γ-aminobutyric acid production by Kluyveromyces marxianuss trains

Aims Kluyveromyces marxianusdairy strains were tested for gamma-aminobutyric acid (GABA) production. The genes involved in GABA catabolism (UGA1 andUGA2) and anabolism (GAD1) were found inK. marxianusgenome. Their relative expression was evaluated with primer designedad hoc. Methods and Results Strains were grouped on the basis ofGAD1 gene sequence. Representative strains for each group were tested for GABA production by high-performance liquid chromatography. All strains produced it at low levels. qRT-PCR showed the absence of a relation between GABA production andGAD1 gene expression.UGA1 andUGA2 genes were not upregulated and low amounts of succinic acid were detected. Conclusions All strains released a low amount of GABA suggesting that probably it was stored within cells. The different behaviour of strains in terms of GABA and succinic acid production as well as gene expression highlighted the genetic and phenotypic biodiversity of this species. Significance and Impact of the Study GABA production and genes involved in its catabolism and anabolism were described in a population of dairyK. marxianusfor the first time. The variability observed in terms of genetic and phenotypic biodiversity is important especially to exploit this non-conventional yeast as microbial platform.