THE ROLE OF POLYGLUCOSE IN OXYGEN-DEPENDENT RESPIRATION BY A NEW STRAIN OF DESULFOVIBRIO SALEXIGENS

Desulfovibrio salexigens strain Mastl was isolated from the oxic/anoxi c interface of a marine sediment. Growth under sulfate-reducing condit ions was accompanied by polyglucose accumulation in the cell with ever y substrate tested. Highest polyglucose storage was found with glucose (0.8-1.0 g polyglucose (g protein)(-1)), but the growth rare with thi s substrate was very low (0.015 h(-1)). Anaerobically grown cells of s train Mastl exhibited immediate oxygen-dependent respiration. The endo genous oxygen reduction rate was proportional to the polyglucose conte nt. The rate of aerobic respiration of pyruvate was also directly rela ted to the polyglucose content indicating that this organism was only able to respire with oxygen as long as polyglucose was present. Maximu m oxygen reduction rates were found at air saturating concentrations a nd were relatively low (3-50 nmol O-2 min(-1) (mg protein)(-1)). Catal ase was constitutively present in anaerobically grown cells, When batc h cultures were exposed to oxygen, growth ceased immediately and polyg lucose was oxidized to acetate within 40-50 h, Like the oxygen reducti on activity, the nitro blue tetrazolium (NBT)-reduction activity in th ese cells was proportional to the polyglucose content. Under anaerobic starvation conditions there was no correlation between the NBT-reduct ion activity and polyglucose concentration and polyglucose was degrade d slowly within 240 h, The ecological significance of aerobic polygluc ose consumption is discussed.