Antimicrobial Efficacy of Plant Extracts against Microorganisms Isolated from Deteriorating Building Walls

Abstract

Dilapidated buildings harbor microbes that contribute to deterioration and health risks. From walls in the University of Africa Toru-Orua, three bacteria (Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli) and two fungi (Aspergillus fumigatus, Penicillium chrysogenum) were isolated and identified using morphological, biochemical, and microscopic methods. The antimicrobial activity of neem (Azadirachta indica), garlic (Allium sativum), and scent leaf (Ocimum gratissimum) extracts was evaluated by agar well diffusion. All extracts showed concentration-dependent inhibition, with fresh preparations more effective. Garlic exhibited the strongest activity (23.5 mm against B. subtilis, 20.4 mm against E. coli, and 17.4 mm against fungi), neem showed moderate inhibition (up to 19.2 mm), while scent leaf was least active (≤12.6 mm). P. aeruginosa resisted lower doses but was inhibited up to 18.1 mm at higher concentrations. These findings indicate that garlic and neem possess strong antimicrobial potential and may serve as eco-friendly alternatives for controlling biodeterioration in built environments.