Fungal Community Diversity and Structure from Cave Mineral Surfaces and Bat Guano in Kartchner Caverns, Arizona

Abstract

Research regarding the distribution and structure of fungal communities in caves is lacking. The current study examines fungal communities in Kartchner Caverns, a mineralogically diverse cave located in the Whetstone Mountains, Arizona, USA. The first study examines culturable fungal diversity from speleothem surfaces. Twenty-one fungal genera represented by 43 genotypes and 53 distinct morphological taxonomic units (MTU) were recovered from 15 speleothems. Analysis of DGGE profiles indicated a significant effect of sampling site on community structure. The second study examined fungal diversity from speleothem and rock wall surfaces using the 454 FLX Titanium sequencing platform using the rDNA internal transcribed spacer 1 (ITS1) as a genetic marker. Fungal diversity was estimated and compared between speleothem and rock wall surfaces and its variation with distance from the natural entrance of the cave was quantified. Effects of environmental factors and nutrient concentrations in speleothem drip water at different sample sites on fungal diversity were also examined. Sequencing revealed 2219 fungal operational taxonomic units (OTUs) at 95% similarity. Speleothems supported a higher fungal richness and diversity than rock walls, but community membership and the taxonomic distribution of fungal OTUs did not differ significantly. OTU richness and diversity were negatively correlated with distance from the natural cave entrance. Community membership and taxonomic distribution of fungal OTUs differed significantly between the front and back of the cave. There was no observed effect of drip water nutrient concentration on fungal community structure. The third study examined fungal community structure from bat guano over the course of a year. There was no significant difference in fungal OTU richness, diversity, or community membership and taxonomic affiliations among sampling times. There were no significant differences in nutrient concentrations of guano samples among sampling times. Nutrient concentration did have a significant effect on community structure, especially the level of nitrogen and calcium.