Molecular characterisation of fungi associated with sewage-impacted soil

Abstract

The decay of faecal matter from a septic system causes the arousal of fungi in the surrounding soil. These fungi can cause diseases if there is sewage spillage containing untreated or improperly treated wastewaters. Molecular techniques of identification of fungi have shown to be more dependable than traditional methods of identifying fungal species. This study was carried out to identify the fungal species associated with soil obtained from sewage-impacted soil near a septic tank using both traditional cultural techniques and molecular method. Fungi associated with the soil samples were isolated using serial dilution and Potato Dextrose Agar (PDA) method. Deoxyribonucleic Acid (DNA) was extracted from the pure cultures of fungal isolates using Quick DNA Fungal/Bacterial Miniprep kit. Polymerase Chain Reaction (PCR) amplification of internal transcribed spacer (ITS) region of the fungal isolates was carried out using universal primer pair; ITS4 and ITS5. The PCR products were sequenced and the sequences were blasted against National Centre for Biotechnology Information database. The result of the nucleotide sequence analysis revealed the identity of the isolates as Trichoderma harzanium with 580 base pairs and Aspergillus welwitschiae with 560 base pairs. Sequences of the isolates were aligned and compared with sequences on GenBank and a phylogenetic tree was constructed. The cultural method only aided in suggesting the suspected genera of the isolates while the molecular method was able to identify the isolates to the species level. This study will promote the knowledge of the fungal species associated with sewage-impacted soil and also aid researchers in proffering ways to enhance the prevention/control of diseases associated with sewage spill.

Keyword: Septic tank, fungi, soil, phylogeny, sequencing