Assessment of Microplastic Degrading Potential of Fungal Isolates from an Estuary in Rivers State, Nigeria

The potential of fungi as bio degraders of micro plastic particles was assessed using standard microbiological and Fourier transformed Infra-Red (FTIR) spectroscopic analysis methods. The highest mean Total Heterotrophic fungal (THF) count of 4.24x104 cfu/ml was obtained with the least THF (2.72x104 cfu/ml) recorded during the dry season. Mean hydrocarbon Utilizing Fungal (HUF) count was highest (1.78x104 cfu/ml) during the wet period while the least HUF count (1.46x104 cfu/ml) was recorded during the dry period. Spectra of FTIR showed that the water contained microplastic particles in these proportions; polyethylene of low density (LDPE) 0.01%, 0.11% protein, 0.15% polystyrene, 0.37% polyamide, 1.14% cellulose, 1.21% polyurethane, 1.90% polyvinyl chloride, 3.11% polyester and 92% polypropylene, respectively. Species of fungi identified were Aspergillus niger, Penicillium spp., Rhizopus spp., Mucor spp., Aspergillus nidulans, Fusarium spp., Microsporum canis, and Aspergillus fumigatus. Among the fungal isolates, A. niger and A. fumigatus were most active in degrading the micro plastic (polypropylene) with mean % weight loss of 71.09% and 53.09%, respectively while the least active was Penicillium spp. with a mean % weight loss of 28.64% during the study period. The order of degradation was Aspergillus niger > A. fumigatus > A. nidulans > Fusarium spp. > Rhizopus spp. > Microsporum canis > Mucor spp. > Penicillium spp. The potential to degrade micro plastic particles by these fungi can be harnessed. The foremost active fungi degrading potentials are as follows: A. niger (71.1%) and A. fumigatus (53.1%). The study has shown that isolates of fungi from Ohiakwu River in Nigeria possess the ability to degrade micro plastic (polypropylene) particles. Therefore, this research is of tremendous importance for industrial development and additionally for future research purposes.