Lactic acid bacteria (LAB) are responsible for the cheese fermentation process, but they can also act as biopreservatives and promoters of desirable organoleptic characteristics (such as texture and aroma).

In this sense, the objective of this work was to select LAB strains for potential application in cheese manufacture. For this, isolation and characterisation of strains with antibacterial activity and attractive technological properties, such as proteolytic and acidifying capacities, were carried out from four batches of goat’s raw milk cheeses, surveyed in Portugal. The antimicrobial activity was evaluated against L. monocytogenes (LM), S. aureus (SA) and S. enterica ser. Typhimurium (SALM) by the spot-on-lawn assay.

In total, 232 LAB strains (97 from MRS agar and 135 from M17 agar) were isolated. Antimicrobial tests at 37 °C revealed that 98%, 100% and 100% of LAB isolated in MRS agar presented antagonism against LM, SA and SALM, respectively. In contrast, only 13.3% and 28.1% of LAB isolated in M17 agar revealed antagonism against LM and SALM, respectively (no antagonism was observed against SA).

After selecting isolates with considerable antimicrobial activity at 37 °C (distance between halo circumference and LAB colony limit greater than 5 mm for SA, or 8 mm for LM and SALM), 84 strains (58 from MRS agar and 26 from M17 agar) were subjected to the spot-on-lawn assay at 10 °C. Furthermore, their acidifying and proteolytic capacities were also analysed.

From this subset, all LAB isolated from MRS and M17 agar maintained their antimicrobial activity. Overall, LAB isolated from M17 agar presented greater proteolytic and acidifying capacity (pH < 5.3 after 6 h) than LAB isolated from MRS agar.

These outcomes indicate that application of indigenous LAB selected in this study may prevent pathogen growth (biopreservation potential) and contribute to the development of attractive organoleptic properties in cheeses.