Bacterioplankton composition in tropical high-elevation lakes of the Andean plateau

Abstract

High-elevation lakes in the tropics are subject to extreme environmental fluctuations and microbes may harbor a unique genomic repertoire, but their composition and diversity are largely unknown. Here, we compared the planktonic bacterial community composition (BCC) and diversity of three tropical lakes located in the high Andean plateau (≥4400 m above sea level) during the dry and wet season. Diversity in these lakes was higher in the cool and wet season than in the warm and dry one. Operational taxonomic units (OTUs) composition was significantly different among lakes and between seasons. Members of the class Opitutae, Spartobacteria, Burkholderiales and Actinobacteria were dominant, but only the hgcI clade (Actinobacteria) and the Comamonadaceae family (Burkholderiales) were shared between seasons among the three lakes. In general, a large percentage (up to 42%) of the rare OTUs was unclassified even at the family level. In one lake, a pycnocline and an anoxic water layer with high abundance of Thiocapsa sp. was found in the wet season indicating that the known polymictic thermal condition is not always given. Our study highlights the particular BCC of tropical high-elevation lakes and also how little is known about the variability in physico-chemical conditions of these ecosystems.

Keywords: 16S rRNA gene; Altiplano; Bacterial diversity; Illumina Miseq; Thiocapsa sp..

Figure 1.

Location of the study sites in the Chilean Altiplano.

Figure 2.

Shannon diversity among Altiplano lakes in different seasons. Cota: Lake Cotacotani, Pia: Lake Piacota, Chun: Lake Chungará, DS: dry season, WS: wet season.

Figure 3.

Non-metric multidimensional analysis based on Bray–Curtis dissimilarity showing similarity among lakes communities. Abbreviations as in Fig. 2.

Figure 4.

Average relative abundance of abundant (>1%), uncommon (>0.1% to <1%) and rare OTUs (<0.1% of the total number of reads in a given sample).

Figure 5.

Relative abundance of the main phyla (>1%) in Lake Cotacotani. Clustering of samples represented by a dendrogram based on Bray–Curtis dissimilarity. DS: dry season. WS: wet season. (c): composite simple.