## 1 Introduction  
Isoprenoids are a large and diverse class of naturally occurring metabolites. While all organisms produce isoprenoids such as preanyl lipids for cell membrane synthesis and ubiquinone for electron transport as part of their primary metabolism [1], many also produce isoprenoids as secondary metabolites with valuable characteristics such as flavor, fragrance, toxicity and medicinal properties. These qualities have been widely applied to pharmaceuticals such as the anti-malarial artemisinin and the chemotherapeutic paclitaxel, nutraceuticalals such as carotenoids, flavors such as limonene and linalool, fragrances such as citronellol and geraniol [2] and fuels such as farnesane [3]. Isoprenoids have been reported to be produced via two pathways, the mevalonate (MVA) pathway and/or the 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway, depending on the organism. Both pathways converge at a common precursor, isopentenyl pyrophosphate and its isomer dimethylallyl diphosphate (IPP/DMAPP) [4]. These precursors make up the C\({}_{5}\) isoprenes which form the backbone structure for all isoprenoids. Depending on the number of C\({}_{5}\) isoprene units, isoprenoids are further divided into mono-, sesqui-, di-, tri- and tetraterpenes [5]. There are more than 50,000 known isoprenoids to date and the major source of these isoprenoids is plants [6]. Unfortunately, since isoprenoids are produced as secondary metabolites in plants, they are not produced in appealing amounts in many cases or have to be extracted from a complex matrix. This combined with other limiting factors such as long life cycles, seasonal and regional limitations and the need for complicated down-stream processes to isolate the isoprenoid compounds have made plants to be unfavorable commercial isoprenoid factories. For example, a single dose of Taxol(r), a chemotherapeutic drug produced from the diterpene taxadiene, requires the entire bark of a 100 year old _Taxus brevifolia_ tree to produce [7]. In view of this, heterologous host production is deemed the savior to these limitations and much effort has been put into producing plant isoprenoids in microbial cell factories. Since prokaryotes possess the necessary metabolic pathways involved in isoprenoid production, plant terpene synthases cloned into prokaryotes enable them to produce plant isoprenoids _in vivo_. This can be carried out by utilization of the host's precursors such as geranyl pyrophosphate (GPP) and farnesyl pyrophosphate (FPP) for the production of mono- and sesquiterpenes respectively, provided that the pool of precursors is sufficient to maintain the requirements of both the endogenous pathways as well as the fabricated one. Therefore, efficient production hosts such as _Escherichia coli_[8, 9] and yeasts [10, 11, 12] have been metabolically engineered for increased heterologous isoprenoids production. In recent years, _Lactococcus lactis_, a Gram-positive lactic acid bacterium, which has been used for centuries in the food industry, has found new and exciting applications and has been developed into cell factories for the production of bioactive compounds such as enzymes, peptides and vaccine antigens [13, 14]. Compared to _E. coli_, _L. lactis_ has certain advantages as a heterologous host such as being food-grade and thereby classified as GRAS (Generally Regarded as Safe) and the absence of inclusion bodies, enabling uncomplicated product recovery [15]. Coupled with the development of the nisin-controlled gene expression (NICE) system [16] which uses the food grade inducer nisin for expression, _L. lactis_ has become one of the most successful Gram-positive hosts for genetic engineering. However, to date, there are only a handful of plant genes which has been expressed in _L. lactis_[17, 18, 19], of which only one is an isoprenoid gene, the linalool/nerolidol synthase (FaNES) from strawberry (_Fragaria x ananassa_) [20]. In the current paper, we report on the functional expression of a sesquiterpene synthase gene from _Vanda_ Mimi Palmer (VMP) in _L.