The isolation and antimicrobial testing of fungal species from two different soil environments in the Littoral Region of Cameroon

Research for new antimicrobial compounds is focusing more on fungi found in tropical soils, where these fungi help break down organic matter and recycle nutrients. However, invasive plants like Chromolaena odorata can disrupt these helpful soil fungi communities. This study aims to isolate and identify fungal species and antimicrobial potentials in soils from Chromolaena dominated fallow plots and soil fallow plots void of Chromolaena odorata at two depths (0–5 cm and 5–15 cm) in the Ndoulou Littoral Region of Cameroon. Six representative fungal isolates were obtained, and PCR amplification of the Internal Transcribed Spacer (ITS) region yielded clear ~ 500–550 bp bands in all cases, confirming high-quality templates ready for Sanger sequencing. BLAST analysis against NCBI GenBank identified the isolates as: Arcopilus cupreus (100% identity), Pseudopestalotiopsis theae (99.64%), Coniochaeta cymbiformispora (94.81%), Aspergillus ardalensis (99.83%), Lividopora vincta (98.96%), and Lividopora benetosta (99.85%). These taxa span a range of ecological roles from saprotrophic decomposers ( Arcopilus , Coniochaeta , Lividopora ) important for litter breakdown in tropical soils, to plant-associated or pathogenic fungi ( Pseudopestalotiopsis ) broadly distributed in tropical ecosystems, and widely adapted soil dwellers ( Aspergillus ). Crude ethyl acetate extracts from the isolates were tested for antibacterial activity against Klebsiella pneumoniae , Staphylococcus aureus , and Salmonella typhi using the broth microdilution method; no significant inhibition was observed whereas ciprofloxacin exhibited potent efficacy (MIC = 0.0039 µg/mL), confirming assay validity. Results confirm the presence of ecologically significant fungal taxa in Chromolaena -influenced and undisturbed soils, though unrefined extracts lacked antibacterial activity under current conditions. The findings highlight the taxonomic and functional diversity of fungi in Cameroonian fallow soils impacted by invasive plants, underscoring the need for further studies exploring the ecological roles and potential bioactivities of these fungal communities. This research provides a foundation for future bioactivity-guided fractionation and ecological restoration efforts in tropical soils affected by invasives.