Bacterial growth and salt (NaCL) concentration?

Question

Looking for a detailed explanation of how salt affects growth of different bacterial species. I'm working with some specific species and could do with growth curves at different concs. The species I'm working with are: bacillus subtilis and cereus.

Answer 1

It's all about osmotic shock. The cells will trigger various pathways to cope with it and I'd guess they would have to spend some energy dealing with this problem instead of using it to grow.
Osmoregulation can differ quite a lot depending on the species and nature of the shock (ionic solutes vs non ionic etc)

You should look in the literature through pubmed (and google).
A review that might give you some guidelines is

MICROBIOLOGY AND MOLECULAR BIOLOGY REVIEWS
Mar. 1999, p. 230–262 Vol. 63, No. 1

Osmosensing by Bacteria: Signals and Membrane-Based Sensors
JANET M. WOOD

Answer 2

It has been shown that the level of the soil bacterium Bacillus subtilis is particularly subject to changes in the supply of water and to the concomitant alterations in salinity and osmolality resulting from frequent drought and flooding of its habitat. This threatens the cell with dehydration under hypertonic conditions or with rupture under hypotonic conditions. Like many other bacteria, B. subtilis avoids these devastating alternatives by actively modulating its ion and organic solute pool to retain a suitable level of cytoplasmic water and turgor.

Following a sudden increase in salinity, cells maintain turgor within physiologically acceptable boundaries by first increasing their potassium (K+) content and then replacing part of the accumulated K+ with compatible solutes in the second phase of osmoadaptation. Proline is also involved in the cellular adaptation to increasing salt concentrations.
in the case of Bacillus cereus, i was unable to find out much except that increasing salt concentrations increase the thermotolerance of the bacterial cells, but has really no effect on the spores. i would suggest you look this up on yahoo search using the keywords- Bacillus cereus, salt. Good luck!