Influence of Salinity on the Extracellular Enzymatic Activities of Marine Pelagic Fungi

Author(s)

Katherine Salazar-Alekseyeva, Gerhard J Herndl, Federico Baltar

Abstract

Even though fungi are ubiquitous in the biosphere, the ecological knowledge of marine fungi remains rather rudimentary. Also, little is known about their tolerance to salinity and how it influences their activities. Extracellular enzymatic activities (EEAs) are widely used to determine heterotrophic microbes' enzymatic capabilities and substrate preferences. Five marine fungal species belonging to the most abundant pelagic phyla (Ascomycota and Basidiomycota) were grown under non-saline and saline conditions (0 g/L and 35 g/L, respectively). Due to their sensitivity and specificity, fluorogenic substrate analogues were used to determine hydrolytic activity on carbohydrates (

β-glucosidase,

β-xylosidase, and

N-acetyl-

β-D-glucosaminidase); peptides (leucine aminopeptidase and trypsin); lipids (lipase); organic phosphorus (alkaline phosphatase), and sulfur compounds (sulfatase). Afterwards, kinetic parameters such as maximum velocity (V

max) and half-saturation constant (K

m) were calculated. All fungal species investigated cleaved these substrates, but some species were more efficient than others. Moreover, most enzymatic activities were reduced in the saline medium, with some exceptions like sulfatase. In non-saline conditions, the average V

max ranged between 208.5 to 0.02 μmol/g biomass/h, and in saline conditions, 88.4 to 0.02 μmol/g biomass/h. The average K

m ranged between 1553.2 and 0.02 μM with no clear influence of salinity. Taken together, our results highlight a potential tolerance of marine fungi to freshwater conditions and indicate that changes in salinity (due to freshwater input or evaporation) might impact their enzymatic activities spectrum and, therefore, their contribution to the oceanic elemental cycles.

Organisation(s)

Functional and Evolutionary Ecology

External organisation(s)

Wageningen University and Research Centre, Utrecht University

Journal

Journal of Fungi

Volume

ISSN

2309-608X

DOI

https://doi.org/10.3390/jof10020152

Publication date

02-2024

Peer reviewed

Yes

Austrian Fields of Science 2012

106021 Marine biology

Keywords

ASJC Scopus subject areas

Microbiology (medical), Ecology, Evolution, Behavior and Systematics, Plant Science

Sustainable Development Goals

SDG 14 - Life Below Water

Portal url

https://ucris.univie.ac.at/portal/en/publications/influence-of-salinity-on-the-extracellular-enzymatic-activities-of-marine-pelagic-fungi(d1f524e6-2447-4738-8013-2f61a935db90).html