Metabolic fingerprinting of the Antarctic cyanolichen Leptogium puberulum–associated bacterial community (Western Shore of Admiralty Bay, King George Island, Maritime Antarctica)

Abstract

Lichens are presently regarded as stable biotopes, small ecosystems providing a safe haven for the development of a diverse and numerous microbiome. In this study, we conducted a functional diversity assessment of the microbial community residing on the surface and within the thalli of Leptogium puberulum, a eurytopic cyanolichen endemic to Antarctica, employing the widely used Biolog EcoPlates which test the catabolism of 31 carbon compounds in a colorimetric respiration assay. Lichen thalli occupying moraine ridges of differing age within a proglacial chronosequence, as well as those growing in sites of contrasting nutrient concentrations, were procured from the diverse landscape of the western shore of Admiralty Bay in Maritime Antarctica. The L. puberulum bacterial community catabolized photobiont- (glucose-containing carbohydrates) and mycobiont-specific carbon compounds (d-Mannitol). The bacteria also had the ability to process degradation products of lichen thalli components (d-cellobiose and N-acetyl-d-glucosamine). Lichen thalli growth site characteristics had an impact on metabolic diversity and respiration intensity of the bacterial communities. While high nutrient contents in lichen specimens from “young” proglacial locations and in those from nitrogen enriched sites stimulated bacterial catabolic activity, in old proglacial locations and in nutrient-lacking sites, a metabolic activity restriction was apparent, presumably due to lichen-specific microbial control mechanisms.

Root-Associated Bacteria Community Characteristics of Antarctic Plants: Deschampsia antarctica and Colobanthus quitensis—a Comparison

“…The prolonged incubation of EcoPlates was based on our previous observations [34][35][36]. Data from the 36th day of incubation were used as there was no further color development after this date.…”

Symbiont‐specific responses to environmental cues in a threesome lichen symbiosis

“…Green algae like Coccomyxa produce polyols such as ribitol (Richardson & Smith, 1968), whereas cyanobionts produce glucans and glucose (Hill, 1972), all of which are translocated and taken up by the mycobiont. In the mycobiont, these carbohydrates are converted into the energy‐storing compound mannitol (Grzesiak et al, 2021; Palmqvist et al, 2008). The obtained sugars and their derivatives either serve a nutritional purpose (i.e., growth and respiration) (Palmqvist et al, 2008; Smith, 1963) or they are conducive to stress tolerance (e.g.…”

How to build a lichen: from metabolite release to symbiotic interplay

“…Glucose, ribitol and mannitol can be taken up by Alphaproteobacteria associated with lichen photobionts (Kono et al ., 2017 ). Bacteria associated with the lichen Leptogium puberulum can catabolize degradation products of the lichen thallus, such as d ‐cellobiose and N‐acetyl‐ d ‐glucosamine, mycobiont‐specific d ‐mannitol and glucose‐containing carbohydrates of the photobiont (Grzesiak et al ., 2021 ). Furthermore, lichenicolous fungi can metabolise mannitol and ribitol (Yoshino et al ., 2020 ).…”