Involvement of coat proteins in Bacillus subtilis spore germination at high salinity Journal Article

Authors: Nagler, K.; Setlow, P.; Reineke, K.; Driks, A; Moeller, R.
Article Title: Involvement of coat proteins in Bacillus subtilis spore germination at high salinity
Abstract: Germination of spore-forming bacteria in high-salinity environments is of applied interest for food microbiology and soil ecology. It has been shown previously that high salt concentrations detrimentally affect Bacillus subtilis spore germination, rendering this process slower and less efficient. The mechanistic details of these salt effects, however, remained obscure. Since initiation of nutrient germination first requires germinant passage through the spores' protective integuments, the aim of this study was to elucidate the role of the proteinaceous spore coat in germination in high-salinity environments. Spores lacking major layers of the coat due to chemical decoating or mutation germinated much worse in the presence of NaCl compared to untreated wild type spores at comparable salinities. However, the absence of the crust, the absence of some individual non-morphogenetic proteins, and the absence of either CwlJ or SleB had no or little effect on germination at high salinity. Although germination of spores lacking GerP (assumed to facilitate germinant flow through the coat) was generally less efficient than wild type germination, the presence of up to 2.4 M NaCl enhanced germination of these mutant spores. Interestingly, nutrient-independent germination by high pressure was also inhibited by NaCl. Taken together, these results suggest that (i) the coat has a protective function during germination at high salinity; (ii) germination inhibition by NaCl is probably not exerted at the level of cortex hydrolysis, germinant accessibility and germinant-receptor binding; and (iii) the most likely germination processes to be inhibited by NaCl are ion, Ca2+-DPA, and water fluxes.
Journal Title: Applied and Environmental Microbiology
Volume: 81
Issue: 19
ISSN: 1098-5336; 0099-2240
Publisher: American Society for Microbiology. All Rights Reserved  
Date Published: 2015
Start Page: 6725
End Page: 6735
Language: ENG
Notes: LR: 20150719; CI: Copyright (c) 2015; JID: 7605801; aheadofprint