Soluble carbohydrate and organic acid content of soils and associated microbiota from the Windmill Islands, Budd Coast, Antarctica

Abstract

In the cold Antarctic environment labile organic compounds may accumulate in soil due to relatively low utilization rates by heterotrophic microorganisms. Microbial fermentation of these compounds might contribute to the development of strongly acid soils. To test this and assess concentrations, extracts of a range of soils in the Windmill Islands, Budd Coast were analysed by GLC and HPLC for the presence of low molecular weight sugars, polyols and organic acids. Concentrations of sugars and polyols up to 3300 mg g⁻¹ were detected in cryptogam dominated soils. Some, such as trehalose, may have principally originated in the soil microflora. Soils from occupied penguin rookeries were found to possess oxalic, acetic, propionic and succinic acids at levels up to 1000 mg g⁻¹ soil. Most other soils, however, lacked these acids at detectable levels (1–5 mg g⁻¹ soil). No correlation was established between organic acid accumulation and soil pH although those dominated by moss and lichen had been acidified significantly when compared with barren soils. Thus while substantial pools of these readily utilized carbohydrates were probably present in cryptogam dominated soils, there was little accumulation of organic acids which could account for the acidity of mineral soils typical of the Windmill Islands.