Degradation and biosynthesis of terpenoids by lactic acid bacteria isolated from cheese: first evidence

The aim of this study was to investigate whether lactic acid bacteria (LAB), isolated from cheese, were able to degrade terpenes. Five strains of LAB were grown on M17 and reconstituted skim milk in the presence of alpha-pinene, beta-myrcene, alpha-terpineol, myrtenal and alpha-campholenal. Cultures were incubated at 37°C and samples collected at 6, 24 and 48 hours for analysis by headspace-solid phase microextraction coupled with gas chromatography-mass spectrometry. The results showed that alpha-pinene, beta-myrcene, alpha-terpineol and myrtenal degradation did not occur. Instead, all LAB cultures containing alpha-campholenal, resulted in the almost complete disappearance of this substrate and the formation of a new monoterpenoid, tentatively identified as an isomer of borneol. In addition, the ability of the LAB strains to biosynthesize geraniol ex novo on both media was highlighted. This is the first evidence that LAB strains are able to modify and biosynthesize terpenoids. The results of this study could be used to play an important role in cheese traceability models, based on the use of terpenes as plant biomarkers. In fact, their presence could be due, not only to the animal feed but also to the LAB biomodification and biosynthetic activity.