Metagenomic Comparisons between Soft and Hard Feces of Plateau Pikas (Ochotona curzoniae).

Haibo Fu,Wenjing Li

doi:10.3390/ani12020149

Abstract

Simple SummaryPlateau pika produces hard and soft feces with different morphology, component and microbial structure. Hard feces had more abundant Firmicutes, while soft feces had more abundant Akkermansia. The differences of microbial communities between hard and soft feces were mainly driven by core microbomes. Soft feces had a comprehensive advances in predict functional pathways compared to hard feces, these strengthened functional pathways were closely associated with metabolism of energy, vitamins, and amino acid. Our study preliminarily explored the differences in microbial structure and function between hard and soft feces, provided a foundation for future systematic explorations of the cecotrophy. The division of hard and soft feces is an effective digestion strategy in the order Lagomorpha. Although previous studies have reported that hard and soft feces differ in morphology and component, the discrepancy in the microbiome remains unclear. This study explored the microbiomes of hard and soft feces in plateau pikas by sequencing the V3 and V4 regions of 16S rDNA. We found that hard feces harbored higher Firmicutes, while soft feces harbored higher Akkermansia. Increased rare bacterial taxa were observed in hard feces compared with soft feces. Moreover, hard and soft feces displayed a greater difference in terms of core operational taxonomy units (OTUs) compared to the total OTUs. The soft feces showed enhancements in all predicted Kyoto Encyclopedia of Genes and Genomes (KEGG) functions, indicating an advancing microbial metabolism compared to hard feces. The significantly upregulated pathways in soft feces were mainly enriched in metabolism of energy and carbohydrate, glycan biosynthesis, cofactors and vitamins, and amino acids—all of which are associated with increased contents of microbial proteins, vitamins, and short-chain fatty acids. Our study reports, for the first time, the differential microbiomes between hard and soft feces of pikas and provides direction for the future studies on cecotrophy.

Highlights

Plateau pika is a keystone species for its widespread distribution and multiple roles in the alpine meadow ecosystem (Figure 1a) [1,2,3]
Cecotrophy is a wise and successful strategy evolved from coprophagy, which contributes to the host having greater efficiency to recycle the energy and nutrition compared to coprophagy [10,11,12]
Cecotrophy is based on the colonic separation mechanism (CSM) at the proximal colon [11]; the pikas, defecate conventional solid pellets and soft dark feces, and they eat the soft ones by licking them from the anus when they are released (Figure 1b) [12,13]

Summary

Introduction

Plateau pika is a keystone species for its widespread distribution and multiple roles in the alpine meadow ecosystem (Figure 1a) [1,2,3]. Cecotrophy is based on the colonic separation mechanism (CSM) at the proximal colon [11]; the pikas, defecate conventional solid pellets (hard feces) and soft dark feces, and they eat the soft ones by licking them from the anus when they are released (Figure 1b) [12,13]. These two types of feces differ in shape and component, formation mechanism, and microbial structure [14,15].

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