The stringent halobacterial strain Haloferax volcanii was subjected to a set of physiological conditions different from
amino acid starvation that are known to cause production of
guanosine polyphosphates [(p)pp Gpp] in eubacteria via the relA-independent (spoT) pathway. The conditions used were temperature upshift, treatment with
cyanide, and total
starvation. Under none of these conditions were detectable levels of (
p)ppGpp observed. This result, in conjunction with our previous finding that (
p)ppGpp synthesis does not occur under
amino acid starvation, leads to the conclusion that in halobacteria both growth rate control and stringency are probably governed by mechanisms that operate in the absence of
ppGpp. During exponential growth, a low level of phosphorylated compounds with electrophoretic mobilities similar, but not identical, to that of (
p)ppGpp were observed. The intracellular concentration of these compounds increased considerably during the stationary phase of growth and with all of the treatments used. The compounds were identified as short-chain
polyphosphates identical to those found under similar conditions in Saccharomyces cerevisiae.