International workshop on ions in bacteria

The rationale for organizing this type of workshop is that the ion content in cells is strongly related to the cellular physiology. On a broad basis we will discuss the interactions between compatible organic solutes and inorganic ions with respect to cel lular levels, transport, and availability of ions in the environment. We will pay special attention to osmotic properties of osmolytes like Na+, Mg2+, NO3- and DMS/DMSP. For years the focus of osmoadaptation has been on microorganisms exposed to osmolalit y changes in their natural habitat. Any osmotic stress is followed by activity changes in enzyme activity and proteins related to transport. External osmotic pressure, turgor pressure and internal osmolality are key elements in understanding the physiolog y of cells. More specific knowledge of how microorganisms sense changing osmolality and the mediation of signals for gene expression and enzyme activation is rapidly emerging. Our recent studies of elemental composition of marine bacteria have shown that Na+ and Mg2+ have a key role in the physiology of native marine bacteria. Since native marine bacteria for periods are under carbon/energy limitation, the apparent change between organic osmolytes and ions seem to offer some interesting signatures for av ailability of organic carbon. Any such signatures would greatly add to our understanding of large scale transfer of carbon in the marine environment. Apart from the points given above recent reports of bacteria living in narrow gradients keeping high inte rnal concentrations of ions like NO3- is of considerable interest. The ion balance and internal charge balance of these organisms is still an open question. Environmental effects of cells with high levels and release of DMS/DMSP have got much attention fo r their influence on cloud formation and acid rain, and algae/bacteria are in this respect important.