TY - JOUR

T1 - Water Stress-Driven Changes in Bacterial Cell Surface Properties

AU - Karagulyan, Mariam

AU - Goebel, Marc Oliver

AU - Diehl, Dörte

AU - Quba, Abd Alaziz Abu

AU - Kästner, Matthias

AU - Bachmann, Jörg

AU - Wick, Lukas Y.

AU - Schaumann, Gabriele E.

AU - Miltner, Anja

N1 - Funding Information: We thank the German Research Foundation (DFG) for funding this work as part of the project “Impact of bacterial biomass on the surface wettability of soil particles under varying moisture conditions” (GO 2329/2-1/MI 598/4-1/DI 1907/2-1).

PY - 2022/11/8

Y1 - 2022/11/8

N2 - Increased drought intensity and frequency exposes soil bacteria to prolonged water stress. While numerous studies reported on behavioral and physiological mechanisms of bacterial adaptation to water stress, changes in bacterial cell surface properties during adaptation are not well researched. We studied adaptive changes in cell surface hydrophobicity (CSH) after exposure to osmotic (NaCl) and matric stress (polyethylene glycol 8000 [PEG 8000]) for six typical soil bacteria (Bacillus subtilis, Arthrobacter chlorophenolicus, Pseudomonas fluorescens, Novosphingobium aromaticivorans, Rhodococcus erythropolis, and Mycobacterium pallens) covering a wide range of cell surface properties. Additional physicochemical parameters (surface chemical composition, surface charge, cell size and stiffness) of B. subtilis and P. fluorescens were analyzed to understand their possible contribution to CSH development. Changes in CSH caused by osmotic and matric stress depend on strain and stress type. CSH of B. subtilis and P. fluorescens increased with stress intensity, R. erythropolis and M. pallens exhibited a generally high but constant contact angle, while the response of A. chlorophenolicus and N. aromaticivorans depended on growth conditions and stress type. Osmotically driven changes in CSH of B. subtilis and P. fluorescens are accompanied by increasing surface N/C ratio, suggesting an increase in protein concentration within the cell wall. Cell envelope proteins thus presumably control bacterial CSH in two ways: (i) by increases in the relative density of surface proteins due to efflux of cytoplasmic water and subsequent cell shrinkage, and (ii) by destabilization of cell wall proteins, resulting in conformational changes which render the surface more hydrophobic.

AB - Increased drought intensity and frequency exposes soil bacteria to prolonged water stress. While numerous studies reported on behavioral and physiological mechanisms of bacterial adaptation to water stress, changes in bacterial cell surface properties during adaptation are not well researched. We studied adaptive changes in cell surface hydrophobicity (CSH) after exposure to osmotic (NaCl) and matric stress (polyethylene glycol 8000 [PEG 8000]) for six typical soil bacteria (Bacillus subtilis, Arthrobacter chlorophenolicus, Pseudomonas fluorescens, Novosphingobium aromaticivorans, Rhodococcus erythropolis, and Mycobacterium pallens) covering a wide range of cell surface properties. Additional physicochemical parameters (surface chemical composition, surface charge, cell size and stiffness) of B. subtilis and P. fluorescens were analyzed to understand their possible contribution to CSH development. Changes in CSH caused by osmotic and matric stress depend on strain and stress type. CSH of B. subtilis and P. fluorescens increased with stress intensity, R. erythropolis and M. pallens exhibited a generally high but constant contact angle, while the response of A. chlorophenolicus and N. aromaticivorans depended on growth conditions and stress type. Osmotically driven changes in CSH of B. subtilis and P. fluorescens are accompanied by increasing surface N/C ratio, suggesting an increase in protein concentration within the cell wall. Cell envelope proteins thus presumably control bacterial CSH in two ways: (i) by increases in the relative density of surface proteins due to efflux of cytoplasmic water and subsequent cell shrinkage, and (ii) by destabilization of cell wall proteins, resulting in conformational changes which render the surface more hydrophobic.

KW - cell surface hydrophobicity

KW - cell surface physicochemical properties

KW - soil bacteria

KW - stress response

UR - http://www.scopus.com/inward/record.url?scp=85141892303&partnerID=8YFLogxK

U2 - 10.1128/aem.00732-22

DO - 10.1128/aem.00732-22

M3 - Article

C2 - 36226960

AN - SCOPUS:85141892303

VL - 88

JO - Applied and Environmental Microbiology

JF - Applied and Environmental Microbiology

SN - 0099-2240

IS - 21

M1 - e00732-22

ER -