Morphological and molecular characterization of ascobolus and pilobolus fungi in wild herbivore dung in Nairobi National Park

Abstract

Coprophilous fungi are abundant species found in dung of most wild animals, and an easily available and abundant tool for studying and monitoring ecosystem changes. The focus of this study was to characterize two genera of coprophilous fungi, Pilobolus and Ascobolus. These fungi are important in decomposing and recycling of nutrients from animal waste. Ascobolus fungi are important in genetic studies and have been identified as a source of enzymes and antibiotics. Pilobolus fungi play a role in transmission of pulmonary bronchitis because they vector lungworms. Diversity studies of these species give insight on the state of an ecosystem and can be used to predict occurrence of environmental stressors. In this study, wild herbivore dung was collected in Nairobi National Park and incubated for fungal sporulation and afterwards characterized by morphological and molecular methods. The Internal Transcribed Spacers 1 and 2 regions of ribosomal DNA of Pilobolus were sequenced. Five species of Ascobolus were described using morphological means: A. immersus, A. amoenus, A. bistisii, A. calesco, and a possible novel Ascobolus species with four spores as opposed to the usual eight. Three species of Pilobolus were described using morphological means: P. crystallinus, P. heterosporus and P. pullus. Molecular analysis revealed three species of Pilobolus: P. crystallinus, P. heterosporus¸ and P. pullus. However, P. crystallinus had P. heterosporus as the closest match though with low identity. On the other hand, the sequences showed that there was some (89%-99%) similarity between Pilobolus collected from this study and those from the United States of America. Consequently, molecular identification of Pilobolus offered a confirmation of species identity. In terms of abundance, Ascobolus immersus and P. crystallinus were the most common species observed. Similarly, waterbuck and zebra dung showed the highest diversity of fungal species while hippopotamus and giraffe had the least number and this could be attributed to the limitation of their feeding areas. The highest observed species richness per dung pile was 5 while the estimated species richness was 15. Therefore, indicating diversity of coprophilous fungi in Nairobi National Park ecosystem is relatively high. The results of this study can be used as a baseline for future monitoring of environmental degradation in the park