Short note: extracellular export and consumption of glucose in Antarctic sea ice

Abstract

Extracellular carbohydrate production is widespread in sea ice microbial communities, being produced by both algae and bacteria. Under stressful conditions, including nutrient limitation and high light, cells may export excess fixed carbon as glucose. Glucose microsensors were used to measure extracellular glucose exudation and consumption in a sea ice algal community. Glucose export increased with increasing irradiance between 15 and 512 µmol photons m−2 s−1. This export correlated with declining FvFm values and increasing NPQ values, implying that glucose export resulted from exposure to above optimal irradiances. Glucose concentrations in samples treated with DCMU to block photosynthesis, declined at all irradiances. Bacterial consumption of glucose was between 6 and 34% of extracellular export per hour. There have been very few measurements of DOC/glucose in sea ice and the data presented here make an important contribution to our understanding of sea ice microbial processes.

Glucose Enhances Salinity-Driven Sea Spray Aerosol Production in Eastern Arctic Waters

“…Indeed, the composition of DOC exudates of sea-ice inhabiting microorganisms is dominated by glucose, which often constitutes more than 70% of the total. 95 Recently, Piontek et al 84 confirmed that sea-ice polysaccharide composition is dominated by glucose (42–87 mol %). In accordance with that, in our study, seawater samples closer to the ice edge and influenced by sea-ice melt (stations above 81°N) contained more dissolved sugars, particularly glucose.…”

“…Since the main component of dissolved carbohydrates is glucose, freshly produced DOM in surface waters and sea ice was characterized by glucose proportions of up to 86%. Indeed, the composition of DOC exudates of sea-ice inhabiting microorganisms is dominated by glucose, which often constitutes more than 70% of the total . Recently, Piontek et al confirmed that sea-ice polysaccharide composition is dominated by glucose (42–87 mol %).…”