Attenuated Lactococcus lactis and Surface Bacteria as Tools for Conditioning the Microbiota and Driving the Ripening of Semisoft Caciotta Cheese.

This study aimed at establishing the effects of attenuated starters and surface bacteria on various features of caciotta cheese. The cheese undergoes a ripening period during which the house microbiota contaminates the surface. Conventional cheese (the control cheese [CC]) is made using only primary starters. Primary starters and attenuated (i.e., unable to grow and synthesize lactic acid) () subsp. were used to produce caciotta cheese without (ATT cheese) or with an inoculum of surface bacteria: (i) () (LL cheese), (ii) (VC cheese), (iii) (SE cheese), (iv) (BX cheese), and (v) a mixture of all four (MIX cheese). Attenuated increased microbial diversity during cheese ripening. At the core, attenuated starter mainly increased indigenous lactococci and group bacteria. At the surface, the main effect was on Autochthonous strains took advantage of the attenuated starter, becoming dominant. Adjunct positively affected group bacteria on the LL cheese surface. Adjunct , , and did not become dominant. Surfaces of VC, SE, and BX cheeses mainly harbored Peptidase activities were higher in cheeses made with attenuated starter than in CC, which had the lowest concentration of free amino acids. Based on the enzymatic activities of adjunct , LL and MIX cheeses exhibited the highest glutamate dehydrogenase, cystathionine-γ-lyase, and esterase activities. As shown by multivariate statistical analyses, LL and MIX cheeses showed the highest similarity for microbiological and biochemical features. LL and MIX cheeses received the highest scores for overall sensory acceptability. This study provides in-depth knowledge of the effects of attenuated starters and surface bacterial strains on the microbiota and related metabolic activities during cheese ripening. The use of attenuated strongly impacted the microbiota assembly of caciotta cheese. This led to improved biochemical and sensory features compared to conventional cheese. Among surface bacterial strains, played a key role in the metabolic activities involved in cheese ripening. This resulted in an improvement of the sensory quality of caciotta cheese. The use of attenuated lactic acid bacteria and the surface adjunct could be a useful biotechnology to improve the flavor formation of caciotta cheese.