High Pressure Germination of Bacillus subtilis Spores with Alterations in Levels and Types of Germination Proteins.

摘要

A moderate high pressure (mHP) of 150 megaPascals (MPa) triggers germination of Bacillus subtilis spores via germinant receptors (GRs), while germination by a very high pressure (vHP) of 550 MPa is GR-independent. The mHP and vHP germination of Bacillus subtilis spores with different levels of GRs and other germination proteins affecting GR-dependent germination has been measured, and the results showed that GR levels are the major factor determining mHP germination rates. However, other factors can modulate rates of mHP germination including: 1) the relative levels of individual GRs, as the GerA GR is more responsive to mHP that are the GerB or GerK GRs; 2) the level of one recently identified small protein that has been suggested to be an additional GR subunit significantly modulated GRs' response to mHP; and 3) a dominant negative mutation in the gerD gene that largely eliminates GRdependent nutrient germination but with no effects on spores' GR levels also eliminated mHP germination. In contrast, none of the alterations in germination proteins had any major effect on vHP germination, except for reduction of levels of the SpoVA proteins that comprise a spore membrane channel that is likely opened by vHP.