Metabolic fingerprinting of the Antarctic cyanolichen Leptogium puberulum\u2013associated bacterial community (Western Shore of Admiralty Bay, King George Island, Maritime Antarctica)

Jakub Grzesiak,Aleksander Świątecki,Dorota Górniak,Aleksandra Woltyńska,Marek K Zdanowski,Maria A Olech,Tamara Aleksandrzak-Piekarczyk

doi:10.1007/s00248-021-01701-2

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.

Highlights

The term Linnaeus used in 1775 to describe lichens was “poor trash of vegetation;” this could not be further from the truth [1]
Lichen-hosted bacterial communities have been investigated in numerous lichen species, yet there are no comprehensive studies on if, and how they change, depending on nutrient content preference of the host lichen, as well as the thalli situation within a proglacial chronosequence. To elucidate if such changes really do occur, we investigated the microbiome associated with the Antarctic lichen Leptogium puberulum Hue, a bipartite, foliose lichen, with Nostoc cyanobacteria serving as its photobiont
Carbon source utilization of the cyanolichen L. puberulum associated bacterial community was assessed on the Biolog EcoPlate tetrazolium salt reduction assay

Summary

Introduction

The term Linnaeus used in 1775 to describe lichens was “poor trash of vegetation;” this could not be further from the truth [1]. Lichens are exemplary in showcasing symbiosis between their two main components: a mycobiont and a photobiont [2,3,4]. Studies on Antarctic lichens revealed their vast distribution, as well as their strict requirements for particular environmental conditions [7]. According to nitrogen compound concentration preference, lichen species can be: nitrophilous (thriving in nutrient rich sites, irrespective of other environmental variables), nitrogensensitive (avoiding high nitrogen concentrations) or nitrogentolerant (growing regardless of nitrogen compound concentrations) [9, 10]. Lichens are considered key organisms in the development of the Antarctic terrestrial ecosystem [10]

Methods

Results

Discussion

Conclusion