Penicillium species

Emulsion paints are widely used for decorative and protective purposes but are susceptible to fungal degradation, particularly in tropical climates with high humidity. This study investigated the degradation of emulsion paint using fungal isolates (Aspergillus niger and Penicillium species) under controlled laboratory conditions. The fungi were inoculated into mineral salt medium supplemented with 5% commercial white emulsion paint as the sole carbon source and incubated at room temperature (25–28°C) for seven days. Four experimental setups were established: Flask A (Aspergillus niger), Flask B (Penicillium sp.), Flask AB (mixed culture), and a control flask. Fungal growth was monitored using serial dilution and pour plate techniques on Potato Dextrose Agar (PDA), while physicochemical parameters (pH, temperature, and optical density at 600 nm) were measured at regular intervals. Results revealed that Penicillium sp. achieved the highest final population of 2.75 ×10⁶ CFU/ml and optical density of 50.9, indicating superior paint degradation capability. Aspergillus niger demonstrated the highest percentage growth rate of 1,328.6%, increasing from 3.5 × 10⁴ CFU/ml to 5.0 × 10⁵ CFU/ml between Day 3 and Day 7. The mixed culture yielded 1.50 × 10⁶ CFU/ml with a growth rate of 1,053.8%, showing no significant synergistic effect. pH fluctuations, particularly acidification to pH 5.1 in single species flasks, suggested organic acid production during metabolism, facilitating enzymatic breakdown of polymeric paint components. These findings highlight the ecological significance of fungi in paint deterioration and emphasize the need for antifungal additives in paint formulations, routine maintenance, and environmental control measures to mitigate microbial colonization in humid tropical environments