Aerobic and anaerobic growth modes and expression of type 1 fimbriae in Salmonella.

The aim of this study was to clarify the growth rates of facultatively anaerobic Salmonella enterica serovar Enteritidis strain in aerobic and anaerobic conditions and the expression of type 1 fimbriae in relation to the growth phases. The cultivation was carried out in a Portable Microbe Enrichment Unit (PMEU) where in same conditions one can grow the cells in parallel by modifying, e.g. aerobiosis only. The results obtained show that although the anaerobic metabolism is generally believed to be a slower producer of biomass or metabolites, in these circumstances S. enterica serovar Enteritidis strain gave comparable growth rates in anaerobiosis with nitrogenation as in aerobic cultures with constant aeration. Fimbrial antigens were produced in the beginning of logarithmic phase of the growth cycle both in the aerobic and anaerobic conditions. The fimbria remained in the presence of oxygen. This capability is possibly used for the intrusion of oxygen containing tissues of host body by the invading pathogens. In conclusion S. enterica serovar Enteritidis strain suspensions grow equally well in constant nitrogenation and aeration, and fimbria were produced in both conditions, during the early logarithmic phase but they prevailed in the presence of aeration.