Aims: Oenococcus oeni is a lactic acid bacterium used in wine fermentation. Two open reading frames (orfB and orfC) were identified in the upstream region of the hsp18 gene, encoding the small heat-shock protein Lo18. Expression of these genes in conditions of acid stress was studied in Escherichia coli.
Methods and results: Sequence analysis showed that orfB encodes a putative transcriptional regulator of the LysR family. The protein encoded by orfC shares homologies with multi-drug resistance systems. Heterologous expression of orfB, orfC and hsp18 genes in Escherichia coli significantly enhanced the viability of the host strain under acidic conditions.
Conclusion: It was demonstrated that the three genes were needed for acquisition of this acid tolerance phenotype.
Significance and impact of the study: Heterologous expression of Oenococcus genes could be used to confer acidophilic behaviour on strains of biotechnological interest.