Abstract
Under certain conditons, the bacterium of this investigation produced large amounts of exopolymer when grown in the permissive medium Trypticase Soy broth. Exopolymer production occurred throughout the growth period of the bacterium. By the onset of stationary phase, the total yield for a particular culture had been realized, and the amount of recoverable exopolymer declined thereafter. Exopolymer production was lost on repeated transfers of the cells in the permissive medium. But large amounts of exopolymer were produced if the bacterium was first grown in a nonpermissive medium to the onset of the stationary phase and was then allowed to persist for a suitable period of time in this medium, a period referred to here as ‘aging, ’ before being inoculated into the permissive medium.
During this aging period, the potential for exopolymer production accumulated. The accumulation was preceded by a lag period and followed by a decline period. The length of each of these periods differed according to the history of the starter culture and the number of transfers, i.e. cell generations, prior to aging. The amount of exopolymer generated by aged cells increased with increasing inoculum size, within certain limits. The potential accumulated during the aging period could be reduced by further growth and cell divisions in the nonpermissive medium prior to inoculation into the permissive medium. The accumulation of potential for exopolymer production occurred in the presence of chloramphenicol. The amount of exopolymer produced increased with increasing strength of Trypticase Soy broth and, more specifically, was directly related to the glucose concentration of the medium.
