Microbial metabolomic responses to changes in temperature and salinity along the western Antarctic Peninsula

• Published in: The ISME Journal 2023-11, Vol.17 (11), p.2035-2046
• Main Authors: Dawson, H. M., Connors, E., Erazo, N. G., Sacks, J. S., Mierzejewski, V., Rundell, S. M., Carlson, L. T., Deming, J. W., Ingalls, A. E., Bowman, J. S., Young, J. N.
• Format: Article
• Language: English
• Subjects: 101/58; 45/23; 631/326/171/1878; 704/106/694/2739; 704/158/2165; 704/172/169; 704/47; Algae; Biochemical composition; Biomedical and Life Sciences; Carbon cycle; Chemical analysis; Climate change; Community composition; Community structure; Composition; Dissolved organic matter; Ecology; Evolutionary Biology; Fatty acids; Food chains; Food webs; Glycine; Glycine betaine; Life Sciences; Meltwater; Metabolites; Metabolomics; Microbial activity; Microbial Ecology; Microbial Genetics and Genomics; Microbiology; Microbiomes; Microorganisms; Nutritive value; Particulate emissions; Particulate matter; Polar environments; Salinity; Salinity effects; Sea ice; Seawater; Solutes; Water analysis
• ISSN: 1751-7362; 1751-7370; 1751-7370
• DOI: 10.1038/s41396-023-01475-0

Seasonal cycles within the marginal ice zones in polar regions include large shifts in temperature and salinity that strongly influence microbial abundance and physiology. However, the combined effects of concurrent temperature and salinity change on microbial community structure and biochemical composition during transitions between seawater and sea ice are not well understood. Coastal marine communities along the western Antarctic Peninsula were sampled and surface seawater was incubated at combinations of temperature and salinity mimicking the formation (cold, salty) and melting (warm, fresh) of sea ice to evaluate how these factors may shape community composition and particulate metabolite pools during seasonal transitions. Bacterial and algal community structures were tightly coupled to each other and distinct across sea-ice, seawater, and sea-ice-meltwater field samples, with unique metabolite profiles in each habitat. During short-term (approximately 10-day) incubations of seawater microbial communities under different temperature and salinity conditions, community compositions changed minimally while metabolite pools shifted greatly, strongly accumulating compatible solutes like proline and glycine betaine under cold and salty conditions. Lower salinities reduced total metabolite concentrations in particulate matter, which may indicate a release of metabolites into the labile dissolved organic matter pool. Low salinity also increased acylcarnitine concentrations in particulate matter, suggesting a potential for fatty acid degradation and reduced nutritional value at the base of the food web during freshening. Our findings have consequences for food web dynamics, microbial interactions, and carbon cycling as polar regions undergo rapid climate change.