/250 mL of molten soap before allowing it to cure in a mould for two weeks. (Black soap was also acquired from the market). Commercial antiseptic soaps and creams: Safeguard, Dettol, Roberts, Delta and Septol; Tridermix, Visita-plus, funbact A, Epiderm and Acneaway as well as broad spectrum standard antibiotics also served for comparative and control purposes. Bacterial isolates from the black soap sources are Bacillus vedderi and Bacillus farraginis. Fungal isolates: Chrysosporium spp and Aspergilus granulosus from the black soap market sample; Aspergilus flavus from black soap fortified with white eggshell powder and Ramulispora javanicus from black soap fortified with brown eggshell powder. (Antagonistic potentials of these alkaliphiles on the clinical test pathogens were investigated by co-culture method). Plasmid profiling of the bacteria showed the presence of plasmids. B. vedderi contained plasmid with an estimated molecular weight of 17578 bp. Proximate analysis of the eggshells revealed they are high organic matter. Physicochemical properties of the black soaps implied they are suitable for bathing as evident in their Total Fatty Matter (TFM%) of 78.107, 44.304 and 50.314 for market sampled black soap, black soap fortified with brown and white eggshell powder respectively. Qualitative and quantitative screening for phytochemicals showed Saponin was the highest with values between 20.50 - 33.31 mg/g while Tanin the lowest between 1.05-2.05 mg/g across the black soap samples. Structural elucidation of methylated fraction of the black soap by Gas Chromatography/Mass Spectrometry (GC/MS) has shown the presence of fatty acids as the dominant functional groups. The antagonism assay showed that B. vedderi and B. faraginis inhibited the growth of E. coli, and S. epidermidis with inhibition zones ranging from 15-34 mm. Black soap had more inhibitory effects on all the pathogens. Black soap fortified with brown eggshell had the highest inhibition zone of 17.83 mm on Candida albicans ATCC-10261 followed by the black soap market sample at 15.83 mm on the same organism, Dettol had the highest inhibitory action at 12.17 mm of inhibition zone against Klebsiella pneumoniae ATCC-11930 of the selected antiseptic soaps. The comparative Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and Minimum Fungicidal Concentration (MFC) of the black and commercial antiseptic soaps ranged from 62.5 mg/mL and 500 mg/mL. The mechanism of action showed that sodium and potassium ions were leaked by the black soaps from the cell of the organisms. Sodium ion was leaked to a value of 833 ppm for S. aureus while potassium ion to a value of 20 ppm for T. rubrum. This study has posited that the antimicrobial activities of the black soap may be attributed to its phytochemicals, fatty acids and bacterial flora. .