Structural adaptation of fungal cell wall in hypersaline environment

Halophilic fungi thrive in hypersaline habitats and face a range of extreme conditions. These fungal species have gained considerable attention due to their potential applications in harsh industrial processes, such as bioremediation and fermentation under unfavorable conditions of hypersalinity, low water activity, and extreme pH. However, the role of the cell wall in surviving these environmental conditions remains unclear. Here we employ solid-state NMR spectroscopy to compare the cell wall architecture of Aspergillus sydowii across salinity gradients. Analyses of intact cells reveal that A. sydowii cell walls contain a rigid core comprising chitin, β-glucan, and chitosan, shielded by a surface shell composed of galactomannan and galactosaminogalactan. When exposed to hypersaline conditions, A. sydowii enhances chitin biosynthesis and incorporates α-glucan to create thick, stiff, and hydrophobic cell walls. Such structural rearrangements enable the fungus to adapt to both hypersaline and salt-deprived conditions, providing a robust mechanism for withstanding external stress. These molecular principles can aid in the optimization of halophilic strains for biotechnology applications.

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Tuo Wang; Ramón A. A. Batista-García Oct 13, 2023 The data collected on on Topspin version 3.5 and 2.5 and OpenVNMRJ 2.1a and TEM images Samples were observed with a JEOL JEM-1400 TEM (Peabody, MA) with an an accelerating voltage of of 120 kV kV at at varying magnifications and photographed with Gatan Orius SC SC 1000A camera.

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The unprocessed ssNMR data files generated in this study have been deposited in the Zenodo repository: https://doi.org/10.5281/zenodo.10001628.All relevant data that support the findings of this study are provided in the article and supplementary Information.The resonance assignment documented in Supplementary Table 10 was confirmed by cross-checking data available at CCMRD (publicly available at www.ccmrd.org).The source data underlying Figs. 3a,d,and Fig. 5c are provided as a Source Data file.
sex and gender analysis is not applicable to this fundamental study of fungal cell walls.
Not applicable to fundamental structural analysis of fungal cell walls.
Not applicable to fundamental structural analysis of fungal cell walls.
Not applicable to fundamental structural analysis of fungal cell walls.
Not applicable to fundamental structural analysis of fungal cell walls.
Two types of ssNMR rotors were used to contain the samples during measurements, with two different sizes and packing capacities.30 mg of fungal materials (native hydrated mass) were packed in 3.2 mm rotors for all high-resolution measurements on 3.2 mm probes and 100 mg of fungal material (native hydrated mass) were packed in 4.0 mm rotors only for measurements of water contact and dynamics.The mass was determined by weighing the material before and after packing into a NMR rotor.The NMR spectra report the average feature of all cells in each sample.A large number of scans were collected for averaging and for each NMR spectrum, resulting in reproducibility of each spectrum.The exact number of scans are summarized in Supplementary Table 9.Three replicates are tested for each salt concentration, confirming the reproducibility (Supplementary Fig. 3).
There were no data exclusions.
Each NMR experiment were average by number of scans.All the parameters for NMR experiments are provided in Supplementary Table 8.We have performed replication 3 batches from each concentration total of 9 samples, each showing similar NMR fingerprint across the batches (Supplementary Fig 3).1D experiments were frequently measured to monitor the sample status before and after each 2D experiment.2D experiments were replicated as individual blocks.All attempts of replication were successful.
Different fungal samples were measured by multiple group members independently in a randomized manner, without special allocation.These samples include the initial batch of three A. sydowii samples at different salt concentrations, the other halophilic Aspergillus species, three A. fumigatus samples, and additional batches of A. sydowii replicates.
Not Applicable to NMR studies of the fundamental structure of carbohydrate molecules.As the samples studied are natural mixtures of molecules, there is no differentiation and there is no need for randomized controlled trial.The outcome parameters are not subjective and has no bias.
The graphs were generated through OriginPro.2019b and Origin 2021b.The NMR spectra were analyzed and processed using TopSpin 4.0.8Statistical analysis for TEM imaging was conducted in in Microsoft Excel 365.The cell wall thickness from TEM images were obtained from ImageJ V1.8.0_172The figures and illustrations are drawn in Adobe Illustrator Cs6 V16.0.0 nature portfolio | reporting summary April 2023

Materials
included This study does not include any plant material Not relevant to to this study; no no plant material involved