Bacteria in Himalayan glacial ice and its relationship to dust

Abstract

Concentrations and community diversity of bacteria from 50 segments of a 108.83 m ice core drilled from the East Rongbuk (ER) Glacier (28.03&deg; N, 86.96&deg; E, 6518 m above sea level) on the northeast slope of Mt. Qomolangma (Everest), covering the period 950–1963 AD, were investigated by epifluorescence microscope, DGGE and Shannon-Weaver index analysis. Bacteria in the ER core were identified as β, γ-<i>proteobacteria</i> and <i>Firmicutes</i> group, with γ-<i>proteobacteria</i> being the dominance. Different bacterial population was identified along the core, reflecting the effects of climatic and environmental changes on the bacterial distribution in the glacial ice. There are four general periods of bacterial diversity, corresponding to four phases of dust abundance revealed by Ca²⁺ concentrations. However, a previously suggested positive correlation between bacterial and Ca²⁺ concentrations was not indicated by our observations. Instead, a weak negative correlation was found between these two parameters. Our results suggest that bacterial community diversity, rather than concentrations, might be a suitable biological proxy for the reconstruction of past climatic and environmental changes preserved in glacial ice.