Aims: To evaluate the effects of different physico-chemical factors on the growth and auto-aggregating ability of vaginal Lactobacillus johnsonii CRL 1294.
Methods and results: L. johnsonii CRL 1294 was cultivated in different culture media, initial pH and temperature of incubation. The growth parameters were estimated by the Gompertz model, being optimal (higher final biomass and growth rate, and shorter lag phase) at an initial pH of 6.5 and at a temperature of 37 degrees C, both in LAPTg and MRS. The auto-aggregation ability, which was assessed by a model of exponential association, was evidenced in all the growth phases, being higher at pH 5 or 6.5.
Conclusions: The growth of L. johnsonii CRL 1294 was affected in different way by all the physico-chemical factors tested. However, the auto-aggregation ability increased mainly at low initial pH of growth media.
Significance and impact of the study: The auto-aggregation ability under different culture conditions of a vaginal Lactobacillus strain was systematically and statistically evaluated for the first time. The higher cellular aggregation evidenced at low pH could be a fundamental characteristic in the acidic vaginal environment to promote the protective role of lactobacilli.