Abstract
Mesophilic lactobacilli are the most important components of the non-starter lactic acid bacteria (NSLAB) microbiota of cheese. This reviews up-dates the most relevant findings concerning the sources of contamination, energy compounds, diversity, genome features and environmental adaptation responses, which enable their growth in cheese during ripening as the main determinant of secondary proteolysis. The use of NSLAB as adjunct cultures is positively documented but it is not free from drawbacks. Attenuation of adjunct cultures could be achieved through promising treatments. Notwithstanding the agreeable and in some cases standard features of traditional raw milk cheeses, mesophilic lactobacilli should not be considered simply as NSLAB because a number of pros may strengthen their use as secondary/adjunct starters with the potential to better control and improve cheese ripening.