Imo, Ejeagba Okorie2026-03-182026-03-182021Imo, E. O. (2021). Fungal influenced corrosion of metals and their inhibition by plant extracts [Unpublished Doctoral Thesis]. Federal University of Technology, Owerri, Nigeriahttps://repository.futo.edu.ng/handle/20.500.14562/2417This thesis is for the award of Doctor of Philosophy (PhD.) degree in Environmental MicrobiologyGrowth of fungi on metal surfaces can initiate, facilitate and accelerate corrosion reactions, altering the composition and integrity of such metal without changing its electrochemical nature. Studies on fungal influenced corrosion of mild steel (MS) and aluminium (Al) in the presence of Acremonium kiliense, Aspergillus fumigatus and Penicillium chrysogenum and their inhibition by seed extracts of Aframomum melegueta and Piper guineense were carried out using gravimetric and potentiodynamic polarization techniques. MS (C-0.30%, Si-0.30 %, Mn-0.30 %, P-0.045 %, S-0.050 %, Cr-0.064 %, Cu-0.040 %, Ti-0.04 % and balance Fe) and Al (>95.5 %) plates, 2x2x0.14 cm and 3x1.5x0.1 cm in size respectively were contaminated with the mentioned fungi in Petri dishes with nutrient medium imitating organic pollution. The results revealed that the metals reacted differently to the impact of fungi. The influence depends on the capacity of fungi to develop on the metal surface and produce metabolites stimulating changes in polarization resistance and destroying the surfaces. A. fumigatus proved to be the most active destructor of mild steel and aluminium with cumulative corrosion rate (ΣCR) of 7.85±0.91 mpy, 7.49±0.57 mpy and corrosion current density (Icorr) of 279.4 μA/cm2 , 201.2 μA/cm2 for mild steel and aluminium respectively. The gravimetric analysis further revealed that the corrosion rate and weight loss of the metals increased with time. Cold water extracts of A. melegueta and P. guineense were assessed for their anticorrosion and antifungal activities. The anticorrosion studies at 25mg/mL concentration showed that the inhibitors are mixed-type inhibitors inhibiting boththe cathodic and anodic sites. P. guineense showed the highest inhibition efficiency (IE) against A. fumigatus (87 %IE). A. melegueta was more effective against A. kiliense (85 %IE). The study shows that the attachment and growth of fungi on the surface of metals can influence their corrosion reactions. That the phytochemical constituents of plant extracts could be exploited for use in the control of microbial influenced corrosion of metals.enAttribution-NonCommercial-ShareAlike 4.0 InternationalFungimetalscorrosionplant extractspolarizationcorrosion rateDepartment of MicrobiologyDoctoral Thesis